The nutritional safety
of wheat-based food products is
compromised
by the presence of the processing contaminant acrylamide. Reduction
of the key acrylamide precursor, free (soluble, non-protein) asparagine,
in wheat grain can be achieved through crop management strategies,
but such strategies have not been fully developed. We ran two field
trials with 12 soft (biscuit) wheat varieties and different nitrogen,
sulfur, potassium, and phosphorus fertilizer combinations. Our results
indicated that a nitrogen-to-sulfur ratio of 10:1 kg/ha was sufficient
to prevent large increases in free asparagine, whereas withholding
potassium or phosphorus alone did not cause increases in free asparagine
when sulfur was applied. Multispectral measurements of plants in the
field were able to predict the free asparagine content of grain with
an accuracy of 71%, while a combination of multispectral, fluorescence,
and morphological measurements of seeds could distinguish high free
asparagine grain from low free asparagine grain with an accuracy of
86%. The acrylamide content of biscuits correlated strongly with free
asparagine content and with color measurements, indicating that agronomic
strategies to decrease free asparagine would be effective and that
quality control checks based on product color could eliminate high
acrylamide biscuit products.
Predictive ecological risk assessment was used to determine whether any riskreduction benefit would result from the installation and operation of wet scrubbers at an aluminum smelter in East Iceland. Sulfur dioxide and hydrogen fluoride exposure will not result in any appreciable risk to mosses, lichens, lodgepole pine, and heather/heath grassland communities beyond the dilution zone without scrubbers. With scrubbers, exceedances of plant criteria may occur beyond the dilution zone. Critical concentrations of polycyclic aromatic hydrocarbons (PAHs) and hydrogen fluoride (HF) in terrestrial wildlife food items were converted to critical air concentrations, which were then compared to modeled air concentrations. Terrestrial wildlife species are not expected to be exposed to PAH concentrations that result in appreciable risk. If wildlife species are assumed to consume only grasses, predicted HF exposures will not result in exceedance of toxicity thresholds. However, if wildlife species are assumed to consume only heather, thresholds are exceeded at some locations for the rock ptarmigan and wood mouse. Results of population modeling indicate no potential for population impacts to rock ptarmigan outside the facility boundary. Impacts to wood mouse carrying capacity are expected to extend beyond the dilution zone with scrubbers, but not without.
Protection of human health and ecosystems is gaining importance in corporate decision-making regarding industrial development. During the design phase for an aluminum smelter in East Iceland, it became necessary to determine whether a wet scrubber system should be installed to reduce sulfur dioxide emissions. Predictive risk assessment was used to determine whether there would be a consequential difference in the level of risk to human and ecological receptors from constituents in air emissions from the aluminum smelter, either with or without wet scrubbers. Benchmark exposure concentrations were established for avian, mammalian, and plant receptors and were compared to air modeling predictions to develop risk estimates. Benchmark concentrations were derived using plant uptake models for fluoride and polycyclic aromatic hydrocarbons (PAHs), and food-web modeling for birds and mammals. Exposure models were developed for all receptors, and populationlevel effects were modeled for plant, bird, and mammal receptors. Results indicated that exposures under both scenarios are lower than risk thresholds, and overall risk was lower for a smelter without wet scrubbers. Thus, although mass loading of sulfur dioxide (and other constituents) would be reduced using wet scrubbers, the corresponding risk to ecological receptors would actually be higher because of higher exposure-point concentrations in air.
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