The blue-green slime that from time to time coats coats Maine's rivers and lakes contain toxins that are known to sicken animals and people. But a growing number of scientists think that these cyanobacterial blooms, which form when nutrients such as fertilizer runoff collect in warm, slow-moving water, may also be connected to the incurable neurodegnerative disease, amyotrophic lateral sclerosis, better known as Lou Gehrig's Disease.

More than 80 experts from the worlds of medicine, ecology and public health are meeting at Bowdoin College through Saturday to discuss research into possible link, including findings in Maine.

Among the scientists getting a lot of attention at Bowdoin this week is Dr. Elijah Stommel, associate professor of neurology at Dartmouth Medical School. For the last four years or so, he and a team of Dartmouth researchers have been studying more than 700 ALS cases in northern New England.

Detailed information has come from 120 completed surveys from ALS patients and their families. Questions touch on: "gender, age, date of diagnosis, habits such as smoking. Smoking's thought to be a risk factor for ALS," said Stommel."

But Stommel also wanted to investigate the hypothesized link between ALS and a toxin in cyanobacteria called BMAA. So he asked patients about their hobbies.

"Whether they go fishing, whether they waterski, whether they go sailing," said Stommel. "We're trying to better understand what patients do and where they've lived in association with these water bodies that have been affected by cyanobacterial blooms."

And based on his research to date, Stommel said, "in the areas where we've looked carefully, it does look like one risk factor for ALS would have been to have spent a considerable amount of time near a lake with a bloom."

Stommel found two clusters of ALS cases in Maine, about a dozen cases recorded in the Bangor area between the early 1990s and mid 2000s, another half dozen cases around the town of Manset, part of Southwest Harbor. He can't say that ALS incidence is related to neurotoxins in the blooms, but "we are concerned about Bangor area because of the history of blooms along the Penobscot River."

Before you cancel a trip down the Penbscot, or to any other body of water in Maine for that matter, take this into consideration. A link between Cyanobacteria and ALS is just a hypothesis at this time.

And even if it were to be proven, researchers say people shouldn't panic. ALS is rare, the ALS Association estimates 30,000 Americans are living with the disease, and the number of people sensitive to a toxin in cyanobacteria would be even smaller,scientists say.

But because ALS is so debilitating, it attacks the patient's muscles, and ability to breathe, scientists are desperate to identify who is most vulnerable.

"Most people can probably tolerate small amounts of this toxin, metabolize it and excrete it without any problem but there might be a few people who need to be very careful," said Dr. Paul Cox. He is executive director of the Institute for Ethnomedicine in Jackson Hole, Wyoming.

Cox said that he's hopeful the scientific community will come up with more treatments beyond one FDA-approved drug that works to slow the progression of ALS. He said one drug company represented at the Bowdoin conference is already developing a drug working off the proposed link between the cyanobacteria toxin and ALS.

"Phoenix Neurological Associates are actually now beginning a Phase Two clinical trial of a medication designed to remove this toxin from the body," said Cox. "So, if the hypothesis is correct, and that's a big if, it will directly lead to new ways to treat this disease."

Charlie Culbertson, a hydrologist with the US Geological Survey based in Augusta, said that he hadn't heard about a possible link between ALS and the toxin in cyanobacterial blooms until several years ago and in some scientific circles, the hypothesis is challenged. But Culbertson said he's convinced there's something to it, and he plans to help the Dartmouth researchers.

"When these blooms die out they leave a signature in sediments," said Culbertson.

Because scientists think it may take 20 to 30 years of exposure to the toxin to see clinical symptoms of ALS, Culbertson wants to study sediment around water bodies for traces of the toxin.

"So we can go back into the sediment record, 30, 40 even 200 years ago and see if there are any indications of toxins, And it may give the neurologists and epidemologists a tool by which to start looking more intensively at clusters," Culbertson said.

In the meantime, Culbertson added, state and federal authorities will continue to watch for and warn about blooms in Maine's rivers and lakes, and try to prevent the pollution that leads to their formation. He points out that there are three new monitoring stations along the Penobscot River, supervised by members of the Penobscot Indian Nation whose members depend on for fishing.