New York, NY —

One in four New Yorkers, and nearly half of Asian New Yorkers, have elevated mercury levels in their blood and the city's Health Department says its survey shows the higher levels are closely related to fish consumption.

REPORTER: Health Department official Dan Kass says the levels are a consequence of uncontrolled burning of fossil fuels which cause mercury deposits to get into the food chain.

KASS: We were a bit surprised, that our levels were so substantially higher than the nation as a whole but it may well be other cities and states that are coastal and that consume a lot of fish have similar levels.

REPORTER: Although these levels are not dangerous to adults, mercury may increase the risk of cognitive delays for children whose mothers had very high mercury levels during pregnancy.