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Environmental Pollution from Illegal Waste Disposal and Health Effects: A Review on the “Triangle of Death”

Maria triassi.

1 Department of Public Health, “Federico II” University, Naples 80131, Italy; E-Mails: ti.aninu@issairt (M.T.); moc.liamg@naflaallessor (R.A.); [email protected] (A.N.); [email protected] (O.C.)

Rossella Alfano

Maddalena illario.

2 Department of Traslational Medical Science, “Federico II” University, Naples 80131, Italy; E-Mail: ti.aninu@oiralli

Antonio Nardone

Oreste caporale, paolo montuori.

The term “triangle of death” was used for the first time by Senior and Mazza in the journal The Lancet Oncology referring to the eastern area of the Campania Region (Southern Italy) which has one of the worst records of illegal waste dumping practices. In the past decades, many studies have focused on the potential of illegal waste disposal to cause adverse effects on human health in this area. The great heterogeneity in the findings, and the bias in media communication has generated great healthcare doubts, anxieties and alarm. This paper addresses a review of the up-to-date literature on the “triangle of death”, bringing together the available information on the occurrence and severity of health effects related to illegal waste disposal. The Scopus database was searched using the search terms “waste”, “Campania”, “Naples”, “triangle of death” and “human biomonitoring”. Despite the methodological and sampling heterogeneity between the studies, this review examines the evidence from published data concerning cancer incidence, childhood mortality and birth defects, so that the current situation, knowledge gaps and research priorities can be established. The review aims to provide a contribution to the scientific community, and to respond to the concerns of the general population.

1. Introduction

The term “triangle of death” was used for the first time by Senior and Mazza in the journal The Lancet Oncology referring to the eastern area of the Campania Region (Southern Italy) which has one of the worst records of illegal waste dumping practices [ 1 ]. Since 1980, waste management in Campania region has been characterized by crisis [ 2 ]. This waste crisis in the Campania Region has resulted in the widely documented illegal disposal of urban, toxic and industrial wastes [ 2 , 3 , 4 , 5 ]. The environmental impacts of illegal waste disposal led to the deterioration of land, as well as ground and surface water, also impacting air quality.

Waste impact depends on waste composition and illegal disposal practices [ 6 ]. Waste composition consists of several types of substances, particularly toxic waste coming from the last phase of the industrial activities: copper, arsenic, mercury, polychlorinated biphenyls, hydrocarbons, etc. [ 4 ]. Waste disposal practices include illegal burying in areas not legally designated as toxic waste dump sites such as cultivable areas, roads and buildings and construction yards [ 7 ]. Furthermore, in the “triangle of death” area, illegal waste burning and the fires set up by residents to burn garbage bags piled up in the streets have contributed significantly to the increase in environmental pollution, particularly of dioxins [ 8 ]. Environmental pollution of waste dumping affects health through both short and long-term effects [ 9 , 10 ]. Examples of short-term effects are congenital anomalies, asthma and respiratory infection [ 11 , 12 ]. General symptoms such as stress, anxiety, headache, dizziness, nausea, eye and respiratory irritation have been also described [ 13 ]. Long-term health effects related to waste exposure include chronic respiratory and cardiovascular diseases, cancer and even brain, nerves, liver, lymphohematopoietic or kidneys diseases [ 14 , 15 , 16 ].

In the past decades, many studies in the area of “triangle of death” have focused on the potential health effects of illegal waste disposal, but they have generated heterogeneous results. Some authors, such as Senior and Mazza [ 1 ], concluded that the high level of cancer mortality in the area can be linked to the level of pollution caused by inadequate waste-control methods and by illegal dumping. Others discount any significant impact of waste mismanagement on public health [ 17 , 18 , 19 , 20 ]. This heterogeneity among studies and especially bias in media communication generated healthcare doubts, anxieties and alarms among residents that have organized committees and associations [ 21 ]. In recent years, these committees and associations have consistently raised the issue of the health effects resulting from the waste crisis in Campania, and many disputes and disagreements took place among local governance structures and the population. In order to solve this problem, in March 2014 the Italian Government adopted a special decree, which allocated 25€ million yearly (for 2014 and 2015) for “health screening” of Campania residents. Based on a systematic review of the up-to-date “triangle of death” literature, the present study brings together the information on the occurrence, severity and potential health effects of illegal waste disposal., This review analyzes the evidence from published data concerning cancer, childhood mortality, birth defects and human biomonitoring, despite the methodological and sampling heterogeneity between studies, in order to establish the current situation, knowledge gaps and research priorities. Thus, this review aims not only to provide a contribution to the scientific community, but also to contribute to address the concerns of the population.

2. Materials and Methods

The review was conducted in two stages. In the first stage, articles were retrieved via online Scopus database searching. The following keywords and combinations of keywords were used: “waste”, “Campania”, “Naples”, “triangle of death” and “human biomonitoring”. Articles were limited to those that were published in English/Italian-language journals from January 2001 to August 2014. During the second stage, titles and abstracts of articles were independently reviewed by two researchers to assess eligibility for inclusion. If there was any uncertainty, the full text article was retrieved. Disagreements were solved after discussion with a third researcher. Primary publications on waste-related health effects and human biomonitoring studies in the population living in Campania Region were the subject of this review. Other types of papers (environmental impact estimate, waste management, environmental sentinels) were only consulted in order to integrate the relevant available scientific information.

Our initial searches generated 100 hits, which were screened leading to removal of 87 records, leaving 13 full text articles that were evaluated. In addition, four more articles, traced through references listed in review articles, were included. For each of the considered health outcome, the results obtained on Campania residents were compared to the health effects in residents living near landfills and incinerators [ 9 , 10 , 13 , 22 ]. Even though in Campania no incinerator has been operating since 2009, we referred to the literature on incinerators for the extensive practice of illegally setting fires to urban and hazardous waste.

Seventeen papers (only one review) on health effects of waste exposure and human biomonitoring in Campania were evaluated. Areas under study included: Naples province; Caserta province; Giugliano, Qualiano; Villaricca and the “triangle of death” (between Acerra, Nola and Marigliano) ( Figure 1 ). Ten papers investigated health effects. All cancers, specific cancers, childhood mortality and birth defects were the health outcomes we considered. All cancers, neoplasms of liver, lung, larynx, bladder, leukemia and lymphoma were evaluated by seven studies; colorectal cancer, sarcoma, childhood mortally and birth defects were evaluated by six studies; gastric and kidney cancer were evaluated by five studies. In some papers multiple outcomes were evaluated. Seven papers focused on human biomonitoring: five investigated biomarkers of exposure and two investigated biomarkers of early effect. The findings of these studies are mainly consistent with the previous review by Barba et al. [ 23 ]. Two summary tables for health effects ( Table 1 ) and human biomonitoring ( Table 2 ), respectively, are presented to show the results.

Maps of the study area. ( a ) Italy; ( b ) Campania Region (southern Italy); ( c ) Location of main municipalities under study in southern part of Caserta Province and in the northern part of Naples Province, including the “triangle of death” marked with red.

Summary table of studies on health effects.

M = male; F = female; a studies that draw their data from the same database. b studies that draw their data from the same database.

Summary table of studies on human biomonitoring.

a studies that draw their data from the same database.

3.1. Studies on Health Outcomes

3.1.1. all cancers.

The mortality observed in the other two municipalities was higher than expected by regional rates, especially for females, even if it did not reach statistical significance [ 3 ]. Another ecological study reported an excess of cancer death in the provinces of Naples and Caserta (196 municipalities) compared with the expected deaths from regional rates, also confirmed by Bayesan estimators (Naples: SMR = 106.1 for males; SMR = 107.3 for females; lower limit of 95% CI > 100. Caserta: SMR = 102.5 for males; SMR = 102.9 for females; lower limit of 95% CI > 100) [ 17 ]. Furthermore, the cancer mortality rate showed by Senior and Mazza in men living in the so called “triangle of death” was higher than the regional standardized death rate (SDR) 321.7 vs . 301.8 per 100,000), even if no confidence interval or standard error were reported [ 1 ]. None of these studies evaluated the exposure assessment of the populations under study, the distance from legal or illegal waste sites or other confounders. Information about exposure has been provided only by a trend analysis conducted in Caserta and Naples municipalities [ 24 ]. Waste exposure was assessed through the waste exposure index (WEI), an index of environmental pressure due to waste dumping activities described by Musmeci et al. [ 25 ]. The analysis revealed a statistically significant excess of risk for all cancer of 6.6% (95% CI = 0.8–12.7) only for women living in the municipalities at highest WEI compared with baseline [ 24 ]. SENTIERI project revealed a significant mortality risk for all cancers in the contaminated site of National concern composed by 77 municipalities of Caserta and Naples Provinces when compared to mortality expected from the Italian rate, also after adjusting for deprivation index (DI) [SMR DI = 109 (90% CI = 108–111) in males; SMR DI = 105 (90% CI = 102–107) in females] [ 26 ]. On the contrary, no statistically significant increase of mortality risk for total cancers was found by two other studies [ 19 , 27 ], considering both WEI and DI.

These results are in contrast with recent evidences on health effect associated with the management of solid waste. Indeed, for total cancers two reviews support an inadequate level of evidence to indicate a role for solid waste [ 9 , 10 , 13 ], whereas limited [ 9 ] or inadequate [ 13 ] evidence has been reported for incinerators.

