U.S. geologists say ash and debris from California wildfires is full of arsenic, lead and other caustic materials that pose a health and safety risk.

The U.S. Geological Survey scientists warn the toxic metals pollute streams and threaten wildlife, the Los Angeles Times said Wednesday.

Tests of some ash from recent wildfires found it was more caustic than ammonia and nearly as caustic as lye, while metals such as arsenic found in the ash would violate federal standards for cleaning up hazardous waste sites.

The scientists are calling for concentrated efforts to clear the ash and before winter rains arrive, the newspaper said. The geologists tested 28 samples from residential areas burned by the Grass Valley fire near Los Angeles and the Harris fire near the Mexico border.

Copyright 2007 by United Press International