barrels with sulfur dioxide gas that they purchased for preserving wine. They can only use sulfur dioxide gas that comes in a container bearing a legal pesticide label permitting its use for sanitizing wooden wine barrels used in wine production. In addition, even though some people promote the use of common household dish washing soap to control certain insects, commercial growers who wish to use soap as an insecticide must use a soap product packaged with an approved pesticide label. Conversely, using an insecticidal soap product for purposes other than controlling insects is illegal unless the label allows for non-insecticidal uses.
Because their purpose is to kill pests, many pesticides, including certain anti- microbial pesticides, are toxic and present risks to users or the environment. As a result, selecting, using, and handling these pesticides require that you gain special skills and training. This chapter describes various types of antimicrobial pesticides and their formulations. It explains pesticide toxicity and discusses how certain factors alter toxicity.
ANTIMICROBIAL PESTICIDE TOXICITY
Toxicity is one of the characteristics used to describe pesticide chemicals. Toxicity is the capacity to cause harm to you, sometimes referred to as potency. Most pesticides, by their nature, must be toxic in order to destroy pests and therefore they usually have a potential for injuring people or the environment. Not all antimicrobial pesti- cides have the same hazard—some are more toxic or potent than others. The effect that a pesticide has on a pest, or even a person who receives an accidental exposure to that pesticide, depends on the amount of exposure to the pesticide. The amount of exposure is the dose. As the dose increases, a pesticide has a greater potential for causing injury. Highly toxic antimicrobial pesticides cause injury at smaller doses and therefore are more hazardous.
Measuring Pesticide Toxicity
One way pesticide manufacturers determine the toxicity of a particular pesticide is by giving measured doses to groups of laboratory animals and observing the results. The developers estimate the lethal dose or lethal concentration of each pesticide in this way. They also discover the maximum dose organisms can tolerate without causing injury. Results from these types of tests predict the pesticide’s hazards to people and nontarget organisms. The U.S. EPA and many states require this important data as part of their pesticide registration process.
The data from animal testing establishes estimated exposure risks to people and provides information on the pesticide’s mode of action. Pesticide developers conduct different types of tests depending on what kind of information they need. In some cases, they feed laboratory animals small sublethal doses of the material on a daily basis. Such studies establish the no observable effect levels (NOEL) and give informa- tion on the long-term, or chronic, effects of exposure. Other special studies assess the potential for causing sterility, birth defects, cancer, and other problems in people. Based on this data, regulatory agencies include a wide margin of safety in permissible exposure levels to protect people from injury or illness.
Short-term toxicity testing helps to predict the acute (or immediate) health ef- fects of exposure to a pesticide product. During a study, researchers give groups of laboratory animals a single, high dose of a product they are testing. They measure immediate responses and study the pesticide’s mode of action. Exposing animals for short periods to large doses of a pesticide helps to predict potential human hazards from exposure to small doses over longer periods.