Consumer Safety

Any substance, given in a sufficient dose, can be harmful. For example, even common household products, such as toothpaste and aspirin can cause nausea and even death if enough is swallowed.

Pesticides are generally more toxic than toothpaste — they are intended to kill insects, weeds, and plant diseases — but the same principle applies: At high levels of exposure, they are toxic, and at other, lesser levels they are not.

The U.S. Environmental Protection Agency (EPA) has set strict standards for chlorpyrifos to protect consumers from potential harm while providing a useful tool for farmers to protect their crops from insect losses.

Any pesticide must go through a thorough scientific assessment of the potential negative effects of that pesticide on human health. To anticipate how a pesticide might impact human health, laboratory animals such as mice and rats are exposed to varying dosages of the pesticide in their food — from very minimal to extremely high levels. Scientists then determine how much exposure the animal can have without any biological effect. This level of exposure forms the basis for setting allowable exposures for people.

Studies have shown that a rodent can be exposed to 500,000 nanograms of chlorpyrifos for each kilogram of body weight (500,000 ng/kg/BW) without being affected in any measurable way.

How much is 500,000 nanograms? The average grain of fine sand weighs about 200,000 nanograms. That means that if a rat grew to 86-kilograms, or 190-pounds (the average weight of a U.S. man), it could eat the equivalent of 215 hypothetical grains of sand made of chlorpyrifos in a single sitting without being affected.

Because animals are different from people, one person is different from another, and children are different from adults, the EPA builds in various safety factors to account for these differences. For chlorpyrifos, that safety factor is 1,000 — or 1,000 times below the level at which the product produces no effect in laboratory tests. That means that a hypothetical 190-pound man would be allowed, at most, not 215 grains of sand, but just two tenths of a single grain of sand at any one time.

But the EPA goes further than that to ensure the safety of the American food supply. Under EPA’s standards for chronic exposure, daily chlorpyrifos exposures to that hypothetical 190-pound man from all sources must not exceed 6% of this already tiny amount, or the equivalent of one one-one hundredth (0.012) of a grain of sand each day. Uses of chlorpyrifos that could not meet this stringent EPA standard were phased out beginning in the year 2000.

Learn more about how the EPA sets its standards and the EPA’s process for registering a pesticide product.

Reducing Food Residues

No one likes the idea of pesticide residues on the food they eat. Equally disturbing to most consumers would be to find insects and larvae in their food. Assisting in the production of high-quality agricultural products, while maintaining human and environmental safety standards, is a responsibility Dow AgroSciences — in collaboration with the EPA and other regulatory agencies — takes seriously. To ensure that consumers would not be exposed to any more than the EPA allows, Dow AgroSciences worked with the EPA to make changes in the way farmers used chlorpyrifos.

An illustration of this commitment can be seen in recent changes in authorized uses of chlorpyrifos. In 2002, the EPA expressed concerns that the way chlorpyrifos was being used on three crops — apples, tomatoes and grapes — could result in more exposure than would be allowable under the Agency’s new health-based standards.

In order to mitigate these exposures, the EPA required that all use of chlorpyrifos products in the United States be discontinued on tomatoes, restricted on apples to pre-bloom applications (when trees are still dormant) and restricted on grapes to yield residues no greater than 0.01 ppm (parts per million) (The previous residue standard for grapes was 0.5 ppm.) Dow AgroSciences updated its product labeling accordingly.

Chlorpyrifos’ Removal from Home Use Market

In the 1990s, concerns about chlorpyrifos exposures to humans and their household pets through residential uses, as well as to wildlife were expressed by the scientific and regulatory communities. These concerns were addressed by the United States EPA through the pesticide reregistration process as modified by the Food Quality Protection Act. Initial output of the EPA’s Reregistration of chlorpyrifos, which was completed in 2002¹ determined that, while dietary exposures remained “below the level of concern for the entire U.S. population, including infants and children,” there were several areas of concern to be addressed:

• EPA believed that chlorpyrifos used within the home might result in more exposure to children and household pets than would be allowable under the Agency’s new health-based standards.
• EPA believed that outdoor home uses authorized at the time, such as landscape and lawn spraying, could pose a risk to wildlife and fish.

By 2000 Dow AgroSciences, by agreement with the EPA, began the phase-out of U.S. in-home uses of chlorpyrifos, Outdoor home uses — for residential lawns and landscaping — were also being phased out at that time.

For golf course use, new guidelines for application were agreed upon and implemented. Buffer zones were also established to prevent the use of the product near bodies of water. Dow AgroSciences added these new guidelines to the product’s label and safety instructions.

As new information comes to light — or as standards change — regulators and registering companies respond.