Even low levels of arsenic lower kids’ IQs

Arsenic in well water, at levels that are not uncommon in the United States, is threatening our children’s intelligence, new research finds.

Researchers from New York and New Hampshire conducted a cross-sectional study of 272 children in grades 3 to 5 from 11 elementary schools in 3 Maine school districts. The children lived in their current homes for an average of about 7 years.

The investigators discovered that the average arsenic measurement of the kitchen tap water in the households of the children in the study was 9.88 µg/L. Almost one-third of the samples exceeded the US Environmental Protection Agency (EPA) Maximum Contaminant Level (MCL) of 10 µg/L or 10 parts per billion (ppb). The highest level recorded was 115.3 µg/L.

After adjusting for a variety of factors, the researchers found that well water arsenic at a level below the MCL set forth by the EPA was significantly negatively associated with children’s scores on the Wechsler Intelligence Scale for Children, 4th edition. Compared with children exposed to <5 µg/L (5 ppb), those exposed to ≥5 µg/L scored about 5 to 6 points lower in both Full Scale Intelligence Quotient (IQ) and most Index scores, including Perceptual Reasoning, Working Memory, and Verbal Comprehension scores. The only Index score that wasn’t significantly affected was Processing Speed.

In addition to affecting intelligence, it is well known that arsenic can cause numerous health problems, including various cancers. To reduce the risk, a number of counties and states have mandated that private wells be tested before the sale of a home or property becomes final. New Jersey has lowered its MCL to 5 µg/L, and other states may soon follow suit.

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