Mobility, spatial variation and human health risk assessment of mercury in soil from an informal e-waste recycling site, Lagos, Nigeria.

Spatial variations and mobility of mercury (Hg) and Hg associations with other potentially toxic elements (PTEs) were studied in soil samples from Alaba, the largest e-waste recycling site in Nigeria and West Africa. Total Hg concentration was determined in surface soil samples from various locations using cold vapour atomic absorption spectrometry (CVAAS) following microwave-assisted acid extraction, while sequential extraction was used to determine operationally defined mobility. The concentrations of the PTEs arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) metals were determined using inductively coupled plasma mass spectrometry (ICP-MS) following microwave-assisted digestion with aqua regia. Total Hg concentration ranged from < 0.07 to 624 mg/kg and was largely dependent on the nature and intensity of e-waste recycling activities carried out. Mobile forms of Hg, which may be HgO (a known component of some forms of e-waste), accounted for between 3.2 and 23% of the total Hg concentration, and were observed to decrease with increasing organic matter (OM). Non-mobile forms accounted for >74% of the total Hg content. In the main recycling area, soil concentrations of Cd, Cd, Cu, Hg, Mn, Ni, Pb and Zn were above soil guideline values (Environment Agency in Science Report, 2009; Kamunda et al., 2016). Strong associations were observed between Hg and other PTEs (except for Fe and Zn) with the correlational coefficient ranging from 0.731 with Cr to 0.990 with As in April, but these correlations decreased in June except for Fe. Hazard quotient values > 1 at two locations suggest that Hg may pose health threats to people working at the e-waste recycling site. It is therefore recommended that workers should be investigated for symptoms of Hg exposure.

Assessment of legacy and alternative halogenated organic pollutants in outdoor dust and soil from e-waste sites in Nigeria: Concentrations, patterns, and implications for human exposure.

E-waste is often processed informally, particularly in developing countries, resulting in the release of harmful chemicals into the environment. This study investigated the co-occurrence of selected persistent organic pollutants (POPs), including legacy and alternative halogenated flame retardants (10 polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), syn and anti-dechlorane plus (DP)), 32 polychlorinated biphenyls (PCBs) and 12 organochlorine pesticides (OCPs), in 20 outdoor dust and 49 soil samples from 7 e-waste sites in Nigeria. This study provides the first report on alternative flame retardants (DBDPE and DP) in Nigeria. The total concentration range of the selected classes of compounds was in the order: ∑10PBDEs (44-12300 ng/g) > DBDPE (4.9-3032 ng/g) > ∑2DP (0.7-278 ng/g) > ∑32PCBs (4.9-148 ng/g) > ∑12OCPs (1.9-25 ng/g) for dust, and DBDPE (4.9-9647 ng/g) > ∑10PBDEs (90.3-7548 ng/g) > ∑32PCBs (6.1-5025 ng/g) > ∑12OCPs (1.9-250 ng/g) > ∑2DP (2.1-142 ng/g) for soil. PBDEs were the major contributors to POP pollution at e-waste dismantling sites, while PCBs were the most significant contributors at e-waste dumpsites. DBDPE was found to be significantly associated with pollution at both e-waste dismantling and dumpsites. Estimated daily intake (EDI) via dust and soil ingestion and dermal adsorption routes ranged from 1.3 to 2.8 ng/kg bw/day and 0.2-2.9 ng/kg bw/day, respectively. In the worst-case scenario, EDI ranged from 2.9 to 10 ng/kg bw/day and 0.8-5.8 ng/kg bw/day for dust and soil, respectively. The obtained intake levels posed no non-carcinogenic risk, but could increase the incidence of cancer at some of the studied e-waste sites, with values exceeding the USEPA cancer risk lower limit (1.0 × 10-6). Overall, our results suggest that e-waste sites act as emission point sources of POPs.

Source identification and human exposure assessment of organophosphate flame retardants and plasticisers in soil and outdoor dust from Nigerian e-waste dismantling and dumpsites.

