Monday, November 13, 2006

Toxin Concentration and Transport in Dust.

Richard Zartman, William Jaynes, Cary Green, Michael San Francisco, and John Zak. TX Tech Univ., Plant and Soil Science Dept., Lubbock, TX 79409-2122

Plant and microbial toxins, allergens, pollen, and spores have a much lower density than soil particles. The lower density of these materials could facilitate effective transport and concentration in dust. Aflatoxin concentrations as great as 41,000 g/kg have been measured in the dust near combines, although grain crops containing 1,000 g aflatoxin/kg must be destroyed. A common health condition termed "farmers lung" is related to human exposure to allergens, pollen, spores, and mycotoxins found in dust. Peanuts contain the allergenic protein, peanut seed lectin (PSL). In this study, a small dust generation/collection device was used to collect dust fractions from soil samples containing PSL. Soil samples (5-g) of Brownfield loamy fine sand (84% sand) and Pullman clay containing 5% peanut extract were used. ELISA was used to measure PSL in the dust fractions. Nitrogen surface areas were used as a measure of particle size. The collected soil fractions ranged from sand or sand-sized aggregates in the residual material (residual fraction) left in the dust generator to silt and clay in the last dust traps (trap3, trap4). Residual fraction surface areas were lower than the original soil sample and progressively increased from trap1 to trap4. Similarly, PSL was depleted in the residual fraction and concentrated (up to 11.6x) in the finer fractions (trap3, trap4). Toxic materials in soil can be transported with soil dust and concentrated in the respirable dust fractions.