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Inappropriate processing and disposal of electronic waste (e-waste) expose workers and surrounding populations to hazardous chemicals, including clastogens and aneugens. Recently, considerable literature has grown around e-waste recycling, associated chemical exposures and intermediate health outcomes, including DNA damage. Micronuclei (MN) frequency has been widely used as a biomarker to investigate DNA damage in human populations exposed to genotoxic agents. We conducted a systematic review of published studies to assess DNA damage in e-waste-exposed populations and performed a meta-analysis to evaluate the association between e-waste exposure and DNA damage. This systematic review with meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement checklist. Articles published in English from January 2000 through December 2020 investigating the associations between e-waste exposure and DNA damage were retrieved from the following three major databases: MEDLINE, ProQuest, and Scopus. Studies that reported the use of MN assay as a biomarker of DNA damage were included for meta-analysis. Studies that also reported other DNA damage biomarkers such as chromosomal aberrations, comet assay biomarkers, 8-hydroxy-2′-deoxyguanosine (8-OHdG), telomere length, apoptosis rate were reported using narrative synthesis. A total of 20 publications were included in this review, of which seven studies were within the occupational setting, and the remaining 13 studies were ecological studies. The review found six biomarkers of DNA damage (micronuclei, comets assay parameters (tail length, % tail DNA, tail moment, and olive tail moment), 8-OHdG, telomere length, apoptosis rate and chromosomal aberrations) which were assessed using seven different biological matrices (buccal cells, blood, umbilical cord blood, placenta, urine and semen). Most studies showed elevated levels of DNA damage biomarkers among e-waste exposed populations than in control populations. The most commonly used biomarkers were micronuclei frequency (n=9) in peripheral blood lymphocytes or buccal cells and 8-OHdG (n=7) in urine. The results of the meta-analysis showed that electronic waste recycling has contributed to an increased risk of DNA damage measured using MN frequency with a pooled estimate of the standardized mean difference (SMD) of 2.30 (95% CI: 1.36, 3.24, p<0.001) based on 865 participants. Taken together, evidence from this systematic review with meta-analysis suggest that occupational and non-occupational exposure to e-waste processing is associated with increased risk of DNA damage measured through MN assay and other types of DNA damage biomarkers. However, more studies from other developing countries in Africa, Latin America, and South Asia are needed to confirm and increase these results' generalizability. [ABSTRACT FROM AUTHOR]

This study examined the associations between PM (2.5 and 10) and global DNA methylation among 100 e-waste workers and 51 non-e-waste workers serving as controls. Long interspersed nucleotide repetitive elements-1 (LINE-1) was measured by pyrosequencing. Personal PM2.5 and PM10 were measured over a 4-hour work-shift using real-time particulate monitors incorporated into a backpack. Linear regression models were used to assess the association between PM and LINE-1 DNA methylation. The concentrations of PM2.5 and PM10 were significantly higher among the e-waste workers than the controls (77.32 vs 34.88, p < 0.001 and 210.21 vs 121.92, p < 0.001, respectively). PM2.5 exposure was associated with increased LINE-1 CpG2 DNA methylation (β = 0.003; 95% CI; 0.001, 0.006; p = 0.022) but not with the average of all 4 CpG sites of LINE-1. In summary, high levels of PM2.5 exposure was associated with increased levels of global DNA methylation in a site-specific manner. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the effects of temperature on the development of the immature stages of Anopheles gambiae (s.l.) mosquitoes. Methods: Mosquito eggs were obtained from laboratory established colonies and reared under eight temperature regimes (25, 28, 30, 32, 34, 36, 38 and 40°C), and 80 ± 10% relative humidity. Larvae were checked daily for development to the next stage and for mortality. Pupation success, number of adults produced and sex ratio of the newly emerged adults were recorded. Larval survival was monitored every 24 h, and data were analysed using Kaplan–Meier survival analysis. Analysis of variance was used where data followed normal distribution, and a Kruskal–Wallis test where data were not normally distributed. Larval and pupal measurements were log‐transformed and analysed using ordinary least square regression with robust standard errors. Results: Increasing the temperature from 25 to 36°C decreased the development time by 10.57 days. Larval survival (X2(6) = 5353.12, p < 0.001) and the number of adults produced (X2(5) = 28.16, p < 0.001) decreased with increasing temperature. Increasing temperatures also resulted in significantly smaller larvae and pupae (p < 0.001). At higher temperatures, disproportionately more male than female mosquitoes were produced. Conclusions: Increased temperature affected different developmental stages in the life cycle of An. gambiae (s.l.) mosquitoes, from larval to adult emergence. This study contributes to the knowledge on the relationship between temperature and Anopheles mosquitoes and provides useful information for modelling vector population dynamics in the light of climate change. [ABSTRACT FROM AUTHOR]