3.1.2. Liver

A geographical study pointed out a very high statistically significant increase of mortality for liver cancer in females (SMR = 181.13; lower limit of 95% CI > 100) in a municipality characterized by multiple dumping sites, compared to Campania Region rates [ 3 ]. Senior and Mazza described very high mortality rate for liver cancer in the “triangle of death” compared with rates seen in Campania (SDR 35.9 vs. 15 per 100,000 in men; 20.5 vs . 8.5 in women), but no confidence interval was reported [ 1 ]. Comba et al. reported excesses of death for liver cancer in Naples province compared with the expected deaths from regional rates (SMR = 117.6 in men; SMR = 114.1 in women; lower limit of 95% CI > 100), while statistical significance was not reached for Caserta Province [ 17 ]. A further cluster analysis of the same municipalities revealed three clusters of liver cancer in the southern part of Caserta Province and in the northern part of Naples Province [ 19 ]. The analysis was standardized by a deprivation index taking into account education, unemployment, housing ownership, surface of dwelling and family structure as possible socioeconomic confounders. In addition, a trend analysis confirmed an excess risk for liver cancer of 19.3% (95% CI = 1.4–40.3) and 29.1% (95% CI = 7.6–54.8) in men and women respectively in municipalities at highest environmental pressure assessed by waste index category compared with baseline [ 24 ]. A significant increase of risk of liver cancer, in term of standardized incidence ratios (SIR), hierarchical Bayesian estimators (BIR) and cluster analysis (BIR = 1.41, 95% CI = 1.17–1.68; BIR = 1.57; 95% CI = 1.28–1.89), was also detected in a two municipalities located in the northern part of Naples Province [ 27 ]. The study also detected a positive trend across WEI groups, but statistical significance was not reached. SENTIERI project revealed a significant mortality risk for liver cancer in the contaminated site of National concern composed by 77 municipalities of Caserta and Naples Provinces [SMR adjusted for DI = 125 (90% CI = 117–134) in males; SMR adjusted for deprivation =126 (90% CI = 114–140) in females] [ 26 ]. Remarkably, none of the reviewed studies took into account confounders (alcohol, smoking, hepatitis) other than socioeconomic ones, which strongly influence liver cancer development in the province of Naples in particular [ 28 ], where HCV and HBV infections are widespread [ 29 ].

The association between liver cancer, waste disposal and incinerator has been recently disconfirmed by several evidences reported in the literature [ 9 , 30 ], although a review found limited association with proximity to incinerator plants [ 10 ].

3.1.3. Lung

Altavista et al. pointed out a statistically significant increase of mortality for lung cancer especially for females in two out of three municipalities under study compared to Campania Region rates (SMR:1st municipality = 121.85, 2nd municipality = 120.94 for males; SMR 2nd municipality = 176.94 for females; lower limit of 95% CI > 100) [ 3 ]. Similar results were reported by four other studies: Comba et al. revealed excess of death for lung cancer in the provinces of Naples and Caserta compared with the expected deaths from regional rates [SMR = 114.1 (males)–126.5 (females); lower limit of 95% CI > 100] [ 17 ]; two other studies showed two clusters of lung cancer in the southern part of Caserta Province and in the northern part of Naples Province [ 19 , 27 ]; a trend analysis revealed only in males of the same municipalities of Naples and Caserta a statistically significant excess relative risk of (95% CI = 0.4–3.3) of death for lung cancer with the increase of waste index category [ 24 ]. In contrast, Senior and Mazza described a mortality rate for lung cancer in the “triangle of death” equivalent to the rates seen in Campania (SDR 97.8 vs . 97.4 per 100,000 in men; no CI or standard error reported) [ 1 ] and no excess of death for lung cancer arose from SENTIERI project [ 26 ]. All the studies didn’t evaluate smoking habits or other confounders and are therefore difficult to interpret. No association between lung cancer, waste disposal and incinerators has nowadays been described in the literature [ 9 ], even if a review found a limited association with proximity to incinerator plants [ 10 ].

3.1.4. Larynx

Altavista et al. pointed out an increase of mortality for larynx cancer in three municipalities characterized by multiple dumping sites, compared to Campania Region rates, but statistical significance was reached only in one municipality for males (SMR = 211.85; lower limit of 95% CI > 100) and in one municipality for females (SMR = 339.42; lower limit of 95% CI > 100) [ 3 ]. Senior and Mazza described a higher mortality rate for larynx cancer in men living in the “triangle of death” compared with Campania rates (SDR 12.8 vs . 8.7 per 100,000; no CI or ES reported) [ 1 ]. Another ecological study confirmed the increase of mortality for larynx cancer in males only in the province of Naples (SMR = 111.8; lower limit of 95% CI > 100) [ 17 ]. Furthermore, the SENTIERI project revealed a statistically significant mortality risk for larynx cancer in males living in the contaminated site of national concern composed by 77 municipalities of Caserta and Naples Provinces [SMR adjusted for deprivation = 115 (90% CI = 105‒127)] [ 26 ]. Even if data are concordant, no study designs evaluated waste pressure in the residence areas and only the SENTIERI study took into account socio-economic deprivation. Furthermore, these results are in contrast with the evidence summarized by two reviews [ 9 , 10 ] and with the evaluation by the epidemiological evidence of SENTIERI project that showed no association between larynx cancer and landfills or incinerators [ 22 ].

3.1.5. Bladder

Studies on bladder cancer are discordant. A geographical study pointed out a significant increase of mortality for bladder in males living in a municipality characterized by multiple dumping sites, compared to Campania Region rates (SMR = 130.12; lower limit of 95% CI > 100) [ 3 ]. Senior and Mazza described a higher mortality rate for bladder cancer in men living in the “triangle of death” compared with rates seen in Campania, while bladder cancer risk in women appeared lower than regional rates (SDR 29.3 vs . 21.7 per 100,000 in males; 3.1 vs . 4,2 per 100,000 in females), even if no confidence interval was reported [ 1 ]. Comba et al. reported excess of death for bladder cancer in the provinces of Naples and Caserta compared with the expected deaths from regional rates (SMR = 110.7 in males; 117.5 in females; lower limit of 95% CI > 100) [ 17 ]. A cluster analysis of the same municipalities revealed two significant clusters of bladder cancer in the southern part of Caserta Province and in the northern part of Naples Province [ 19 ]. Three other studies revealed no risk of death for bladder cancer in the same areas, adding information about intensity of waste-related exposure and socio-economic deprivation [ 24 , 26 , 27 ].

Although not conclusive, these data are consistent with the literature on bladder cancer: two reviews [ 9 , 10 ], the evaluation of the epidemiological evidence of SENTIERI project [ 22 ] and one study on 15 landfills highlight an inadequate level of evidence to indicate a role for solid waste and incinerators [ 30 ].

3.1.6. Stomach

A statistically significant decrease in mortality for gastric cancer was found by a geographical study in males of a municipality of Naples characterized by multiple dumping sites compared to Campania Region rates (SMR = 56.1; upper limit of 95% CI < 100) [ 3 ]. No risk arose from SENTIERI project in the contaminated site of National concern composed by Caserta and Naples province [ 26 ]. By contrast, Comba et al. reported statistically significant excess of death for gastric cancer in males living in the province of Caserta compared with the expected deaths from regional rates (SMR= 129.3 in men; SMR = 118.2 in women; lower limit of 95% CI > 100) [ 17 ]. A cluster analysis of the same municipalities detected a big cluster of gastric cancer in the north-western part of Naples and south-western part of Caserta Province, mainly due to male mortality [ 19 ]. These results were confirmed by a trend analysis which revealed in men living in 35 municipalities of Caserta and Naples a statistically significant excess relative risk (5.2%; 95% CI = 1.8‒8.7) of death for gastric cancer with the increase of waste index category [ 24 ].

No association between gastric cancer and waste disposal and incinerator is supported by the last evidences in the literature [ 9 ], even if two less recent studies found limited association with proximity to incinerator plants [ 10 , 22 ].

3.1.7. Colorectal

The only study suggesting an increase of risk of colorectal cancer in the Campania Region is the report of Senior and Mazza that described a higher mortality rate for colorectal cancer in women in the “triangle of death” compared with rates seen in Campania (SDR 29 vs. 26.4 per 100,000), but no confidence interval was reported [ 1 ]. No association was found by five other different studies [ 3 , 17 , 19 , 26 , 27 ]. These results are consistent with the evidence summarized by a review, that argues the association between colorectal cancer and waste disposal and incinerators [ 9 ], although a less recent review found limited association with proximity to incinerator plants [ 10 ].

3.1.8. Leukemia and Lymphoma

Data reported by Senior and Mazza described higher mortality rates for leukemia in males living in the “triangle of death” compared with rates seen in Campania (SDR 13.1 vs . 10.1 per 100,000), and higher leukemia and lymphoma in both sexes living in this area than in the rest of Campania area, and were referred to the “Local Health District Naples 4” [SDR 28.2 vs . 17.9 (in males); 18.7 vs. 16.1 (in females) per 100,000], even though the study didn’t provide any information about confidence interval or exposure data [ 1 ]. On the other hand, no statistically significant excess of risk for leukemia and lymphoma was found by Altavista et al. [ 3 ], nor was it found for non-Hodgkin lymphoma (NHL) by Fazzo et al. [ 19 ]. Similar results were provided by another geographical study, except for an excess of risk (SMR = 109.1; lower limit of 95% CI > 100) of NHL, found only in women living in the province of Naples [ 17 ]. Taking into account the deprivation index, a study found statistically significant excess of relative risk (5.7%; 95% CI = 0.2‒11.5) of death for NHL only in men with the increase of waste index category [ 24 ]. Another study identified a statistically significant cluster of leukemia in the total population of Naples Province [relative risk (RR) = 1.33; p -value = 0.05], as well as a significant increase of risk for leukemia and NHL (in terms of SIR, however it was not confirmed by BIR analysis) [ 27 ]. The SENTIERI Project found no significant increase of risk for leukemia or lymphoma in the contaminated site of National concern composed by 77 municipalities of Caserta and Naples Provinces [ 26 ].

