They found that blood mercury levels were not consistently associated with adverse performance on a broad range of tests of cognitive function. This study may help policy makers with future decisions about mercury emissions from power plants as well as fish consumption recommendations for older adults. The study is published in the April 20, 2005, issue of the Journal of the American Medical Association (JAMA).
"Our study provides no evidence to challenge the government's current recommendations for blood mercury levels, but neither does it indicate that they are safe. The key point is that the aging population may be more sensitive to toxic chemicals and this is the first study to examine mercury exposure in the older U.S. population," said Megan Weil, MHS, lead author of the study and a PhD-candidate in the Bloomberg School of Public Health's Department of Environmental Health Sciences.
Weil explained that the Environmental Protection Agency bases its recommendations on studies of children and women of childbearing age. From these studies, they determined that blood mercury levels should not exceed 5.8 g/L. The median mercury level in study participants was 2.1 g/L and only approximately 10 percent of subjects exceeded the government guideline.
The researchers analyzed the blood samples of 474 study participants, who were part of the larger Baltimore Memory Study. They also administered 12 cognitive function tests, which measured language, memory, attention, concentration, reaction time and other brain functions. The study authors found that higher blood mercury levels were as
Contact: Kenna Lowe
Johns Hopkins University Bloomberg School of Public Health