Distribution of polycyclic aromatic hydrocarbons in soils at Guiyu area of China, affected by recycling of electronic waste using primitive technologies

Hormonal, liver, and renal function associated with electronic waste (e-waste) exposure in Dhaka, Bangladesh

Electronic waste (e-waste) contains numerous metals and organic pollutants that have detrimental impacts on human health. We studied 199 e-waste recycling workers and 104 non-exposed workers; analyzed blood, urine, and hair samples to measure heavy metals, hormonal, liver, and renal function. We used quantile regression models to evaluate the impact of Pb, Cd, and Hg on hormonal, liver and renal function, and the role of DNA oxidative damage in mediating the relationship between exposures and outcomes. Exposed workers had higher blood lead (Pb) (median 11.89 vs 3.63 µg/dL), similar blood cadmium (Cd) (1.04 vs 0.99 µg/L) and lower total mercury (Hg) in hair (0.38 vs 0.57 ppm) than non-exposed group. Exposed workers also had elevated median concentrations of total triiodothyronine (TT3), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urinary albumin, albumin creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR) were significantly higher than non-exposed group (p≤0.05). Sex hormones including luteinizing hormone, follicle stimulating hormone, estrogen, progesterone and testosterone concentrations were not significantly different between exposed and non-exposed (all p≥0.05). The median concentration of ALT was 4.00 (95% CI: 0.23, 7.77), urinary albumin was 0.09 (95% CI: 0.06, 0.12) and ACR was 1.31 (95% CI: 0.57, 2.05) units higher in the exposed group compared to non-exposed group. Pb was associated with a 3.67 unit increase in the ALP (95% CI: 1.53, 5.80), 0.01 unit increase in urinary albumin (95% CI: 0.002, 0.01), and 0.07 unit increase in ACR (95% CI: 0.01, 0.13). However, no hormonal, renal, and hepatic parameters were associated with Cd or Hg. Oxidative DNA damage did not mediate exposure-outcome relationships (p≥0.05). Our data indicate e-waste exposure impairs liver and renal functions secondary to elevated Pb levels. Continuous monitoring, longitudinal studies to evaluate the dose-response relationship and effective control measure are required to protect workers from e-waste exposure.

Internal exposure risk based on urinary metabolites of PAHs of occupation and non-occupation populations around a non-ferrous metal smelting plant

The emission of various metals from non-ferrous metal smelting activities is well known. However, relative investigations on potential occupational exposure of organic pollutants are still limited. Herein, total of 619 human urine samples were collected from workers engaged in smelting activities and residents living near and/or far from the smelting sites, and ten mono-hydroxylated metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) in human urine were determined. The median levels of Σ₁₀OH-PAHs in smelting workers (25.6 ng/mL) were significantly higher (p < 0.01) than that of surrounding residents (9.00 ng/mL) and rural residents as the control (8.17 ng/mL), indicating an increase in occupational PAH exposure in non-ferrous metal smelting activities. The composition profiles of OH-PAH congeners were similar in three groups, in which naphthalene metabolites accounted for 76-82% of the total. The effects of smoking, drinking, gender, BMI, and occupational categories on urinary OH-PAHs were considered. The partial correlation analysis showed an insignificant effect of non-ferrous metal smelting activities on PAH exposure for surrounding residents. In the health risk assessments, almost all smelting workers had cancer risks exceeded the acceptable level of 10^-6. This study provides a reference to occupational PAH exposure and reinforce the necessary of health monitoring among smelting workers.

Levels, profiles and potential human health risks of brominated and parent polycyclic aromatic hydrocarbons in soils around three different types of industrial areas in China

Brominated polycyclic aromatic hydrocarbons (Br-PAHs) are an emerging class of persistent organic pollutants with toxicity similar to dioxins. Industrial thermal processes have been identified as major sources of Br-PAHs in the current environment. However, studies on soil contaminations with Br-PAHs around industrial areas were scarce. In this study, 18 Br-PAHs and 16 PAHs were analyzed in soils around an electronic waste dismantling area (EDA), an industrial area that mainly performed steel smelting (SSP), and an industrial area mainly performed secondary copper smelting (SCS). The mean concentrations of Br-PAHs and PAHs were 1362 pg/g and 1034 ng/g, 582 pg/g and 13,938 ng/g, and 307 pg/g and 2211 ng/g in the soil around EDA, SSP, and SCS, respectively. The order of Br-PAH concentrations among three industrial areas was inconsistent with that of PAHs, suggesting that there may be some differences in contamination characteristics of Br-PAHs in three types of industrial areas. The significant correlation between Br-PAHs and parent PAHs indicated that direct bromination may be the main formation pathway of Br-PAHs in soils in EDA. The result of principal component analysis further revealed that the congener pattern of Br-PAHs in soils around EDA is different from that of SSP and SCS. It was found that the ratio of 1-BrPyr and 3-BrFlu can be applied to identify environmental contamination with Br-PAHs from e-waste dismantling. The health risk assessment results showed that there were some soil samples with carcinogenic risks above the risk threshold in each industrial area, and deserve our concern.

Four-year population exposure study: Implications for the effectiveness of e-waste control and biomarkers of e-waste pollution

E-waste pollution has emerged as a significant environmental concern. To assess the impact of e-waste control on human pollutant exposure risk and identify appropriate biomarkers to classify e-waste pollution levels, we performed longitudinal population exposure monitoring research in an e-waste recycling area in China after e-waste control. The urinary levels of oxidative stress markers and typical pollutants emitted during e-waste recycling, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs), were continuously monitored in the surrounding population (including 275 children and 485 adults) from 2016 to 2019 using high-performance liquid chromatography-tandem mass spectrometry and inductively coupled plasma-mass spectrometry. The results showed that exposure to PAHs, VOCs and heavy metals was significantly associated with oxidative stress levels in urine. After e-waste control, the exposure levels of most PAHs and VOCs and a few heavy metals in the population significantly decreased. Interestingly, the level of 8-hydroxy-2'-deoxyguanosine (a biomarker of oxidative DNA damage) in children significantly decreased by 17.6 %, from 9.45 μg/g CRE in 2017 to 7.79 μg/g CRE in 2019 (p < 0.01). Thus, implementing e-waste control measures effectively reduced the human exposure risk to e-waste pollutants. Urinary tin (Sn), s-phenylmercapturic acid (PMA), 2-&3-hydroxyfluorene (2-&3-OHF), 3-hydroxyphenanthrene (3-OHPhe), and 1-hydroxypyrene (1-OHP) levels decreased significantly and monotonically over time (p < 0.01). The levels of urinary Sn and PMA in combination with 1-OHP, 2-&3-OHF, or 3-OHPhe as biomarkers demonstrated an excellent ability to classify e-waste pollution. These biomarkers will facilitate evaluations of the effectiveness of the governmental pollution regulations and policy measures. Additionally, children were generally exposed to higher levels of heavy metals and VOCs and suffered higher levels of oxidative stress damage than adults, suggesting that children are more vulnerable to e-waste pollution. This work will provide a reference for e-waste management and control.

Heterologous spatial distribution of soil polycyclic aromatic hydrocarbons and the primary influencing factors in three industrial parks

Soil polycyclic aromatic hydrocarbons (PAHs) generated from industrial processes are highly spatially heterologous, with limited quantitative studies on their main influencing factors. The present study evaluated the soil PAHs in three types of industrial parks (a petrochemical industrial park, a brominated flame retardant manufacturing park, and an e-waste dismantling park) and their surroundings. The total concentrations of 16 PAHs in the parks were 340-2.43 × 10³, 26.2-2.63 × 10³, and 394-2.01 × 10⁴ ng/g, which were significantly higher than those in the surrounding areas by 1-2 orders of magnitude, respectively. The highest soil PAH contamination was observed in the e-waste dismantling park. Nap can be considered as characteristic pollutant in the petrochemical industrial park, while Phe in the flame retardant manufacturing park and e-waste dismantling park. Low molecular weight PAHs (2-3 rings) predominated in the petrochemical industrial park (73.0%) and the surrounding area of brominated flame retardant manufacturing park (80.3%). However, high molecular weight PAHs (4-6 rings) were enriched in the other sampling sites, indicating distinct sources and determinants of soil PAHs. Source apportionment results suggested that PAHs in the parks were mainly derived from the leakage of petroleum products in the petroleum manufacturing process and pyrolysis or combustion of fossil fuels. Contrarily, the PAHs in the surrounding areas could have been derived from the historical coal combustion and traffic emissions. Source emissions, wind direction, and local topography influenced the PAH spatial distributions.

