sentences:  Use of leaded gasoline has been reduced or eliminated in most developed nations, and lead levels in US children have been substantially reduced by policies relating to lead reduction.Even slightly elevated lead levels around the age of 24 months are associated with intellectual and academic performance deficits at age 10 years.Certain, at least previously, widely used organochlorides, such as dioxins, DDT, and PCB, have been associated with cognitive deficits.