From 2001 to 2004, tens of thousands of people in Washington, D.C., unknowingly drank tap water that contained lead. The “D.C. lead-in-water crisis” was one of the most serious episodes of heavy-metal contamination of drinking water in modern U.S. history. Although officials working for D.C.’s water utility, the Washington Area Sewer Authority (WASA), the D.C. Department of Health (DC DOH), and the U.S. EPA knew about the problem, the public was in the dark. The contamination persisted for three years before the Washington Post informed D.C. residents about the situation in a story published in 2004.
The news outraged parents who were worried about their children’s health, angered politicians who hadn’t been told, and created anxiety among public-health experts who initially feared a community-wide crisis. Children’s health was the focus of concern because lead’s effects on neurodevelopment are notorious—low levels of exposure can cause a long list of problems that include hyperactivity, decreased learning ability, and trouble paying attention.
In the aftermath of the crisis, public-health experts, including scientists from the U.S. Centers for Disease Control & Prevention, examined blood lead data collected by DC DOH and water lead data collected by WASA and concluded that there had been little if any harm to the public.
This “no harm” conclusion defied previous studies that showed that drinking water contaminated with high levels of lead can markedly raise children’s blood lead levels, and the results were very influential. But a study published today in Environmental Science & Technology (DOI: 10.1021/es802789w) reveals that hundreds of babies and toddlers in D.C. were affected by the contamination from 2001 to 2003. In babies under 16 months of age living all over the city, the contaminated tap water caused the incidence of elevated blood lead levels to increase by more than 400%. For toddlers, the substantial increases were largely confined to certain neighborhoods, where an unlucky combination of lead water pipes and highly contaminated tap water created the conditions for higher exposure. In these high-risk neighborhoods, the incidence of high blood lead levels among toddlers more than doubled in 2001 and remained high until 2004.
“This new paper is important and very persuasive,” says Harvard Medical School pediatrician Michael Shannon, an expert in children’s lead exposure. “This is the first paper about the D.C. lead crisis to get it right. The authors really show quite convincingly that the lead in the drinking water resulted in lead poisoning in some children.”
The paper’s coauthors, Virginia Tech environmental engineer Marc Edwards and Children’s National Medical Center pediatrician Dana Best, set out to determine the impact of the D.C. lead crisis by looking at the most vulnerable group—babies—living in the neighborhoods where the contamination was the greatest.
The scientists accomplished their goal, but these results suggest many new questions as well as provide new answers. Most important, why did previous studies miss the effects? And what lessons does the D.C. lead crisis have for the rest of the nation?
Editor’s Note: Renner will explore the story behind the science of this paper in an upcoming ES&T news article.