Mercury levels in women’s blood are dropping, and not because they’re eating less fish, a new study says.
The analysis showed that blood mercury levels in women of childbearing age dropped by about one-third between 2001 and 2010 compared with 1999 and 2000.
"There was very little change in the amount of fish consumed and mercury levels in fish tissue did not decline," said Betsy Southerland, director of the Office of Science and Technology in the EPA’s water division. "This suggests that women may have shifted to eating types of fish with lower mercury concentrations."
Agency scientists analyzed measurements of blood mercury levels taken as part of nationwide health surveys by the Centers for Disease Control and Prevention. The drop was most pronounced between 2001 and 2004, the study says. The changes were small after that, with a slight increase in the last few years.
Exposure to mercury in the United States comes almost exclusively from eating contaminated fish and shellfish, though most of it contains only trace amounts. When the metal is released into the environment--often from coal combustion or mining--it converts into methylmercury and accumulates in the food web, building up in the tissue of large, old, predatory fish.
Mercury can harm the brain and nervous system, particularly of children and fetuses, who are more susceptible to the poison because they are still developing.
The federal government says people should not eat shark, swordfish, king mackerel or tilefish because of high levels of mercury. Instead, they should limit their intake to about 12 ounces a week of shrimp, salmon, pollock and catfish, which are low in mercury.
The government also suggests opting for canned light tuna, which has less mercury than albacore, and checking for local advisories before eating fish from lakes, rivers and coastal waters.
The EPA study says further research is needed to determine whether the drop in mercury in women’s blood is linked to a change in their eating patterns and whether health advisories are playing a role.