BACKGROUND: Women of childbearing age (WOCBA) are encouraged to include fish in their diets as a source of omega-3 fatty acids and other nutrients essential to maternal and fetal health. However, special health guidelines should be followed to reduce serious health risks associated with exposures to fish contaminated with methylmercury. Recent research suggests that awareness of these advisories is low, and some infants in the Lake Superior basin continue to have elevated mercury levels at birth. We examined hair-mercury levels among WOCBA in northern Wisconsin as part of a larger educational intervention to increase awareness of fish consumption advisories.
METHODS: Women aged 18 to 45 from Lake Superior coastal counties in Wisconsin completed a detailed fish consumption questionnaire and provided hair samples for mercury analysis. Participants with mercury levels exceeding 1 microgram per gram (µg/g), the Environmental Protection Agency’s guideline for acceptable mercury exposure, were classified as cases. Fish consumption habits, including meal frequency and species consumed, were examined in detail for each case.
RESULTS: Of the 255 women participating in the study, five met the case definition for an elevated mercury level. Reported fish consumption during the last 12 months varied considerably among cases, ranging from <1/week to nearly 1 meal/day. Species and origin of fish meals also differed from case to case, with some women consuming primarily purchased fish and others consuming mostly locally-caught fish. For most cases, there was clear evidence of deviating from consumption advice in a substantial way, including consuming fish on the ‘do not eat’ list for WOCBA and exceeding consumption frequency guidelines in place for certain species. Finally, all cases reported very little knowledge of health advisories, and indicated low adherence to advisories.
CONCLUSIONS: This case-series highlights several unique dietary patterns, all of which led to an elevated mercury exposure. The only clear consistency among cases was the lack of knowledge about, and low adherence to, health advisories for mercury. Increased outreach and educational efforts should be continued among WOCBA, even among infrequent fish consumers, due to the importance of species and waterbody source influence. Personalized dietary counseling may be a valuable resource to identify sources of mercury exposure and suggest actionable advice.