Identification of specific halogenated polycyclic aromatic hydrocarbons in surface soils of petrochemical, flame retardant, and electronic waste dismantling industrial parks

Halogenated polycyclic aromatic hydrocarbons (Cl/Br-PAHs) have received tremendous attention due to their high toxicity. To identify the emission pattern of Cl/Br-PAHs from various industrial productions, understand the formation mechanisms and the influence on the surroundings, this study investigated the surface soils of three typical industrial parks. Generally, traces of Cl-PAHs were much lower than Br-PAHs. The mean Cl-PAH concentrations followed the trend of petrochemical industrial park (3.12 ng/g), brominated flame retardant (BFR) manufacturing park (1.48 ng/g), and electronic waste dismantling park (0.26 ng/g). However, the BFR manufacturing park had the highest mean Br-PAH concentration (21.6 ng/g), significantly higher than the other two parks. Generally, higher levels of the chemicals were found in the parks than in their surroundings, except for the electronic waste dismantling park. The massive addition of chlorine additives in crude oil and its by-products, plus the enormous quantity of brominated brines used in BFR productions, favor Cl/Br-PAH formation. Analyzing the homolog compositions of Cl/Br-PAHs suggested that 3- or 4-ring Cl/Br-PAHs were typically come from the petrochemical industrial park and electronic waste dismantling park. Contrarily, 4- or 5-ring Cl/Br-PAHs were predominantly come from the BFR manufacturing activity. This study provides fingerprints to trace the Cl/Br-PAH emissions during industrial production and analyzes the formation mechanism.

Occurrence and fate of polycyclic aromatic hydrocarbons from electronic waste dismantling activities: A critical review from environmental pollution to human health

Electronic waste (e-waste) is one of the fastest-growing solid wastes and has become an urgent issue due to the potential adverse consequences of exposure to emitted toxic pollutants, especially for these occupational exposed workers and local residents. In this review, the environmental occurrences, emission characteristics, sources, and possible adverse effects of polycyclic aromatic hydrocarbons (PAHs) emitted from primitive e-waste dismantling activities are summarized. In general, the atmospheric levels of PAHs at typical e-waste sites, e.g., in Guiyu, China, have substantially decreased by more than an order of magnitude compared with levels a decade ago. The PAH concentrations in soil from old e-waste sites in China are also generally lower than those at newly emerged e-waste sites in India, Pakistan and Ghana. However, elevated concentrations of PAHs have been reported in human milk, hair and urine from the populations near these e-waste sites. Source apportionment both from bench-scale studies to field observations has demonstrated that the pyrolysis and combustion processing of electronic circuit board are mainly responsible for the emissions of various PAHs. In addition, some specific PAHs and their derivatives, such as triphenylbenzene, halogenated and oxygenated PAHs, have frequently been identified and could be considered as indicators in routine analysis in addition to the 16 U.S. EPA priority PAHs currently used.

Profile of atmospheric particulate PAHs near busy roadway in tropical megacity, India

Objective: This study focuses on the profile of ambient particulate polycyclic aromatic hydrocarbons (PAHs), their seasonal distribution, source identification and human health risk assessment due to inhalation exposure of ambient PAHs in Delhi, India.Materials and Methods: Two sampling sites were chosen, one at roadway (MH) and other at urban background (JNU) site in Delhi. Determination of PAHs was carried with the help of HPLC with UV detector. Principal component analysis and Molecular diagnostic ratios were used for the source apportionment of PAHs. Health risks associated with inhalation of particulate PAHs were assessed using benzo(a)pyrene equivalent concentration and incremental lifetime cancer risk (ILCR) approach.Results: The results showed that the average mass concentration of Σ₁₆ PAHs near roadway (67.8 ± 40.2 ng m^-3) is significantly higher than urban background site (56 ± 30 ng m^-3). Moreover, source apportionment study indicated that major PAH-emission sources in Delhi NCR are traffic and coal combustion. ILCR values at both the sites fall in the range of 10^-2-10^-4 that corresponds to the priority risk level (10^-3) and higher than the acceptable risk level (10^-6).conclusions: The high PAHs concentration at MH site was due to it's nearness to busy traffic area. Thus, the spatial variations in PAHs were influenced by local emission sources. The high PAHs level during the winter season can be due to their higher emissions from local heating sources, shift of gas/particle partitioning toward the particulate phase at low temperature and reduced photochemical degradation of some PAHs in winter. The low level of PAHs in monsoon season can be attributed to their wet scavenging and higher percentage in vapor phase. PCA showed that the emissions from vehicles predominate at MH site; whereas, coal combustion and traffic both are the significant PAHs sources at JNU site. Health risk assessment revealed that the highest exposure risks occur at busy traffic site, thereby indicating a significantly higher health risk to the population of Delhi.

Passive Air Sampling of PCDD/Fs, PCBs, PAEs, DEHA, and PAHs from Informal Electronic Waste Recycling and Allied Sectors in Indian Megacities

Xenobiotic chemical emissions from the informal electronic waste recycling (EW) sector are emerging problem for developing countries, with scale and impacts that are yet to be evaluated. We report an intensive polyurethane foam disk passive air sampling study in four megacities in India to investigate atmospheric organic pollutants along five transects viz., EW, information technology (IT), industrial, residential, and dumpsites. Intraurban emission sources were estimated and attributed by trajectory modeling and positive matrix factorization (PMF). ∑₁₇PCDD/Fs, ∑₂₅PCBs, ∑₇plasticizers, and ∑₁₅PAHs concentrations ranged from 3.1 to 26 pg/m³ (14 ± 7; Avg ± SD), 0.5-52 ng/m³ (9 ± 12); 7.5-520 ng/m³, (63 ± 107) and 6-33 ng/m³ (17 ± 6), respectively. EW contributed 45% of total PCB concentrations in this study and was evidenced as a major factor by PMF. The dominance of dioxin-like PCBs (dl-PCBs), particularly PCB-126, reflects combustion as the possible primary emission source. PCDD/Fs, PCBs and plasticizers were consistently highest at EW transect, while PAHs were maximum in industrial transect followed by EW. Concentrations of marker plasticizers (DnBP and DEHP) released during EW activities were significantly higher (p < 0.05) in Bangalore than in other cities. Toxic equivalents (TEQs) due to dl-PCBs was maximum in the EW transect and PCB-126 was the major contributor. For both youth and adult, the highest estimated inhalation risks for dl-PCBs and plasticizers were seen at the EW transect in Bangalore, followed by Chennai and New Delhi.

Using Polychlorinated Naphthalene Concentrations in the Soil from a Southeast China E-Waste Recycling Area in a Novel Screening-Level Multipathway Human Cancer Risk Assessment

Polychlorinated naphthalene (PCN) concentrations in the soil at an e-waste recycling area in Guiyu, China, were measured and the associated human cancer risk due to e-waste-related exposures was investigated. We quantified PCNs in the agricultural soil and used these concentrations with predictive equations to calculate theoretical concentrations in outdoor air. We then calculated theoretical concentrations in indoor air using an attenuation factor and in the local diet using previously published models for contaminant uptake in plants and fruits. Potential human cancer risks of PCNs were assessed for multiple exposure pathways, including soil ingestion, inhalation, dermal contact, and dietary ingestion. Our calculations indicated that local residents had a high cancer risk from exposure to PCNs and that the diet was the primary pathway of PCN exposure, followed by dermal contact as the secondary pathway. We next repeated the risk assessment using concentrations for other carcinogenic contaminants reported in the literature at the same site. We found that polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and PCNs caused the highest potential cancer risks to the residents, followed by polychlorinated biphenyls (PCBs). The relative importance of different exposure pathways depended on the physicochemical properties of specific chemicals.

Polycyclic Aromatic Hydrocarbons (PAHs) in Fired Clay Bricks Incorporating Cigarette Butts

Cigarette butts (CBs) are the most common littered waste in the world and may contain polycyclic aromatic hydrocarbons (PAHs) from the incomplete combustion of tobacco during burning. Therefore, to investigate the potential PAH residual remaining in fired clay bricks (FCBs) incorporating CBs and examine the environmental impact of utilizing toxic waste in the production of FCBs, a comprehensive PAH extraction analysis was conducted. The Soxhlet extraction method was utilized to conduct a qualitative and quantitative analysis of sixteen toxic Environmental Protection Authority (EPA) Polycyclic Aromatic Hydrocarbons (PAHs) in FCB samples incorporating CBs using gas chromatography-mass spectrometry (GC-MS). The concentrations of the mean total (Σ)PAHs for FCBs incorporating 0%, 0.5%, 1%, 1.5%, and 2% CBs by weight (wt) were found to be 0.183, 0.180, 0.242, 0.234, and 0.463 µg/mL. As expected, PAHs with higher water solubility and volatility, naphthalene, fluorene, anthracene, pyrene, fluoranthene, and chrysene were found at higher concentrations compared to lipophilic PAHs. The ΣPAH concentrations for all five FCB-CB mixes were well below the EPA Victoria solid waste hazard categorization threshold for industrial waste. Moreover, the samples were studied for their carbon content using the carbon, hydrogen, nitrogen, and sulfur (CHNS) analyzer and thermogravimetric analysis (TGA). The results confirm an almost 100% combustion process of CBs during the firing process. A content less than 0.3% suggests that all carbon within the FCB-CB mixture relatively disappeared during the firing process up to 1050 °C. However, further research regarding the emission of volatile organic compounds (VOCs) during the production of FCBs incorporating CBs should be conducted.

