By KRISTEN SENZ
Sunday News Correspondent
ENFIELD – The risk of developing a fatal neurodegenerative disease is 25 times higher than the norm for people who live around Mascoma Lake, according to researchers studying the possibility of a link between lake bacteria and neurological illness.
Over a recent six-month period, three people residing on the north shore of Mascoma Lake were diagnosed with Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig's Disease. So far, nine cases of the disease have been confirmed near the lake.
Doctors and scientists at Dartmouth-Hitchcock Medical Center in Lebanon say there is strong evidence that suggests cyanobacteria, single-celled organisms that form on lakes and ponds and release harmful toxins, are an environmental trigger for the development of ALS in people who are genetically predisposed to the illness.
"Statistically, if you live near some lakes, there appears to be a higher risk of ALS," said Dartmouth-Hitchcock neurologist Dr. Elijah Stommel.
The national incidence rate of ALS, a disease that attacks the nerve cells that control voluntary movement, is two people per 100,000. Around lakes and ponds with cyanobacteria blooms in New England, that rate increases to 4.5 people per 100,000. At Mascoma Lake, the rate is 50 people per 100,000.
Researchers in New Hampshire have yet to find the specific neurotoxin, known as BMAA (beta Methylamino L-alanine), that is believed to trigger ALS, but it has been found in water bodies with cyanobacteria blooms elsewhere in the world.
"We think we will be able to find the toxin," said Stommel, who is working with other doctors and researchers to collect water and fish samples, and to gather hair and brain tissue from people who have been diagnosed with ALS in Enfield.
People living around other lakes, including Winnisquam Lake in Belknap County and Willand Pond in Somersworth, also recently have been diagnosed with ALS, but the highest concentration of cases in the state has been found at Mascoma Lake.
Cyanobacteria, often referred to as blue-green algae, have survived on Earth for more than 200 million years and contain chlorophyll, which enables photosynthesis. The biological purpose for cyanobacteria blooms and the toxins they release remains unknown, said Dr. Tracie Caller, a resident at Dartmouth-Hitchcock who works with Stommel in studying the potential link to ALS.
"These are the oldest organisms on Earth," Caller said. "They actually are partly responsible for creating our atmosphere."
Dumping of sewage and other pollutants, including yard waste such as grass clippings, is believed to trigger cyanobacteria blooms. Nitrogen and phosphorous, which come from runoff created by development, also are recognized as contributors.
Pollution in Mascoma Lake was at its peak in the 1970s, prior to the passage of the federal Clean Water Act, Caller said, and exposure from that era may be responsible for the recent spike in ALS cases.
"The cases we're seeing now, we think might be related to what was going on 10, 20 or 30 years ago," she said.
Researchers first began studying unexpected pockets of ALS after a high concentration of cases was found in Guam among people who ate a certain type of bat. The bats fed on nuts that contained BMAA, which was found to have caused the disease. Other populations at higher risk for ALS include Italian soccer players and veterans of the first Iraq war, Caller said, but no one knows why.
Cyanobacteria blooms appear as a blue-green or pea-green scum on the surface of lakes, ponds and rivers. They release a variety of harmful toxins, including microcystine, which causes liver cancer and liver failure in humans and animals. Jody Connor, a limnologist with the New Hampshire Department of Environmental Services, said the toxin has caused acute liver failure in dogs and has been responsible for some pet deaths.
"Oftentimes, pets die and nobody knows why, and a lot of times, vets don't know that pets that drink water with cyanobacteria are likely going to get sick," Connor said.
New Hampshire was one of the first states to develop a standard for cyanobacteria testing, as well as a procedure for related beach closures and lake advisories. And the limnology center, which Connor leads, is working to educate lake associations and the public.
Connor said it's important for people to heed the state's warnings, recognize what the blooms look like and know what to do if they see them. If you see scum on a lake's surface, even if it's only in one area, avoid swimming and keep pets out of the water. Take a picture of the bloom or collect a water sample, and call the state's cyanobacteria hotline at 419-9229.
"I carry the phone with me all the time, and I try to answer it seven days a week," he said.
If and when researchers find the tiny BMAA molecule in Mascoma Lake or elsewhere in the state, "I think it would really help us in preventing disease and/or maybe even finding a cure" for ALS, Caller said.
A definitive link could also have a dramatic impact on lakefront property values in New Hampshire.
Stommel and Caller are awaiting lab-test results from water and fish samples collected from Mascoma Lake, Winnisquam Lake, Willand Pond and Webster Lake in Franklin.
"We're hoping to sample as many lakes with blooms as we can get to this summer," Caller said.