Here is just a partial list of correlates, risk factors, and possible causes that have been the subject of serious studies:
At Northwestern University, Claudia Persico, David Figlio, and Jeffrey Roth have a working paper titled "
Inequality Before Birth: The Developmental Consequences of Environmental Toxicants." The abstract:
Millions of tons of hazardous wastes have been produced in the United States in the last
60 years which have been dispersed into the air, into water, and on and under the ground.
Using new population-level data that follows cohorts of children born in the state of
Florida between 1994 and 2002, this paper examines the short and long-term effects of
prenatal exposure to environmental toxicants on children living within two miles of a
Superfund site, toxic waste sites identified by the Environmental Protection Agency as
being particularly severe. We compare siblings living within two miles from a Superfund
site at birth where at least one sibling was conceived before or during cleanup of the site,
and the other(s) was conceived after the site cleanup was completed using a family fixed
effects model. Children conceived to mothers living within 2 miles of a Superfund site
before it was cleaned are 7.4 percentage points more likely to repeat a grade, have 0.06 of a standard deviation lower test scores, and are 6.6 percentage points more likely to be
suspended from school than their siblings who were conceived after the site was cleaned.
Children conceived to mothers living within one mile of a Superfund site before it was
cleaned are 10 percentage points more likely to be diagnosed with a cognitive disability
than their later born siblings as well. These results tend to be larger and are more
statistically significant than the estimated effects of proximity to a Superfund site on birth outcomes. This study suggests that the cleanup of severe toxic waste sites has significant positive effects on a variety of long-term cognitive and developmental outcomes for children.
From the paper:
Children conceived before cleanup were 10 percentage points more likely to be diagnosed with a cognitive disability than their siblings conceived after the site was cleaned. In addition, there is a small suggestive increase in the likelihood of being diagnosed with autism within one mile of a Superfund site for the siblings who were conceived before or during cleanup, relative to their siblings conceived after cleanup.
The estimates of the likelihood of repeating a grade, having lower test scores, or having a
behavioral incident are also somewhat stronger than the estimates for the two mile radius. However, an important caveat is that the likelihood of having a behavioral incident and autism results are sensitive to the type of specification and distance used to estimate them.
