Abstract
Chronic inorganic arsenic (iAs) exposure currently affects tens of millions of people worldwide. To accurately determine the proportion of urinary arsenic metabolites in residents continuously exposed to iAs, we performed arsenic speciation analysis of the urine of these individuals and determined whether a correlation exists between the concentration of iAs in drinking water and the urinary arsenic species content. The subjects were 165 married couples who had lived in the Pabna District in Bangladesh for more than 5 years. Arsenic species were measured using high-performance liquid chromatography and inductively coupled plasma mass spectrometry. The median iAs concentration in drinking water was 55 μgAs/L (range <0.5-332 μgAs/L). Speciation analysis revealed the presence of arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid in urine samples with medians (range) of 16.8 (7.7-32.3), 1.8 (<0.5-3.3), 13.7 (5.6-25.0), and 88.6 μgAs/L (47.9-153.4 μgAs/L), respectively. No arsenobetaine or arsenocholine was detected. The concentrations of the 4 urinary arsenic species were significantly and linearly related to each other. The urinary concentrations of total arsenic and each species were significantly correlated with the iAs concentration of drinking water. All urinary arsenic species are well correlated with each other and with iAs in drinking water. The most significant linear relationship existed between the iAs concentration in drinking water and urinary iAs + MMA concentration. From these results, combined with the effects of seafood ingestion, the best biomarker of iAs exposure is urinary iAs + MMA concentration.
Highlights
In Bangladesh, the United Nations International Children’s Emergency Fund (UNICEF) and other nongovernmental organizations encouraged a massive shift from drinking microbially contaminated surface water to groundwater accessed by tube wells to reduce infant mortality associated with diarrheal diseases in the 1960s
To accurately determine the proportion of urinary arsenic metabolites in residents continuously exposed to inorganic arsenic (iAs), we performed arsenic speciation analysis of the urine of these individuals and determined whether a correlation exists between the concentration of iAs in drinking water and the urinary arsenic species content
The urinary concentrations of total arsenic and each species were significantly correlated with the iAs concentration of drinking water
Summary
In Bangladesh, the United Nations International Children’s Emergency Fund (UNICEF) and other nongovernmental organizations encouraged a massive shift from drinking microbially contaminated surface water to groundwater accessed by tube wells to reduce infant mortality associated with diarrheal diseases in the 1960s. The International Agency for Research on Cancer (IARC) concludes that there is sufficient epidemiological evidence for the toxicity of iAs in humans such as carcinogenicity of the lungs, skin, and urinary bladder [4]. Methylation of iAs to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) has been demonstrated in humans and several mammalian species [5]. These metabolites are less reactive in tissue constituents than iAs and are readily excreted in urine. In 2010, the IARC classified MMA and DMA as group 2B compounds, and arsenobetaine (AsBe) and other organic arsenic compounds that are not metabolized in humans as group 3 compounds [10]. Because HPLC-ICPMS analysis can determine whether subjects have ingested seafood and the presence or absence of arsenic metabolites more precisely than hydride generation atomic absorption spectrophotometry (HG-AAS), HPLC-ICP-MS is indispensable for biological monitoring of residents exposed to iAs
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