Chapter 4: Pesticides

Pesticides are created and used to kill weeds or pests. Unfortunately, their harmful health effects do not always end with the pests or weeds they eliminate. In fact, a growing body of research has associated some pesticide exposure with serious health effects. A number of the pesticides currently on the market are known to be carcinogenic, mutagenic or toxic to the nervous system, development or reproduction. Health effects of a variety of pesticides range from irritation of skin and eyes, to nervous system damage, to cancer.

This study tested for the presence of organophosphate pesticide breakdown products in the urine of ten Oregonians. About 70% of insecticides (pesticides that kill insects) used in the United States are organophosphate pesticides. Approximately 80 million pounds of organophosphate pesticides are used annually in the United States, with 75% of their use in agriculture as one way to prevent pest damage to crops.⁶⁵ Organophosphate pesticides are chemically similar to chemical warfare agents originally produced during World War II and work by interfering with the nervous system of insects, as well as humans, other mammals, birds, and fish. Organophosphate pesticides inhibit cholinesterase, an enzyme that breaks down acetylcholine. Acetylcholine is a neurotransmitter that allows nerves to function properly. Inhibition of cholinesterase by organophosphate pesticides leads to the accumulation of acetylcholine, interfering with proper nerve function.

People are commonly exposed to low levels of pesticides through fruit and vegetable consumption, contacting pesticide-contaminated surfaces and dust, and breathing air near pesticide applications (both indoors and outdoors). Pesticides are found in our lawns, gardens, parks, workplaces, schools, homes, in the food we eat, the water we drink, and the air we breathe. Although most of us are exposed to pesticides, two groups are of particular concern—farmers and farm workers —because of their more frequent and higher levels of exposure and children because of their physiology, development and habits.

Widespread exposure to organophosphate pesticides has been documented by the CDC and scientists with studies showing that a large number of people in the U.S. have breakdown products of organophosphate pesticides in their urine.⁶⁶ These studies show that some groups, especially young children, have levels above those deemed “acceptable” by EPA. Because organophosphate pesticides generally do not persist in the environment for long periods of time and do not build up in the body fat of humans and other animals, the fact that these pesticides were found in a high percentage of test subjects indicates that most people are exposed to these chemicals on a frequent basis.

Pesticides in Oregonians

We tested for a series of pesticide breakdown products, or metabolites, that indicate exposure to organophosphate pesticides. We found the metabolites dimethylphosphate (DMP) and dimethylthiophosphate (DMTP) in two participants, which is indicative of exposure to several organophosphate pesticides including azinphos methyl and malathion.* These insecticides are commonly used in agriculture. Malathion is also found in some home-use products. Two participants had detectable levels of diethylphosphate (DEP), suggesting they had been exposed to the organophosphates diazinon or chlorpyrifos, or other less commonly used pesticides. Two of our participants had four different pesticide metabolites: DMP, DMTP, DEP, and diethyldithiophosphate (DEDTP).

Doug Phillips had levels of DMP, DEP, and DEDTP that put him in the top 10% nationally; Doug Stamm’s levels of DMP and DEP were also in the top 10%.⁶⁷ Upon learning of the pesticide levels in his body, Doug Stamm expressed confusion as to how they got there. He doesn’t use pesticides on his lawn, and he tries to eat organic produce as much as possible. He was disappointed that his personal effort to keep his body free of pesticides has not been enough.

Organophosphates do not persist in the body, so these levels reflect recent exposures.

Figure 6 shows our participants’ exposures to organophosphates. The chart shows the number of metabolites of these pesticides detected out of a total of five tested.