Data from the literature are not conclusive with respect to association of leukemia and NHL with waste management: no association between leukemia, NHL and landfills or incinerators is supported by a recent review [ 9 ], while one study detected a significant risk for leukemia in residents near benzene waste sites [ 31 ], and three more studies found limited association of NHL with proximity to incinerator plants [ 10 , 22 , 30 ].

3.1.9. Kidney

An ecological study reported statistically significant excess of death for kidney cancer in females living in the province of Naples compared with the expected deaths from regional rates (SMR = 120.7; lower limit of 95% CI > 100) [ 17 ]. A cluster analysis found a cluster of kidney cancer in the total population, located in the north-western part of Naples Province [ 19 ]. No excess of risk for kidney cancer was found by three other studies, that also evaluated waste-exposure pressure and socioeconomic confounders [ 24 , 26 , 27 ]. These results are consistent with recent literature on the health impact of landfills and incinerators, that found inadequate evidence for a link to kidney cancer [ 9 , 10 ].

3.1.10. Soft-Tissue Sarcoma

A cluster analysis on 35 municipalities of Naples Province served by a Cancer Registry, revealed a statistically significant cluster of soft-tissue sarcoma (STS), even if no correlation with waste exposure index was detected [ 27 ]. Two previous geographical studies [ 17 , 19 ] and a trend analysis showed no statistically significant increased risk of cancer death for STS [ 24 ]. A more recent geographical study focused on the topic and found no significant increase in incidence of STS other than for gastrointestinal stromal tumors (GIST) in males [SIR 2.04 (overall), 95% CI = 1.26‒3.11; SIR 2.20 (males), 95% CI = 1.10‒3.94; not significant SIR 1.88 (females), 95% CI = 0.90‒3.46] [ 32 ].

No evidence of association between STS and landfills is nowadays supported by the literature, whereas limited association has been reported for people living in proximity of incinerators, in relation to emissions of dioxins [ 9 , 10 , 22 ].

3.1.11. Childhood Mortality and Malformations

In the first pilot study on health effects to waste exposure in communities living in the Campania Region, a significant risk increase was found for low birth weight, fetal distress and infantile cancers in residents of some municipalities of Caserta, where waste dumping, both legal and illegal, were mainly located [ 5 ]. Similar results arose from three studies: an ecological study reported increases of observed birth defects, especially cardiovascular and urogenital malformations, in the provinces of Naples and Caserta compared to the expected ones based on regional rates [ 17 ]. A cluster analysis of the same area revealed statistically significant clusters of total congenital malformations (five clusters), cardiovascular (two clusters), urogenital (three clusters) and limb malformations (only one cluster) [ 19 ]. A trend analysis of the same municipalities revealed a statistically significant increasing trend for urogenital anomalies [excess relative risk (ERR) = 13.8; 95%CI = 5l8 to 22l5] and a decreasing trend for cardiovascular anomalies (ERR = −5.3; 95% CI = −9.4 to −1). Comparisons between highest exposure waste municipalities and baseline were statistically significant for urogenital (ERR = 82.7; 95% CI = 25.6–165.7) and nervous system malformations (ERR = 83.5; 95% CI = 24.7–169.9) [ 24 ]. By contrast, no risk for congenital malformations was detected by Altavista et al. in populations living in three municipalities of Campania Region characterized by multiple dumping sites, although no information about exposure assessment or confounders was provided [ 3 ]. The SENTIERI project detected no risk of death for congenital malformations for all ages in the contaminated site of National concern composed by 77 municipalities of Caserta and Naples Provinces and even a statistically decreased in risk when considering only 0–1 year children [SMR adjusted for deprivation = 97 (90% CI = 88–106) for all ages; SMR adjusted for deprivation = 90 (90% CI = 83–97) for 0–1 year children] [ 26 ].

Recent reviews on the potential health hazards of waste management found a limited evidence of association between congenital malformations and living near landfills (of urogenital and nervous systems) and incinerators (urogenital and orofacial) [ 9 , 11 , 13 ], although two previous reviews found a limited evidence of higher risk of congenital anomalies in residents near landfills, and inadequate evidence for people living near incinerators [ 10 , 22 ].

3.2. Studies on Human Biomonitoring

Six studies investigated the link between waste-related pollution and biomarkers assessment in humans. Two studies identified high dioxin levels in breast milk of 94 primiparae living in Naples and Caserta provinces, and detected a positive correlation with age of sampled women, illegal waste fires and environmental dioxin risk index (EDR), that is an index based on dioxins concentrations in buffalo milk samples [ 33 , 34 ]. Illegal waste fires appeared to be a more important determinant of dioxin exposure in milk for women living in an area at low risk compared to high risk areas. Moreover, shorter telomere length and lower telomerase activity were found in peripheral blood mononuclear cells of healthy pregnant women living in north-east Naples area, who were affected by intense waste pressure compared to women living in non-polluted area [ 35 ]. In a study on assessment of DNA damage by Random Amplification of Polymorphic DNA (RAPD) in Paracentrotus lividus embryos exposed to amniotic fluid, different polymorphisms were found in embryos exposed to amniotic fluid from 15 residents living in north-east Naples area compared with those related non-polluted area citizens (Avellino), giving evidence that pollution levels in the “triangle of death” adversely affected human amniotic fluids [ 36 ]. On the contrary, a more recent study found PCDD/Fs and PCBs serum level in the population living in the Naples area that were lower than current values observed in populations living in exposed areas. Moreover the study detected no significant differences between serum dioxin concentrations in people living in “triangle of death” and its surroundings [ 18 ]. Similarly, a study on women living in Giugliano, a municipality affected by open-air waste combustion accidents, found PCDD/Fs and PCBs levels in breast milk significantly lower compared with those of donors from two cities highly polluted, that were Piacenza and Milan (Italy) [ 20 ]. Furthermore, the SEBIOREC study found biomarkers’ concentrations in Campania region compatible with European and Italian current values, excepted for a relative overexposure to some pollutants (As, Hg, dioxins) detected in four municipalities of Naples characterized by high waste pressure [ 37 ].

4. Discussion

One of the main problems in assessing the impact on health-related waste is the inadequacy of information. In fact, our initial searches generated 100 hits. Most of them deal with waste management, policy, economic evaluation, sociological features or environmental sentinels. The Campania Region has been characterized by a waste crisis since the 80s, hence the presence of such a large number of manuscripts is not surprising, but only 13 of them dealt with health effects and human biomonitoring. Several reasons might account for this: first of all, the best studies to investigate a link between exposure and health effects are descriptive, and use routine data (health statistics in this particular case) from the population supposed to be at risk. Routine data are often available with delay (death statistics 1994–2001 were used to the first time in 2006 [ 17 ]), which probably causes a delay in publication of evidences and reduces the probability of finding manuscripts on this specific topic in the literature. In order to define the population at risk, most studies have been focusing on identifying the exact location of waste disposals, that in Campania are often illegal and difficult to find. In addition, biomonitoring studies in human have been performed only recently probably because of difficulty in recruiting donors. Only in 2004 the Civil Protection commissioned a research to a task composed by experts from World Health Organization, from the Italian “Istituto Superiore di Sanità” and from Campania Region to investigate the potential health effect related to waste mismanagement only in 2004.

Although many reviews are available, the lack of data on exposure levels represents the major issue in the evaluation of health effects arising from exposure to waste [ 9 , 10 , 16 , 38 ]. Furthermore, in Campania the difficulty in exactly identifying waste arrangement and locating illegal waste dumping, sinking and burning complicates the matter. The population at risk has been hard to identify, and this could represent one of the main causes of delay in publication of evidences about potential health effects related to waste exposure. Residential population have been exposed to a mixture of chemicals, often toxic substances blended in with urban waste, since the 80s, and low exposures, even if extended in time, are usually hard to identify. Exposure was estimated only in two studies through a synthetic index based not only on distance from dumping sites, but also on intrinsic characterization of the waste disposal (toxic and hazardous substances are often blend in with urban waste), on percentage of resident population and on the characterization of neighboring areas by a geographic information system (GIS) [ 24 , 27 ]. Furthermore, the application of this exposure index, performed by Musmeci et al. [ 25 ], in the study of Fazzo et al. [ 19 ] finds some limits, as pointed out by the authors, because of the modest consistency between the two correlation studies, that result in lower statistical power. Another limit lies in the fact that the index does not take into account the burden of illegal waste fires as suggested by the findings of Rivezzi et al. [ 34 ]. Indeed, exposure to fires resulted in larger increases of dioxin concentrations in people living in low risk areas than those from high risk areas [ 34 ]. In addition, low-dose exposures affect the relative risk in small increments that are difficult to distinguish from those introduced by confounding factor [ 16 ]. No study reviewed or evaluated confounding factors other than socioeconomic ones (education, unemployment, housing ownership, surface of dwelling and family structure), so that any conclusion has to be viewed in the light of variability and uncertainty in the results. Another constraint of the studies on residents in Campania Region is that health data are far from being exhaustive. All the studies presented draw their data from the Cancer Registry of Local Health Authority “Naples 4”, and from the National Hospital Discharge Records database, the National Bureau of Statistics (ISTAT) that are compromised by problems related to codification quality [ 39 ], delayed availability and lack of information.

