Lower IQ levels resulting from prenatal mercury exposure cost the United States approximately $8.7 billion annually in lost earnings potential, according to a study published in the Feb. 28 online issue of NIH's journal Environmental Health Perspectives, the AP/Long Island Newsday reports (Barrett, AP/Long Island Newsday, 2/28). High levels of mercury -- which accumulates in the environment, the flesh of fish and the bodies of people who eat fish -- have been shown to contribute to birth defects, and several studies have demonstrated a subtle loss of mental acuity in the offspring of women who consume fish during pregnancy (Kaiser Daily Reproductive Health Report, 2/7). Dr. Leonardo Trasande and colleagues from the Mount Sinai Center for Children's Health and the Environment and the Albert Einstein College of Medicine of Yeshiva University in New York used data from a 2000 CDC cohort study that examined the frequency of high mercury levels in women of childbearing age. Based on the data, the researchers estimated that between 316,588 and 637,233 infants are born each year with umbilical cord blood mercury levels high enough to be linked to a loss of between 0.2 and 24 IQ points (AP/Long Island Newsday, 2/28). The low estimate was calculated based on the assumption that umbilical cord blood mercury levels are equivalent to the maternal blood mercury levels, and the high estimate assumes, as previous studies suggest, that umbilical cord blood has a 70% higher concentration of mercury than maternal levels (Trasande et al., Environmental Health Perspectives, 3/1).

Impact of IQ Loss
Researchers then used methodology previously used to determine the economic impact of lead exposure, which also has been linked to losses in mental acuity, to determine annual lost earnings potential associated with neurodevelopmental impacts of prenatal mercury exposure (Lowy, Scripps Howard News Service, 2/28). Although the study estimated an $8.7 billion loss of earnings potential annually because of prenatal mercury exposure, the total loss could range from $2.2 billion to $43.8 billion annually, according to the study (Steinkraus, Racine Journal Times, 3/1). The study was supported by a grant from the National Institute of Environmental Health Sciences and was published with the aim of influencing congressional debate over federal legislation that would change how the government regulates emissions from power plants and other sources (AP/Long Island Newsday, 2/28).