Evaluation of mercury exposure reduction through a fish consumption advisory program for Anishinaabe tribal members in Northern Wisconsin, Michigan, and Minnesota.

The Great Lakes Indian Fish and Wildlife Commission has an extensive program to inform Anishinaabe tribal members from northern Wisconsin, Michigan, and Minnesota who harvest and consume walleye about the health risks of consuming these fish, and to encourage harvest and consumption practices that reduce exposure to MeHg. We report here the results of a probabilistic analysis of exposure to methyl mercury (MeHg) among tribal members who consume walleye. The model predicts that the potential for greatest exposures to MeHg occur among women of child-bearing age and children who consume large walleye from lakes that contain heavily contaminated (MeHg concentration >0.5 mg/kg) fish. The analysis allows GLIFWC to evaluate, focus, and fine-tune its initiatives to protect the health of tribal members in ways that result in exposure and risk reduction for tribal harvesters, women of child-bearing age, and children, while maintaining important tribal lifeways, which include the harvest and consumption of walleye.

Structure-activity relationships for aquatic toxicity to Tetrahymena: halogen-substituted aliphatic esters.

The toxicity of a series of 21 mono- and dihalogenated aliphatic monoesters has been evaluated using a Tetrahymena pyriformis population growth impairment assay. A structure-activity model has been developed for toxicity data (log(IGC50(-1))), using the 1-octanol/water partition coefficient (logKow) and the energy of the lowest unoccupied molecular orbital (ELUMO) as descriptors. A statistically robust plane (log of the inverse of the 50% growth inhibitory concentration (IGC50(-1)) = 0.34logKow - 0.84 (ELUMO) + 0.04; n = 15, r2 = 0.85, s = 0.26, F = 33, Pr > F = 0.0001) was found for monohalogen-substituted derivatives. These substances are thought to exhibit toxicity via the soft electrophilic mode of toxic action. This toxicity is imparted by the leaving ability of the halogen, which is enhanced when it is placed in close proximity to the carbonyl group. This leaving ability allows haloesters, especially alpha-haloesters, to undergo an SN2, addition-elimination substitution electro(nucleo)philic reaction. Outliers to the above model broadly fell into two groups: small reactive molecules (e.g., propylbromoacetate) that were more toxic than predicted and molecules in which the reactive center was sterically hindered by an alkyl group (e.g., ethyl-2-bromoisovalerate), which were less toxic than predicted.