WASHINGTON -- The government has shot down an effort to ban arsenic-treated lumber used in playgrounds and elsewhere.

Environmentalists say chromated copper arsenate (CCA) treatment that protects wood from insects and decay poses a health threat.

The Consumer Product Safety Commission voted unanimously against a ban requested by environmental groups. Officials said a ban isn't needed because most manufacturers already have stopped using the treated wood and other makers soon will follow suit.

CCA manufacturers and the Environmental Protection Agency previously agreed to phase out the wood treatment for most consumer uses by the end of 2003.

Almost all wooden playground equipment has been treated with the pesticide. Critics worry that children can get cancer-causing arsenic residue on their hands and put their hands in their mouths.

In a report released earlier this year, government scientists found that some children may face an increased risk of developing lung or bladder cancer over their lifetimes from playing on playground equipment made from CCA pressure-treated wood.

The treated wood has also been used in picnic tables and wood decks.

Arsenic occurs naturally in the air, soil, water and in some foods. Experts say that while exposure to arsenic from these sources could be much higher than the exposure from playgrounds for some children, CCA-treated playgrounds could be a significant source of arsenic for other children on those days that include a playground visit.

Lumber companies say the wood is safe, but they have agreed to phase it out by the end of the year.