Electronic waste (e-waste) dismantling and dumpsite processes are major sources of organophosphate flame retardant and plasticiser emissions and may pose potentially adverse effects on environment and human health. In 20 outdoor dust and 49 soil samples collected from four e-waste dismantling and three e-waste dumpsites in two States of Nigeria (Lagos and Ogun), we identified 13 alternative plasticisers (APs), 7 legacy phthalate plasticisers (LPs), and 17 organophosphorus flame retardants (OPFRs) for the first time in African e-waste streams. In the samples from dismantling sites, the range (median) concentrations of ∑13APs, ∑7LPs, and ∑17OPFRs were 11-2747 µg/g (144 µg/g), 11-396 µg/g (125 µg/g), and 0.2-68 µg/g (5.5 µg), in dust respectively and 1.8-297 µg/g (55 µg/g), 1.3-274 µg/g (48.5 µg/g), and 1.6-62 µg/g (1.6 µg/g), in soil respectively. Results for soil samples from e-waste dumpsites were (6.6-195 µg/g (23.7 µg/g), 6.0-295 µg/g (54.8), and 0.4-42.3 µg/g (9.0 µg/g) for ∑13APs, ∑7LPs, and ∑17OPFRs respectively. Overall, concentrations of APs were significantly higher at the dismantling sites (p = 0.005) compared to dumpsites, levels of LPs were higher at dismantling sites but not significant, while OPFR concentrations were significantly higher in dumpsite samples (p = 0.005). Plasticisers were found to be major contributors to pollution at e-waste dismantling sites, while OPFRs were associated with both automobile dismantling and e-waste dumpsite processes. Following particle size fractionation of selected soil samples, higher concentrations of targeted compounds were observed in the smaller mesh (180 µm) soil sieve fraction. For dust, the total median estimated daily intake via ingestion and dermal adsorption (EDIing and EDIderm) ranged from 43 to 74 ng/kg bw/day and 0.4-0.7 ng/kg bw/day, respectively. Correspondingly, 4.6-45 ng/kg bw/day and 0.015-0.57 ng/kg bw/day were the values found for soil, respectively. According to these results, the targeted chemicals do not appear to pose a non-carcinogenic risk to e-waste workers through ingestion or dermal contact of bio-accessible fractions of the chemicals. Human biomonitoring campaigns are recommended in the Nigerian e-waste environment considering the elevated concentration levels found for the majority of targeted compounds and that risk parameters required for exposure assessment were only available for a limited number of compounds.

Wastewater-based epidemiology for the assessment of population exposure to chemicals: The need for integration with human biomonitoring for global One Health actions.

WBE has now become a complimentary tool in SARS-CoV-2 surveillance. This was preceded by the established application of WBE to assess the consumption of illicit drugs in communities. It is now timely to build on this and take the opportunity to expand WBE to enable comprehensive assessment of community exposure to chemical stressors and their mixtures. The goal of WBE is to quantify community exposure, discover exposure-outcome associations, and trigger policy, technological or societal intervention strategies with the overarching aim of exposure prevention and public health promotion. To achieve WBE's full potential, the following key aspects require further action: (1) Integration of WBE-HBM (human biomonitoring) initiatives that provide comprehensive community-individual multichemical exposure assessment. (2) Global WBE monitoring campaigns to provide much needed data on exposure in low- and middle-income countries (LMICs) and fill in the gaps in knowledge especially in the underrepresented highly urbanised as well as rural settings in LMICs. (3) Combining WBE with One Health actions to enable effective interventions. (4) Advancements in new analytical tools and methodologies for WBE progression to enable biomarker selection for exposure studies, and to provide sensitive and selective multiresidue analysis for trace multi-biomarker quantification in a complex wastewater matrix. Most of all, further developments of WBE needs to be undertaken by co-design with key stakeholder groups: government organisations, health authorities and private sector.

Concentrations and Toxic Implications of Dioxin-Like Polychlorinated Biphenyls in Soil Samples from Electrical Power Stations in Lagos, Nigeria.

Dioxin-like polychlorinated biphenyls (dl-PCBs) are ubiquitous chemicals which mediate toxicity in a way similar to polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans. In silico modeling was used to predict the absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of eight dioxin-like PCBs in soil samples of 12 power stations in Lagos, Nigeria. Concentrations of Σdl-PCB8 in soil samples ranged from 490 to 61,000 pg g-1 , with mean concentrations of 17,000 pg g-1 . The corresponding toxic equivalent (TEQ) concentrations of Æ©dl-PCB8 ranged from 0.01 to 450 pg TEQ g-1 , with a mean value of 42 pg TEQ g-1 . Mean TEQ concentrations for Æ©dl-PCB8 in soil samples from all but one of the sites exceeded the Canadian guideline value of 4 pg TEQ g-1 and the US and German guideline values of 5-10 pg TEQ g-1 . However, the TEQ concentrations obtained were all below the US action level of 1000 pg TEQ g-1 . The ADMET predictions revealed that all studied dl-PCBs are inhibitors of three major isoforms (1A2, 2C9, and 2C19) of cytochrome P450 enzyme. Acute oral toxicity (median lethal dose) predictions revealed that all target dl-PCBs were class III compounds. Hepatotoxicity and carcinogenicity were positive, signifying that the studied compounds all have a tendency to elicit these effects. Occupational daily TEQ exposure via soil ingestion was estimated for an average adult worker weighing 70 kg. The maximum exposure obtained was 0.14 pg TEQ kg-1 body weight day-1 , which is half of the European Food Safety Authority (EFSA) tolerable daily intake (TDI) for dioxin-like compounds. This raises concern over the possible exceedance of the EFSA TDI for these workers if other dietary and nondietary exposure pathways and dioxin-like compounds are considered. Environ Toxicol Chem 2022;41:800-809. © 2021 SETAC.

