While many are concerned about shrinking numbers of sharks being killed for shark fin soup, researchers at the University of Miami say people should avoid the Asian delicacy for health reasons.

A new study has found high concentrations of BMAA in shark fins -- a neurotoxin linked to neurodegenerative diseases in humans including Alzheimer's and Lou Gehrig disease (ALS).

The researchers said eating shark fin soup and cartilage pills can pose a significant risk of developing degenerative brain diseases.

Seven species of shark found in waters throughout South Florida were tested for this study: Blacknose, blacktip, bonnethead, bull, great hammerhead, lemon, and nurse sharks.

Co-author Deborah Mash did a study in 2009 looking at BMAA levels in the brains of patients dying of Alzheimer's and ALS. She found the patients had unusually high levels, up to 256 nanograms per milligram (ng/mg).

Looking at the shark fins, they researchers found between 144 ng/mg and 1836 ng/mg of BMAA.

"Estimates suggest that fins from as many as 70 million sharks end up in soup. As a result, many shark species are on the road to extinction. 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," the study's co-author Dr. Neil Hammerschlag said in a release Thursday.

The study appears in the latest edition of the journal Marine Drugs.

Several Ontario municipalities have enacted shark fin bans, including Toronto, Pickering, Oakville, Mississauga, Brantford, and London.