The Health Costs of Our Food Production System: Pesticide Exposure and Effects on Farmers, Farm Workers, and Rural Residents
This essay is in response to: How does our nation's reliance on pesticides affect the health of those who plant and harvest our food?
Our current conventional agricultural system relies heavily
on synthetic pesticides, and when pesticide exposure is mentioned, the first
thought that may come to mind is pesticide residues on food. But for those who
live in agricultural areas or work on conventional farms, exposure is a
full-body experience. Farm workers have the highest exposures, since they are
often involved in applying pesticides or working in the crop soon after the
pesticides are applied. And ironically, people seeking a bucolic rural
lifestyle may also have higher exposures simply from living near farms where
pesticides are used.
Farm workers and rural residents are exposed to pesticides
through touching plants or other surfaces contaminated with pesticides, drinking
water, and merely breathing the air.
Dermal contact with treated plants can be a significant
source of exposure for workers reentering fields after pesticide applications,
particularly for workers involved in tasks that require contact with treated
plants, such as picking fruit, pruning branches, and training vines. Also a
concern for farm worker families is take-home exposure, where workers bring
pesticide residue into the home on their clothes and shoes.
Drinking water may also be a source of exposure in
agricultural areas. Many pesticides are soluble enough in water to leach
through the soil and into groundwater or run off to surface waters. If they do
not readily degrade, they can contaminate ground and surface water sources of
drinking. Herbicides are particularly problematic in this regard, and the US
Geological Survey water monitoring program indicates that many areas in the
Midwest and other locations have extensive ground and surface water pesticide contamination,
predominantly from herbicides such as atrazine, metolachlor, acetochlor, and
alachlor used on corn and soybean fields.
Airborne spray drift of pesticide aerosols and dusts from a
poorly done application is also a major source of exposure for both farm
workers and rural residents. While spray drift can occur with any pesticide, a
subset of chemicals are inherently volatile and can evaporate off of the
application site for several days to several weeks after the application. This
volatilization drift is a more insidious, but no less problematic, source of inhalation
exposure for some pesticides. While EPA attempts to regulate spray drift
through label instructions, the agency is only now beginning to consider
exposures from volatilization drift.
California’s Air Resources Board
and Pesticide Action Network (PAN)
have both done air monitoring to evaluate the scope and magnitude of airborne
pesticides, and have found that for some pesticides, legal use results in
inhalation doses that far exceed levels of concern set by regulatory agencies.
The most problematic pesticides for inhalation exposure are the fumigants
methyl bromide, 1,3-dichloropropene, metam sodium, chloropicrin and methyl
iodide. For these pesticides, the high application rates (hundreds of pounds per
acre) and very high volatility of these nearly gaseous chemicals contribute to
their drift potential, and acute poisoning incidents that affect tens to
hundreds of people are not uncommon.
Volatilization drift is also an issue for insecticides such as endosulfan, chlorpyrifos,
diazinon, and malathion, and certain fungicides and herbicides, including chlorothalonil
and trifluralin, which PAN found repeatedly in several studies.
Several research centers, most notably the Pacific Northwest
Agricultural Safety and Health (PNASH) Center at the University of Washington
and the Center for Environmental Research and Children’s Health at the
University of California, Berkeley,
have studied how the proximity of pesticide use relates to pesticide residues
in house dust and pesticide metabolites in urine. Their results show that homes
within a few hundred feet of fields have higher concentrations of pesticides in
dust; correspondingly, the children living in those homes have higher levels of
pesticide metabolites in their urine than those who live further away. Children
are particularly vulnerable to exposure because of their behaviors—they spend
more time on the ground or floor and put objects in their mouths as a means of
exploring. They also breathe more air, drink more water, and eat more food per
pound of body weight than an adult does, which provides a higher dose of
Health Effects of Pesticides
The acute and chronic health effects that result from
pesticide exposure are most prevalent in people with the highest exposures. Elevated
risks of certain kinds of cancer, Parkinson’s disease, autism and other
neurological effects, reproductive and developmental disorders, and increased
respiratory disease have all been associated with exposure to pesticides. While
there isn’t space to review all of these effects in detail in this article, the
work of several research groups who focus on pesticides and health effects
provides a good introduction to the health effects of pesticide exposure.