Meeting sustainable development goals via robotics and autonomous systems.

Robotics and autonomous systems are reshaping the world, changing healthcare, food production and biodiversity management. While they will play a fundamental role in delivering the UN Sustainable Development Goals, associated opportunities and threats are yet to be considered systematically. We report on a horizon scan evaluating robotics and autonomous systems impact on all Sustainable Development Goals, involving 102 experts from around the world. Robotics and autonomous systems are likely to transform how the Sustainable Development Goals are achieved, through replacing and supporting human activities, fostering innovation, enhancing remote access and improving monitoring. Emerging threats relate to reinforcing inequalities, exacerbating environmental change, diverting resources from tried-and-tested solutions and reducing freedom and privacy through inadequate governance. Although predicting future impacts of robotics and autonomous systems on the Sustainable Development Goals is difficult, thoroughly examining technological developments early is essential to prevent unintended detrimental consequences. Additionally, robotics and autonomous systems should be considered explicitly when developing future iterations of the Sustainable Development Goals to avoid reversing progress or exacerbating inequalities.

An exploratory evaluation of the potential pulmonary, neurological and other health effects of chronic exposure to emissions from municipal solid waste fires at a large dumpsite in Olusosun, Lagos, Nigeria.

Open municipal solid waste (MSW) combustion is a major emission source of particulate air pollution, polycyclic aromatic hydrocarbons, and more exotic hazardous organic pollutants including polychlorinated biphenyls and brominated flame retardants. However, the adverse impact of MSW combustion emission on health among the general population is unknown. Therefore, a cross-sectional study was conducted to explore the associations between potential exposure to MSW combustion-related air pollution and symptoms of adverse health effects among residents of a community adjacent to a large open landfill in Lagos, Nigeria. Using ordinal logistic regression and controlling for age, sex, and smoking, it was observed that residence for ≥ 11 years had increased odds (p < 0.05) of daily occurrence of tingling/numbness/whiteness of fingers (2.614), headaches (2.725), memory problems (2.869), tremor/cramps (2.748), and confusion (3.033) among other symptoms. These results indicate adverse health impacts of chronic exposure to MSW combustion emission.

Children's exposure to hazardous brominated flame retardants in plastic toys.

We report concentrations of brominated flame retardants (BFRs) in 23 plastic samples from 20 new and second-hand children's toys sourced from the UK that had been previously shown to be Br-positive by XRF. The results reinforce existing evidence that the recycling of BFR-treated electronic plastics has led to the unintentional BFR contamination of articles not required to be flame-retarded. The principal BFRs detected were PBDEs (and in particular BDE-209), HBCDD and TBBP-A. PBDEs were detected in all samples with a maximum concentration of BDE-209 of 2500 mg/kg, and while TBBP-A was detected in 11 samples with a maximum concentration of 3100 mg/kg. HBCDD was detected in 14 cases and was present in four toys at concentrations (139-840 mg/kg) that would currently prevent their sale on the EU market. While estimated exposures to PBDEs via accidental ingestion of toy plastic fell well below USEPA reference doses, a child weighing 8.67 kg and ingesting 8 mg/day of a toy (the default assumption of the European Commission's Toy Safety Directive for scraped-off toy material) contaminated at our arithmetic mean concentration would be exposed to 0.2 ng/kg bw/day BDE-99. This compares closely to a health-based limit value (HBLV) proposed in The Netherlands of 0.23-0.30 ng/kg bw/day BDE-99. Of greater concern, the same child playing with a toy contaminated at the maximum concentration in this study would be exposed to 1.4 ng/kg bw/day BDE-99, thereby exceeding the HBLV. This paper is the first to consider BFR exposure via incidental ingestion of plastic from both contemporary and historical toys, revealing it to be considerable and for some children their most significant pathway of exposure.

Physico-Chemical Analysis of Wastewater Discharge from Selected Paint Industries in Lagos, Nigeria.

