Increase in chemical disposals.

Industrial and federal facilities in the United States released more than 4 billion pounds of chemicals into the environment in 2005, according to the latest yearly compilation of data from the Environmental Protection Agency's Toxics Release Inventory. Chemical releases had increased by 117 million pounds, or 3 percent, over the past year.

The EPA collects information on nearly 650 toxic chemicals that facilities emit into the air, release into waters, or dispose of in landfills or underground wells.

The metal-mining industry was the largest discharger of chemicals in 2005, accounting for slightly more than 1 billion pounds. This industry also claimed the largest increase from 2004, 96 million pounds. Releases from electric utilities came in a close second in 2005 and showed the second-largest increase--39 million pounds--from 2004.

The inventory also includes data on the disposal of chemicals that persist in the environment and accumulate in body tissues. In 2005, lead or lead compounds accounted for 98 percent, or 469 million pounds, of such toxic chemicals. Releases of mercury and mercury compounds added another 4.4 million pounds.--A.C.