Examining American Alligators as Sentinels of Toxic Trace Element Exposure in Human Populations
Frances Nilsen, Thomas Rainwater, Stephen E. Long, Tracey B. Schock, Philip Wilkinson, Arnold Brunell, Brittany Kassim, John Bowden
Mercury (Hg) is a ubiquitous toxic element eliciting a myriad of health problems including Minamata disease. Exposure to methylmercury, the most toxic bioaccumulative form of Hg, occurs through aquatic dietary sources. Many nations have consumption advisories in place for Hg containing fish species however, not all communities abide. Subsistence hunting communities and populations including marine mammals in their diet are routinely exposed to Hg concentrations far above the advisory limits. To effectively monitor the health effects of such high Hg exposures, a sentinel species is needed. One that is more accessible than the marine mammals that are currently used as proxies for elevated contaminant concentrations. Due to the unique environmental conditions of the southeastern Atlantic coast of the United States, the accumulation of Hg in this region is greater than in most other locations. Upper trophic level predators in this region have high concentrations of Hg and other contaminants. In this study, the Hg and other trace element concentrations are examined in American alligators from seven sites along the southeastern Atlantic coast. The observed concentrations for the four toxic elements, (arsenic, cadmium, lead and Hg) are comparable to concerning human concentrations, with Hg spanning the broadest range. This wide range of Hg concentrations observed makes the alligator a useful sentinel species for Hg exposure for a variety of different human populations and dietary exposure scenarios.