This hypothesis is often put forth to in the US. The strongest studies of the lead hypothesis, however, compare data across multiple countries, which regulated

This hypothesis is often put forth to in the US. The strongest studies of the lead hypothesis, however, compare data across multiple countries, which regulated lead-containing paint and gasoline at different times. These studies demonstrate that crime drops in each country at a similar period after the decrease in lead exposure, and at a rate that corresponds to the rate of decrease in lead exposure.