A quarter of adult New Yorkers have elevated blood mercury levels. According to survey results released today by the New York City Health Department (read the full stats here), 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. The Health Department says these levels may increase the risk of cognitive delays for children whose mothers had high mercury levels during pregnancy. The Department also claims these elevated levels pose little if any health risk for most adults. . . Hmm. Right. So how come Canada’s “safe” mercury level is half that of the U.S., while Britain’s and China’s are one-third? JULIA WHITTY