Most of the studies taken into account show only small increases of health risk (RR between 1 and 2) for the residents in Campania. These results are hard to explain also because different effect measures (SMR, RR, ERR, SIR, BIR, SDR) have been used in the studies, so that no direct comparison can be done, even for the same measure (e.g. SMR), and a single result is impossible to summarize. In addition, all the studies investigate multiple effects, which increases the chance of a false positive result (error type 1). Despite these constraints, this review provides new relevant information. Most studies analyzed in the review find a significant increase of total , liver and lung cancer mortality in the Region; even if the study design, the heterogeneity of distribution, the lack of information on confounders different from socioeconomic ones, which are important in such multifactorial pathologies, can support only a possible role rather than a causal inference. All studies on larynx show an excess of risk only in men, furthermore no study evaluated confounding factors neither intensity of waste exposure. Some studies reveal an excess of risk for bladder and stomach cancer only in men, additionally the excess of risk for bladder cancer disappears when considering confounding factors, and no trend risk is revealed comparing areas of different waste-exposure pressure. Similar results have been detected for kidney cancer in women. Even if some studies suggest a higher risk of death for this cancer in Campania Region residents, this hypothesis has not been confirmed by more recent studies that evaluated waste-exposure pressure and socioeconomic confounders. Data reported for leukemia and lymphoma are discordant and non-comparable in both sexes, thus suggesting more a role of other risk factors in the two genders rather than an association with waste exposure. No risk has been detected for colorectal cancer and soft-tissue sarcoma . The link between higher incidence of GIST and living in Campania needs to be clarified, since no given etiological hypothesis still exists, and the mentioned environmental contamination by PCDD/F and PCB has been recently debated [ 18 ]. Congenital malformation (particularly urogenital) outbreaks in the Region linked to environmental pollution need further investigation, since the evidence up to date only suggests a possible role of waste-related exposure.

Regarding the biomonitoring, despite several surveys detected bioaccumulation of different pollutants in animals of Campania Region [ 40 , 41 , 42 , 43 , 44 ], evidence on humans are not conclusive. Studies on biomarkers of early effect reveal a possible correlation between pollution levels in the “triangle of death” and adverse effects to human health. The SEBIOREC study limits to dioxins and heavy metals the possible overexposure due to waste mismanagement in the Region, and defines municipalities that might deserve closer health surveillance [ 37 ]. Some data reported for dioxin in breast milk indicate that the source of contamination could be the illegal waste burning, since no incinerator was operating when the analysis was conducted [ 33 ]. Moreover, a long lasting human exposure could be hypothesized because of correlation with age. By contrast, two more recent studies, even based on a limited number of subjects, show values of serum/milk dioxin lower than other European countries and Italy, thus suggesting that waste related pollution does not have an impact on health as significant as supposed in the last years [ 18 , 20 ].

The findings presented so far suggest a possible role for environmental waste in the increasing cancer rates detected in the Region, but evidence for a causal relationship is still weak, mainly due the lack of exposure information and confounders control. Since possible health dangers attracted considerable media attention and protest actions, at the beginning of 2014 Italian authorities issued emergency measures to face growing pressure and guarantee the safety of Campania region. Emergency measures included a dedicated decree (law n.6 6 February 2014), known as “Land of Fires” Decree, that was shaped to tackle environmental and industrial emergencies and to support the development of the most deprived areas. Main targets of the decree were mapping and remediation of contaminated sites, health screening of resident population, territory control and economic recovery. Nevertheless its constraints, the Land of Fires Decree was innovative and proved the real interest of institutions towards citizens. First, the mapping of contaminated land represented not only a necessary action of environmental restoration but also a needful answer to the agri-food industry, that experienced hard times for the simultaneous existence of waste and economic crisis. In fact, media scaremongering generated deep skepticism in both consumers and major brands concerning Campania products, to the point that, to safeguard consumers’ concerns, suppliers begun to provide their raw materials outside of the Region. The decree allowed to classify soils, depending on vulnerability, in “food” and “no food”, pointing out definitively which lands were banned from food production. However, the decree did not find unidirectional answers to Campania’s problems because of critical issues imposed by the crisis itself. For example, the decree introduced the crime of burning waste deposited in areas not intended for landfill, neglecting the issue of special and hazardous waste. The legislature, in fact, would have to be more radical and hard about waste origin, in particular industrial, and factors that cause illegal waste burying or burning as final destination. Finally, other critical issues of particular importance concerned health safety. The decree appropriated 25 billion € of funds yearly (for 2014 and 2015) for “health screening” of residents in Campania and Apulia region, that were recognized by the WHO as high environmental risk areas since 1986 because of their metallurgic industries. The decree hasn’t clarified the meaning of “health screening”. Currently, screenings that have scientific evidence of effectiveness and efficiency are only three: mammography for breast cancer, Pap tests for the cervical cancer and fecal occult blood test for colorectal cancer [ 45 , 46 , 47 ]. But they may be hasty and inappropriate to be carried out for all Campania residents. We hypothesize that the decree probably refers to biomonitoring activities, based on markers of susceptibility, exposure and early effects, as a first approach to study citizens of affected areas. In fact, even if exposure data on animals are available, biomonitoring studies on humans are only a few. Future studies are warranted to better clarify total burden of exposure to low levels of pollutants in the long range, and to identify early biological effect. Biomarkers are just one avenue to improve the measurement of exposure, susceptibility and disease; the field of cancer epidemiology finds its new challenge in exposomes, that promise to provide further insights in environmental health [ 48 , 49 ] and offer the opportunity to throw light also on Campania region scenario. Further studies are needed to confirm the early effects detected in response to the exposure to waste burning and dumping by De Felice et al. [ 35 ] and Guida et al. [ 36 ]. Finally, the “Land of Fires” Decree, in order to deploy its full potential, should represent only the beginning of multiple coordinated and targeted government actions to follow.

5. Conclusions

Although many intrinsic limits affect contrasting studies and data [ 14 , 20 ], overall available findings point out a possible long term role of waste, as suggested by positive correlation with outcomes as liver and lung cancer mortality, in addition to a short term effect waste-related (less than 1 year), confirmed by association with congenital malformation, which is compatible with the lack of remediation of the polluted sites and persistence of waste mismanagement to date. Research on exposure to pollutants confirms a possible exposure to illegal waste fires in the “triangle of death”, nevertheless no risk excess for diseases has been recognized to be related to incineration (sarcomas, non-Hodgkin lymphomas), and has been detected in resident population. Further studies are needed to better define waste related-health effects, since updated data are still far from being conclusive. In spite of methodological and sampling heterogeneity among studies, this review compiles the data in a harmonized and effective way, so that the current status, knowledge gaps and research priorities can be established. Thus, the present review wishes not only to provide a contribution to the scientific community, but also to support recommendations for mitigating pollution sources and risks in the area of concern. A similar process of analysis may be carried out for other areas and pressures in order to facilitate policy making at regional, national as well as at European level.

Acknowledgments

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Author Contributions

Maria Triassi conceptualized the study. Maddalena Illario, Antonio Nardone and Oreste Caporale searched articles, collected data and draft the manuscript. Paolo Monutori and Rossella Alfano carried out literature analysis, interpretation and discussion on statistical methods. All the authors significantly contributed to the final version of the manuscript. Maddalena Illario additionally revised the manuscript for English language.

Conflicts of Interest

The authors declare no conflict of interest.

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PHOENIX: Towards a circular economy of plasmix waste—A systemic design approach

Plastic recycling is a critical aspect of achieving a circular economy, aiming to reduce fossil fuel dependency, greenhouse gas emissions, and biodiversity impacts from uncontrolled disposal routes. The study outlines the evolving landscape of plastic recycling in the European Union (EU), addresses challenges, and emphasizes the need for innovative approaches to achieve circular economy goals. This paper delves into the innovative approaches and strategies employed by the PHOENIX project, a multidisciplinary project funded by the Cariplo Foundation, which focuses on plasmix – a complex mixture of plastics often excluded from recycling due to its heterogeneous composition. The authors utilize a systemic design approach, integrating survey results, interviews, literature reviews, and case studies to provide a comprehensive understanding of plasmix and propose novel solutions. Key findings include the application of design from recycling, systemic design strategies, and the utilization of plasmix in new product developments. It presents survey insights and stakeholder perspectives, and introduces systemic strategies applied in the project. The study concludes with valuable considerations for future research and underscores the significance of such initiatives in reshaping the plastic recycling paradigm.

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Publication history

Acknowledgements.

We acknowledge the Cariplo Foundation for funding for this research. Special recognition goes to the Scientific Coordinator, Marco Parolini, as well as Marco Ortenzi and Stefano Gazzotti for their invaluable contribution in developing and supplying materials for the project's workshop. Their expertise significantly enhanced our understanding of material chemistry. We would also like to express our gratitude to the entire team of the PHOENIX project from the University of Milan and the University of Eastern Piedmont for their collaboration and dedication. We also express our appreciation to COREPLA, the Italian National Consortium for the recycling and recovery of PPW, for sharing insights and providing updates on the plastic situation in Italy through meetings and interviews. Their valuable assistance in organizing field visits, reviewing the survey and the holistic diagnosis is also acknowledged. We would like to thank Barbara Stabellini, and Valeria Massari for their dedicated collaboration on the project. We would like to acknowledge Francesco Quaglia for his work during his MSc thesis, and the students of the ‘Design for Plasmix’ workshop, including tutor Odo Fioravanti, for their valuable contributions to the project.

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Evaluating the consequences of household hazardous waste diversion on public health and ecological risks of leachate exposure

• Original Paper
• Published: 06 April 2022
• Volume 19 , pages 4407–4420, ( 2022 )

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• H. Gholampour Arbastan 1 &
• S. Gitipour   ORCID: orcid.org/0000-0002-0694-7110 1  

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Household hazardous waste (HHW) includes approximately 1% of municipal solid waste (MSW), which is related to the lack of efficient separate collection schemes co-disposed with MSW in many countries worldwide. In this research, the effect of HHW diversion on leachate quality and consequent reduction in risks to the environment and human health was investigated. In this regard, physicochemical parameters of MSW leachate samples with and without hazardous fraction were characterized. Next, leachate pollution index (LPI) and associated risks were assessed. The results showed that the source separation of HHW decreases the LPI value by 13.48% and improves the potential of leachate for biological treatment, leading to a reduction in leachate treatment costs and complexity. Based on risk assessment results, HHW diversion could lower cancer risks of organic compounds and heavy metals to acceptable levels for adults and children. Moreover, by the source-separating of HHW, hazard indices for aquatic and terrestrial bioassays reduced by 41.5 and 36%, respectively. Furthermore, despite the comparatively low generated amount of HHW, this fraction should be emphasized due to its unintended effects for public health and the environment.

