In the United States, the requirement that all new cars be equipped with catalytic converters signalled the eventual demise of TEL, since lead poisons the converters. With the health threat well known and alternatives available, leaded gasoline has virtually disappeared in the United States, Canada, Japan and Australia, and its use is rapidly declining in Western Europe. But it is widely believed throughout the industry that TEL is a sunset product, its elimination only a matter of time. The TEL manufacturers' refusal to phase out production contributes significantly to the delay in worldwide conversion to unleaded gasoline. This kind of prevention works because the emissions are eliminated almost entirely at the source.
Studies show that air lead levels declined in U.S. cities as the use of leaded gasoline declined.
In addition, the removal of lead from gasoline has resulted in a significant decline in lead poisoning cases. In New York City, prior to 1975, when lead was taken out of gasoline, three out of every 10 children tested had blood lead levels higher than the Centers for Disease Control's recommended limit, according to Piomelli of Columbia University's Children's Hospital. After 1975, that figure decreased twenty-fold, to three in 200. Some countries in Latin America are now beginning to look at measures to stop this attack on the brain development of their children. Mexico, with perhaps the worst problem in the hemisphere, has reduced the lead content of its gasoline dramatically since 1980.