Forget the Unattainable ‘Zero’ Level

People in Lompoc, who recently had their air sampled through a special $145,000 state appropriation, should be comforted by the fact that nothing new or alarming was found. The news is probably a big disappointment to activists who had expected the study would point a finger at pesticide use.

The state-funded study was designed to see what levels of pesticide traces might be present in the air. That’s a reasonable question. Lompoc is an area where suburbia is encroaching on traditional agricultural lands and respiratory illnesses were reported by the state Office of Environmental Health Hazard Assessment to be higher there than in other areas. Now that the air monitoring study has been conducted and the results are in, it is time for health authorities to look for another explanation for possible elevated rates of respiratory illness in the community.

There are no surprises in the preliminary data and there should be no alarm from its findings. A high percentage of the air samples taken during a pesticide-use season contained no detectable traces of any pesticides. At the detection level that was used, it means “none” but not zero. In other samples indicating trace levels, the concentrations were too low to be confirmed with analytical certainty. Even when the presence of a pesticide in an air sample was measurable, the concentration in air was far below any level of health concern.

It is not surprising that sensitive analytical methods detected low levels of pesticide in the air, especially during the growing season when pesticides are applied. It is normal that chemicals applied through air will be detected in low levels in large air samples. The most frequently detected insecticides are used in agriculture and to protect homes and commercial buildings. Science today has the ability to detect very low levels of almost any substance in the environment. The question that must be asked, though, is what level of detection is cause for concern?

For the past 30 years, I have studied the environmental fate and effects of pesticides, and during the past dozen years, the exposures of farm workers, pesticide applicators and Californians using pesticides in their homes. The Lompoc air concentrations are far lower than levels that could cause adverse effects in people who are routinely exposed to pesticides through their work or in their homes.

When pesticides are properly handled and applied, people who are exposed on a daily basis show no ill effects from contact with particular products and everything else that is contacted in a day. Why should we accept any detectable level? What is wrong with zero? Zero is almost impossible to attain, given the fact that scientists can find infinitesimal amounts in the environment. Not that long ago, when scientists could detect chemicals in the environment in the parts per million range--a very small amount--many samples were judged to contain “zero.” Today, we have tests to routinely detect stuff at levels a thousand and even a million times lower than that. While that seems awfully low, it is not zero.

The Lompoc study was designed to find those near-zero levels. To achieve zero, we have to give up something. In the case of Lompoc agriculture, we would have to give up tools that allow us to grow high quality fruits and vegetables, which are a mainstay of the local economy and a major contributor to world food supply. That’s quite a trade-off, especially given that the traces of agricultural chemicals in Lompoc air are well below levels that have any health significance to people or the environment.