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Introduction

Globally, over 2.01 billion tons of municipal solid waste (MSW) are generated every year; which is expected to increase by 70% and hit 3.40 billion tones in 2050 (Kaza et al. 2018 ). Rapid growth of MSW generation, especially in developing countries, has been accompanied by several environmental effects.

Leachate is a major negative consequence of mismanagement of MSW which could pose various risks to the environment and human health (Ferronato and Torretta 2019 ). The findings of previous studies indicate that the leachate quality can be affected by waste composition, and other factors such as moisture content, presence of adsorbents in MSW stream, landfilling method, and landfill age (Fabris et al. 2010 ). Leachate, as an unpleasant and concentrated liquid, is a combination of various organic compounds, heavy metals, ammonium, total solid, and the like (Iravanian and Ravari 2020 ). More precisely, the previous studies reported a wide range of pollutants in the quality analysis of MSW leachate such as the contaminants of emerging concerns (CECs) (Masoner et al. 2014 ), 35 organic compounds listed as priority pollutants, as well as heavy metals with carcinogenic and non-carcinogenic effects (Slack 2007 ). A number of researchers believe that the above-mentioned contaminants are originated from household hazardous wastes (HHW) (Ozkaya 2005 ; Parvin and Tareq 2021 ; Slack et al. 2005 ; Wang et al. 2020 ; Yu et al. 2020 ).

Hazardous wastes are characterized by their flammability, reactivity, explosiveness, and toxicity properties (United States Federal Code, 1976 ). Waste such as fertilizers, paints, old solvent, pharmaceuticals, wood preservatives, indoors and outdoors pesticides, heavy metal-containing products (e.g., fluorescent lamps), home and vehicle maintenance, personal care, household cleaning products, biological-infectious waste, and batteries, are listed as HHW subcategory (Delgado et al. 2007 ; Gholampour Arbastan and Gitipour 2020 ).

By considering waste electrical and electronic equipment (WEEE) as HHW, the percentage of this fraction in MSW stream will be about 0 to 4%; otherwise, it would be 0 to 1% by weight (Slack and Letcher 2011 ). HHW is commonly collected and managed with non-hazardous MSW streams due to the lack of a proper source-separation program in many countries like Iran (Rupani et al. 2019 ). Therefore, due to the high percentage of landfilling in developing countries, a significant amount of HHW is buried in disposal sites (Kaza et al. 2018 ). Accordingly, the potential risks of emitted leachate to water bodies significantly increase due to the high concentration of toxic substances in such waste, meaning threatening to public health, as well as aquatic and terrestrial bioassays (Baderna et al. 2011 ; Ghosh et al. 2015 ). Also, a few studies indicated that the contaminants leaked or discharged due to the improper management of industrial and hazardous waste can pose serious threats to human health (especially children), ecosystem, and the environment which could play a key role in the occurrence and prevalence of acute and chronic diseases and reproductive disorders among residents living in the vicinity of landfill sites (Fazzo et al. 2017 ).

Although some studies have been conducted on human health and ecological risks assessment of leachate (Baderna et al. 2011 ; Ghosh et al. 2015 ; Parvin and Tareq 2021 ; Torkashvand et al. 2021 ), no study has focused on the effect of HHW diversion on leachate quality, public health, and ecological risks. Therefore, this research aims to evaluate HHW diversion effects on the leachate quality, pollution index, as well as human health and ecological risk of leaked leachate to the groundwater.

Materials and methods

Study area and sample collection.

Tehran, as the capital of Iran, has a population of 8,693,706 people, constitutes around 11% of the population of Iran. The results of waste management master plan (WMMP) in Tehran denote that the average generation rate of MSW is 0.764 kg/person/day. Official reports indicated that 8% of total weight of MSW is roughly allocated to leachate (Islamic City Council of Tehran, 2021 ). Curbside collection service was provided to collect and transfer generated MSW from 22 districts and 123 neighborhoods of Tehran to 11 waste transfer stations (WTSs) every day. In the next step, the mixed MSW from the WTSs was transported to Aradkouh processing and disposal complex (APDC) by semi-trailers. After separating recyclable solid waste in APDC manually, residuals are disposed of into the composting plant, incinerator, and landfill (Rupani et al. 2019 ). Among the 11 defined Tehran WTSs, Darabad, Zanjan, Kuhak, Hakimiyeh, Shahr-e-Rey, and Azadegan were selected as sampling points since they cover approximately 5.6 million people including 1.87 million households (more than half of total households in Tehran) who are living in 10 different districts. On average, these stations receive 536, 546, 829, 817, 321, and 792 tons of MSW per day from different districts of Tehran, respectively (Islamic City Council of Tehran, 2021 ). The main inclusion criteria were the distribution in all over the city and the higher peak capacity in comparison with other stations. Figure  1 illustrates the allocated waste to WTSs.

The details of sampling points

Like the previous studies (Delgado et al. 2007 ; Ojeda-Benítez et al. 2013 ), the sample size of households living in each area covered by the WTSs was determined using Eq.  1 (Cochran 1977 ).

where n shows the sample size, Z α /2 indicates the required level of statistical significance, p is the estimated proportion of a population attribute, q  =  p  − 1, N refers to the population size, and e is considered as the desired level of precision with a maximum variability of 50% ( p  = 0.5) and a confidence level of 95% with ± 5% precision. Table 1 indicates the required sample size for 1,875,295 households living in each district covered by a WTS.

As shown in Table 1 , in the stations with less than 40 samples (i.e., Darabad and Shahr-e-Rey), 40 were considered as the minimum. Therefore, a sample size of 408 was regarded for the households living in the areas covered by the target WTSs. These households were randomly selected and trained face-to-face by Tehran waste management organization (TWMO) trainers. On the first day, the sample households were asked to dispose of their waste in a plastic bag without any source-separation as usual. The generated municipal solid waste with the hazardous fraction (MSWH) was collected by a door-to-door collection system and delivered to the WTSs. On the next day, they were asked to dispose of non-hazardous municipal solid waste and HHW (according to the list presented to households (Gholampour Arbastan and Gitipour 2020 )), each separately in two plastic bags. The municipal solid waste source-separated (MSWS) and HHW were collected door-to-door and transported to the WTSs by open garbage trucks without compactor. At the WTSs, the collected MSWS bags were emptied, and misplaced HHW was separated manually. In the next step, MSWS and MSWH samples were compacted and stored in two separate containers. Leachate samples were collected from the mixture of derived leachate from MSWS and MSWH of the 6 WTSs. Next, the collected samples were transferred to the laboratory instantly and stored at 4 °C until the next steps. Due to the small amount and a variety of waste types and chemical composition of HHW, the above-mentioned procedures were repeated three times and the average was reported.

Chemicals and materials

All chemicals and solvents were purchased from Sigma-Aldrich (Steinheim, Germany) and Merck (Darmstadt, Germany). High purity grade (> 99%) pyrethroids pesticides were purchased from Dr. Ehrenstorfer (Augsburg, Germany). Poly-Sery HLB (6 cc, 200 mg) and Poly-Sery PSD SPE cartridges were supplied by (ANPEL, China). Membrane filters (0.45 μm) were supplied by Merck Millipore (Darmstadt, Germany).

Analytical methods

Physicochemical analysis.

Physicochemical parameters of MSWS and MSWH leachate samples were analyzed in accordance with the standard methods for evaluating water and wastewater (APHA 2013 ).

Heavy metals analysis

An atomic absorption spectrometer (AAS) was used to determine the concentrations of lead (Pb), nickel (Ni), chromium (Cr), zinc (Zn), iron (Fe), cadmium (Cd), and copper (Cu) in the filtered samples (AANALYST 200, Perkin Elmer, USA). Cd, Fe, Cr, Pb, Zn, Ni, and Cu hollow cathode lamps were used as light source at wavelengths of 228.8, 248.3, 357.9, 283.3, 213.9, 232.0, and 324.8 nm, respectively. In addition, a linear regression method was used for the calibration curve. An atomic absorption spectrometry with the manual cold vapor (Varian-AA240FS), a vapor generation accessory (VGA-77), and a GBC-932 atomic absorption spectrometer couple with hydride generation system (HG-AAS, 3000, AUS) were used to measure the concentrations of mercury (Hg) and arsenic (As) in leachate samples, respectively.

BTEX determination in leachate samples

Extraction for analyzing benzene, toluene, ethylbenzene, and xylene (BTEX) in both MSWS and MSWH leachate samples proceeded as described before (Fakhari et al. 2012 ). In the practical procedures, 15 mL of a filtered leachate sample was placed in 18 mL headspace vial. A PTFE-faced silicone septum was used for capping the vial. The temperature of the sample was held constant at 80 °C and stirred at 750 rpm for 15 min via a water bath and magnetic stirrer.

The enriched headspace vapors with BTEX compounds were manually injected to the GC injector through a flexible HP-5 fused silica capillary column (12 cm × 0.32 mm × 0.25 µm). Gas chromatographic analyses were performed using an Agilent 4890 gas chromatograph (Wilmington, DE, USA) equipped with a split/ splitless injector and flame ionization detector (FID). A 30 m × 0.25 mm (internal diameter) fused silica capillary column coated with a 0.25 µm film thickness of HP-5 and ultra-pure nitrogen (99.999% purity) at a constant flow rate of 1 mL/min were used as the analytical GC column and carrier gas, respectively. The GC oven temperature program has set as follows: the oven temperature was held at 55 °C for 10 min, then increased to 120 °C at a rate of 15 °C/min and held for 1 min at this temperature. The temperature of the detector (FID) was 300 °C. Finally, the injection port was held at 250 °C.

