In 2001 the District of Columbia’s water authority began using a new process to disinfect water, changing from chlorination to chloramination, to reduce the potentially carcinogenic effect of chlorination by-products. A side-effect that developed from this otherwise improved process was the release of large doses of lead into the drinking water supply, which had previously been bound to the water pipes by chlorine. Although now fixed, the original chloramination process released lead levels far higher than the Environmental Protection Agency’s standards of no more than 15 parts per billion into the water supply.

During the over 3 year period, seventeen percent of D.C. homes had lead levels of 100 parts per billion, and 1% of homes had readings of 1000 parts per billion. A leading researcher at Simon Fraser University estimates that these children could have increased risk of attention-deficit hyperactivity disorder or conduct disorders, or a 4 to 7 point drop in IQ.

Source: ScienceNews