Vol. 11, No. 2, 2005 Page 5
The neurological impairment caused by children's prenatal exposure to mercury, a powerful neurotoxin, is estimated by a new study to cost the United States billions of dollars annually.
Leonardo Trasande and colleagues used an "environmentally attributable fraction" model—the same methodology previously used to calculate the economic costs of lead toxicity—to calculate the economic effects of mercury exposure. The researchers limited their analysis to the neurodevelopmental effects of mercury, and in particular to reductions in intelligence.
Using data from a 2000 study by the Centers for Disease Control and Prevention, the researchers determined that between 316,000 and 637,000 children each year have umbilical cord blood mercury levels higher than 5.8 micrograms per liter, a level associated with a loss of IQ. The resulting loss of productivity, they note, lasts over the entire lifetimes of affected individuals. "This lost productivity is the major cost of methylmercury toxicity," they say, "and it amounts to $8.7 billion annually (range $2.2-$43.8 billion, 2000 dollars)."
Trasande et al. note that this may be an underestimate, because they did not take into account the costs of mercury exposure to children during the first two years of life, when the blood-brain barrier is vulnerable to penetration by methylmercury. They also point out that their figures do not take into account non- IQ effects of mercury toxicity, such as alterations in behavior. While the effects of mercury on behavior have not been well studied, the researchers note that lead—another neurotoxin—is strongly linked to antisocial behavior and criminality.
"Public health and economic consequences of methylmercury toxicity to the developing brain," Leonardo Trasande, Philip J. Landrigan, and Clyde Schechter, Environmental Health Perspectives, February 2005 (epub in advance of publication).