From inequitable to sustainable e-waste processing for reduction of impact on human health and the environment

Recycling of electric and electronic waste products (e-waste) which amounted to more than 50 million metric tonnes per year worldwide is a massive and global operation. Unfortunately, an estimated 70-80% of this waste has not been properly managed because the waste went from developed to low-income countries to be dumped into landfills or informally recycled. Such recycling has been carried out either directly on landfill sites or in small, often family-run recycling shops without much regulations or oversights. The process traditionally involved manual dismantling, cleaning with hazardous solvents, burning and melting on open fires, etc., which would generate a variety of toxic substances and exposure/hazards to applicators, family members, proximate residents and the environment. The situation clearly calls for global responsibility to reduce the impact on human health and the environment, especially in developing countries where poor residents have been shouldering the hazardous burden. On the other hand, formal e-waste recycling has been mainly conducted in small scales in industrialized countries. Whether the latter process would impose less risk to populations and environment has not been determined yet. Therefore, the main objectives of this review are: 1. to address current trends and emerging threats of not only informal but also formal e-waste management practices, and 2. to propose adequate measures and interventions. A major recommendation is to conduct independent surveillance of compliance with e-waste trading and processing according to the Basel Ban Amendment. The recycling industry needs to be carefully evaluated by joint effort from international agencies, producing industries and other stakeholders to develop better processes. Subsequent transition to more sustainable and equitable e-waste management solutions should result in more effective use of natural resources, and in prevention of adverse effects on health and the environment.

Shifts in a Phenanthrene-Degrading Microbial Community are Driven by Carbohydrate Metabolism Selection in a Ryegrass Rhizosphere

Plants usually promote pollutant bioremediation by several mechanisms including modifying the diversity of functional microbial species. However, conflicting results are reported that root exudates have no effects or negative effects on organic pollutant degradation. In this study, we investigated the roles of ryegrass in phenanthrene degradation in soils using DNA stable isotope probing (SIP) and metagenomics to reveal a potential explanation for conflicting results among phytoremediation studies. Phenanthrene biodegradation efficiency was improved by 8% after 14 days of cultivation. Twelve and ten operational taxonomic units (OTUs) were identified as active phenanthrene degraders in non-rhizosphere and rhizosphere soils, respectively. The active phenanthrene degraders exhibited higher average phylogenetic distances in rhizosphere soils (0.33) than non-rhizosphere soils (0.26). The K_a/K_s values (the ratio of nonsynonymous to synonymous substitutions) were about 10.37% higher in the rhizosphere treatment among >90% of all key carbohydrate metabolism-related genes, implying that ryegrass may be an important driver of microbial community variation in the rhizosphere by relieving the carbohydrate metabolism pressure and improving the survival ability of r-strategy microbes. Most K_a/K_s values of root-exudate-related metabolism genes exhibited little change, except for fumarate hydratase that increased 13-fold in the rhizosphere compared to that in the non-rhizosphere treatment. The K_a/K_s values of less than 50% phenanthrene-degradation-related genes were affected, 30% of which increased and 70% behaved oppositely. Genes with altered K_a/K_s values had a low percentage and followed an inconsistent changing tendency, indicating that phenanthrene and its metabolites are not major factors influencing the active degraders. These results suggested the importance of carbohydrate metabolism, especially fumaric acid, in rhizosphere community shift, and hinted at a new hypothesis that the rhizosphere effect on phenanthrene degradation efficiency depends on the existence of active degraders that have competitive advantages in carbohydrate and fumaric acid metabolism.

PAH exposure is associated with enhanced risk for pediatric dyslipidemia through serum SOD reduction

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) is linked to abnormal lipid metabolism, but evidence regarding PAHs as risk factors for dyslipidemia is lacking.

OBJECTIVE

To investigate the respective role and interaction of PAH exposure and antioxidant consumption in the risk for pediatric dyslipidemia.

METHODS

We measured the concentrations of serum lipids, superoxide dismutase (SOD) and urinary hydroxylated PAHs (OH-PAHs) in 403 children, of which 203 were from an e-waste-exposed area (Guiyu) and 200 were from a reference area (Haojiang). Biological interactions were calculated by additive models.

RESULTS

Guiyu children had higher serum triglyceride concentration and dyslipidemia incidence, and lower serum concentration of high-density lipoprotein (HDL) than Haojiang children. Elevated OH-PAH concentration, and concomitant SOD reduction, were both associated with lower HDL concentration and higher hypo-HDL risk (∑₃OH-Phes: B for lgHDL = -0.048, P < 0.01; OR for hypo-HDL = 3.708, 95% CI: 1.200, 11.453; SOD: B_T3 for lgHDL = 0.061, P < 0.01; OR_T3 for hypo-HDL = 0.168, 95% CI: 0.030, 0.941; all were adjusted for confounders). Biological interaction between phenanthrol exposure and SOD reduction was linked to dyslipidemia risk (RERI = 2.783, AP = 0.498, S = 2.537). Children with both risk factors (higher ∑₃OH-Phes and lower SOD) had 5.594-times (95% CI: 1.119, 27.958) the dyslipidemia risk than children with neither risk factors (lower ∑₃OH-Phes and higher SOD).

CONCLUSION

High PAH exposure combined with SOD reduction is recommended for predicting elevated risk for pediatric dyslipidemia. Risk assessment of PAH-related dyslipidemia should take antioxidant concentration into consideration.

Distribution and Chiral Signatures of Polychlorinated Biphenyls (PCBs) in Soils and Vegetables around an e-Waste Recycling Site

The distribution and composition of polychlorinated biphenyls (PCBs) within soil-plant systems around a notorious e-waste recycling site were investigated. The average total PCB concentrations in rhizospheric soils (RSs) and nonrhizospheric soils (NRSs) were 2160 and 1270 pg g^-1 dry weight (DW), respectively. PCBs were more enriched in RS than NRS for most vegetable species. PCB accumulation in plant tissues varied greatly among plant cultivars, ranging from 4020 to 14 500 pg g^-1 DW in shoots and from 471 to 24 400 pg g^-1 DW in roots. The compositions of PCBs in soil and plants showed that hexa- and hepta-chlorinated PCBs were preferentially accumulated in soils, while tri- and tetra-PCBs were abundant in plant tissues. These results indicated that low-chlorinated PCBs might be prone to accumulation and transfer within plants, which was confirmed by the relationship between the root concentration factor and octanol-water coefficient. The first eluting enantiomers of PCB 84 and PCB 95 were preferentially transferred between the soil and plants, while the stereoselectivity of PCB 136 varied among plant species. A significant difference in enantiomeric fractionation of PCB 84 between the soil and roots indicated that enantiomeric enhancement of PCB 84 occurred during its translocation from soil to root, whereas no such difference was observed in these chiral PCBs during their translocation from the root to the shoot.