Extracting and analyzing phenolic compounds

Like the previous studies, solid phase extraction (SPE) (Reitzel and Ledin 2002 ) and derivatization (Padilla-Sánchez et al. 2011 ) procedures were conducted to determine the trace concentrations of phenolic compounds in leachate samples. In brief, pH of analytes (leachate samples and standard solutions) was adjusted to 2 with concentrated hydrochloride acid (2 M). Solid phase extraction was performed using Poly-Sery PSD cartridges with 200 g styrene–divinylbenzene copolymer sorbent material (ANPEL Crop., China). The Poly-Sery PSD cartridges were conditioned with 2 mL ethyl acetate and 2 mL MeOH followed by 5 mL of acidified ultrapure water (pH = 2). Then, the analyte was placed onto the conditioned cartridges, and the SPE cartridges were dried using nitrogen for 30 min. Subsequently, cartridges were eluted by 4 mL ethyl acetate. The eluate was gently concentrated in the nitrogen stream to 860 µL and added to 20 µL of pyridine (Py) and 100 µL anhydride acetic acid (AAA) to perform the derivatization reaction. The mixture was being stirred for 2 min in a rotary agitator and injected directly to the GC later. Phenolic compounds in the prepared samples were detected using an Agilent 7890 gas chromatograph equipped with an Agilent 5975 mass spectrometer with a quadrupole mass analyzer. A HP-5 MS (30 m × 0.25 mm i.d. 0.25 μm) and ultrapure helium (99.9999% purity) at the constant flow of 1 mL/min were used as capillary column and carrier gas, respectively. Mass spectrum was operated in the selected ion monitoring (SIM) mode to quantify phenolic compounds in leachate samples. The samples were injected in splitless mode. Gas chromatography (GC) oven temperature program was developed as follows: Initial equilibrium temperature of 60 °C for 2 min and 8 °C/min to 290 °C held for 5 min.

Preconcentration of pyrethroid pesticides and GC–MS analysis

SPE method was employed in the manner described in previous study for the preconcentration of target pyrethroids pesticides (Rocha et al. 2012 ). In other words, Poly-Sery HLB cartridges (6 cc, 200 mg, ANPEL Corp., China) were preconditioned with 5 mL of ethyl acetate, followed by the same volume of methanol and ultrapure water. The filtered MSWS and MSWH leachate samples were passed through the HLB cartridges at a constant flow rate of 2 mL/min. Next, the cartridges were eluted using 5 mL of ethyl acetate. Finally, the extract reduced gently using nitrogen streams. About 1 g anhydrous sodium sulfate was added to the sample bottle, and the bottle was washed 3 times with 4 mL dichloromethane to remove any excess water. Subsequently, the washing solution was concentrated to 1000 µL via gentle nitrogen streams and added to extract analyte and injected to GS–MS. The quadrupole mass spectrum was adjusted in the SIM mode, and 1 µL of sample was injected in the splitless mode. In addition, perfluorotributylamine (PFTBA) was employed to calibrate the mass axes of mass spectrometer. Target pyrethroids were determined using an Agilent 7890 gas chromatograph coupled to a 5975A MS. This apparatus was equipped with a HP-5MS ((5%phenyl)-95% Polydimethylsiloxane) (30 m × 0.25 mm id) capillary column with a 0.25 µm film thickness, coated with fused silica. The data were analyzed by MSD ChemStation software (E.02.01.1177). The GC–MS interface, quadruple, MS source, and GC injection port temperatures were kept at 290, 150, 230, and 290 °C, respectively. The GC oven was maintained for 2 min at 90 °C, ramp 7 °C/min to 290 °C and held for 5 min at this temperature.

Statistical analysis

The experimental results were presented as means ± standard deviation of triplicates. Shapiro–Wilk test was used to assess the normality of distributions of obtained data. In accordance with the results of the Shapiro Wilk test, a t -test at p -value < 0.05 and a Wilcoxon rank-sum test were used to compare statistical differences between the mean concentrations of heavy metals and organic contaminants in MSWS and MSWH leachate samples for normally and non-normally distributed data, respectively. IBM SPSS version 25 was used for data analysis.

Leachate pollution index (LPI)

Kumar and Alappat ( 2005 ) proposed a quantification method for leachate contamination potential of different landfills on a comparative scale with reference to leachate pollution index (LPI). LPI is widely used in ranking of landfill sites, assigning resources, conducting technical analysis, implementing standards, as well as systematic evaluation and public information. The LPI formulation process consists of choosing variables, obtaining weights for the selected pollutant variables, formulating their subindices curves, and accumulating the pollutant variables. In this study, chloride, cyanide, and total coliform were not analyzed based on LPI calculation parameters. Therefore, the modified equation as described in (Kumar and Alappat 2005 ) was used for calculating the LPI.

where LPI shows the weighted additive LPI, W i indicates the weight of the ith pollutant variable, P i represents the sub-index score of the i th leachate pollutant variable, and m is the number of leachate pollutant parameters for which data are available.

Human health risk assessment

Chronic exposure to heavy metals and other toxicants in the environment through potential exposure pathways is considered as the potentially detrimental factors for human health (Tay et al. 2019 ). Based on a function of hazard and exposure, risk assessment is defined as the process of evaluating the probability of occurring any possible magnitude of adverse health impacts over a specific period of time (Bempah and Ewusi 2016 ). The quantification of the risk level usually gives the health risk assessment for each potentially toxic organics and inorganics, which is expressed in terms of a carcinogenic or a non-carcinogenic health risk. This study separately assessed both carcinogenic and non-carcinogenic risks created by exposing to leachate samples (Wongsasuluk et al. 2014 ).

Based on the hypothesis of previous studies (Baderna et al. 2011 ; Ghosh et al. 2015 ), dilution ratio was assumed 1:100 and ingestion was considered as the main exposure route in order to examine the adverse effects of leachate leakage of the MSWS and MSWH to water on human health and the environment. The diluted concentrations of each contaminant were used to determine the human health and ecological risks. For heavy metals and organic compounds, the dose received (chronic daily intake CDI; average daily dose, ADD) through ingestion by adults and children was calculated via Eq.  3 (Baderna et al. 2011 ; USEPA 2004 ).

where CDI is the chronic daily intake of pollutants through ingestion pathway (CDI ing ) (mg/kg/ day), C refers to the concentration of the pollutants in (μg/L), and WI shows the water ingestion rate (L/day). Its average consumption rates for children and adults are 1 and 21 per day, respectively. The body weight (BW) of child and adult groups is 15 and 70 kg, respectively. ED shows the durations of human exposures for children and adults were 6 years and 30 years, respectively. EF represents the exposure frequency of 350 (days/year), and AT is the averaging time of human exposure: AT = 70 × 365 for carcinogenic risk and AT = ED × 365 days for non-carcinogenic risk.

Non-carcinogenic risks

The hazard quotient (HQ), as given in Eq.  4 , was used to assess the potential for non-carcinogenic risks of exposure to each pollutant. HQ signifies the ratio between the reference dose (RfD) and average daily dose (ADD) of each pollutant.

where HQ shows the hazard quotient, and RfD indicates the reference dose for the selected compound (mg/kg/ day).

To estimate the total potential non-carcinogenic health risks triggered by exposure to a mixture of pollutants in contaminated water by leachate, the computed HQs for each element were integrated and expressed as a hazard index (HI) as defined by Eq.  5 :

According to the (USEPA 2004 ) where HQ/HI < 1, the exposed population is improbable to experience adverse health effects. If HQ/HI > 1 then there may be concern for potential non-carcinogenic effects.

Carcinogenic risks

Carcinogenic risks were calculated for any compound with a slope factor (SF) value /(mg/kg/day), namely As, Pb, Cr, benzene, ethylbenzene, 2,4,6 TCP, and PCP by using the following equation:

where CR shows the cancer risk, SF is the slope factor /(mg/kg/day) as an upper-bound estimate of risk per dose increment which can be used to estimate risk probabilities for different exposure levels. Cancer risk was divided into negligible risk (CR < 10 −6 ), acceptable low risk (1 × 10 −6  ≤ CR < 5.1 × 10 −5 ), acceptable high risk (5.1 × 10 −5  ≤ CR < 10 −4 ), and unacceptable risk (CR ≥ 10 −4 ) (Legay et al. 2011 ).

Ecological risk assessment

Ecological risk assessment (ERA) is used for evaluating and comparing the impacts of stressors, often chemical high-risk pollutants (HRPs), on the local environment. In ERA, an undesired event often relies upon the chemical HRPs of interest and on the risk assessment scenario, which may adversely affect creatures, populations, or ecological communities (He and Huang 2019 ). ERAs provide technical support in management decisions such as allowing a discharge to a body of water, cleaning up a spill, or harvesting limits to set for a natural resource (Suter and Norton 2018 ).

Based on the study of (Baderna et al. 2011 ), the present research estimated the ecological risks to the environment through their hazard quotients (HQs) defined by the following equation:

where PEC shows the predicted environmental concentration resulting from the chemical analysis of both MSWS and MSWH leachate at 1:100 dilution, and PNEC represents the predicted no-effect concentration.

The risk assessments for terrestrial (small rodents such as mice, rats, or rabbits) and aquatic ( Oncorhynchus mykiss or Pimephales promelas ) environments were performed by assuming a water daily intake of 20 ml, an average body weight of 100 g, and a ratio of water intake to body weight of 1, respectively. The following equation yields PEC:

where C indicates the concentration of pollutant in the contaminated water by MSWS and MSWH leachates, WDI shows water daily intake (L/day), and BW represents the body weight (kg).

