Under the High Production Volume (HPV) Challenge Program, companies are “challenged” by EPA to make health and environmental effects data publicly available on chemicals produced or imported in the United States in the greatest quantities. HPV chemicals are classified as those chemicals produced or imported in the United States in quantities of 1 million pounds or more per year. As of June 2007, companies have sponsored more than 2,200 HPV chemicals, with approximately 1,400 chemicals sponsored directly through the HPV Challenge Program and over 860 chemicals sponsored indirectly through international efforts. The U.S. EPA is issuing a final rule under the Toxic Substances Control Act (TSCA) requiring manufacturers of 19 high production volume (HPV) chemicals to test the health and environmental effects of the chemicals and submit the data to the agency. EPA Administrator Lisa P. Jackson has made assuring the safety of chemicals one of her top priorities.