A Toxin Blooms

In a 2004 study published in the Proceedings of the National Academy of Sciences (PNAS), Harvard-educated biologist and Institute for Ethnomedicine Director Paul Alan Cox, Ph.D. and colleagues found the neurotoxin B-methylamino-l-alanine (BMAA) in nine deceased Canadian Alzheimer’s patients but none of the toxin in 14 others who died of causes other than neuro-degeneration. In a 2009 study conducted by Deborah Mash, a University of Miami (UM) neurology professor, dying Alzheimer’s and ALS patients were reported to have BMAA concentrations of 256 nanograms per milligram (ng/mg) in their brains while healthy people had no detectable amounts. Now a new UM study, co-authored by Mash and published February 21, 2012 in the journal Marine Drugs, reveals BMAA concentrations from 144 ng/mg to 1,836 ng/mg in the fins of seven South Florida shark species.

BMAA exists in cyanobacteria, which is richly concentrated in algae blooms. Algae blooms are becoming increasingly prevalent, particularly in the wake of annual expansive dead zones brought on by conventional agricultural fertilizer runoff and sewage pollution. The BMAA toxins in cyanobacteria-rich algae are consumed by fish, which are in turn eaten by sharks.

UM’s findings could become another compelling argument for the worldwide banning of the Chinese-consumed “shark fin soup,” a dish that kills an estimated 70 million of the threatened marine predators every year. “Because sharks play important roles in maintaining balance in the oceans, not only is shark fin soup injurious to the marine environment, but our study suggests that it is likely harmful to the people who are consuming them,” said co-author Neil Hammerschlag, director of UM’s marine conservation program.

But scientists warn that that the toxic warfare of BMAA is widespread in virtually every cyanobacteria-rich environment, from hot springs to dusty deserts. Currently, no protective regulation of the neurotoxin is in place. “The thing is very little has been done on BMAA because it is a new wave, a new understanding,” Hammerschlag added. “We’re only starting to understand the scope of the problem.”

Cox has been at the forefront of exploring the link between BMAA and neuro-degenerative diseases. In 2003, Cox and fellow biologists Susan J. Murch and Sandra Anne Banack reported in PNAS why the indigenous Chamorro people of Guam were 50 to 100 times more likely than other world populations to succumb to ALS, dementia and Parkinson’s symptoms such as paralysis and shaking: high BMAA toxicity brought on by diet. The Chamorro people made tortillas out of ground cycad seeds and ate feral pigs and whole fruit bats known as “Mariana flying foxes,” both of which consumed cycad seeds. When Banack and Cox analyzed Mariana flying fox bat skins, they found that their BMAA levels averaged 3,556 ng/mg.

“We decided that if [BMAA] wasn’t in the bats, we’d just move on,” Cox said.

Since that discovery, BMAA analysis on other organisms has been cropping up in various scientific publications. In the 2010 study “Cyanobacterial Blooms and the Occurrence of the neurotoxin BMAA in South Florida Aquatic Food Webs,” researchers found the commonly ingested seafoods pink shrimp, largemouth bass and blue crab to contain BMAA levels comparable to or even exceeding those in the Mariana flying fox bats analyzed by Cox. One blue crab had 6,976 ng/mg of BMAA—twice the amount found in the Guam bat skin.

Unfortunately, seafood may not be the only carrier of BMAA. Agricultural fields can be irrigated with water stemming from cyanobacterial algae blooms, thus allowing BMAA to get into milk, meat and vegetables. “We encourage water managers to take a closer look at cyanobacterial blooms,” Cox says.

Continuing research into the role of BMAA in the development of neurodegenerative disease may lead to new drugs for ALS, Alzheimer’s, Parkinson’s and other conditions in the future. “I was struck by how many more research groups are now working in this field,” said Brian Dickie, director of research at the Motor Neurone Disease Association. “There is definitely greater acceptance that this avenue should be pursued.”