To calculate PNEC concentrations, ecological parameters and assessment factors (AF) for studying aquatic species ( Oncorhynchus mykiss or Pimephales promelas ) and small rodents (rats) were obtained from the previously selected (Baderna et al. 2011 ), peer-reviewed databases such as ECOTOX (USEPA 2021 ), and advanced ChemIDPlus ( 2021 ).The potential ecological risk was assessed according to a widely used risk ranking criterion. HQ values were divided into low or negligible (0.1 < HQ < 1), medium (1 ≤ HQ < 10), and high ecological risk (HQ > 10) (Mendoza et al. 2015 ).

Results and discussion

Household hazardous waste composition.

In the previous study, the effect of seasonal variations on the composition and generation rate of HHW in Tehran was investigated. The results indicated that the generation rate of HHW was within the range of 6.26–8.25 g/person/day with a mean value of 7.27 g/person/day, representing 0.95% of the municipal solid waste stream in the city. Figure  2 displays a detailed composition of HHW in Tehran (Gholampour Arbastan and Gitipour 2020 ).

Composition of HHW in Tehran

Target pollutant analysis

Table 2 indicates the average concentration of target pollutants in MSWS and MSWH leachate samples. Based on the results, source separation of HHW mitigates heavy metals, pesticides, BTEX, and phenolic compounds concentrations by 59.6, 69.9, 64.6, and 81.2%, respectively.

As presented in Table 2 , though the separation of HHW at the source caused the reduction in more than half of concentration of metals with carcinogenic effects (i.e., arsenic, chromium, and lead), but still these metals concentrations even in MSWS leachate are above their safe limits of world health organization (WHO) in wastewater. In addition to metal-containing non-hazardous MSW including textiles, food packaging, and leather, crop contamination with Tehran Oil Refinery leakage could be considered as the main sources of the mentioned contaminants (Pourang and Noori 2014 ).

Phenolic compounds including chlorinated phenolic compounds (CPs) and methylated phenols (cresols) are considered as hazardous materials due to their properties such as toxicity, flammability, carcinogenicity, and mutagenicity (Duan et al. 2018 ). The average concentration of cresols in the MSWH samples is in good agreement with the reported average concentration of cresols in the fresh engineering landfill leachate (48 μg/L) (Ozkaya 2005 ), and is dramatically lower than the concentration value (17.3 mg/L) in hazardous landfill leachate, which indicated the effect of hazardous waste on cresols concentration in leachate properly. Separating HHW from MSW stream drops cresols concentration to 5.7 μg/L, which is consistent with the result of the pervious study conducted in Japan, a pioneer on HHW management, to examine municipal landfill leachate (Kurata et al. 2008 ). The results of the previous studies indicated that increasing chlorine bonds can enhance both the octanol–water partition coefficients ( K ow ) and dissociation constant ( K a ), and reduce water solubility of CPs and their concentrations in leachate which are in accordance with the present experimental data (Duan et al. 2018 ). The 81.2% reduction in total concentrations of CPs in MSWS could be attributed to separate containers of chlorine-releasing agents such as household bleach and phenolic disinfectants from MSW stream which are widely consumed during COVID-19 pandemic in Iran (Yari et al. 2020 ).

Regarding BTEX compounds, the lowest and the highest reduction were observed in benzene (57.7%) and ethylbenzene (72.1%), respectively. Previous studies reported that benzene is found in HHW category and non-hazardous waste fraction such as cigarette filter in high concentration. Contrarily, HHW is among the main sources of ethylbenzene in leachate. Compared to toluene, xylene is typically found in HHW in higher concentration. In addition, it is more compliant against the interaction of detergents (Fabris et al. 2010 ), which can intensify MSWH and MSWS variations.

As indicated in Table 2 , the average concentrations of permethrin, cypermethrin, and deltamethrin are reduced by 76.7, 65.8, and 61.6% in MSWS samples, respectively. The highest reduction was observed for permethrin contaminant since it is used for medicinal purposes in addition to household pesticides. The remaining pyrethroids in MSWS results from food waste such as rice and animal origin food (Dallegrave et al. 2018 ) are contaminated by pesticides.

Based on the statistical analysis, significant differences ( ρ  < 0.05) were observed between the average concentrations of As, Cd, Cr, Hg, Ni, Pb, cresols, 2CP, 2,4DCP, 2,4,6TCP, phenol, BTEX, and pesticides in MSWS and MSWH samples. Despite higher concentrations of Cu and PCP in MSWH than MSWS samples, the lack of significant differences ( ρ  > 0.05) between average concentrations of these pollutants may be related to the presence of copper and pentachlorophenol in the composition of non-hazardous wastes such as non-ferrous and wood waste, respectively.

LPI is extensively used as an appropriate quantitative tool for diagnosing hazardous leachate and predicting adverse effects on water body (Kumar and Alappat 2005 ). The present study compared the LPI values for both MSWH and MSWS leachate samples.

Table 3 indicates the LPI values of 25.07 and 28.98 for both MSWS and MSWH leachate, respectively. Kumar and Alappat ( 2005 ) showed that the LPI values of leachate from hazardous industrial waste landfills are significantly higher than domestic waste landfills. The result is consistent with the finding of current study. Although source separation of HHW reduced the LPI value by 13.48%, both the LPI values were dramatically higher than the standard limit (7.378) needed to release into the environment, which requires leachate treatment.

As shown in Table 3 , COD and ammonia nitrogen play important roles in exceeding the LPI standard limit, which have been highlighted in previous studies (Naveen et al. 2017 ). In the present study, ammonia nitrogen and COD values in MSWS decreased by approximately 33.7 and 14.2% compared to MSWH, respectively. A reduction by one third of ammonia nitrogen value indicates that HHW such as home cleaners, oil-based solvents, and fertilizers may affect ammonia concentration in leachate although the protein fraction of MSW (Yirong et al. 2017 ) is a main source of nitrogen. As presented in Table 3 , the highest reduction in three sub-indices is related to LPI hm (30.04%), followed by LPI inorganic (18.85%), and LPI organic (1.87%).

Table 4 presents average daily dose (ADD), chronic daily intake (CDI), hazard quotient (HQ), hazard index (HI), and carcinogenic risk values of heavy metals and organic compounds for adults and children through ingesting contaminated water by MSWS and MSWH leachates.

Based on the results in Table 4 , the HI value of contaminated water by MSWS leachate decreased by 38.56% for all population groups in comparison to MSWH. However, HI values were higher than the threshold (HI > 1) for both adults and sensitive groups. Like the results of previous studies, ammonia allocated 89.58 and 96.63% of the hazard index values in MSWS and MSWH, respectively (Baderna et al. 2011 ; Naveen et al. 2017 ). Although the HQ values of heavy metals and other studied contaminants for both MSWS and MSWH are lower than the threshold (HQ < 1) for children and adults, the ingestion of leachate-contaminated water may pose non-carcinogenic risks to human health due to high concentrations of ammonia.

Carcinogenic risks of heavy metals (i.e., As, Cr, and Pb), and organic compounds such as benzene, 2,4,6-trichlorophenol, ethylbenzene, and pentachlorophenol, for adults and children were evaluated through ingesting the contaminated water by MSWS and MSWH leachates. As shown in Table 4 , the calculated CRs of organic compounds in all leachate samples were negligible for adults and children, and CRs of the contaminated water by MSWH leachate among adults was acceptably low for chromium and lead, and acceptably high for arsenic. After HHW segregation, cancer risk levels for arsenic and lead decreased to the acceptable low and negligible levels, respectively. However, As and Cr for MSWH samples exceeded the threshold of CRs (10 −4 ) for children. HHW diversion can properly reduce the cancer risks of drinking leachate-contaminated water to an acceptable level for sensitive groups. The results are confirmed by previous studies, which indicated that CRs of heavy metals for leachate-contaminated water were at the unacceptable risk levels for adults and children in Pakistan and Italy (Baderna et al. 2011 ; Iqbal et al. 2019 ). In other words, cancer risks of drinking water from nearby wells for children is the unacceptable and acceptable low risk for As, and Cr, respectively (Baghvand and Mashhadi 2009 ). The present study proved that HHW diversion from MSW stream could significantly reduce the cancer risks of leachate leakage.

The ecological risk assessment was performed on fish species and small mammals due to the leakage of MSWS and MSWH leachates to the water environment.

As indicated in Table 5 , remarkable induced-risk reductions in target bioassays were noticed due to the HHW separation. It should be mentioned that a great portion of the ecological risk due to ingestion of contaminated water by MSWS and MSWH leachates was attributed to their high ammonia concentrations, which in previous studies were discussed. (Baderna et al. 2011 ; Ghosh et al. 2017 ; Naveen et al. 2017 ).

Several studies reported that leachate-contaminated water exposure changes the ratio of internal organs such as brain, heart, kidney, and liver to the total body weight of small rodents. Likewise, the exposure increases the frequency of chromosomal aberrations (CA) and micronucleus (MN) formation in bone marrow, protein oxidation content (PCO) in viscera, number of sperms with morphological head defects, as well as DNA–protein crosslinks (DPC) formation in the brain, spleen, liver, and kidney of mice in a concentration-dependent manner. Thus, as it was already mentioned, the higher concentration of the contaminants in the contaminated water by MSWH leachate samples poses greater potential ecological risks to small mammals (Ghosh et al. 2017 ).

Based on the results of the studies conducted on evaluating leachate toxicity on fish species, the range of toxicity in MSW leachate samples varies from being confirmed (40 > EC 50  > 10) to severe toxic (EC 50  > 9), which is mainly related to the constituents of the MSW leachate samples such as ammonium ion, heavy metals, NaCl, and pyrethroid pesticides (Ghosh et al. 2017 ).

