Washington, D.C. ? Toxic chemical pollution from the nation’s industrial plants, mines and factories declined by 5 percent in 2007, the government said Thursday.

Companies reported releasing 4.1 billion pounds of toxic chemicals into the air, water and onto land in 2007, down from 4.26 billion pounds in 2006.

Less pollution went into the nation’s air and water. About a third of the chemicals, or 1.3 billion pounds were released into the air, a 7 percent reduction. Another 232 million pounds were discharged into waterways in 2007, 5 percent less than the previous year.

Despite these declines, the Environmental Protection Agency data shows more mercury, lead and polychlorinated biphenyls entered the environment. Releases of these types of chemicals, which remain in the environment for long periods of time and accumulate in body tissues, rose one percent in 2007.