The state of Virginia is protesting the Navy's plan to coat the hulls of its fleet with a toxic chemical, contending that more should be learned about the chemical's potential ill effects on humans and marine life, a state official said yesterday.

The Navy has not done enough research to justify its position that organotin -- used to fight the growth of barnacles and other organisms on ship hulls -- will have no significant impact on the marine environment at the Norfolk Naval Shipyard in Portsmouth, said Keith Buttleman, administrator of the Virginia Council on the Environment.

Buttleman has written to the commander of the Naval Sea Systems Command in Washington requesting the service to delay implementing the antifouling chemical until a thorough environmental impact statement can be completed.

An environmental assessment report sent by the Navy to the state last month said the effects of organotin were too slight to warrant a more elaborate impact statement.

The Navy said the use of organotin would reduce fleet fuel costs by 15 percent -- an annual savings of $150 million -- because of the increased efficiency of ships with clean hulls. An additional savings of $5 million a year would result from lower ship-cleaning costs, the assessment said.

The Navy declined comment yesterday on Virginia's request to delay the chemical's use.

Buttleman said the state has not decided what to do if the Navy refuses to comply with the request, but said options include court action or a request to Congress to block the plan. Virginia plans to contact other states with Navy ships to learn their position on the use of the pesticide, he said.

Organotin is approved for use by the Environmental Protection Agency and has been used for years by recreational boaters, said Frank O. Perkins, director of the Virginia Institute of Marine Science in Gloucester Point. But recent innovations have allowed scientists to measure the effects of much lower concentrations of organotin than previously had been possible.

"The more we know about it, the worse it looks," said Perkins. "It's very unfortunate that this stuff is so toxic because it is very effective in stopping barnacles."

Ram Tripathi, a toxicologist with the Virginia state health department, added: "Who knows how serious this is going to be? Basically, if the stuff gets into ocean water it will concentrate in shellfish and might be consumed by humans."

"The most prudent thing to do would be to go into a holding pattern," Buttleman said.

An EPA spokesman said that in light of new knowledge about organotin, the agency is reviewing the Navy's proposal and expects to have its findings Aug. 22.