Study examines mercury exposure in pregnant women

A new study published by researchers at SUNY Downstate Medical Center's School of Public Health assesses mercury levels in pregnant women and examines dietary and environmental sources of exposure to mercury. The research, which focuses on an urban immigrant community, examined risk factors that may be associated with elevated mercury levels, measured through urine and cord blood samples. The study, published this month in the Journal of Environmental Monitoring, found that foreign-born immigrant women from the Caribbean are at higher risk for elevated levels of mercury in the blood, predominantly from dietary sources such as large fish. The full article is available at http://xlink.rsc.org/?doi=C2EM10835F

Laura Geer, PhD, MHS, assistant professor in the Department of Environmental and Occupational Health Sciences at SUNY Downstate's School of Public Health, and Patrick J. Parsons, PhD, chief of the Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, were the main collaborators on the study, "Assessment of Prenatal Mercury Exposure in a Predominately Caribbean Immigrant Community in Brooklyn, NY." The study can be read in the journal's online edition at (To Come). The School of Public Health at SUNY's University at Albany, where Dr. Parsons is professor and chair of the Department of Environmental Health Sciences, also contributed to the study, which was also conducted in collaboration with SUNY Downstate's Department of Obstetrics and Gynecology. The research was sponsored by The New York Community Trust.

The study elaborates on previously identified risk factors of in utero mercury exposure. Mercury exposure is a continuing concern in immigrant communities due to risk factors such as maternal country of origin, fish consumption, and ritualistic use of elemental mercury in religious ceremonies. For infants and children, the primary health concern is possible damage to cognitive and central nervous system development related to maternal exposure.

Dr. Geer and her team used a combination of assessment methods to determine exposure levels. A questionnaire designed in collaboration with health professionals from the Caribbean community assessed the frequency of fish consumption, ritualistic practices, occupational exposures, number of dental amalgams, and use of mercury-containing skin and household products. [SUNY Downstate is located in an area of Brooklyn that includes one of the largest Caribbean-American communities in the United States.]

Analysis of cord blood for mercury revealed that 16 percent of samples exceeded the estimated equivalent of the U.S. Environmental Protection Agency's Reference Dose. Cord blood samples generally reflect organic mercury that has been acquired through maternal food consumption. Predictors of cord blood levels included maternal fish consumption and foreign birth of the mother.

Urine mercury levels, which are more likely to reflect environmental exposure to inorganic mercury, were significantly lower than cord blood levels. Predictors of urine mercury also included foreign birth of the mother, as well as the number of dental amalgams and special product use. There were no reports of mercury use in ritualistic practices or in cosmetics; however, some women reported use of religious medals and charms. Women participating in the study were informed of any elevated test results.

Although the study population was selected as a convenience sample, the mercury levels were lower -- in this higher-risk population -- than those estimated based on maternal blood levels from the NYC Health and Nutrition Examination Survey (HANES) of 2004, indicating the possibility of lower exposure since the NYC HANES study was conducted.

Putting this into context, Dr. Geer explains that the elevated cord blood mercury samples seen in some study subjects were still not at levels that are known to be associated with adverse health or developmental effects. However, she notes that the study indicates a need for further study and mercury-exposure prevention efforts tailored to this group, and that subjects were contacted and offered further testing. Furthermore, efforts should target health care providers, health agencies, and community advocates who provide avenues of education for women of childbearing age concerning appropriate dietary fish selection, and potential sources of mercury in the home. Dr. Geer points out that the new widespread use of fluorescent light bulbs, which contain a small amount of inorganic mercury and may expose people when they break, as well as the possibility of exposure from discarded computer equipment, are two current but little recognized sources.

Dr. Geer said, "Our study shows that women of Caribbean origin are at high risk for mercury exposure, owing to the consumption of specific types of fish and other factors. Since mercury can harm a child's development both in and beyond the womb, mercury should be kept at the lowest possible levels. Community education efforts should target Caribbean-American women to accomplish this."

Dr. Geer, assisted by Fay Callejo, MPH, from the School of Public Health, is in the process of completing a follow-up study to identify educational strategies to facilitate community awareness of mercury exposure sources, particularly for women of childbearing age.

Dr. Geer recommends that people familiarize themselves with how to protect their children and their homes from mercury exposure. As suggested by the U.S. Environmental Protection Agency (EPA), five things they can do include:

Learn how to enjoy a diet that includes fish while minimizing exposure to fish species that have high mercury levels.

Learn which products are likely to contain mercury. Avoid use of mercury-containing skin-lightening creams.

Properly recycle or dispose of any mercury-containing products in the home.

Handle mercury-containing products such as thermometers and compact fluorescent bulbs carefully to avoid breakage.

And learn how properly to clean up a mercury spill. Never use a vacuum cleaner.