Assessment of the geo-environmental effects of activities of auto-mechanic workships at Alaoji Aba and Elekahia Port Harcourt, Niger Delta, Nigeria

Geo-environmental assessment of activities of auto–mechanics at Alaoji Aba and Elekahia Port Harcourt, both in the Niger Delta region, Southern Nigeria were carried out with the main objective of determining the extent of soil contamination arising from anthropogenic activities within mechanic villages (MVs). Geochemical analysis of soil samples from the study area revealed that the concentrations of the trace metals ranged from <1 mg/kg for chromium (Cr) to 1,925 mg/kg for the lead (Pb). Soil analysis for polycyclic aromatic hydrocarbon (PAH) and total petroleum hydrocarbon (TPH) across the area revealed concentrations ranging from <0.02 to 1.80 mg/Kg and from <1.00 to 38,327 mg/kg respectively. Elevated levels of the heavy metals and TPH were observed at MV in Alaoji Aba when compared to MV in Elekahia Port Harcourt, and the control sites. These could be attributed to contamination due to the presence of these auto-mechanics in the area for over thirty years. The concentration of Pb and Cd recorded in some sample points were above USEPA (United State Environmental Protection Agency) and the National Environmental Standards and Regulations Enforcement Agency (NESREA) permissible limits. Results of PAH analysis showed the presence of naphthalene, phenanthrene, pyrene, fluorene, benzo(a)anthracene, acenaphthene, methylnaphthalene. Risk assessment analysis showed significant geo-accumulation values for Cd and Pb indicating heavy contamination. The monomial risk factor of the heavy metals in the MVs are in the order Cd >Pb>Cr, while potential ecological risk index analysis showed values indicating very high risk, considerable risk and a moderate risk to the area under study as well as the surrounding environment. These results suggest that the soils from the MVs which represent the mechanic workshops at Alaoji Aba and Elekahia Port Harcourt are considered to be of pollution concern due to elevated Pb and Cd levels. Hence, there is a serious need to regularly monitor the activities of auto-mechanics in the study area.

Soil concentrations and soil-air exchange of polycyclic aromatic hydrocarbons in five Asian countries

The Asia Soil and Air Monitoring Program (Asia-SAMP) is a large-scale monitoring program spanning China, Japan, South Korea, Vietnam and India. 47 polycyclic aromatic hydrocarbons (PAHs) were analyzed in 169 concurrently collected surface soil samples across the five study regions. Total PAH concentrations (∑₄₇PAHs) ranged from 13.1 to 7310 ng/g dry weight, with a median value of 272 ng/g dry weight. Higher concentrations of ΣPAHs were recorded in soils from urban areas, followed by soils from rural areas and background soils. Low correlation coefficients were found between PAHs concentrations with population density, surface air temperature and soil organic content. A trend of depleting high molecular weight PAHs and enrichment of low molecular weight PAHs occurred from east to west in Chinese soils. Based on atmospheric PAHs detected in almost the same sampling sites, the equilibrium status of PAHs in the atmosphere and on the ground was investigated. Sample sites with a soil-air equilibrium status for different PAH congeners recorded differences, and differences were recorded between seasons. 2-ring PAHs were mainly volatilized, and 5- & 6-ring PAHs were mainly deposited in all seasons and across all study regions. 3- & 4-ring PAHs were more affected by soil-air transfer, showing a tendency to accumulate in soils in cold regions/seasons and to be re-volatilized into the atmosphere in warm regions/seasons. Partitioning and exchange of PAHs among soil and air were significantly affected by the air temperature.

Birth outcomes associated with maternal exposure to metals from informal electronic waste recycling in Guiyu, China

BACKGROUND

Informal electronic waste (e-waste) recycling is a rapidly growing industry. Informal e-waste recycling creates a mixture of chemicals that can be harmful to humans, especially vulnerable populations like pregnant women and young children.

OBJECTIVES

We aimed to analyze the associations between birth outcomes and living in a community with a history of informal e-waste recycling.

METHODS

The e-waste Recycling Exposure and Community Health (e-REACH) Study enrolled pregnant women in Guiyu, an informal e-waste recycling site (n = 314), and an unexposed control site (Haojiang) (n = 320) at delivery. We analyzed maternal whole blood samples for lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn). We captured data in newborns on birth weight, birth length, head circumference, body mass index (BMI), and Ponderal Index (PI). We compared the birth outcomes between sites after adjustment for covariates, and examined the associations with individual and the mixture of metals.

RESULTS

The neonates from Guiyu had smaller head circumference (adj β -1.96 cm, 95% CI -2.39, -1.52), BMI (adj β -0.77 kg/m2, 95% CI -1.03, -0.51), and PI (adj β -2.01 kg/m3, 95% CI -2.54, -1.47). Birth weights were lower in Guiyu compared to Haojiang, but the difference was not significant (β -51, 95% CI -132, 29). Cumulative exposure to metals was related to lower head circumference, BMI, and PI, but not related to birth weight.

DISCUSSION

We observed slight and statistically significant differences in the head size, BMI, and PI of neonates, but not birth weight, from Guiyu when compared to neonates from Haojiang. Cumulative metal exposure may partially account for the findings.

Soil and sediment contamination by unsubstituted and methylated polycyclic aromatic hydrocarbons in an informal e-waste recycling area, northern Vietnam: Occurrence, source apportionment, and risk assessment

Improper processing activities of e-waste are potential sources of polycylic aromatic hydrocarbons (PAHs) and their derivatives, however, information about the environmental occurrence and adverse impacts of these toxic substances is still limited for informal e-waste recycling areas in Vietnam and Southeast Asia. In this study, unsubstituted and methylated PAHs were determined in surface soil and river sediment samples collected from a rural village with informal e-waste recycling activities in northern Vietnam. Total levels of PAHs and MePAHs decreased in the order: workshop soil (median 2900; range 870-42,000 ng g^-1) > open burning soil (2400; 840-4200 ng g^-1) > paddy field soil (1200; range 530-6700 ng g^-1) > river sediment samples (750; 370-2500 ng g^-1). About 60% of the soil samples examined in this study were heavily contaminated with PAHs. Fingerprint profiles of PAHs and MePAHs in the soil and sediment samples indicated that these pollutants were mainly released from pyrogenic sources rather than petrogenic sources. The emissions of PAHs and MePAHs in this area were probably attributed to uncontrolled burning of e-waste and agricultural by-products, domestic coal and biomass combustion, and traffic activities. Carcinogenicity and mutagenicity of PAHs in the e-waste workshop soils were significantly higher than those of the field soils; however, the incremental lifetime cancer risk of PAH-contaminated soils in this study ranged from 5.5 × 10^-9 to 4.6 × 10^-6, implying acceptable levels of human health risk. Meanwhile, concentrations of some compounds such as phenanthrene, anthracene, fluoranthene, benz[a]anthracene, and benzo[a]pyrene in several soil samples exceeded the maximum permissible concentrations, indicating the risk of ecotoxicological effects.

Insights into biomonitoring of human exposure to polycyclic aromatic hydrocarbons with hair analysis: A case study in e-waste recycling area

In this study, 96 pairs of hair and urine samples were collected from e-waste (EW) dismantling workers of an industrial park, as well as residents living in surrounding areas. The concentrations of polycyclic aromatic hydrocarbons (PAHs) and hydroxylated PAH metabolites (OH-PAHs) were analyzed . The results show that concentrations of Σ₁₅PAHs ranged from 6.24 to 692 ng/g dry weight (dw) and Σ₁₂OH-PAHs from undetected to 187 ng/g dw in hair external (hair-Ex), and ranged from 31.7 to 738 ng/g dw and 21.6 to 1887 ng/g dw in hair internal (hair-In). There was no significant difference in exposure levels between EW dismantling workers and residents of the surrounding area. For the parent PAHs, the concentrations of Σ₁₅PAHs of hair-In were comparable with those of hair-Ex for all populations except for the child residents. On the contrary, for the OH-PAHs, the concentrations of Σ₁₂OH-PAHs of hair-In were 9-37 times higher than those of hair-Ex for populations. Moreover, the congener profiles of OH-PAHs of hair-In were different from those of hair-Ex, but similar to that of urine. Particularly, 3-OH-Bap, which is a carcinogenic metabolite, was only detected in the hair-In. These results indicate that OH-PAHs in hair-In, just like in urine, are mainly derived from endogenous metabolism and could be considered as reliable biomarkers for PAHs exposure. However, there was almost no significant correlations between hair-In and urine for OH-PAHs. This indicates that more attention should be paid to OH-PAHs when conducting PAHs exposure risk assessment using hair, which will help to obtain more reliable and comprehensive information on health risk assessments.

Health Consequences for E-Waste Workers and Bystanders-A Comparative Cross-Sectional Study

Informal e-waste recycling is associated with several health hazards. Thus far, the main focus of research in the e-waste sector has been to assess the exposure site, such as the burden of heavy metals or organic pollutants. The aim of this study was to comprehensively assess the health consequences associated with informal e-waste recycling. A questionnaire-based assessment regarding occupational information, medical history, and current symptoms and complaints was carried out with a group of n = 84 e-waste workers and compared to a control cohort of n = 94 bystanders at the e-waste recycling site Agbogbloshie. E-waste workers suffered significantly more from work-related injuries, back pain, and red itchy eyes in comparison to the control group. In addition, regular drug use was more common in e-waste workers (25% vs. 6.4%). Both groups showed a noticeable high use of pain killers (all workers 79%). The higher frequency of symptoms in the e-waste group can be explained by the specific recycling tasks, such as burning or dismantling. However, the report also indicates that adverse health effects apply frequently to the control group. Occupational safety trainings and the provision of personal protection equipment are needed for all workers.

