mercury poisoning. WildAid, a wildlife non-governmental organization, warned that eating too much shark fin can cause sterility in men. It is known that larger fish such as shark, tuna, and swordfish contain high levels of mercury and methylmercury salts. For nursing mothers, young children, and pregnant women or those who wish to be, the United States Food and Drug Administration has advised avoiding consumption of fish high in mercury. High concentrations of BMAA are present in shark fins. Because BMAA is a neurotoxin, consumption of shark fin soup and cartilage pills may pose a risk for degenerative brain diseases such as Alzheimer's and ALS, as well as Parkinson's disease. Counterfeit shark fins often also contain toxins. Market and demand Early use Shark fin soup was reported in Ming dynasty writings and by the Qing dynasty was considered a "traditional part of formal banquets"; in Chinese cuisine, it was considered to be one of the eight treasured foods from the sea. It was popular with Chinese emperors because it was rare, and tasty only after a complicated and elaborate preparation. By the time of the Qing dynasty, shark fin soup was in high demand. Its manual of cuisine, the Suiyuan shidan, indicates that the shark fin was eaten as soup, stew, and even as a stir-fry, but in all cases the fin had to be boiled for two days. The popularity of shark fin soup rose in the late-18th and early-19th centuries as standards of living began to improve. Demand peaks, c. 2000 In the late-20th century, shark fin soup was a popular delicacy in China, and was eaten in Chinese restaurants around the world. The increasing wealth of the middle class raised demand. The shark fin trade more than doubled between 1985 and 2001. Based on information gathered from the Hong Kong trade in fins, the market was estimated in 2004 to be growing by five percent each year. Consumption of shark fin soup had risen dramatically with the affluence of the middle class, as Chinese communities around the world enjoyed increasing income levels. The high price of the soup meant it was often used as a way to impress guests, or for celebrations such as weddings, banquets, and important business deals. It was used to communicate wealth, power, and prestige, as it was believed to show respect, honor, and appreciation to guests as well as to intimidate them as