U.S. researchers say a neurotoxin linked to neurodegenerative diseases in humans, including Alzheimer\'s and Lou Gehrig\'s disease, has been found in shark fins. Scientists at the University of Miami say high concentrations of the BMAA neurotoxin suggest consumption of shark fin soup and cartilage pills may pose a significant health risk for degenerative brain diseases. Sharks are among the most threatened of marine species worldwide, primarily killed for their fins alone to fuel the growing demand for the soup, an Asia delicacy, a UM release said Wednesday. \"Estimates suggest that fins from as many as 70 million sharks end up in soup,\" researcher Neil Hammerschlag said. \"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,\" he said. Seven species of shark -- blacknose, blacktip, bonnethead, bull, great hammerhead, lemon and nurse sharks -- were tested for the study. \"The concentrations of BMAA in the samples are a cause for concern, not only in shark fin soup, but also in dietary supplements and other forms ingested by humans, \" study co-author Deborah Mash, director of the University of Miami Brain Endowment Bank, said. \"Not only does this work provide important information on one probable route of human exposure to BMAA, it may lead to a lowering of the demand for shark fin soup and consumption of shark products, which will aid ocean conservation efforts,\" Hammerschlag said.