Nor do organic farmers marketing produce grown free of chemicals get any special
protections, causing problems for some farmers who have lost their organic certifica-
tion. One baby food company was outraged to learn that its products had been con-
taminated by pesticides through no fault of its own.
Homeowners who believe they have been exposed to pesticides must offer proof of
harm, either with tests showing chemical residues on their property, or medical evi-
dence. Many more homeowners are beginning to fight, but their cases are rarely pub-
licized due to out-of-court settlements.^6
Some methods for ranking agricultural pesticides by their potential hazard as air
contaminants have been proposed based on use, volatility, toxicity, and other factors.
Ultimately, rankings are used to determine exposure reduction or public health prior-
ities. One of the initial uses of the ranking developed by the California Department
of Pesticide Regulation, called the (pesticide) toxic air contaminant (TAC) ranking, is
to direct air monitoring of agricultural pesticides in California. The California Air
Resources Board conducts air monitoring in regional urban centers and in agricul-
tural communities that are selected on the basis of area use of the monitored pesti-
cides. For the monitored pesticides, an opportunity exists to calculate inhalation risk.^7
Pesticides That Reach the Atmosphere
What happens to pesticides that are applied, and how much pesticide residue
enters the atmosphere? This is not a simple question to answer. The fate of pesticides
in the environment is dependent on many factors, such as their physical and chemical
properties, the weather, and how, when, and where they were applied. Recent studies
have shown that many pesticides readily evaporate into the atmosphere. Evaporation
is a continuous process that occurs over weeks, months, and years, until all the pesti-
cide molecules are degraded. Depending on the pesticide, 75 percent or more of an
application can ultimately be lost through evaporation.
Annual deposition of selected pesticides by rain has been calculated in several areas
of the country. The amount deposited generally accounts for less than 1 percent of
the total applied. Although this seems like very little, it can represent many tons for
some high-use pesticides. In addition, rain and snow are not the only way pesticides
are deposited to the earth’s surface. Deposition of vapors and particles also occurs,
but there is an inadequate understanding of these dry deposition processes.^8
Conclusions
The combined results from the local, region, and national monitoring studies indi-
cate that a wide variety of pesticides are present in the atmosphere. Nearly every pesti-
cide that has been investigated has been detected in air, rain, snow, or fog throughout
the country at different times of the year. Also, there is ample evidence that some long-
lived pesticides used in one area of the country migrate through the atmosphere and
are deposited in other areas of the country, sometimes in areas where pesticides are not
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