Clinical and Health Affairs
What Physicians Can Do to Reduce Occupational and Incidental Pesticide Exposure
A Guide to Best Practices
By Neal Holtan, M.D., M.P.H., Marion Warwick, M.D., M.P.H., and Bruce Bomier, M.P.H.
Abstract
Residents of rural areas trust their physicians to provide them with accurate, unbiased information about pesticides and the effect they can have on health. Educating patients about using pesticides safely and avoiding contact with them need not be difficult or time-consuming and can be based on universal precautions that are already being practiced in the health care industry. This article discusses the prevalence of pesticide use in the United States, the ways people can be exposed, and several best practices for helping patients reduce their chance of exposure to pesticides that can cause illness.
Studies have shown that the public is concerned about the health effects of pesticide exposure. A focus group and telephone survey conducted in 2002 by the Environmental Resource Council in Anoka, Minnesota, and funded by the Minnesota Institute of Public Health in Mounds View and the Bush Foundation in St. Paul unveiled significant concerns among residents of rural Minnesota about the long-term human health risks of pesticide exposure (unpublished data). Some participants remembered the days, typically before 1970, when there was far less concern about pesticides and their risk to health. Others identified current “bad actors,” a few individuals who use pesticides recklessly. A large proportion of respondents, about 75%, were concerned about pesticides as a possible cause of chronic disease, especially cancer, in their families or communities. Survey respondents also overwhelmingly identified physicians and university agricultural extension agents as the most reliable sources of information about pesticides and human health.
Primary care physicians, especially those practicing in agricultural areas, are in an excellent position to provide their patients with information about pesticide use. Some physicians, however, have shied away from discussing pesticides with their patients because they are unfamiliar with the health effects of pesticide exposures or they are concerned about lack of time to cover yet another prevention topic.
The good news is that pesticide safety education for patients need not be difficult or time-consuming. Physicians are already familiar with a concept that is applicable to pesticide use: universal precautions, the hugely successful set of occupational safety practices that is based on the premise that all body fluids from all patients are potentially dangerous sources of infection. Physicians understand the value of practices such as using protective clothing and equipment, handling body fluids with care and minimizing direct contact with them, and reducing the duration and amount of exposure to body fluids. These same practices can easily be modified to protect workers who use pesticides, particularly those who work as commercial applicators in agricultural settings and are most heavily exposed.
Universal precautions for pesticides similarly rest on the idea that any and all pesticides or chemicals are potentially injurious to human health at any level of exposure. Applying the concept does not require having detailed knowledge about particular pesticides or their potential effects on human health. The focus instead is on employing common-sense measures to protect workers such as using protective barriers, clothing, and equipment; reducing the duration and amount of exposure; and avoiding unintentional absorption, ingestion, or inhalation of pesticides. Recent research coordinated through the U.S. Public Health Service’s Agricultural Health Study has shown that such protective practices in the handling and application of pesticides reduce the constituent body burden of pesticides among the people who apply them and their families.1
Although applying the universal precautions approach to pesticides does not require extensive knowledge of pesticides, physicians should be aware of basic facts about the prevalence of pesticide exposure and the ways people, including their patients, might be exposed. They should also begin to familiarize themselves with the growing body of research attempting to link disease with pesticide exposure.
Prevalence of Pesticide Exposure
Pesticides are commercial compounds used to kill or otherwise control pests. They include fungicides, insecticides, herbicides, repellants, rodenticides, and disinfectants.2 There are several hundred “active” base chemicals that are used in more than 25,000 products registered for use as pesticides in the United States. Inert ingredients are also added to commercial pesticides to render a product safer through dilution, allow for easier application, ensure a longer or shorter period of activity, control the distance a pesticide may travel during application, and make the pesticide more water-soluble for more efficient cleansing of equipment. Surveys by the Environmental Protection Agency (EPA) in the 1990s found that 84% of households in the United States use pesticides.3 According to one survey, an estimated 4 million workers were occupationally exposed to pesticides.4 The agricultural industry accounted for the majority of commercial pesticide use (at least 75%), with other use occurring in buildings, food handling facilities, golf courses and parks, athletic fields, and forests.