Persistent, bioaccumulative, and toxic properties of liquid crystal monomers and their detection in indoor residential dust

Liquid crystal monomers (LCMs) are used widely in liquid crystal displays (LCDs), which are dramatically changing the world due to the provision of convenient communication. However, there are essentially no published reports on the fate and/or effects of LCMs in the environment. Of 362 currently produced LCMs, 87 were identified as persistent and bioaccumulative (P&B) chemicals, which indicated that these chemicals would exhibit resistance to degradation and exhibit mobility after entering the environment. Following exposure to mixtures of LCM collected from 6 LCD devices, significant modulation of 5 genes, CYP1A4, PDK4, FGF19, LBFABP, and THRSP, was observed in vitro. Modulation of expressions of mRNAs coding for these genes has frequently been reported for toxic (T) persistent organic pollutants (POPs). In LCM mixtures, 33 individual LCMs were identified by use of mass spectrometry and screened for in 53 samples of dust from indoor environments. LCMs were detectable in 47% of analyzed samples, and 17 of the 33 LCMs were detectable in at least 1 sample of dust. Based on chemical properties, including P&B&T of LCMs and their ubiquitous detection in dust samples, the initial screening information suggests a need for studies to determine status and trends in concentrations of LCMs in various environmental matrices as well as tissues of humans and wildlife. There is also a need for more comprehensive in vivo studies to determine toxic effects and potencies of LCMs during chronic, sublethal exposures.

Finding a relationship between mobility factors of selected heavy metals and soil particle size in soils from children's playgrounds

In the 3-year study, heavy metals mobility factors for soils of public playgrounds within Owerri metropolis were correlated with soil particle size. Such studies could develop a body of knowledge that could enable detection and quantification of potential risk of metals to children from playground soil without actually involving children. Calculated values of mobility factors were subjected statistical treatment and to obtain descriptive statistics. Regression analysis of mobility factors and particle size were determined. Copper and zinc were most mobile elements, while cobalt was least mobile. Result showed that clay particle size had strong influence on mobility factors. The significance of this study is that recent estimation of mobility factors of metals are used to expand its possible understanding and application to fundamental and practical problems of ecotoxicology of metals which could reflect metals potentials to cause harm thereby permitting the evaluation of metals toxicity without direct involvement of children.

Vertical profile of soil/sediment pollution and microbial community change by e-waste recycling operation

The present study aims to assess the effect of electronic waste (e-waste) recycling on microbial community and the underlying modulation mechanism. Core soil/sediment samples were collected from an abandoned e-waste burning site and neighboring farmland/stream sites in Guiyu, China. High concentrations and health risks of toxic heavy metals, particularly, Sb and Sn, and halogenated flame retardants (HFRs), including decabromodiphenyl ether (BDE 209) and decabromodiphenyl ethane (DBDPE) were mostly retained at the top surface layers of soils/sediments (0-30cm) after more than one year of natural vertical diffusion and microbe-facilitated biodegradation. Heavy metals, such as Ag, Cd, Cu, Pb, Sb, and Sn, played a critical role for the reduction of microbial diversity. This is the first study reporting the open burning of e-waste caused an obvious heat effect and enriched thermophilic/mesophilic microbes in local area. The acid washing during e-waste recycling process may result in the enrichment of acidophilic microbes. This investigation showed that e-waste processing operation resulted in not only severe pollution of the soils/sediments by various pollutants, but also reduction of microbial diversity that was difficult to self-store by the local ecosystem.

Global trends and future prospects of e-waste research: a bibliometric analysis

Electronic waste (e-waste) has been widely studied by scholars all over the world, but the research topics and development trends in this field are still unclear. This study aimed to explore the status quo, hot topics, and future prospects in the field of e-waste. Data of publications were downloaded from the Web of Science Core Collection. We used CiteSpace V, Histcite, and VOSviewer to analyze literature information. A total of 2800 papers in e-waste research were identified, and the number of publications increased rapidly after 2004. Six thousand five hundred seventy-three authors participated in the e-waste research, but 70.01% of the authors published only 1 article. The most productive country in this field was China (1146 publications), and the most productive institution was the Chinese Academy of Sciences (370 publications). The Waste Management (225 publications) was the most productive journal, and Environment Science & Technology (9704 co-citations) was the most co-cited journal. The main hot topics in e-waste field were management and recycling of e-waste in developing countries, health risk assessment after exposure to organic pollutants, degradation and recovery of waste metal materials, and impact of heavy metals on children's health. The frontier topic was degradation.

Trends of electronic waste pollution and its impact on the global environment and ecosystem

Electronic waste (e-waste) is used for all electronic/electrical devices which are no more used. Conventionally, waste management policies are desfighandle the traditional waste. Although e-waste contains toxic materials, however, its management is rarely focused by policy makers; therefore, its negative impact on the global environment, ecosystem, and human health is aggravated. The review outlines the categories of e-waste materials, major pollutants including ferrous/non-ferrous metals, plastics, glass, printed circuit boards, cement, ceramic, and rubber beside, some valuable metals (such as copper, silver, gold, platinum). Toxic elements from e-waste materials, released in the air, water, and soil, include arsenic, cadmium, chromium, mercury, and lead, causing pollution. Although their roles in biological systems are poorly identified, however, they possess significant toxic and carcinogenic potential. It is therefore critical to monitor footprint and device strategies to address e-waste-linked issues from manufacturing, exportation, to ultimate dumping, including technology transmissions for its recycling. This review traces a plausible link among e-waste condition at a worldwide dimension, as far as settlement procedures to keep it secure and carefully monitored when traded. Their fate in the three spheres of the earth, i.e., water, soil, and air, impacts human health. The strategies and regulation to handle e-waste generation at the global level have been discussed. Graphical abstract .

Phthalates in residential and agricultural soils from an electronic waste-polluted region in South China: distribution, compositional profile and sources

Electronic waste (e-waste) recycling has proven to be a significant source of phthalate (PAE) contamination in the environment. A detailed investigation was conducted to understand the concentration, distribution, profile and possible source of PAEs in residential and agricultural soils from Guiyu, Shantou, China, the largest e-waste processing and recycling areas in the world. Sixteen PAEs were analysed in 46 surface soil samples from three different sampling areas in terms of individual and total concentrations, together with pH and soil organic matter. High concentrations of the total PAEs were found in residential area A (more than 20,000 ng g^-1), revealing a clear urban pulse, whereas in residential area B and agricultural areas, concentrations were lower than 10,000 ng g^-1. The dominant PAEs were bis (2-nbutoxyethyl) phthalate, bis (4-methyl-2-pentyl) phthalate and dicyclohexyl phthalate. These PAEs were high-molecular weight PAEs (alkyl chains ≥ 6 carbons) and mainly derived from polyvinyl chloride commonly used in electrical and electronic equipment, indicating a distinctive composition in relation to the e-waste area. Three individual and the total PAEs exhibited significant positive correlations with pH. Principal component analysis indicated that PAEs were mainly distributed in three groups according to the alkyl chain length and potential source. This study showed that the informal e-waste recycling has already introduced PAEs into surrounding areas as a pollutant which should draw more attention and regulatory control.

Metal concentrations in pregnant women and neonates from informal electronic waste recycling

Electronic waste (e-waste) is the fastest growing solid waste stream worldwide and mostly ends up in developing countries where residents use primitive methods for recycling. The most infamous e-waste recycling town, Guiyu in Southeast China, has been recycling since the mid-1990s. E-waste contains several harmful chemicals, including lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn). In 2011-12, the e-waste Recycling Exposures and Community Health (e-REACH) Study enrolled 634 pregnant women living in Guiyu and Haojiang, a control site, both in Shantou, China. The women completed a questionnaire and gave maternal blood, cord blood, and maternal urine, which were analyzed for Pb, Cd, Cr, and Mn. Maternal blood Pb, Cd, and Cr concentrations were significantly higher in Guiyu compared to Haojiang. In Guiyu, the geometric mean of Pb concentration in maternal blood was 6.66 µg/dL (range: 1.87-27.09 µg/dL) and was 1.74-fold greater than in Haojiang (95% CI: 1.60, 1.89). In cord blood, Pb concentration was 1.53-fold higher in Guiyu (95% CI: 1.38, 1.68). In maternal urine, Cd (ratio: 2.15, 95% CI: 1.72, 2.69) and Mn (ratio: 2.60, 95% CI: 2.04, 3.31) concentrations were significantly higher in Guiyu in comparison to Haojiang. In conclusion, pregnant women in Guiyu were at risk for increased exposure to heavy metals.

