Mercury exposure through diet in pregnant women and women of childbearing age

Abstract

The study examined the stage of clean-up of the Port Lavaca bay sites in Texas, which were polluted during the early 1990's by effluent containing mercury (Hg) from a chloralkali plant. In addition to Hg intoxication through environmental contaminations, human exposure through dietary fish and other seafoods occurred. Bacteria converts inorganic Hg to alkyl organic compounds and subsequently the metal crosses the blood brain barrier thus exerting adverse effects on the fetal developing nervous system. In order to conduct a survey of dietary Hg exposure, blood was collected from pregnant women and those of childbearing age at routine clinic visits at each of three centers in South Texas cities (Galveston, Texas City, Port Lavaca/Victoria, TX). A questionnaire sought dietary and lifestyle information including consumption, sources of fish and other seafoods. A significant number of subjects (119 out of 175, 68%) ate fish caught locally. The blood Hg concentrations (µg L⁻¹) range varied with the location of the study centers: City of Galveston 2.6–62; Texas City 2.8–111.8; and the Port Lavaca areas 3.02–126.7. The concentrations of blood Hg was directly proportional to the number of fish meals consumed for each species considered. Mean blood Hg concentrations for no fish meals per week were: Port Lavaca 4.5 (N = 3), Galveston 4.3 (N = 3), Texas City 3.5 (N = 10). For >3 fish meals per week, the mean blood Hg concentrations were: Port Lavaca, 48.0 (N = 53), Galveston 29.1 (N = 35), Texas City, 36.1 (N = 31). Data show that residues of Hg were still present in 1994 despite the clean-up efforts.

Keywords:

• mercury
• pregnant women
• fish
• diet

Acknowledgements

Funding for this study was provided by the UTMB Small Grants Program, 1994 and the UTMB Hispanic Center of Excellence Grant, 1996. We also thank Dr. Fatima Nayeem and Ms. Emily Gifford for their help with manuscript preparations.