One in four NYC adults has elevated blood mercury levels.

Fish Still Part of a Healthy Diet, but Pregnant and Breastfeeding Women and Children Under 6 Should Avoid Fish High In Mercury Follow-up Studies of Fish Sold in Local Markets Underway A quarter of adult New Yorkers have elevated blood mercury levels, according to survey results released by the Health Department, and the elevations are closely tied to fish consumption. Asian and higher-income New Yorkers eat more fish, and have higher average mercury levels, than others both locally and nationally. These mercury levels pose little if any health risk for most adults, but may increase the risk of cognitive delays for children whose mothers had very high mercury levels during pregnancy.