The results of the present study indicated that HQ of the contaminated water by MSWH is higher than the permissible limit (HQ ≥ 1) due to the existence of heavy metals (i.e., cadmium, mercury, nickel, copper, and lead), ammonia, pesticides, and phenolic compounds. In addition, the hazard quotients of phenolic compounds and pesticides are in the medium risk range, while heavy metals for aquatics display a greater risk. However, ammonia represents the greatest risk, which is predicted to be more than 1000 times than the permissible limit.

The HQ of MSWS leachate decreased by 36 and 41.5% for aquatic and terrestrial bioassays, respectively. The highest reduction was observed in pesticides, followed by ammonia, and heavy metals. After HHW diversion, the ecological risk of mercury and phenolic compounds for aquatic environment reduced to moderate and low risk, respectively. However, the risk of drinking contaminated water by MSWS leachate is still high for aquatic animals due to the presence of ammonia and some heavy metals, and accordingly a treatment process is required before discharging leachate to the environment.

Regarding the results of previous studies, MSW leachates increased mortality and caused a significant increase in the number of immature red blood cells, frequency of micronucleus (MN), and formation of binucleated cells in the fishes exposed to contaminated water in a dose-dependent manner (Ghosh et al. 2017 ). Therefore, implementing the source separation of HHW and decreasing the concentration of pollutants result in reducing the above-mentioned negative effects and toxicity of leachate.

The results of the present study confirmed that HHW diversion in the MSW stream can reduce the ecological risk, which is consistent with the results of Bakare et al. ( 2005 ).

The present study sought to evaluate the effect of HHW diversion on leachate quality and consequent reduction in risks to the environment and human health. Physicochemical analysis of leachate samples with (MSWH) and without (MSWS) household hazardous waste, were conducted to evaluate leachate pollution index (LPI) and associated risks.

Based on physicochemical analysis, a statistically significant difference ( p -value < 0.05) in average concentrations of target pollutants was observed, except for Cu and PCP in MSWS and MSWH. Although the results indicated that both the LPI values were above the leachate discharge standard due to the higher concentration of pollutants, especially ammonia, the source separation of HHW fraction was able to considerably reduce the LPI value (13.48%), and improve the potential of leachate for biological treatment leading to lower treatment costs.

Considering the results of the human health risk assessment, HHW diversion reduced the HI values for non-carcinogenic health risks by 38.56% for all population groups. Furthermore, the separation of HHW from MSW stream decreases the carcinogenic risks of leachate-contaminated water consumption for arsenic and chromium for sensitive groups below the acceptable levels. Based on the results of the present study, the risk caused by leachate exposure in aquatic and terrestrial environments by separating HHW at the source can lead to a reduction of 41.5 and 36%, respectively.

In spite of the low percentage of HHW, a reduction in pollutant concentration up to 94% indicated that the effects of this kind of waste on leachate quality are inevitable. Therefore, an appropriate management system including HHW source separation, collection, and disposal should be implemented for improving leachate quality and decreasing risks to environment and human health.

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Gholampour Arbastan, H., Gitipour, S. Evaluating the consequences of household hazardous waste diversion on public health and ecological risks of leachate exposure. Int. J. Environ. Sci. Technol. 19 , 4407–4420 (2022). https://doi.org/10.1007/s13762-022-04063-5

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Recycling of paper/wood industry waste for hydromechanical stability of expansive soils: A novel approach

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Research output : Contribution to journal › Article › peer-review

This article presents a sustainable solution to repurpose paper/wood industry waste as a geotechnical construction material. A novel lignosulphonate (LS)-based composite admixture (CA) was used in this study to cope with construction problems pertaining to expansive soils. Surface water infiltration in terms of rainfall and surface water irrigation are the prime factors that cause volumetric change behavior and a drastic reduction in shear strength due to loss in suction that eventually causes failure in expansive soils. Such failures are comprised of complex hydromechanical phenomena and their remediation requires special attention. In this context, this study for the first time deals with the use of LS-based CA as a remedy to such failures in expansive soils considering the hydromechanical properties. To better understand the hydraulic response, the specially designed soil-column model tests (SCMTs) were conducted. Besides, different geotechnical experiments and microstructural analyses were carried out to analyze the hydromechanical behavior of CA treatment against the varying degree of saturation (S r ). The results showed that LS-based CA treatment increases the water holding capacity over a suction range of 78.4 kPa and air entry value (AEV) by 33%. Also, the SCMT showed that the wetting-front depth (WFD) at full saturation in CA treated expansive soil was 4–10% quicker than untreated expansive soil. In addition, for the increase in S r from optimum to 100%, the decrease in cohesion (c) value for untreated and treated soil was found to be 88% and 39.8%, and the increase in compressibility was 37% and 17%, respectively, highlighting better resistance against S r . Whereas, the swelling potential was completely eradicated with a significant reduction in volumetric shrinkage by 43% compared to untreated soil. The microstructural analyses showed the development of apparent aggregation with the S r in untreated expansive soil, whereas the CA treatment-induced better structure with bigger size particles with disrupted inter and intra assemblage pore spaces. The results showed that LS-based CA manifests substantial hydromechanical stability against variation in S r . Overall, this study provides the scientific basis to the practitioners for the pragmatic use of LS-based CA in treating expansive soil problems.

• Expansive soils
• Hydromechanical stability
• Paper/wood industry waste
• Soil-column model test
• Waste management

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• 10.1016/j.jclepro.2022.131345

T1 - Recycling of paper/wood industry waste for hydromechanical stability of expansive soils

T2 - A novel approach

AU - Ijaz, Nauman

AU - Rehman, Zia ur

AU - Ijaz, Zain

N1 - Publisher Copyright: © 2022 Elsevier Ltd

PY - 2022/5/10

Y1 - 2022/5/10

N2 - This article presents a sustainable solution to repurpose paper/wood industry waste as a geotechnical construction material. A novel lignosulphonate (LS)-based composite admixture (CA) was used in this study to cope with construction problems pertaining to expansive soils. Surface water infiltration in terms of rainfall and surface water irrigation are the prime factors that cause volumetric change behavior and a drastic reduction in shear strength due to loss in suction that eventually causes failure in expansive soils. Such failures are comprised of complex hydromechanical phenomena and their remediation requires special attention. In this context, this study for the first time deals with the use of LS-based CA as a remedy to such failures in expansive soils considering the hydromechanical properties. To better understand the hydraulic response, the specially designed soil-column model tests (SCMTs) were conducted. Besides, different geotechnical experiments and microstructural analyses were carried out to analyze the hydromechanical behavior of CA treatment against the varying degree of saturation (Sr). The results showed that LS-based CA treatment increases the water holding capacity over a suction range of 78.4 kPa and air entry value (AEV) by 33%. Also, the SCMT showed that the wetting-front depth (WFD) at full saturation in CA treated expansive soil was 4–10% quicker than untreated expansive soil. In addition, for the increase in Sr from optimum to 100%, the decrease in cohesion (c) value for untreated and treated soil was found to be 88% and 39.8%, and the increase in compressibility was 37% and 17%, respectively, highlighting better resistance against Sr. Whereas, the swelling potential was completely eradicated with a significant reduction in volumetric shrinkage by 43% compared to untreated soil. The microstructural analyses showed the development of apparent aggregation with the Sr in untreated expansive soil, whereas the CA treatment-induced better structure with bigger size particles with disrupted inter and intra assemblage pore spaces. The results showed that LS-based CA manifests substantial hydromechanical stability against variation in Sr. Overall, this study provides the scientific basis to the practitioners for the pragmatic use of LS-based CA in treating expansive soil problems.

AB - This article presents a sustainable solution to repurpose paper/wood industry waste as a geotechnical construction material. A novel lignosulphonate (LS)-based composite admixture (CA) was used in this study to cope with construction problems pertaining to expansive soils. Surface water infiltration in terms of rainfall and surface water irrigation are the prime factors that cause volumetric change behavior and a drastic reduction in shear strength due to loss in suction that eventually causes failure in expansive soils. Such failures are comprised of complex hydromechanical phenomena and their remediation requires special attention. In this context, this study for the first time deals with the use of LS-based CA as a remedy to such failures in expansive soils considering the hydromechanical properties. To better understand the hydraulic response, the specially designed soil-column model tests (SCMTs) were conducted. Besides, different geotechnical experiments and microstructural analyses were carried out to analyze the hydromechanical behavior of CA treatment against the varying degree of saturation (Sr). The results showed that LS-based CA treatment increases the water holding capacity over a suction range of 78.4 kPa and air entry value (AEV) by 33%. Also, the SCMT showed that the wetting-front depth (WFD) at full saturation in CA treated expansive soil was 4–10% quicker than untreated expansive soil. In addition, for the increase in Sr from optimum to 100%, the decrease in cohesion (c) value for untreated and treated soil was found to be 88% and 39.8%, and the increase in compressibility was 37% and 17%, respectively, highlighting better resistance against Sr. Whereas, the swelling potential was completely eradicated with a significant reduction in volumetric shrinkage by 43% compared to untreated soil. The microstructural analyses showed the development of apparent aggregation with the Sr in untreated expansive soil, whereas the CA treatment-induced better structure with bigger size particles with disrupted inter and intra assemblage pore spaces. The results showed that LS-based CA manifests substantial hydromechanical stability against variation in Sr. Overall, this study provides the scientific basis to the practitioners for the pragmatic use of LS-based CA in treating expansive soil problems.

KW - Expansive soils

KW - Hydromechanical stability

KW - Paper/wood industry waste

KW - Recycling

KW - Soil-column model test

KW - Waste management

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U2 - 10.1016/j.jclepro.2022.131345

DO - 10.1016/j.jclepro.2022.131345

M3 - Article

AN - SCOPUS:85126586525

SN - 0959-6526

JO - Journal of Cleaner Production

JF - Journal of Cleaner Production

M1 - 131345