NEWPORT — Citing the environmental icon Rachel Carson, dense scientific studies, and their own years on the water, local lobstermen are calling on one town after another around Narragansett Bay to stop using a mosquito abatement chemical that they believe is killing local lobsters.

Town public works crews place the chemical, methoprene, into tens of thousands of storm drains around the Bay each summer to kill mosquito larvae that could grow into adults and help spread the sometimes fatal West Nile virus.

The strategy is strongly supported by the chemical’s maker as well as the state Health Department and the state Department of Environmental Management. They insist the larvicide is a safe and critical tool in reducing mosquito populations and protecting public health.

But the lobstermen believe the methoprene is stunting the growth of young lobsters, much like it does to mosquito larva.

Emotions are rising on both sides. Lobstermen have seen their catches fall by more than half in the last several years, causing nearly everyone to lose money and some to quit and sell their boats. On the state’s side, no one wants to have to say they didn’t do everything they could to protect Rhode Islanders from disease.

“All we’ve said is give us a guarantee it isn’t killing the lobsters,” said Dennis Ingram, one of the more outspoken lobstermen. “But nobody says a word. They can’t.”

Alan Gettman, the state’s mosquito abatement coordinator, says he can find no scientific evidence that the work he is doing puts local lobsters at risk. But he is concerned about the lobstermen’s efforts.

“I just don’t like that we are now setting a course of using something less reliable. We’re dealing with a public health phenomenon here.”

So far, the lobstermen have won the backing of 11 communities. Only one, Providence, has turned them down.

Save the Bay supports the lobstermen too, arguing that the environmental effects of methoprene, trade name Altosid, need further study.

And state Rep. Raymond E. Gallison Jr., D-Bristol, has introduced legislation banning the chemical’s use throughout the state. The goal, he said, is to keep methoprene out of the Bay.

The lobstermen vow to keep up their campaign until every town stops using the chemical.

Ingram, Pat Heaney and Lanny Dellinger, president of the Rhode Island Lobstermen’s Association, met near their boats at the State Pier here recently and explained why they think something is happening in Narragansett Bay and the public should be concerned.

“We figure there won’t be a lobster industry in a short time if this keeps up,” said Dellinger. “All the state wants to do is control us, but you can’t keep polluting the environment and still get fish.”

Local lobster catches topped off in 1999 with about 3,500 tons. Each of the following years got progressively worse. In 2005, the last year with complete figures, the take was less than 1,500 tons.

In response, the lobstermen have greatly reduced the number of traps they set and accepted one new size restriction after another designed to leave lobsters in the water longer so they can successfully reproduce.

Still, the catch remains low. And many lobsters, particularly those caught close to shore, are coming up with a disfiguring, and still unexplained, shell disease.

Now the lobstermen are finding oddities never seen before in their traps: female lobsters that have molted their shells while they are still covered with eggs.

What they are not seeing is even more disturbing — young lobsters.

The lobstermen blame methoprene, which the state DEM started distributing to communities after mosquitoes carried the West Nile virus into the state in 2000.

West Nile was big news when it erupted for the first time in New York in the summer of 1999. Some 69 people were stricken and 7, all elderly, died.

Gettman predicted mosquitoes and birds would bring West Nile to Rhode Island within the next year and he was right.

In response, state officials set up programs to trap and test mosquitoes, test dead birds and keep track of human infections.

Along with the surveillance, the DEM urged the public to empty sources of standing water and enlisted local public works crews to drop methoprene into storm drains. Killing mosquitoes while they are larvae, the state reasoned, was safer than spraying insecticides to kill adult mosquitoes.

Since then, 10 people have contracted West Nile in Rhode Island, but there have been no deaths.

Each year, the state buys about $80,000 worth of methoprene — for use in an estimated 125,000 storm drains — and a bacteria-based larvicide called Bacillus sphaericus to kill mosquito larvae in surface waters. Both chemicals disrupt the larvae and prevent them from maturing. Methoprene does so by mimicking the larva’s growth hormone; Bacillus sphaericus attacks its gut.

The lobstermen fear methoprene does the same thing to lobsters, which are distant relatives of mosquitoes. But they have no objection to the Bacillus sphaericus.

Gettman says the Bacillus sphaericus is less effective in storm drains because it floats and so is easily washed out. After each rainfall, more has to be put into drains — that’s why Providence turned down the lobstermen.

Saying they’d rather fish than sue, the lobstermen first appealed to the DEM to switch to exclusive use of Bacillus sphaericus. When that failed, they started approaching individual towns.

After Gallison submitted legislation to ban any use of methoprene, there was a late-night hearing at the State House.

Central Life Sciences, the manufacturer of methoprene, brought scientists who said there has been no trouble with methoprene during 35 years of wide use.

While in high concentrations it can kill lobsters, it is never used in concentrations even close to those levels, said Maija Mizens, the company’s director of toxicology.

The company also brought a woman from Massachusetts who testified that her child was killed by a mosquito borne disease, Eastern equine encephalitis.

Actually, the bill’s total ban — including other uses —was more than the lobstermen wanted, or thought prudent. And the mother’s appearance warned them that they will look bad should people start getting sick from mosquito-borne disease.

“We feel we hold the moral high ground on this,” said Heaney. “But all we need is one person to get sick.”

Dellinger said he thinks the warnings about West Nile are based on a lot of scare tactics from chemical companies. Studies have shown that many people get West Nile with no symptoms.

“Now everyone wears sunscreen,” adds Ingram. “People should protect themselves from mosquitoes, too.”

DEM’s Gettman says that while DEM prefers methoprene, it is not turning away from towns that decide to switch to bacteria-based larvicides. Using Bacillus sphaericus, he said, is better than doing nothing.

The lobstermen repeatedly say that the state of Maine banned methoprene to protect its valuable lobster stocks. But when asked about that, Henry Jennings, director of the Maine Board of Pesticide had a two-word response: “Categorically, no.”

Maine does not have a mosquito control program, he said. Two study groups voiced negative opinions about the product, but Jennings said the state has never taken an official position.

Stanley Cobb, a professor emeritus at URI who spent a lifetime studying lobsters, says he doesn’t think either side has proven its case: the state can’t prove methoprene is effectively reducing the incidence of West Nile, and the lobstermen can’t prove it is killing lobsters.

But until more questions are answered, he thinks its use should be stopped.

“If everybody sat down in the same room and worked out where the holes were in the evidence, they could set some priorities and get some answers,” Cobb said.

An effort is under way to answer some of the lobstermen’s questions. Thanks to a $2.3-million grant sponsored in 2006 by Sen. Jack Reed and Sen. Olympia Snow, R-Maine, dozens of lobsters were pulled out of the Bay last week and shipped to 15 researchers around the country. They will appraise the lobsters’ health and look for answers to the shell disease and for indications of methoprene.

“I look at shell disease and it doesn’t make any sense,” says Kathleen Castro, a Rhode Island Sea Grant fisheries extension leader who is leading the lobster research project. “It’s a huge warning that we’re doing a number on our ecosystem.”

plord@projo.com