A recent study in New Zealand found that blood lead levels of 3.5 micrograms / dL, which is the lowest easily detectable level, were associated with a drop of 1

A recent study in New Zealand found that blood lead levels of 3.5 micrograms / dL, which is the lowest easily detectable level, were associated with a drop of 1 IQ. People during the times of lead paint and leaded gasoline often had levels of 80 micrograms / dL. It seriously messed them up.