The results of a recent study conducted by researchers from Columbia University, which was published online in the scientific journal Environmental Health, shows that school children attending schools in Maine who are exposed to high levels of arsenic in their drinking water exhibit a decline in child intelligence. This study builds on previous studies that looked at the impact of arsenic exposure on child intelligence conducted in Bangladesh and other South Asian countries.
Jospeh Graziano, professor of Environmental Health Sciences at Columbia University's Mailman School of Public Health, together with his team of research associates, assessed the intelligence of 272 children between grades 3 to 5. The children, whose average age was 10, attended schools within three Maine school districts where water used for drinking and cooking originated from private water wells that are known to contain high levels of arsenic.
The researchers assessed the intelligence of the children with a commonly used intelligence assessment tool – the Wechsler Intelligence Scale for Children (WISC-IV) – and found that children exposed to arsenic in their drinking water had lower scores across most of the WISC-IV indices. After controlling for external factors such as parental intelligence and education, size of the family, school district and other characteristics related to the home environment, children who had high levels of exposure to arsenic (> 5ppb) in their drinking water exhibited a decline of 5-6 points in Full Scale, Working Memory, Perceptual Reasoning and Verbal Comprehension scores. According to Gail Wasserman, professor of Medical Psychology in the Department of Psychiatry at Columbia University and lead author of the paper, this decline in intelligence is significant and could translate into learning problems and problems with schoolwork.
The researchers took water samples from an external point of entry as well as from the kitchen faucet. They also analyzed drinking habits, how long the family had lived in their home, together with how the water well was constructed and if any water filters were used.
Water arsenic levels recorded in water samples taken from the kitchen faucet measured 9.88 ppb on average, with over 30% exceeding the standard of 10 ppb recommended by the EPA and WHO. The highest level of arsenic measured was 115.3 ppb – more than 10 times higher than the EPA standard.
“The strength of associations found in this study is comparable to the modest increases that have been found in blood lead, an established risk factor for diminished IQ,” said Dr. Graziano.
“Our findings of adverse impact in a U.S. sample, particularly in performance-related functioning, gives confidence to the generalizability of findings from our work in Bangladesh, where we also observed a steep drop in intelligence scores in the very low range of water arsenic concentrations,” said Dr. Graziano.
“Collectively, our work in Bangladesh and in Maine suggests that aspects of performance intelligence, particularly perceptual reasoning and working memory, are impacted by exposure to arsenic in drinking water.”
How to Protect Your Kids
There is currently an outreach program underway tasked at educating families who are at risk of arsenic exposure in the region. Dr Graziano points out that a standard filter available at hardware stores in inadequate for removing arsenic from drinking water. However, affected households can take measures to address the situation. Dr Graziano and his fellow experts recommend that those exposed to high levels of arsenic in their drinking water should filter their drinking water with a high quality filter that is capable of removing arsenic.
Gail A Wasserman, Xinhua Liu, Nancy J LoIacono, Jennie Kline, Pam Factor-Litvak, Alexander van Geen, Jacob L Mey, Diane Levy, Richard Abramson, Amy Schwartz, Joseph H Graziano. A cross-sectional study of well water arsenic and child IQ in Maine schoolchildren. Environmental Health, 2014; 13 (1): 23 DOI: 10.1186/1476-069X-13-23