Here's some new research from Jessica Wolpaw Reyes highlighting a point that's not nearly as well-known as it should be. Public policies to remove brain-destroying lead from low-income communities pays off huge dividends:
Childhood exposure to even low levels of lead can adversely affect neurodevelopment, behavior, and cognitive performance. This paper investigates the link between lead exposure and student achievement in Massachusetts. Panel data analysis is conducted at the school-cohort level for children born between 1991 and 2000 and attending 3rd and 4th grades between 2000 and 2009 at more than 1,000 public elementary schools in the state. Massachusetts is well-suited for this analysis both because it has been a leader in the reduction of childhood lead levels and also because it has mandated standardized achievement tests in public elementary schools for almost two decades. The paper finds that elevated levels of blood lead in early childhood adversely impact standardized test performance, even when controlling for community and school characteristics. The results imply that public health policy that reduced childhood lead levels in the 1990s was responsible for modest but statistically significant improvements in test performance in the 2000s, lowering the share of children scoring unsatisfactory on standardized tests by 1 to 2 percentage points. Public health policy targeting lead thus has clear potential to improve academic performance, with particular promise for children in low income communities.
The transmission of social and academic disadvantage through childhood lead exposure is one of the most insidious forms of inequality in the United States. A small child has literally no ability whatsoever to control what kind of water pipes, nearby highways, or building paint he or she is exposed to while growing up. But the disadvantages of early childhood lead exposure—both reduced IQ and diminished impulse control—last throughout life and tend to put one in the very circumstances where you'd end up raising a child who faces heightened lead exposure. And since money spent on removing lead today won't really pay off for another few decades, politicians are inadequately incentivized to pony up the relatively modest sums of money that could make an enormous long-term difference.