A new procedure for alkaline digestion of hair was used for the selectivedetermination of total and inorganic mercury by flameless atomic absorption and the determination of methylmercury by an improved gas-chromatographic procedure. The precision of the measurements by atomic absorption for total, inorganic, and organic mercury (by difference) was 1.9%, 6.5%, and 2.1%, respectively. Recoveries...

Sulfate-reducing bacteria (SRB) in anoxic waters and sediments are the major producers of methylmercury in aquatic systems. Although a considerable amount of work has addressed the environmental factors that control methylmercury formation and the conditions that control bioavailability of inorganic mercury to SRB, little work has been undertaken analyzing the biochemical mechanism of methylmer...

We studied the biomagnification of total mercury and methylmercury in a subtropical freshwater lake, Caddo Lake, Texas and Louisiana, USA. The present study is unique in that it not only included invertebrates (seven species) and fish (six species) but also an amphibian (one species), reptiles (three species), and mammals (three species). Nonfish vertebrates such as those included in the presen...

Three generations of mallard ducks (Ana~ platyrh!lncllo.s! "-'ere fed either a control diet or a diet containing 0.5 ppm mercury in the form of methylmercury. The !~vel$ of men.-ury in adult tissues and eggs remained about the same over 3 generations. The methylmercury di~ had no effect on adult weights or weight changes during the reproductive season. Females fed a diet containin~ 0.5 ppm merc...

In 2001, the U.S. Environmental Protection Agency derived a reference dose (RfD) for methylmercury, which is a daily intake that is likely to be without appreciable risk of deleterious effects during a lifetime. This derivation used a series of benchmark dose (BMD) analyses provided by a National Research Council (NRC) panel convened to assess the health effects of methylmercury. Analyses were ...

1 Advances in genetics have allowed for greater investigation into the complex microbial 2 communities mediating mercury methylation in the environment. In wetlands in particular, 3 dissolved organic matter (DOM) may influence methylmercury production both through direct 4 chemical interactions with mercury and through substrate effects on the environmental 5 microbiome. We conducted microcosm ...

In classical pharmacology, oral bioavailability of a toxicant is defined as that fraction of an orally administered dose reaching the systemic circulation of the animal. The present study estimates the bioavailability of methylmercury in channel catfish (Ictalurus punctatus) by comparing concentrations in the blood through time after oral and intra-arterial (IA) administration. Catfish were can...

Global atmospheric changes carry the potential to disrupt the normal cycling of mercury and its compounds. Acid rain may increase methylmercury levels in freshwater fish. Global warming and increased ultraviolet radiation may affect the global budget of methylmercury, including its formation and degradation in both biotic and abiotic environments. In this article we review current knowledge on ...

Top marine predators present high mercury concentrations in their tissues as consequence of biomagnification of the most toxic form of this metal, methylmercury (MeHg). The present study concerns mercury accumulation by Guiana dolphins (Sotalia guianensis), highlighting the selenium-mediated methylmercury detoxification process. Liver samples from 19 dolphins incidentally captured within Guanab...