^{Figure 6. The number of organophosphate pesticide metabolites detected in participant urine.}

Health Effects of Organophosphate Pesticides

Organophosphate pesticides can cause short-term adverse health effects from acute exposures as well as adverse health effects as a result of chronic, low-level, persistent exposures. Health effects from acute organophosphate pesticide exposure include irritation of the nose, throat, and skin causing burning, stinging and itching as well as rashes and blisters. Nausea, dizziness and diarrhea are also common.⁶⁸ People with asthma may have very severe reactions to some pesticides, particularly pyrethrin/pyrethroids, organophosphate and carbamate pesticides. In many cases, symptoms of pesticide poisoning mimic symptoms of colds or the flu. Since pesticide-related illnesses appear similar or identical to other illnesses, pesticide poisonings may be frequently misdiagnosed and under-reported. Immediate symptoms may not be severe enough to prompt an individual to seek medical attention, or a doctor might not even think to ask about pesticide exposure.

Health effects from chronic exposure to organophosphate pesticides include memory and attention deficits, as well as increased depression, anxiety and irritability.⁶⁹ Recent studies in U.S. populations with no obvious symptoms of acute pesticide exposures have linked higher levels of chronic exposure to organophosphate insecticides in utero with reduced birth weight, head circumference, and gestational length in infants.70 In addition, there is emerging evidence that chronic low-level exposure to these chemicals may adversely effect both psycho-motor and mental development in more highly exposed infants.⁷¹ Pediatric asthma,⁷² cancer,⁷³ and birth defects74 are also a focus of concern, but the data linking such outcomes with exposure are limited. Since the health effects of chronic organophosphate pesticide exposures may not appear for weeks, months, or even years after exposure, it is often difficult to link health impacts to specific exposures.⁷⁵

Scientific studies in farm worker populations indicate that developmental exposure to organophosphate pesticides is a real threat to the health of people. A 2005 study of children born to farm workers in California’s Salinas Valley found that infants with the greatest exposure to organophosphate pesticides had more abnormal reflexes.⁷⁶ Studies on this same population have also demonstrated that mothers with higher exposures are at increased risk for preterm birth.⁷⁷ Researchers in Oregon found that adults with greater exposures to organophosphate pesticides scored lower in tests of attention span and motor function.⁷⁸

Policy Changes Needed

Current federal regulations need to make protecting public health a priority. Although the EPA requires manufacturers to test pesticides for harmful effects, current regulations do not prevent the use of pesticides that have been associated with cancer or other harmful health impacts. The current federal pesticide law—the Federal Insecticide, Fungicide, and Rodenticide Act—protects a pesticide’s uses unless the chemical poses an “unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of the use of any pesticide.”

So, as long as it is perceived that the economic benefit to using a particular pesticide outweighs the health risks, the law will allow for its use. There are problems with this approach. First, many pesticides have not been fully evaluated as to their human or environmental health impacts. Second, this cost-benefit analysis does not take into account the fact that there are often safer alternatives to achieving the end goal—reducing weeds and pests—that have fewer or no negative health impacts. In deciding whether a specific pesticide should be allowed, the analysis should also take into account whether there is a safer alternative.

• Support and implement Integrated Pest Management at all Oregon schools, childcares, and public parks. Safer pest management strategies, such as Integrated Pest Management (IPM), use alternatives to chemical-intensive practices. IPM is a systems approach to pest management based on an understanding of pest ecology. It begins with steps to accurately diagnose the nature and source of pest problems, and then relies on a range of preventive tactics and biological controls to keep pest populations within acceptable limits. Reduced-risk pesticides are used if other tactics have not been effective, as a last resort, and with care to minimize risks. IPM is not a new approach to pest management and is being used by school districts and park systems throughout the country. Schools and parks can significantly decrease and ultimately eliminate their use of hazardous pesticides while successfully and cost-effectively managing pest problems in school buildings and on school and park grounds. IPM is a program of prevention, monitoring, and control that offers the opportunity to eliminate or drastically reduce hazardous pesticide use. IPM is intended to establish a program that utilizes cultural, mechanical, biological, and other non-toxic practices, in combination with least hazardous chemicals as a last resort.

• Require full disclosure of all product ingredients on pesticide labels. Nearly every one of the over 20,000 pesticide products in the United States contains ingredients that are called "inert." "Inerts," sometimes comprising up to 99.9% of a pesticide product, are used to make these products more potent or easier to use. The name does not mean they are biologically, chemically, or toxicologically inert. In fact, many inerts threaten human and environmental health.⁷⁹ Yet, right now, inert ingredients are not required to be listed on pesticide labels. This means we don’t know the chemicals we are being exposed to and are unable to find out.
  

