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ENVIRONMENTAL AND TOXICOLOGICAL PROPERTIES OF HERBICIDES
Citation:
FAIRBROTHER, A. ENVIRONMENTAL AND TOXICOLOGICAL PROPERTIES OF HERBICIDES. Presented at Central Oregon Coast Watershed Council Meeting, Newport, OR, May 12, 2006.
Description:
Herbicides comprise over 75% of all the agricultural pesticide use in the United States. This amounts to over 500 million pounds of active ingredients applied each year. The US EPA has the responsibility to register these products and label them for use such that unintended effects to nontarget organisms are minimized. There are many different classes of herbicides, some of which target only broadleafed plants, others only grasses, while still others affect a broader spectrum of plant types. Most of these chemicals work through interrupting plant-specific metabolic pathways such as photosynthesis or production of plant-specific amino acids. Thus, they generally are not acutely toxic to fish, wildlife, or humans although a few have been shown to possibly have subtle effects at low doses after long exposures. The way the chemicals are formulated for their application (generally as a spray) affects how long they remain in the environment (their half life) and whether or not they will be water soluble. This is important as the potential for fish and wildlife to be affected depends directly on how the chemical moves through the environment. These general characteristics of herbicides will be reviewed, and specific attention paid to the herbicides used in the forest industry of the mid-Oregon Coast Range.