In 2009, EPA initiated a proceeding in response to a citizen's petition under section 21 of the Toxic Substances Control Act (TSCA) to investigate potential lead hazards associated with the manufacture, processing, and distribution in commerce of lead wheel balancing weights ("wheel weights"). Lead is highly toxic, especially to young children. According to a U.S. Geological Survey study in 2003, 65,000 tons of lead wheel weights were in use in the United States and approximately 2,000 tons of these weights were lost from vehicles into the environment. Voluntary actions on the part of U.S. auto manufactures and a European Union ban on their use has reduced the number of lead wheel weights, but they continue to be a predominant product in the tire replacement market.