Methylmercury Measurements in Dried Blood Spots from Electronic Waste Workers Sampled from Agbogbloshie, Ghana

Abstract

Biomonitoring methylmercury (MeHg) exposure is problematic in resource-limited settings and with difficult-toaccess populations where traditional biomarker approaches present logistical, economic, and ethical issues. The present study aimed to validate the use of dried blood spots (DBS) to assess MeHg exposure in a real-world contaminated field setting. Whole-blood and DBS samples were collected from electronic waste workers (n = 20) from Agbogbloshie (Ghana) in 2017, and DBS were also artificially created in the laboratory using the field-collected blood. Whole-blood MeHg concentrations averaged 0.84 µg/L, which was not different from levels measured in the corresponding DBS samples (field-collected or artificially created). Whole-blood MeHg comprised 61% of the blood total Hg concentrations. Linear regression analysis revealed no differences in MeHg concentrations between whole-blood samples and field-collected DBS (slope 0.89, R 2 = 0.94) and between field and laboratory DBS (slope 0.89, R 2 = 0.96). The MeHg content in DBS punch blanks averaged 0.86 pg and thus was not of concern. These findings indicate that DBS are a suitable tool for assessing MeHg exposure in real-world environmental settings that may be heavily contaminated.

A state-of-the-science review and guide for measuring environmental exposure biomarkers in dried blood spots

“…Sample field blanks averaged 0.15 ± 0.19 and 1.77 ± 4.06 µg/L for Me-Hg and I-Hg, respectively. There is a need for Hg speciation Used DBS assay developed by Santa-Rios et al (2020) [ 47 ] Santa-Rios 2021 [ 70 ] Me-Hg 20 electronic waste workers (Ghana) Cross-sectional Me-Hg detected in nearly all samples; excellent agreement with venous blood values; Me-Hg contamination was low in contaminated field setting Used DBS assay developed by Santa-Rios et al (2021) [ 47 ] Spliethoff 2008 [ 92 ] PFOS, PFOSA, PFHxS, PFOA, PFNA 110 pooled NDBS sample composites representing 2640 infants (New York state) Temporal biomonitoring (1997–2007) PFOS, PFOSA, PFHxS, PFOA showed exponential declines after the year 2000; DF >90% for all analytes Included initial method development and validation using spiked DBS samples Pooled composite samples were 24 ×;6-mm diameter punches (~322 µL blood) Ma 2013 [ 93 ] PBDE congeners 51 pooled NDBS sample composites representing 1224 infants Temporal biomonitoring (1997–2011) PBDE exposure declined after 2004; DF 86%, 45%, and 43% for BDEs-47, -99, and -100, respectively. LOQs 0.003, 0.008, 0.008 ng/mL, respectively Included initial method development and validation using spiked DBS samples Pooled samples were equivalent to 24 ×;6-mm diameter DBS punches (~322 µL blood) Ma 2014 [ 90 ] PCBs and OCPs 51 pooled NDBS sample composites representing 1224 infants Temporal biomonitoring (1997–2011) PCBs and p,p’-DDE significantly declined from 1997 to 2001 with p,p’-DDE showing continued significant declines through 2011; >50% DF for 12 PCBs and 2 OCPs Included initial method development and validation using spiked DBS samples Pooled samples were equivalent to 24 × 6-mm diameter DBS punches (~322 µL blood) Bell 2018 [ 94 ] PFOS, PFOA, BPA 3111 NDBS samples (Upstate KIDS study, 2008–2010) Longitudinal birth cohort study PFOS, PFOA not associated with birth size independent of plurality; BPA negatively associated with birth size in twins.…”

“…Santa-Rios et al also extended their assay [ 47 ] to measure Me-Hg in DBS samples collected from electronic waste workers ( n = 20) in Ghana [ 70 ]. DBS samples and venous blood were collected from the same study participants.…”

“…T-Hg was measured in venous blood samples. Only one sample fell below the MDL for Me-Hg [ 70 ]. There was excellent agreement between Me-Hg values measured in field-collected DBS samples, artificially created DBS samples, and gold standard venous blood samples [ 70 ].…”

“…Only one sample fell below the MDL for Me-Hg [ 70 ]. There was excellent agreement between Me-Hg values measured in field-collected DBS samples, artificially created DBS samples, and gold standard venous blood samples [ 70 ]. Average Me-Hg concentrations were ~0.84 µg/L and Me-Hg speciation was 61% [ 70 ].…”

Metal Exposures, Noise Exposures, and Audiometry from E-Waste Workers in Agbogbloshie, Ghana

“…Some recent literature has explored metals and metalloids in the blood of e-waste workers [88][89][90]. One study examined levels of numerous trace elements in their urine and this study found high levels of As, which was not found to be due to drinking water, but likely fish and shellfish sources [42].…”