More than 1 million licensed pesticide applicators are at risk for adverse long-term health effects from acute poisoning and from repeated low- and mid-level exposures.4 There is concern that recurring mid-level exposures may lead to long-term, remote health problems such as neurodegenerative diseases, mental health issues, and cancer. Commercial applicators receive mandatory training to become licensed, but to date that training has not included information about long-term health effects of low- or mid-level exposures. Ideally, training will eventually include the promotion of practices to prevent or reduce recurring occupational exposures. In the meantime, physicians can educate patients along these lines and reinforce safety messages. Individuals who don’t handle pesticides in their work are still exposed to them through a variety of direct and indirect routes, including the air, groundwater, food, soil, and indoor and outdoor objects.
Air. Pesticides may contaminate the air through aerial spraying, environmental drift, poor containment, and wind, rain, and fog. Proper application methods dramatically limit this unwanted and unintended dispersion.
Water. States closely monitor major aquifers for pesticide contamination, and municipalities test public water systems for pesticides. However, private wells can be a source of exposure for humans, as they are not monitored. Lawn and garden chemicals are also of concern, as they can contaminate groundwater.5
Food. Pesticides are found often at trace levels on the surfaces of fruits, vegetables, and other foods. Accumulation of pesticides also occurs in freshwater fish at the top of the food chain. Levels are especially high in bottom-feeding fish or larger fish that eat smaller plants and animals. Pesticides can accumulate in the tissues of livestock that eat food containing pesticides as well. In addition, terrestrial crops can accumulate pesticides that are in the soil through root uptake or from windblown dust that adheres to the crop.
Soil. Repeated application of pesticides can lead to concentrations in soil that leave the land unsuitable for agriculture, thereby jeopardizing the food supply over time.
Indoor and outdoor vectors. Indoor contamination results from air drift or from humans or pets carrying pesticide residue into homes or buildings. Once inside, they bind to carpeting, furniture, draperies, blinds, toys, and other objects. Unlike in the outdoors, residue remains for longer periods because there is no sunlight, rain, or wind to break it down or carry it away. Indoor carpeting, in particular, accumulates high levels of pesticides. The U.S. Agricultural Health Study found that many pesticides are easily traced from commercial use to contamination of indoor areas.1 Multiple pesticides and other contaminants have been found in dust and ambient air inside homes.6 Recent research shows that hygiene and proper management substantially limit household burdens of pesticides.7
Children are much more likely to have direct contact with pesticide residue on furniture, carpets, pets, lawns, and toys because they crawl on floors, have extensive hand-to-mouth contact, and wear less clothing to protect them. The U.S. Agricultural Health Study found higher body burdens of pesticides in infants and children compared with adults in the same home.1 This is significant not only because children are more likely to be exposed to pesticides but also because of the effect a small amount can have on them.
Children are particularly susceptible to adverse effects of pesticide exposures because they absorb more pesticide for their weight than adults, their breathing and metabolic rates are higher than adults’, and they have more skin surface relative to their size. They also may be more prone to toxic effects of certain pesticides because their immune systems are less developed than those of adults.
Health Effects of Pesticide Exposure
Pesticides enter the human body by inhalation, absorption through the skin and eyes, and ingestion through the mouth and gastrointestinal tract. Once absorbed, the pesticides are typically distributed to other parts of the body and, if they are lipid-soluble, stored in body fat.5,8,9 Body burdens may increase with repeated exposures and can vary, depending on the individual’s health status, medication use, immune status, metabolism, genetics, and interaction with chemicals or food that may result in higher levels of accumulation than expected.
