Taipei, Nov. 2 (CNA) Long-term and excessive consumption of deep sea fish can result in hyperactivity disorder in children and heart problems and even infertility in adults, a Taipei Veterans General Hospital doctor warned Saturday. Reporting her conclusions at an international conference sponsored by the hospital, toxicologist Wu Ming-ling said her conclusions were based on her study of mercury toxicity from fish consumption in 31 outpatients between 2007 and 2011. Wu said all 31 of the patients displayed high mercury concentrations in their blood and hair primarily because of overconsumption of deep sea fish, and six showed signs of mercury toxicity. She suggested that people consume deep sea fish no more than once a month and not eat the fish's skin and innards. Small children and pregnant women should simply stay away from the food group altogether. Wu said the six children in the study all showed signs of hyperactivity, slow development, unclear speech, concentration difficulty and irritability. The families of the children consumed deep sea fish between five and seven times a week. Wu said that although fish is considered to be healthy and nutritious, deep sea and large fish are often at the upper stream of the food chain and are vulnerable to mercury or dioxin pollution. She pointed to the case of a 41-year-old mother who was found during a physical examination to have a high level of mercury in her hair and was also suffering from thyroid swelling and chronic fatigue problems. The mother took Wu's advice to cut back on fish consumption, but because the family still ate fish two times a day, mercury concentrations in the mother's hair and blood remained several times higher than the normal level. The mother later took her family for check-ups at Veterans General Hospital, and all five members showed high levels of mercury in their hair and blood. The family's five-year-old boy and three-year-old girl also had signs of mercury toxicity.
The three-year-old girl had a mercury level of 205.7 ppb in her blood, or 40 times the ideal level of between 5 and 10 ppb recommended by the World Health Organization (WHO), and 52.28 ppm of mercury in her hair, far higher than the 1 ppm recommended by the WHO. Wu cited the example of another patient, a 35-year-old man who ate deep sea fish three or four times a week and was found to have six times the normal level of mercury in his hair and twice the normal level of mercury in his blood. The man was unable to have children after several years of marriage, Wu said, noting that high levels of mercury have been shown to be related to infertility in medical studies. In addition, the man also had high lead levels, which also reduced the quality of his sperm. Wu said the patient has since reduced his consumption of fish to one time a week and exercised more, resulting in the reduction of his mercury levels. In response, a fishery official acknowledged Saturday that large fish in the deep sea do accumulate higher levels of mercury, but he said that as long as people don't eat too much deep sea fish, they can eat it daily without worry. Tsai Jih-yao, deputy director of the Fisheries Agency, said that he himself "eats fish at almost every meal except for breakfast." (By Lung Jui-yun and Lilian Wu)