摘要：Objectives. Elevated arsenic levels in tube-well water in Bangladesh have prompted extensive mitigation projects. We evaluated the effectiveness of long-term mitigation efforts by longitudinally measuring arsenic exposure in pregnant women and their children, the most susceptible population groups. Methods. The study was nested in a population-based nutrition intervention in Matlab, Bangladesh. Mother–child pairs (n = 1951) were followed from 2001 to 2003, beginning in early gestation and continuing to 5 years postpartum. We measured arsenic concentrations in urine (U-As) of the 5-year-old children by using high-performance liquid chromatography online with hydride generation and inductively coupled plasma mass spectrometry and compared them with earlier childhood U-As and maternal U-As during pregnancy. Results. Children had elevated U-As at 5 years old (median = 51 μg/L, 5th–95th percentiles = 16–355 μg/L), and U-As distribution was similar to that observed in the mothers during gestation. Children's U-As at 5 years old significantly correlated with their U-As at 1.5 years old and to maternal U-As during early and late gestation. Conclusions. Despite major mitigation efforts, arsenic exposure remains highly elevated in rural Bangladesh. Further mitigation strategies are required and must be rigorously evaluated for long-term efficacy. Hundreds of millions of people worldwide are chronically exposed to inorganic arsenic, primarily through consumption of contaminated drinking water. Arsenic is a potent human carcinogen that also causes numerous noncancer health effects. 1 Recent studies showed that fairly low arsenic exposures during pregnancy are associated with higher rates of fetal loss during pregnancy, infant death, low birth weight, and adverse effects on child development. 2 – 5 Because of the severe health consequences of arsenic exposure, extensive arsenic remediation efforts have been undertaken in countries such as Bangladesh that are severely affected by high arsenic concentrations in drinking water. A recent review of the extensive nationwide screening of arsenic in tube-well water in Bangladesh concluded that, although some 20 million Bangladeshis are estimated to have ready access to contaminated well water (> 50 μg As/L), many of these people have undoubtedly changed their water source to a new or existing “arsenic-free” (< 50 μg As/L) water source. 6 Unfortunately, assessments of intervention programs most often relied solely on interviews with participants and sampling of drinking water, without assessing the actual ingested dose. Matlab, a rural area 53 kilometers southeast of Dhaka, the capital of Bangladesh, is one of the areas most severely affected by arsenic in ground water. 7 The main reason is its location along the large Meghna River, which receives its water from the Ganges and Brahmaputra Rivers, bringing arsenic and other minerals from the Himalayan mountains. 8 Tube wells provide drinking water for more than 95% of the population, 9 and approximately 70% of the more than 13 000 tube wells in the area exceed the World Health Organization (WHO) guideline value of 10 micrograms per liter. 7 Community education, through a series of village information meetings, was used to encourage people to switch to wells with lower arsenic concentrations (< 50 μg As/L), which were painted green. Additional mitigation options (pond sand filters, home-based “3-pitcher” filters, rainwater harvesters, and community-based arsenic removal filters) were also introduced. 10 Pregnant women were prioritized for well-testing and education efforts. In interviews conducted in Matlab in 2004, 60% of respondents who were aware that their household water source was contaminated with high levels of arsenic reported that they had switched to another source of drinking water. 11 We evaluated the efficiency of the mitigation activities by measuring biomarkers of the internal dose of arsenic over time since the end of 2001. We evaluated arsenic exposure in children (n = 1951) who were part of a longitudinal study on arsenic exposure and child health and development in Matlab, beginning early in their mothers’ pregnancy.