Research has shown that a number of chronic health problems are connected with pesticide exposure:
Skin irritation. Skin is a primary route of exposure, particularly for those who handle, apply, and spray pesticides. The most common adverse effect is contact dermatitis, either direct irritant or the allergic type. Adverse skin effects can become chronic or permanent.10-12
Cancers. Cancers of the following organs have been potentially associated with exposures to certain pesticides: brain, lungs, prostate, liver, kidney, bladder, thyroid, skin, nasal sinuses, buccal cavity (mouth), esophagus, stomach, pancreas, colon, rectum, eye, breast, uterus, cervix, blood (leukemia, multiple myeloma), lymph nodes (Hodgkin’s lymphoma, non-Hodgkin’s lymphoma), and soft tissues (sarcoma). The precise relationship between these cancers and pesticide exposure is not yet understood, and it is currently impossible to confirm or quantify causal relationships. However, research appears to show at least a correlation between exposures to certain pesticides and the development of various cancers.13
Conditions of the nervous system. At high doses, pesticides affect both the central and peripheral nervous systems. Several studies have shown a possible relationship between exposure to certain pesticides and Parkinson’s disease.14,15 Others point to damage to the peripheral nervous system. Reduced motor and sensory nerve conduction velocities have been shown among applicators of organophosphate pesticides as well.16,17 Other studies have not shown a direct measurable connection between pesticide exposures and conditions of the nervous system.18 These inconclusive research findings diminish firm conclusions but support a resolve to reduce exposure to all pesticides.
To Learn More
- The Minnesota Medical Association and the Environmental Resource Council are jointly sponsoring the online CME course Physician Interaction with Patients and Families about Pesticide Exposure, which is available through June 30, 2011, at www.pesticideeducation.com/
course. See the website for more information or contact Bruce Bomier at the Environmental Resource Council, 763/753-9713 or bmbomier@envrc.org. The course can be taken at no cost. If you wish to sign up for 1.5 CME credits, the processing fee is $25. A brochure for patients is also available for download and distribution at no cost.
- The National Pesticide Information Center has a number of fact sheets on inert ingredients as well as active ingredients found in pesticides. For more information, go to www.npic.orst.edu/
npicfact.htm.
- The National Institute for Occupational Safety and Health has compiled a searchable database of nearly 3,000 acute cases of exposure to certain pesticides. To find out more, go to www2.cdc.gov/niosh-sensorpesticides/search.asp.
- The Environmental Protection Agency provides general information about pesticides and symptom indicators at www.epa.gov/opp00001/
about/types.htm. |
Mental health conditions. Studies of workers exposed to organophosphates indicate an increased prevalence of depression, stress, and fatigue in comparison with controls.
19 Workers with significant exposures to chlorpyrifos had poor performance on mood-scale tests and neurobehavioral tests.
20 Other pesticides have been associated with decreased memory, learning ability, vigilance, and neuropsychiatric test performance. The possible connections between mental health problems and pesticide exposures is a relatively unexplored field of research, but preliminary findings support the goal of reducing occupational pesticide exposures in order to reduce a person’s risk.
Poor fetal development. Certain pesticides appear to have negative effects on embryogenesis and fetal development. Some pregnant women exposed to certain pesticides such as phosphates, carbamates, and halogenated hydrocarbons have a higher prevalence of malformed fetuses (teratogenesis) and fetal morbidity.21,22
Universal Precautions
Pesticide applicators are taught to read and understand the information on product labels written by pesticide manufacturers in conjunction with the Environmental Protection Agency (EPA). These labels generally provide instructions for use and handling as well as warnings about acute exposure and poisoning. They do not include information about possible long-term adverse health effects. The National Institute for Occupational Safety and Health has compiled a searchable database of nearly 3,000 acute cases of exposure to certain pesticides.23 The EPA provides general descriptions of pesticide types that can provide clues about symptoms to look for after an acute occupational exposure.24
Although connections between low- and mid-level pesticide exposure and the subsequent development of chronic diseases such as cancer have not been conclusively shown, it is thought prudent to minimize exposure to occupational pesticides just in case there is a causal relationship. People who apply pesticides need more information about the importance of limiting these recurring, subacute occupational exposures.25 They may falsely conclude that pesticides are safe because the products are readily available in the marketplace and because the labels on them bear an EPA seal, a precautionary statement, and the logo of a reputable chemical company. In addition, some compounds listed as “inert” on the labels are inert to the pest, rodent, insect, or fungus for which the pesticide is targeted but are not necessarily harmless to humans. Descriptions of inert ingredients are not required on pesticide labels, and the percentage of inert ingredients is typically more than 50% and can exceed 90% of the weight of a pesticide. The labels also do not take into consideration the issue of potentiation or adverse synergies with other exposures or health conditions. Thus, universal precautions help to augment the information found on labels and further protect pesticide users from dangerous exposures.
