Lead exposure lowers fourth graders’ test scores

Lead exposure is related to lower test scores among Wisconsin fourth graders, according to a new study by researchers at the University of Wisconsin–Madison.

“What we find is that even low amounts of lead exposure during early development have direct, measurable, negative consequences for children’s school performance later in life,” says Mike Amato, a doctoral candidate in psychology and environmental studies and one of the authors of the study, recently published in the journal Annals of Epidemiology.

Students in Milwaukee Public Schools were included in the study, which was coordinated by researchers at UW–Madison and the Wisconsin Department of Health Services.

Researchers matched medical records of children who had been tested for lead exposure with their school records. Even after controlling for differences in test scores due to poverty, gender, English proficiency and other factors, children who had been exposed to lead scored lower on each subject of the fourth grade Wisconsin Knowledge and Concepts Exam (WKCE), which measures student competence in reading, math and other basic subjects.

The study found that environmental lead exposure, usually occurring from contaminated dust and soil around older homes, poses a significant challenge to schools striving to meet WKCE standards.

“There’s a lot of discussion about what schools should do to increase educational proficiency,” says Marty Kanarek, a professor of population health sciences affiliated with the Nelson Institute for Environmental Studies at UW–Madison. “It’s a very complex issue with multiple causes, but lead exposure is part of the equation.”

The most common source of lead exposure is contaminated dust from paint in older homes, according to Amato. “Children exposed to moderate amounts of lead often do not show immediate symptoms,” he explains. “However, our study suggests that effects can last long after the initial exposure and have a measurable impact on test scores.” 

The study also found that lead exposure rates among African-American and Hispanic children were roughly double those of white children. Kanarek says lead exposure in children is a matter of social justice.

“Students who have been exposed to lead are at a considerable disadvantage the first day they show up at school, before they’ve even met a teacher,” says Kanarek. “Lead exposure decreases cognitive ability in all children regardless of race, but the fact that African-American and Hispanic students were twice as likely as white students to be exposed suggests part of the racial achievement gap may be directly due to lead in the environment. If that’s true, then educational reforms alone will not eliminate the problem. We need to clean up contaminated housing.”

For more information on childhood lead exposure and how to prevent it, Wisconsin residents should contact the Department of Health Services Wisconsin Healthy Homes and Childhood Lead Poisoning Prevention Program at 608-266-5817 or visit the Lead-Safe Wisconsin website.