Lead (exposure) in the Time of Standardized Tests

by Haifa Haroon on March 2, 2013

You know the drill: Clear your desk. #2 pencils only. Fill in the oval on your Scantron. If you change your answer, erase it completely.*

Just about every school year, students throughout Michigan spend a week taking the Michigan Educational Assessment Program (MEAP) test. The purpose of the test is to gauge how well students and schools are performing in 5 subject areas – reading, writing, math, science & social studies. The school district can use the results to guide curriculum improvements.

In addition to the content, several other factors influence academic success including teaching style, our health, parental education, family income – and early lead exposure.

Courtesy of Mr. Katzoff.org

Research has linked early lead exposure and high blood lead levels (BLL > 5ug/dl) in children with cognitive impairment, behavioral problems, lower IQ scores, hyperactivity and aggressiveness. However, the association between lead exposure and academic achievement has not been as well studied.

A recent study in the American Journal of Public Health reported an inverse relationship between blood lead levels among children under 6 years (1st grade or lower) and MEAP scores. The researchers obtained blood lead surveillance data for children under 6 years in Detroit and matched their identity to MEAP test results for grades 3, 5 and 8. The researchers found a dose-response relationship between the two variables. Increased BLL was associated with “less than proficient” scores even when controlling for factors such as race, gender, grade level, language, maternal education and SES. (Note: The test scores have 4 levels: advanced, proficient, partially proficient and non proficient). BLLs greater than 10ug/dL at age 6 or under was associated with over twice the probability of scoring “less than proficient” on MEAP tests at grade 3,5 and 8 in comparison to individuals with BLLs less than 1ug/dL

The average BLL among this study group was 7.12ug/dL. This is higher than the CDC reference level of 5ug/dL, which was lowered in 2012 from what was referred to as the blood lead “level of concern”, 10ug/dL. This is a small amount-  a microgram (ug) is a millionth of a gram and a deciliter (dL) is almost half a cup.

Detroit has one of the highest prevalences of elevated BLLs in the US –  4.6% in children, compared to the national average of 1.4%. Among large cities, it has the 4th highest number of childhood lead poisoning cases.

No. of children with BLL of 10ug/dL or greater by zipcode
Courtesy of Michigan.gov

Lead-based paint is one of the main sources of lead exposure in Detroit. Although it was banned in 1978, over 50% of the houses in Detroit were built before 1950. As the paint deteriorates, the lead-based chips and dust fall to the ground, increasing access to young children, who may ingest or inhale the particles.

Other sources of lead exposure in Detroit include food/liquids stored in lead glazed containers, water traveling through old lead pipes and soil. Lead in soil is deposited after being released from industrial plants. In Detroit, exposure through soil and lead dust is a concern for individuals that live near these sites.

Although over 1 million children age 6 and under in the US still have blood lead levels at or above the new CDC standard, overall blood lead levels have been decreasing. In the graph below, you can see the BLL decline in Detroit. Additionally, children under 6 that live in the city of Detroit are required by the Detroit Department of Health and Wellness Promotion (DHWP) to get tested yearly for lead. This is important because it identifies children that may be at risk for the negative health effects of long term lead exposure early on.

Courtesy of Michigan.gov

*The test is now offered online, so this may not apply as much. I feel ancient.