Mercury Exposure Among Flathead Indian Reservation WIC Participants

Methylmercury has been linked to neurodevelopmental deficits in young children and children exposed in-utero, as well as cardiovascular disease in adults. Previous studies of lake trout from Flathead Lake, Montana, have shown elevated levels of methylmercury, resulting in updated fish consumption guidelines. Thousands of lake trout are donated to reservation food banks through the “Mack Days” fishing tournaments. Women, Infant and Children program (WIC) participants, representing the most vulnerable population for mercury health effects may receive free fish from the food banks. A previous survey of local Native women from the WIC program showed that approximately 50% eat fish, and that the majority were not aware of any fish consumption advisories. Dietary surveys are frequently inaccurate, therefore, a follow-up with actual hair mercury analysis was necessary to determine if any of these participants are at an elevated risk from excessive methylmercury exposure. Hair samples were collected on various days and at multiple food bank locations on the reservation. Mercury levels were determined in samples of 20-25 mg of hair, 3 cm of length, representing a 3-month integrated exposure, using EPA method 7473. Preliminary results demonstrate that ~73% sampled show little to no fish consumption (<100 ppb). ~26% sampled ate a moderate amount of fish (100<x<500 ppb). This shows that although women in the program are offered free fish from the local Mack Days event, many do not take advantage of this resource. Explanations for low fish consumption will be determined after further review of the surveys.