Storing E-waste in Green Infrastructure to Reduce Perceived Value Loss through Landfill Siting and Landscaping: A Case Study in Nanjing, China

Electronic waste (e-waste) represents a severe global environmental issue due to the fast upgrading and updating of electronic products and the high environmental risk. Current low recycling technology, high economic cost, and weak disposal capability make it difficult for e-waste to be rendered 100% harmless. E-waste disposal requires new site-selection methods and site-saving technology to take into account the loss of public perceived value. This study attempts to improve e-waste disposal through siting and landscaping to reduce perceived value loss. The first step is to determine the minimum distance for landfill siting by surveying the minimum loss of perceived value and to use the geographic information system (GIS) to sketch the suitable landfill site thereafter. To optimize the landfill landscape, a landscape infrastructure and its filling process have been designed to reduce the environmental risk and ensure future reuse potential. The application case showed that the minimum distance is 521 m, which was sensitive to the educational level and occupation of residents. The key to landfill landscaping is the construction of isolation layers and the integration of the landfill and urban landscape. The method described in this paper is characterized by minimizing the perceived loss of value to the public, reducing environmental risks, and preserving the resource value of e-waste. This design could provide an alternative to current electronic waste processing methods.

Using Pb Isotope to Quantify the Effect of Various Sources on Multi-Metal Polluted soil in Guiyu

Guiyu is known as one of the largest e-waste disposal and recycling sites in China, which suffers greatly from heavy metal pollution. By evaluating the concentrations and distribution of 21 metal elements with Principal Component Analyses (PCA), five principal components were identified, which accounted for 70.4% of the information of the initial data matrix, including one e-waste recycling source, two geological sources, one source of human activities and one ocean aerosol source. Among them, the source of human activities cannot be detailed only by PCA. By using Pb isotope, the unexplained source was judged as battery sludge. Combining 21 metallic and metalloid element datasets with Pb isotope concentrations is more accurate and effective to identify uncertain sources in soil.

Environmental and health implications of trace metal concentrations in street dusts around some electronic repair workshops in Owerri, Southeastern Nigeria

Assessment of trace metal concentrations in street-deposited sediments around some selected electronic repair workshops in Owerri, Imo State, Nigeria, was carried out. The objective of the study was to determine the concentrations of trace metals, namely nickel (Ni), chromium (Cr), lead (Pb), copper (Cu), cadmium (Cd), and zinc (Zn), in surface dusts from streets within some electronic repair workshops in Owerri, Imo State, Nigeria. Dust samples were collected from seven locations within the month of January 2014 during the dry season when the onset of dust was high in the area. The samples were air-dried, sieved, and digested in aqua regia, with the concentrations of trace metals determined with atomic absorption spectroscopy, Agilant FS 240AA model (USA). Results of the study revealed all the trace metals assessed except Cr in dust sample from Aladinma (ALA). Though elevated concentrations of Zn and Cu were observed in all the sampled locations, the concentrations did not exceed the Dutch intervention values. Risk assessment of the heavy metals showed high average daily dose (ADD) of the heavy metals for children and adults at New Market 2 (NMK2), New Market 1 (NMK1), and Tetlow (TEL), which could be attributed to the presence of electronic repair workshops and activities of electronic scrap dealers within these areas. It was observed that the values of hazard quotient (HQ) were less than 1, while that of hazard index (HI) were all below 1-5, indicating that the heavy metals pose no health risk to adults and children in the environment. However, there may be potential danger if the waste generated from the electronic repair workshops and electronic scrap dealers are not properly disposed and managed.

A strong spatial association between e-waste burn sites and childhood lymphoma in the West Bank, Palestine

A paper in the International Journal of Cancer analyzed Palestinian cancer registry data in the West Bank from 1998 to 2007, showing a cluster of elevated cancer incidence in rural villages in south-west Hebron, with a 4.10 risk ratio for childhood lymphoma (p = 0.0023). The paper called for investigation of the environmental or genetic etiologies of this cluster in an otherwise unremarkable rural area.¹ Our research in these same villages shows them to be the center of an extensive informal electronic and electrical waste (e-waste) dismantling industry in Palestine, operating for almost two decades. This entails extensive open-burning of e-waste components to extract valuable metals or dispose of nonvaluable waste, releasing high concentrations of hazardous contaminants, which may be an important factor in the elevated cancer incidence. We offer a first step in assessing this link. We applied a novel multitemporal object-based method to map the prevalence and intensity of e-waste burn sites in the entire Hebron Governorate (1,060 km² ) between 1999 and 2007. A weighted standard deviation ellipse of cumulative burn activity covers a smaller area (247 km² ) very closely matching the childhood lymphoma cluster: it contains 85% of the core cluster area (RR of 4.1), and falls almost entirely (95%) within the broader area of elevated risk (RR of 2.8). Extensive international evidence linking informal e-waste processing to elevated cancer incidence and this strong spatial association of e-waste burning activity with a distinct unexplained cancer cluster in the Palestinian context signals the urgent need for investigation and intervention.

Polycyclic aromatic hydrocarbons in surface waters and riverine sediments of the Hooghly and Brahmaputra Rivers in the Eastern and Northeastern India

Sixteen priority polycyclic aromatic hydrocarbons (PAHs) regulated by the United States Environmental Protection Agency (USEPA) were analyzed in surface waters and riverine sediments of Brahmaputra and Hooghly Rivers, along urban-suburban-rural transects. ∑₁₆ PAHs concentrations were higher in Hooghly riverine sediment (HRS) (Avg, 445 ng g^-1) than Brahmaputra riverine sediment (BRS) (Avg, 169 ng g^-1) dominated by 4-ring PAHs. In contrast, PAHs concentrations in surface water of Brahmaputra River (BRW) (Avg, 4.04 μg L^-1) were comparable with Hooghly River (HRW) (Avg, 4.8 μg L^-1), with dominance by 3-ring PAHs. Toxic PAHs (BaA, Chr, BbF, BkF, BaP, InP and DBA) were dominant in sub-urban transect of HRS (Avg, 387 ng g^-1) and BRS (Avg, 14 ng g^-1). Diagnostic ratios, principal component analysis (PCA) and ring wise composition suggested combustion as the main PAHs source in these riverine belts. In BRS, higher PAHs in suburban and rural transects were attributed to incomplete combustion of fossil fuel and biomass burning. In HRS, >85% of high molecular weight PAHs were found in the industrial areas of the suburban transect possibly associated with the discharge of industrial effluents. Harbor and port activities were other major contributors of HMW-PAHs in Hooghly riverine system. Carcinogenic potency estimated in terms of toxic equivalent (TEQ) was several folds higher in HRS (Avg, 106 ng TEQ g^-1) compared with BRS (Avg, 2.5 ng TEQ g^-1). Mostly low molecular weight PAHs are likely posing a risk to fishes in both the rivers. Risk on edible fish species may be a matter of concern considering the regular consumption of fishes in this region.

Biodegradation in seawater of PAH and alkylphenols from produced water of a North Sea platform

Operational planned discharges of produced water (PW) to the marine environment from offshore oil production installations, contain low concentrations of dispersed oil compounds, like polycyclic aromatic hydrocarbons (PAHs) and alkylated phenols (APs). Biotransformation in natural seawater (SW) of naphthalenes/PAHs and phenol/APs in field-collected PW from a North Sea platform was investigated in this biodegradation study. The PW was diluted in SW from a Norwegian fjord, and the biodegradation study was performed in slowly rotating carousels at 13 °C over a period of 62 days. Naphthalenes/PAHs and phenol/APs biotransformation was determined by first-order rate kinetics, after normalization against the recalcitrant biomarker 17α(H),21β(H)-Hopane. The results from this study showed total biotransformation half-lives ranging from 10 to 19 days for groups of naphthalenes and PAHs, while half-lives for APs (C0- to C9-alkylated) were 10-14 days. Biotransformation half-lives of single compounds ranged from 8 to >100 days for naphthalenes and PAHs (median 16 days), and from 5 to 70 days (median 15 days) for phenols and APs. Four of the tested PAHs (chrysene, benzo(b)fluoranthene, benzo(e)pyrene, benzo(g,h,i)perylene) and one AP (4-tert-butylphenol) showed biotransformation half-lives >50 days. This is one of a few studies that has investigated the potential for biodegradation of PW in natural SW. Methods and data from this study may be used as a part of Risk Based Approaches (RBA) for assessments of environmental fate of PW released to the marine environment and as part of the persistence related to risk.

