EPA: sea life hormones not hurt by dispersants

WASHINGTON (Reuters) - Initial tests of the dispersant BP Plc is using to break up oil in the Gulf of Mexico show that it does not harm endocrine systems in aquatic life, U.S. regulators said on Wednesday.

The tests looked at eight dispersants but did not look at effects of the products when mixed with oil, the Environmental Protection Agency said.

The effect on endocrines, or hormones, in sea life is only one of the concerns some scientists have about the use of dispersants to break up oil.

Some scientists say dispersants have resulted in huge underwater clouds of dissolved hydrocarbons that have robbed the waters of oxygen. They fear life is choked by the clouds and that chemicals in the clouds will poison plankton and sea larvae before making their way into animals higher up the food chain.

The EPA tested eight dispersants on small fish and mysid shrimp, including the one BP is using on the worst oil spill in U.S. history, Corexit 9500, made by Nalco Holding Co.

"In the tests we performed, all of the dispersants are roughly equal in toxicity and generally less toxic than oil," Paul Anastas, the EPA's assistant administrator for research and development, told reporters in a teleconference.

The EPA had directed BP to analyze alternative products to Corexit 9500 to see if any were less toxic, but BP said it could not find a safer alternative.

Corexit 9500 was found to be one of the least toxic dispersants to small fish, the EPA said.

The EPA said more tests were necessary before determining whether one dispersant is better or worse than others. In the next test EPA will look at acute toxicity of oil mixed with dispersant on two species and compare the results with tests on the toxicity of oil alone.

(Reporting by Timothy Gardner; Editing by David Gregorio and Walter Bagley)