Elevated arsenic exposure and efficient arsenic metabolism in indigenous women around Lake Poopó, Bolivia

Jessica De Loma,Noemi Tirado,Franz Ascui,Michael Levi,Marie Vahter,Karin Broberg,Jacques Gardon

doi:10.1016/j.scitotenv.2018.11.473

Abstract

Elevated concentrations of inorganic arsenic, one of the most potent environmental toxicants and carcinogens, have been detected in well water around Lake Poopó, Bolivia. This study aimed to assess human exposure to arsenic in villages around Lake Poopó, and also to elucidate whether the metabolism and detoxification of arsenic in this population is as efficient as previously indicated in other Andean areas. We recruited 201 women from 10 villages around Lake Poopó. Arsenic exposure was determined as the sum concentration of arsenic metabolites (inorganic arsenic; monomethylarsonic acid, MMA; and dimethylarsinic acid, DMA) in urine (U-As), measured by HPLC-HG-ICP-MS. Efficiency of arsenic metabolism was assessed by the relative fractions of the urinary metabolites. The women had a wide variation in U-As (range 12–407 μg/L, median 65 μg/L) and a markedly efficient metabolism of arsenic with low %MMA (median 7.7%, range: 2.2–18%) and high %DMA (80%, range: 54–91%) in urine. In multivariable-adjusted linear regression models, ethnicity (Aymara-Quechua vs. Uru), body weight, fish consumption and tobacco smoking were associated with urinary arsenic metabolite fractions. On average, the Uru women had 2.5 lower % (percentage unit) iAs, 2.2 lower %MMA and 4.7 higher %DMA compared with the Aymara-Quechua women. Our study identified several factors that may predict these women's arsenic methylation capacity, particularly ethnicity. Further studies should focus on mechanisms underlying these differences in arsenic metabolism efficiency, and its importance for the risk of arsenic-related health effects.

Highlights

Arsenic concentrations in drinking water above the WHO guideline of 10 μg/L affect an estimated number of 140 million people worldwide (Ravenscroft et al, 2009)
Arsenic is a potent group 1 carcinogen (IARC, 2012), which has been associated with nephrotoxicity, diabetes, and cardiovascular, pulmonary and skin diseases (Minatel et al, 2018)
84% of the women were of AymaraQuechua ethnicity, the rest being of Uru ethnicity

Summary

Introduction

Arsenic concentrations in drinking water above the WHO guideline of 10 μg/L affect an estimated number of 140 million people worldwide (Ravenscroft et al, 2009). In Latin America, elevated water arsenic concentrations, usually from natural-occurring volcanic sources, have been described in 14 out of 20 Latin American countries, and N10 million people are estimated to be exposed to arsenic (Bundschuh et al, 2012). The actual human exposure to arsenic of people living in this area has not been studied. Very limited studies have described human arsenic exposure in Bolivia (Archer et al, 2005; Smolders et al, 2006)

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