Pollution is so bad in Eastern Europe that it is causing economic as well as environmental decay, an American researcher said in a report Saturday.

Rivers are so foul they can't be used for industrial cooling and children become sickened by toxic chemicals in the air.Cleanup costs will be astronomical, and must be treated as an essential part of the region's economic recovery, argues Hilary French, a senior researcher at the Worldwatch Institute.

"Given the degraded environment's toll on human health and biological productivity, decontaminating Eastern Europe and the Soviet Union is best seen as a precondition to economic development, not an obstacle," she writes.

Despite the report's catalog of horrors, it voices optimism that improvement should be possible.

"The emergence of a fairly strong environmental movement there is certainly a very hopeful sign," French said in an interview. "And the problems are severe enough that it is widely recognized that they'll have to be dealt with."

She cites estimates by East European economists that Poland is losing 10 percent to 20 percent of its gross national product each year to environmental degradation.