A number of excellent epidemiological studies have been done
(or are in progress) focusing on the incidence of different cancers in farmers
and farm workers. The Agricultural Health Study run by the National Cancer
Institute is a large, prospective study of farmers and their spouses, involving
over 89,000 participants from Iowa and North Carolina. Findings
demonstrate that overall cancer occurrence among members of the study group is
significantly lower than comparable populations, a fact attributed to a lower
use of tobacco products among farmers and a more active lifestyle.
Nevertheless, there are several types of cancer that occur more frequently
among farmers and their spouses, including prostate cancer, melanoma, and ovarian
cancer. Links between lung, colon, and some blood-related cancers and use of
specific pesticides have also been established by this work.
The California Cancer Registry
has published a number of studies on farm workers and cancer, with findings
that workers have elevated risks of lymphomas and leukemias, as well as
prostate, brain, cervix, and stomach cancers.
The CHAMACOS project has been studying the farm worker
population in the Salinas Valley since 1999 to examine the effects of
pesticides, other chemicals, and other factors on children’s health. A
project of the UC Berkeley Center for Environmental Research and Children’s
Health, CHAMACOS has focused on chemical exposure, health effects, and genetic
factors affecting pesticide metabolism and excretion. A recent review article
by the CHAMACOS researchers provides perspectives on pesticides and
neurodevelopment, with the research showing a link between in utero exposure to organochlorine and organophosphorus pesticides
and impaired neurodevelopment. This
finding is consistent with the work from the Columbia Center for Children’s
Environmental Health in which an increased incidence of pervasive developmental
disorders were observed for children exposed to insecticides in utero in an urban setting.
Other research groups have used California’s Pesticide Use
Reporting data to go beyond worker exposures and study the relationship between
exposures and health effects for the larger rural community. These studies demonstrate
links between locations of pesticide use and higher incidences of Parkinson’s
disease, cancer, asthma, and autism, providing evidence for exposure through
Finally, the Pesticide Education Center has summarized a
number of epidemiological studies on cancer in adults and children,
neurological effects, and reproductive outcomes as related to pesticide
These summaries provide information on links between disease outcomes and
exposures to certain classes of pesticides, specific occupational exposures, or
locations of residence.
Our nation’s reliance on pesticides to produce our food has
come at a cost to those who work in farming and live in rural communities. But
it doesn’t have to be this way. We should take a cue from Europe and begin by
removing the most toxic pesticides from the market. In the US, the fumigant
pesticides have the highest exposure potential and should be among the first to
go. In California, where pesticide use tracking is implemented, we know that
this would remove 30 million pounds of toxics from the environment each year.
This would account for approximately 20% of the agricultural use pesticides,
but represents a much larger fraction of the highly toxic pesticides applied in
The role of government in this process should be to provide
assistance to farmers to transition to less toxic methods of farming. This
could be done by restructuring crop insurance programs, providing advice through
extension services, and funding research into new methods of pest management,
expansion of existing methods to commercial scale, and development of crop
varieties that don’t require heavy doses of toxic pesticides to survive. The
net result will be a healthier food system from top to bottom. Food consumers,
farmers and farm workers, and rural residents will all benefit.
Editor's note: if
you'd like to take action on pesticide policy, click here.
Lee S-J, Mehler L, Beckman J, et al.
Acute Pesticide Illnesses Associated with Off-Target Pesticide Drift from
Agricultural Applications—11 States, 1998–2006. Envi. Health Persp. doi: 10.1289/ehp.1002843
Pacific Northwest Agricultural Safety and Health Center, University of
Washington. Chemical Exposure.
Mills PK, Dodge J, Yang R 2009. Cancer in Migrant and Seasonal Hired Farm
Workers. J. Agromedicine 14:185–191.
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