As coastal communities gear up for beach cleanups on April 18, the Washington Department of Ecology is reminding volunteers to keep an eye out for silver 1-liter canisters that could have potentially harmful contents inside.

Ecology has received recent reports of these unmarked aluminum canisters being spotted along the Washington coastline, including Olympic National Park wilderness beaches.

These appear to be the same type of containers found along beaches from Tillamook, Ore., to Vancouver Island in 2008.

The containers found last year contained residual aluminum phosphide, a pesticide used on cargo ships. When exposed to air, the chemical becomes a toxic gas.

"Beach cleanup volunteers encounter lots of trash and debris, and we want to make sure they know what to do if they come across these containers," said Ron Holcomb, Ecology's acting spill response supervisor for the Southwest and Olympic Peninsula region.

Ecology's spills and hazardous materials response team has the following advice for volunteers:

_ Don't remove the plastic lid from the canister. It could have some of the chemical inside. Without removing the lid, carefully collect the canister and store in a location away from the waterline. Report the location of the canisters to Ecology, 360-407-6300, or to any Olympic National Park ranger station or by calling 360-565-3000.

_ Recycle canisters that are found without lids. Any chemical residue would have been released as gas when the lid was removed.

Ecology and the Coast Guard worked together in 2008 to locate and collect nearly 100 of the fumigant canisters along Washington's coast.

While there's no way to know the exact source of the canisters, Ecology believes cargo ships carrying grain and other food products used the aluminum phosphide to control pests while in transit. The canisters were either improperly thrown or washed overboard after use.