Effluents from the paint industry have been a major source of environmental pollution. There is a need to investigate the compliance of wastewater discharged from paint industries with regulatory standards. In response, this study evaluates the physicochemical parameters of both raw and treated wastewater, the wastewater treatment plants (WWTPs) efficiencies as well as the compliance level of five selected paint manufacturing companies in Lagos, Nigeria with some regulatory standards: Federal Ministry of Environment (FME) in Nigeria, World Health Organization (WHO) and Department of Water Affairs (DWA) in South Africa. All parameters investigated were analysed using standard methods. The values of pH, electrical conductivity (EC) and total dissolved solids (TDS) levels were in the range of 4⁻12.2, 149.1⁻881.3 mS/m and 1100⁻6510 mg/L, respectively. The range of other parameters include total suspended solids (TSS); 0⁻2470 mg/L, TS; 1920⁻6510 mg/L, chloride; 63.8⁻733.8 mg/L, dissolved oxygen (DO); 0⁻6.7 mg/L, oil and grease (O & G); 44⁻100 mg/L, biochemical oxygen demand (BOD); 162.8⁻974.7 mg/L, chemical oxygen demand (COD); 543⁻1231 mg/L, nitrates;12.89⁻211.2 mg/L, phosphate; below detection limit (bdl)⁻0.02 mg/L, sulphate; 195⁻1434 mg/L, nickel; bdl⁻1.9 mg/L while copper, lead and chromium were below detection limits. The results indicated that the WWTPs of the studied paint companies were ineffective in reducing the TS, TSS, BOD, COD and (O & G) to acceptable limits. Routine monitoring of wastewater from paint industries is therefore recommended to prevent the risk of contamination to the receiving watershed which many communities rely on as source for domestic water.

Concentrations of polychlorinated biphenyls in soil and indoor dust associated with electricity generation facilities in Lagos, Nigeria.

Concentrations of 7 indicator polychlorinated biphenyls (PCBs) were measured in dust and soil samples from 12 power stations collected over the two major seasons of the Nigerian climate. Median Æ©PCB7 concentrations in soil ranged from 2 ng/g for power station A to 220 ng/g for power station I; while those in dust ranged from 21 ng/g for power station L to 2200 ng/g for power station I. For individual congeners, median PCB concentrations ranged from 3.8 ng/g for PCB 101 to 52 ng/g for PCB 180 in dust, and <0.07 ng/g for PCB 28 to 5.9 ng/g for PCB 153 in soil. The type of power station activity exerted a significant influence on concentrations of ΣPCB7 in dust and soil (generation > transmission > distribution). Congener patterns in dust and soil samples were compared using principal component analysis (PCA) with those in transformer oil samples from 3 of the power stations studied and with common PCB mixtures (Aroclors). This revealed congener patterns in soil were more closely related to that in the transformer oil than dust. Congener patterns in most samples were similar to Aroclor 1260. Concentrations of PCBs in soil samples close to the transformers significantly exceeded those in soil sampled further away.

Polybrominated diphenyl ethers and polychlorinated biphenyls in dust from cars, homes, and offices in Lagos, Nigeria.

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in dust from 16 cars, 12 homes, and 18 offices in Lagos, Nigeria. These represent the first and second reports respectively of contamination of Nigerian indoor dust with these contaminants, and the second report on PCBs in car dust worldwide. Concentrations of BDE-47 and BDE-99 in two car dust samples (9300 and 3700 ng g(-1) for BDE-47 and 4200 and 19,000 ng g(-1) for BDE-99), are amongst the highest ever reported in car dust. ANOVA comparison with Canada, New Zealand, the UK, and the USA; reveals concentrations of BDEs-28, 49, 47, 66, 100, 99, 154, and 153 in Nigerian house dust, to be significantly lower than in Canada and the USA, with those of BDE-49 and 154 significantly lower than in New Zealand and the UK. Concentrations of BDE-209 in Nigeria were significantly lower than concentrations in the UK and the USA; while concentrations of PCB-180 were significantly greater than those in New Zealand, the UK, and the USA. Median concentrations of PCBs in cars were substantially higher than in the only previous study (in Kuwait and Pakistan). While median concentrations of PBDEs in cars generally exceeded those in homes, this was significant only for BDEs-49, 154, and 197, with concentrations in cars significantly greater than those in offices for BDEs-49 and 154. Contrastingly, concentrations of all target PCBs in offices exceeded significantly those in cars. This study underlines the truly global distribution of indoor contamination with PBDEs and PCBs.