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Chronic exposure to inorganic arsenic (In-As) from drinking water is associated with different health effects, including skin, lung, bladder, and kidney cancer as well as vascular and possibly reproductive effects. In-As is metabolized through the process of methylation, resulting in the production and excretion of methylated species, mainly monomethylarsenate (MMA) and dimethylarsenate (DMA). Because a large percentage of the dose is excreted in urine, the distribution of urinary In-As, MMA, and DMA is considered a useful indicator of methylation patterns in human populations. Several factors affect these patterns, including sex and exposure level. In this study, we investigated the profile of urinary In-AS, MMA, and DMA of pregnant women. Periodic urine samples were collected from early to late pregnancy among 29 pregnant women living in Antofagasta, Chile, who drank tap water containing 40 µg/L In-As. The total urinary arsenic across four sampling periods increased with increasing weeks of gestation, from an initial mean value of 36.1 to a final value of 54.3 µg/L. This increase was mainly due to an increase in DMA, resulting in lower percentages of In-As and MMA and a higher percentage of DMA. Our findings indicate that among women exposed to moderate arsenic from drinking water during pregnancy, changes occur in the pattern of urinary arsenic excretion and metabolite distribution. The toxicologic significance of this is not clear, given recent evidence suggesting that intermediate methylated species may be highly toxic. Nevertheless, this study suggests that arsenic metabolism changes throughout the course of pregnancy, which in turn may have toxicologic effects on the developing fetus. [ABSTRACT FROM AUTHOR]

Objective: Arsenic is associated with numerous health effects. We investigated the association between arsenic exposure from drinking water and anemia during pregnancy., Methods: We conducted a prospective cohort pregnancy study in two Chilean cities with contrasting drinking water arsenic levels: 40 microg/L versus <1 microg/L. This analysis included 810 women who gave birth to live, singleton infants and had at least one hemoglobin determination during pregnancy., Results: Arsenic exposed women were more likely to be anemic during pregnancy after adjusting for other factors. Furthermore, as pregnancy progressed, the prevalence of anemia rose more sharply among those in the exposed versus unexposed city: 49% versus 17%., Conclusion: This study suggests an association between moderate arsenic in drinking water and anemia during pregnancy. Further research is needed to identify the specific types of anemia underlying the association.

Inorganic arsenic (In-As) is a well-known toxicant and carcinogen found naturally in surface and groundwater around the world. Exposure can cause skin lesions, adverse reproductive outcomes, and cancer. There are two main pathways of arsenic (As) metabolism in humans: the reduction reactions, and the oxidative methylation reactions, where methyl groups are attached to As compounds to form monomethylarsenate (MMA) and dimethylarsenate (DMA). MMA, DMA, and In-As are excreted in urine. Urinary levels of another metalloid, selenium (Se), have recently been shown to be associated with increased As excretion and altered metabolite distribution. This study investigates this association, using data collected in a larger prospective study of arsenic and reproductive effects in Chile. This analysis included 93 pregnant women from Antofagasta. Data on demographic, behavioral, and other characteristics were obtained via interviews conducted by trained midwives, and spot urine samples were analyzed for As and Se concentration using inductively coupled plasma-mass spectrometry (ICP-MS). Urinary Se levels were found to be correlated with urinary As levels in bivariate analysis (r = 0.68, P < 0.01). Multiple linear regression analyses revealed that higher urinary Se levels were associated with increased urinary As excretion, increased %DMA, and decreased %In-As. The results of this study suggest that in populations exposed to arsenic, Se intake may be correlated with urinary As excretion, and may alter As methylation.

Background: Arsenic exposures from drinking water increase the risk of various cancers and noncancer health endpoints. Limited evidence suggests that arsenic may have adverse human reproductive effects. We investigated the association between drinking water arsenic exposure and fetal growth, as manifest in birth weight., Methods: We conducted a prospective cohort study in two Chilean cities with contrasting drinking water arsenic levels: Antofagasta (40 micro g/L) and Valparaíso (<1 micro g/L). Study subjects completed in-depth interviews and provided urine samples for exposure analysis. We obtained pregnancy and birth information from medical records. The birth weight analysis was restricted to liveborn, singleton infants born between December 1998 and February 2000., Results: The final study group consisted of 424 infants from Antofagasta and 420 from Valparaíso. After controlling for confounders, results of the multivariable analysis indicated that Antofagasta infants had lower mean birth weight (-57 g; 95% confidence interval = -123 to 9)., Conclusion: This study suggests that moderate arsenic exposures from drinking water (<50 micro g/L) during pregnancy are associated with reduction in birth weight, similar in magnitude to that resulting from other environmental exposures such as environmental tobacco smoke and benzene.