Said, “Lead in gasoline can explain up to 90 percent of the rise and fall in violent crime over the past half century.” Battery reference work done by Rick Nevin, a consultant working on a study for the U.S. Department of Housing and Urban Development. Mr Nevin determined that as the number of cars on the road using leaded fuel between the 1940s and 1970s was increasing, there were more lead emissions. During that period the crime rate increased significantly. Once unleaded gasoline replaced leaded gasoline and emissions plummeted, crime rates began to decline