Lead exposure is associated with risk of impaired coagulation in preschool children from an e-waste recycling area

Environmental lead exposure leads to various deleterious effects on multiple organs and systems, including the hematopoietic system. To explore the effects of lead exposure on platelet indices in preschool children from an informal, lead-contaminated electronic waste (e-waste) recycling area, we collected venous blood samples from 466 preschool children (331 from an e-waste area (Guiyu) and 135 from a non-e-waste area (Haojiang)). Child blood lead levels (BLLs) were determined by graphite furnace atomic absorption spectrophotometry, while platelet indices were quantified using a Sysmex XT-1800i hematology analyzer. Higher blood lead levels are observed in e-waste lead-exposed preschool children. Significant relationships between high blood lead levels (exceeding current health limits) and elevated platelet count (PLT), plateletcrit (PCT), mean platelet volume (MPV), and platelet large cell ratio (P-LCR) were also uncovered. Furthermore, the median PLT and PCT levels of children from the exposed group both exceeded the respective recommended maximum reference range value, whereas the reference group did not. Location of child residence in Guiyu and BLLs were both risk factors related to platelet indices. These results suggest that high blood lead exposure from e-waste recycling may increase the risk of an amplified coagulation process through the activation of platelets in preschool children.

Microbial community structure and function in sediments from e-waste contaminated rivers at Guiyu area of China

The release of toxic organic pollutants and heavy metals by primitive electronic waste (e-waste) processing to waterways has raised significant concerns, but little is known about their potential ecological effects on aquatic biota especially microorganisms. We characterized the microbial community composition and diversity in sediments sampled along two rivers consistently polluted by e-waste, and explored how community functions may respond to the complex combined pollution. High-throughput 16S rRNA gene sequencing showed that Proteobacteria (particularly Deltaproteobacteria) dominated the sediment microbial assemblages followed by Bacteroidetes, Acidobacteria, Chloroflexi and Firmicutes. PICRUSt metagenome inference provided an initial insight into the metabolic potentials of these e-waste affected communities, speculating that organic pollutants degradation in the sediment might be mainly performed by some of the dominant genera (such as Sulfuricurvum, Thiobacillus and Burkholderia) detected in situ. Statistical analyses revealed that toxic organic compounds contributed more to the observed variations in sediment microbial community structure and predicted functions (24.68% and 8.89%, respectively) than heavy metals (12.18% and 4.68%), and Benzo(a)pyrene, bioavailable lead and electrical conductivity were the key contributors. These results have shed light on the microbial assemblages in e-waste contaminated river sediments, indicating a potential influence of e-waste pollution on the microbial community structure and function in aquatic ecosystems.

Organic contamination and remediation in the agricultural soils of China: A critical review

Soil pollution is a global problem in both developed and developing countries. Countries with rapidly developing economies such as China are faced with significant soil pollution problems due to accelerated industrialization and urbanization over the last decades. This paper provides an overview of published scientific data on soil pollution across China with particular focus on organic contamination in agricultural soils. Based on the related peer-reviewed papers published since 2000 (n=203), we evaluated the priority organic contaminants across China, revealed their spatial and temporal distributions at the national scale, identified their possible sources and fates in soil, assessed their potential environmental risks, and presented the challenges in current remediation technologies regarding the combined organic pollution of agricultural soils. The primary pollutants in Northeast China were polycyclic aromatic hydrocarbons (PAHs) due to intensive fossil fuel combustion. The concentrations of organochlorine pesticides (OCPs) and phthalic acid esters (PAEs) were higher in North and Central China owing to concentrated agricultural activities. The levels of polychlorinated biphenyls (PCBs) were higher in East and South China primarily because of past industrial operations and improper electronic waste processing. The co-existence of organic contaminants was severe in the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei Region, which are the most populated and industrialized regions in China. Integrated biological-chemical remediation technologies, such as surfactant-enhanced bioremediation, have potential uses in the remediation of soil contaminated by multiple contaminants. This critical review highlighted several future research directions including combined pollution, interfacial interactions, food safety, bioavailability, ecological effects, and integrated remediation methods for combined organic pollution in soil.

Heavy metal remediation with Ficus microcarpa through transplantation and its environmental risks through field scale experiment

The phytoremediation efficiency of various metals by Ficus microcarpa was evaluated through a real scale experiment in the present study. The root biomass production of the species varied significantly from 3.68 to 5.43 g because of the spatial heterogeneity of different metals. It would take 4-93 years to purify the excess Cd of the experimental site. Mercury was the most inflexible element which can barely be phytoremediated by F. microcarpa. After the species transplanted from the polluted soil to the clean site, Cd and Cu were transferred to the rhizosphere soil to different extent while the bulk soil was barely influenced. Relative to Cd and Cu, significantly fewer amounts of Pb and Hg were released. The highest concentrations of Cd, Cu, Hg and Pb in the clean soil were far below their corresponding safe thresholds for agricultural land after 3 months of the polluted plants were cultivated and metal concentrations of plant leaves were negligible, both indicated the low ecological risk of transplantation. Results from this study suggested a feasible disposal method for metal rich plants after phytoremediation.

Elevated lead levels from e-waste exposure are linked to decreased olfactory memory in children

Lead (Pb) is a developmental neurotoxicant and can cause abnormal development of the nervous system in children. Hence, the aim of this study was to investigate the effect of Pb exposure on child olfactory memory by correlating the blood Pb levels of children in Guiyu with olfactory memory tests. We recruited 61 preschool children, 4- to 7-years of age, from Guiyu and 57 children from Haojiang. The mean blood Pb level of Guiyu children was 9.40 μg/dL, significantly higher than the 5.04 μg/dL mean blood Pb level of Haojiang children. In addition, approximately 23% of Guiyu children had blood Pb levels exceeding 10.00 μg/dL. The correlation analysis showed that blood Pb levels in children highly correlated with e-waste contact (r_s = 0.393). Moreover, the mean concentration of serum BDNF in Guiyu children (35.91 ng/ml) was higher than for Haojiang (28.10 ng/ml) and was positively correlated with blood Pb levels. Both item and source olfactory memory tests at 15 min, 5 h and 24 h after odor exposure showed that scores were lower in Guiyu children indicative of reduced olfactory memory in Guiyu children. Olfactory memory tests scores negatively correlated with blood Pb and serum BDNF levels, but were positively associated with parental education levels. At the same time, scores of both tests on children in the high blood Pb level group (blood Pb levels > 5.00 μg/dL) were lower than those in the low blood Pb level group (blood Pb levels ≤ 5.00 μg/dL), implying that Pb exposure decreases olfactory memory in children. Our findings suggest that Pb exposure in e-waste recycling and dismantling areas could result in an increase in serum BDNF level and a decrease in child olfactory memory, in addition, BDNF might be involved in olfactory memory impairment.

The evaluation of polycyclic aromatic hydrocarbons (PAHs) biodegradation kinetics in soil amended with organic fertilizers and bulking agents

The aim of this study was to investigate the polycyclic aromatic hydrocarbons (PAHs) biodegradation kinetics in soils fertilized with organic amendments (sewage sludge, compost), bulking agents (mineral sorbent, silicon dioxide in form of nano powder), and novel compositions of those materials. The scope of conducted works includes a cyclic CO₂ production measurements and the determinations of PAHs content in soil samples, before and after 3-months of incubation. Obtained results show that the use of both type of organic fertilizers have a positive effect on the PAHs removal from soil. However, the CO₂ emission remains higher only in the first stage of the process. The best acquired means in terms of PAHs removal as well as most sustained CO₂ production were noted in samples treated with the mixtures of organic fertilizers and bulking agents. In conclusion the addition of structural forming materials to the organic fertilizers was critical for the soil bioremediation efficiency. Therefore, the practical implementation of collected data could find a wide range of applications during the design of new, more effective solutions for the soil bioremediation purposes.

Heavy Metals and Polycyclic Aromatic Hydrocarbons in Soil from E-waste Dumpsites in Lagos and Ibadan, Nigeria

BACKGROUND

Soil contamination from heavy metals and polycyclic aromatic hydrocarbons (PAHs) released during informal e-waste processing and disposal poses human and ecological health risks in Nigeria.

OBJECTIVES

This study assesses the levels of heavy metals and PAHs in soils of e-waste dumpsites in Lagos and Ibadan, Nigeria.

