Analysis of potential mercury policies: the impact of stream basin characteristics on susceptible populations.

Human exposure to Hg through fish consumption from local waterways is an ongoing concern to regulatory decision makers. Previously described population exposure and bioaccumulation models were combined to analyze the impact of potential policies on susceptible populations. The combined model simulated the problem of Hg exposure by examining the system from the point of Hg in the water column to its concentration in population biomarkers.

A dynamic model using monitoring data and watershed characteristics to project fish tissue mercury concentrations in stream systems.

A complex interplay of factors determines the degree of bioaccumulation of Hg in fish in any particular basin. Although certain watershed characteristics have been associated with higher or lower bioaccumulation rates, the relationships between these characteristics are poorly understood. To add to this understanding, a dynamic model was built to examine these relationships in stream systems.

Development and evaluation of a dynamic model that projects population biomarkers of methylmercury exposure from local fish consumption.

A dynamic model was developed to project Hg concentrations in common biomarkers of exposure in response to changes in Hg concentrations in predatory fish from local waters. The model predicts biomarkers in susceptible populations for intake rates representing the mean, 90th, 95th, and 99 th percentiles of populations of interest. The biomarkers the model calculates are blood methylmercury, total hair Hg, and fetal blood methylmercury.

History and results of the two inter-laboratory round robin endotoxin assay studies on cotton dust.

Background: In the US cotton industry, airborne cotton dust levels are regulated, and other countries are moving to specify safety limits for airborne endotoxins. There is concern about potential respiratory health hazards associated with agricultural and other organic dusts. In laboratories, ranking which samples have high and low levels of endotoxin is usually in good agreement between laboratories.

Inter-laboratory analysis of endotoxin in cotton dust samples.

Background: Currently there are no mandated exposure limits for endotoxin, but recommended limits have been proposed and interest expressed in developing quantitative standards for endotoxin. A limitation for developing a quantitative standard for endotoxin is the measurement variability between laboratories. Inter-laboratory variability of up to four orders of magnitude has been reported for replicate samples.

Partially opened triple helix is the biologically active conformation of 1-->3-beta-glucans that induces pulmonary inflammation in rats.

1-->3-beta-Glucans produce pulmonary inflammation in rats and are commonly found in indoor air dust samples. Conformation is an important factor determining the biological activity of 1-->3-beta-glucans. The partially opened triple-helix conformation induced by NaOH treatment and the annealed triple-helix conformation have been identified by fluorescence resonance energy transfer spectroscopy in our previous study.