• Support and fund pesticide stewardship programs. In 1999 Oregon DEQ implemented a Pesticide Stewardship Partnership (PSP) to identify problems and improve water quality associated with pesticide use. The PSP approach encourages and supports voluntary changes that can result in measurable environmental improvements. In the past four years, pilot projects in the Columbia Gorge have shown substantial improvements in water quality associated with measurable changes in pesticide management.⁸⁰ Continuing funding of this innovative, collaborative program can provide an effective alternative to traditional regulatory approaches.
  

• Support the continuation of Oregon’s Pesticide Use Reporting System (PURS). PURS provides information on all pesticide use in the state. It requires businesses to report annual pesticide use while personal home use is evaluated through surveys. The goal of the program is to collect information that will lead to a better understanding of pesticide use in Oregon and its effect on public and environmental health. The statute authorizing PURS is set to expire December 2009.

Reducing Your Exposure to Pesticides

Although some exposure to pesticides is difficult to avoid, you can significantly reduce pesticides in your diet and your surroundings with a few simple steps.

Buy local, organic, or sustainably produced. Produce which is certified Organic, Food Alliance, or Salmon-Safe may cost more, but buying sustainably produced, in-season food from your local market is usually the best assurance of reduced pesticides or pesticide-free produce. Also, be aware that smaller growers may not have obtained organic certification because of costs or other reasons, so talking to and getting to know your farmer is a wonderful way to learn if they are pesticide-free. Recent research has shown that organic diets significantly lower children’s exposure to pesticides.⁸¹ Ask your grocer to start carrying local, organic, or sustainably produced food if it doesn’t already.

Wash your produce prior to eating. You can easily make your own produce wash using a very diluted solution of mild dishwashing detergent (1 teaspoon detergent per gallon, or 4 liters, water). For grapes, strawberries, green beans, and leafy vegetables, swirl the foods in a dilute solution of dish detergent and water at room temperature for 5 to 10 seconds, then rinse with slightly warm water. For the other fruits and vegetables, use a soft brush to scrub the food with the solution for about 5 to 10 seconds, then rinse again with slightly warm water. Another option is commercial vegetable and fruit washes, which have been formulated to remove chemical residue from produce; these are available online or at your local health food stores and some supermarkets.

Grow your own fruits and vegetables. The best way to offer your family organic fruits and vegetables is to grow your own. You can grow many fruits and vegetables in flower pots or other containers right in your yard, back porch, patio, or balcony. Even a small garden can be very productive for family use. You can plant one or two different crops in your yard and encourage a neighbor to grow others—then share the harvests.

Avoid using pesticides in your home and garden. There are many non-chemical methods of pest control that are safe and effective. Pesticides such as weed killers and insecticides should be used as a last resort, if at all. Focus on preventive techniques, which are most effective in the long run. Also consider these specific recommendations:

• Many commercial ant and roach killers contain toxic pesticides. Use diatomaceous earth and other less toxic controls to rid your home of these pests.
  

• Use pet combs, frequent vacuuming and other non-toxic controls of fleas. Many flea collars, sprays, and dips contain dangerous pesticides.
  

• Limit lawn areas and grow native plants adapted to the Northwest. Information on growing native plants can be found here.
  

Advocate for pesticide reduction in your school, childcare center, and parks. Many school districts, cities, and counties have policies to replace toxic pesticides with safer practices such as IPM. Help your community become one of them.

Choose clothing made from organic or materials. Conventionally produced cotton is responsible for 25% of the world’s insecticide use.⁸² Look for clothing made from organic cotton or hemp, which is easily grown with limited pesticides.

NEXT: CHAPTER 5 - BISPHENOL A

^{* DMTP, DMP, and DEP are “non-specific” metabolites of organophosphate pesticides, meaning they may result from exposure to more than one pesticide.}