METHODS

Composite soil samples were collected at depths of 0-15 cm, 15-30 cm and 30-45 cm from major e-waste dumpsites in Lagos and Ibadan and analyzed for lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr) and PAHs to evaluate the potential contaminant contribution from e-waste activities. Control samples were collected at the Botanical Garden, University of Ibadan. Samples were analyzed for heavy metals after acid digestion using atomic absorption spectrophotometry, while PAHs were extracted using cold solvent extraction and quantified by gas chromatography-mass spectrometry. Blank determination and recovery studies were carried out for each metal. Contamination and ecological risks were assessed using soil contamination indices such as contamination factor, geo-accumulation and pollution load indices, and potential ecological risk index to categorize contaminant concentrations and associated impacts. Soil physico-chemical characteristics such as pH and total organic matter were also determined.

RESULTS

Metals concentrations in the dumpsite soils ranged from 114-2,840 mg/kg and not detectable - 6.50 mg/kg for Pb and Cd, and 42.8-5,390 mg/kg, 27.5-3,420 mg/kg, 11.0-128 mg/kg and 94.0-325 mg/kg for Cu, Zn, Ni and Cr, respectively. Serious metals accumulation was observed at every e-waste dumpsite, as shown by the pollution load index. The potential ecological risk values were between 584 and 10,402 at all of the dumpsites, signifying very high ecological risk. The total PAHs ranged from 1,756-2,224 μg/kg at the 0-15 cm level, 1,664-2,152 μg/kg at 15-30 cm and 278 μg/kg in the top- and sub-soil of the control site.

DISCUSSION

The total PAHs in the soil of e-waste dumpsites was significantly higher than in the control soil.

CONCLUSIONS

The results of this study indicate that indiscriminate dumping and open burning of e-waste are potential sources of PAH and toxic metal emissions, which can pose serious human health and ecological risks.

Occurrence, profiles, and toxic equivalents of chlorinated and brominated polycyclic aromatic hydrocarbons in E-waste open burning soils

We conducted this study to assess the occurrence, profiles, and toxicity of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) and brominated polycyclic aromatic hydrocarbons (Br-PAHs) in e-waste open burning soils (EOBS). In this study, concentrations of 15 PAHs, 26 Cl-PAHs and 14 Br-PAHs were analyzed in EOBS samples. We found that e-waste open burning is an important emission source of Cl-PAHs and Br-PAHs as well as PAHs. Concentrations of total Cl-PAHs and Br-PAHs in e-waste open burning soil samples ranged from 21 to 2800 ng/g and from 5.8 to 520 ng/g, respectively. Compared with previous studies, the mean of total Cl-PAH concentrations of the EOBS samples in this study was higher than that of electronic shredder waste, that of bottom ash, and comparable to fly ash from waste incinerators in Korea and Japan. The mean of total Br-PAH concentrations of the EOBS samples was generally three to four orders of magnitude higher than those in incinerator bottom ash and comparable to incinerator fly ash, although the number of Br-PAH congeners measured differed among studies. We also found that the Cl-PAH and Br-PAH profiles were similar among all e-waste open burning soil samples but differed from those in waste incinerator fly ash. The profiles and principal component analysis results suggested a unique mechanism of Cl-PAH and Br-PAH formation in EOBS. In addition, the Cl-PAHs and Br-PAHs showed high toxicities equivalent to PCDD/Fs measured in same EOBS samples when calculated based on their relative potencies to benzo[a]pyrene. Along with chlorinated and brominated dioxins and PAHs, Cl-PAHs and Br-PAHs are important environmental pollutants to investigate in EOBS.

Accumulation of polybrominated diphenyl ethers in breast milk of women from an e-waste recycling center in China

Polybrominated diphenyl ethers (PBDEs) can be transferred to infants through the ingestion of breast milk, resulting in potential health risk. In this study, PBDEs, hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and 2,2',4,4',5,6'-hexachlorobiphenyl (CB-153) in human milk from women living adjacent to e-waste recycling sites of Wenling, China, were investigated. The median level of PBDEs in samples from residents living in the e-waste recycling environment >20years (R₂₀ group, 19.5ng/g lipid weight (lw)) was significantly higher than that for residents living in Wenling <3years (R₃ group, 3.88ng/g lw) (p<0.05), likely ascribable to specific exposure to PBDEs from e-waste recycling activities. In the R₂₀ group, most congeners (except for BDE-209) were correlated with each other (p<0.05). Moreover, CB-153 showed significant association with most PBDE congeners, rather than BDE-209. The relationship indicated that most BDE congeners other than BDE-209 shared common sources and/or pathways with CB-153, e.g., dietary ingestion. The correlations between BDE-209 and other congeners were different in the two groups, likely suggesting their different exposure sources and/or pathways for PBDEs. Although estimated dietary intake of PBDEs for infants via breast milk was lower than the minimum value affecting human health, the PBDE exposure of infants should be of great concern because of their potential effect on the development of neonates over long-term exposure. OH-PBDEs were not detected in the collected samples, which is in accordance with reports in published literature, likely indicating that they were not apt to be accumulated in human milk.

The assessment of source attribution of soil pollution in a typical e-waste recycling town and its surrounding regions using the combined organic and inorganic dataset

Guiyu is a well-known electronic waste dismantling and recycling town in south China. Concentrations and distribution of the 21 mineral elements and 16 polycyclic aromatic hydrocarbons (PAHs) collected there were evaluated. Principal component analyses (PCA) applied to the data matrix of PAHs in the soil extracted three major factors explaining 85.7% of the total variability identified as traffic emission, coal combustion, and an unidentified source. By using metallic or metalloid element concentrations as variables, five principal components (PCs) were identified and accounted for 70.4% of the information included in the initial data matrix, which can be denoted as e-waste dismantling-related contamination, two different geological origins, anthropogenic influenced source, and marine aerosols. Combining the 21 metallic and metalloid element datasets with the 16 PAH concentrations can narrow down the coarse source and decrease the unidentified contribution to soil in the present study and therefore effectively assists the source identification process.

Polycyclic aromatic hydrocarbon concentrations, compositions, sources, and associated carcinogenic risks to humans in farmland soils and riverine sediments from Guiyu, China

The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were measured in 23 farmland soil samples and 10 riverine sediment samples from Guiyu, China, and the carcinogenic risks associated with PAHs in the samples were evaluated. Guiyu is the largest electronic waste (EW) dismantling area globally, and has been well known for the primitive and crude manner in which EWs are disposed, such as by open burning and roasting. The total PAH concentrations were 56-567 ng/g in the soils and 181-3034 ng/g in the sediments. The Shanglian and Huamei districts were found to be more contaminated with PAHs than the north of Guiyu. The soils were relatively weakly contaminated but the sediments were more contaminated, and sediments in some river sections might cause carcinogenic risks to the groundwater system. The PAHs in the soils were derived from combustion sources, but the PAHs in the sediments were derived from both combustion and petroleum sources.

Associations between polycyclic aromatic hydrocarbon (PAH) exposure and oxidative stress in people living near e-waste recycling facilities in China

Emission of polycyclic aromatic hydrocarbons (PAHs) from e-waste recycling activities in China is known. However, little is known on the association between PAH exposure and oxidative damage to DNA and lipid content in people living near e-waste dismantling sites. In this study, ten hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) and two biomarkers [8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA)] of oxidative stress were investigated in urine samples collected from people living in and around e-waste dismantling facilities, and in reference population from rural and urban areas in China. The urinary levels of ∑10OH-PAHs determined in e-waste recycling area (GM: 25.4μg/g Cre) were significantly higher (p<0.05) than those found in both rural (11.7μg/g Cre) and urban (10.9μg/g Cre) reference areas. The occupationally exposed e-waste workers (36.6μg/g Cre) showed significantly higher (p<0.01) urinary Σ10OH-PAHs concentrations than non-occupationally exposed people (23.2μg/g Cre) living in the e-waste recycling site. The differences in urinary Σ10OH-PAHs levels between smokers (23.4μg/g Cre) and non-smokers (24.7μg/g Cre) were not significant (p>0.05) in e-waste dismantling sites, while these differences were significant (p<0.05) in rural and urban reference areas; this indicated that smoking is not associated with elevated levels of PAH exposure in e-waste dismantling site. Furthermore, we found that urinary concentrations of Σ10OH-PAHs and individual OH-PAHs were significantly associated with elevated 8-OHdG, in samples collected from e-waste dismantling site; the levels of urinary 1-hydroxypyrene (1-PYR) (r=0.284, p<0.01) was significantly positively associated with MDA. Our results indicate that the exposure to PAHs at the e-waste dismantling site may have an effect on oxidative damage to DNA among selected participants, but this needs to be validated in large studies.