SREL Reprint #3702

Integrating mercury concentrations in American alligators (Alligator mississippiensis) with hunter consumption surveys to estimate exposure risk

Laura V. Kojima1,2, Tracey D. Tuberville1,3, and Benjamin B. Parrott1,2

1Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina, USA
2Eugene P. Odum School of Ecology, University of Georgia, Athens, Georgia, USA
3Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia, USA

Abstract: Mercury is a naturally occurring element but is also considered a widespread contaminant due to global anthropogenic activity. Even in moderate amounts, mercury (Hg) is an established neurotoxin and is associated with a range of adverse outcomes both in humans and wildlife. Humans in the United States are most commonly exposed to Hg through contaminated food or drinking water, and the consumption of game species, particularly those occupying higher trophic levels, has the potential to expose hunters to high concentrations of Hg. In the present study, we determined Hg concentrations in tail muscle and blood from American alligators (Alligator mississippiensis) inhabiting a region (Savannah River Site, SC, USA) with known Hg contamination. We then integrated these data with alligator harvest records and previously published surveys of alligator meat consumption patterns to estimate potential exposure risk. We found that the average Hg concentrations in tail muscle (1.34 mg/kg, wet wt) from sampled alligators exceeded the recommended threshold for Hg exposure based on the World Health Organization's guidelines (0.5 mg/kg, wet wt). In addition, based on regional consumption patterns reported for both adults and children, we estimated Hg exposures (x̄Adult = 0.419 µg/kg/day, x̄Child = 2.24 µg/kg/day) occurring well above the US Environmental Protection Agency methylmercury reference dose of 0.1 µg/kg/day. Although the two reservoirs sampled in the present study are not currently open to alligator hunting, they are connected to waters that are publicly accessible, and the extent of alligator mobility across these sites is not known. Together, the findings reported in the present study further demonstrate the need for active monitoring of Hg concentrations in game species, which can convey substantial exposure risks to the public.

Keywords: Risk assessment; wildlife toxicology; metal accumulation; mercury; bioaccumulation

SREL Reprint #3702

Kojima, L. V., T. D. Tuberville, and B. B. Parrott. 2023. Integrating mercury concentrations in American alligators (Alligator mississippiensis) with hunter consumption surveys to estimate exposure risk. Environmental Toxicology and Chemistry 42(2): 525-534.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).