Lead, however is another story.
Exposure to lead in early childhood significantly contributes to lower performances on end-of-grade (EOG) reading tests among minority and low-income children, according to researchers at Duke University and North Carolina Central University.
"We found a clear dose-response pattern between lead exposure and test performance, with the effects becoming more pronounced as you move from children at the high end to the low end of the test-score curve."This certainly isn't new. They found that a good chunk of the difference between test scores of black and white kids could be attributed to differences in the amound of lead they have in their blood, which can be explained by the fact that they average poorer than whites. I.e., another "racial" difference turns out to be social.