Use of protective equipment and general good hygiene are the keys to eliminating or reducing pesticide exposure to the skin, lungs, eyes, nose, and mouth. People who apply pesticides should always use protective clothing and equipment, wear long sleeves and pants, wash their hands, and avoid eating, drinking, or using tobacco products while handling them.
Pesticide-contaminated equipment needs to be cleaned in an isolated area, and extra care should be taken to prevent tracking of even trace doses of pesticides into the home on clothing or shoes. Clothing used during the application of pesticides should never be included in the general laundry but cleaned separately, preferably outside the home. The effectiveness of taking such precautions with clothing and equipment in order to reduce human exposure to pesticides is mounting.7,26-32
In 2005, the Environmental Resource Council and the Minnesota Institute of Public Health convened a task force of experts in agricultural science, toxicology, public health, and medicine and university extension services agents to find ways to promote safe pesticide handling among commercial pesticide applicators and others. They created 7 best-practice messages to convey to applicators. These practices may also be valuable for communicating with patients about how to reduce their exposure to pesticides.
♦ Best Practice 1
Read labels and follow directions, but understand the limitations. Pesticide labels are developed through extraordinary effort by the EPA and the chemical companies that produce pesticides. Information about health risks from the inert ingredients contained in pesticides is not required. Thus, in case of a significant acute exposure, the exposed person should bring the label to an emergency room for review by medical personnel. The label will place a pesticide in one of 3 categories: “danger,” “warning,” or “caution.” The word “danger,” often associated with the word “poison,” is printed in red with a skull and crossbones, indicating that the compound is so highly toxic that ingesting as little as a teaspoon can cause death. “Warning” indicates that a moderately toxic compound can still be fatal or cause significant skin irritation or eye damage. “Caution” means that a larger amount, typically, an ounce to a pint, ingested orally can be fatal. These categories obviously relate to accidental ingestion and not to chronic exposure.
♦ Best Practice 2
Use protective clothing and equipment. Stay physically separated from pesticides by using barriers, clothing, goggles, respirators, and other protective equipment. Prevent exposure to skin, lungs, eyes, nose, and mouth by wearing gloves and protective clothing.
♦ Best Practice 3
Be prepared for the unexpected and reduce the chance of exposure. Be vigilant in order to prevent accidents while using pesticides. Assess each situation, anticipate unexpected problems, and think about exposures that occur at lower levels than were previously considered safe. For example, use nozzles that accommodate wind, evaporation, specific gravity, and plant adhesion. Properly calibrate droplet size and pressure in order to avoid overspray. Also, clear the area to be treated of other humans and animals. Do not let young children or pets come in contact with pesticides or inadvertently transport even small amounts into the home.
♦ Best Practice 4
Avoid all possible routes of ingestion. Never eat, drink, or use tobacco products when mixing, loading, or applying pesticides. Protect the mouth from contamination. Wash hands frequently, as hand-to-mouth contact is the most common source of ingestion.
♦ Best Practice 5
Use proper clean-up methods. When the job is over, wash and decontaminate equipment (including safety equipment) quickly and thoroughly at a location as far away from other people as possible. Never launder pesticide-contaminated clothing with general laundry; wash contaminated clothing in a separate facility if at all possible. Most pesticide products are water-soluble, and a good washing with soap and water in an isolated clean-up area works for equipment, clothing, and people.
♦ Best Practice 6
Control dispersion of pesticides and avoid exposing children and pregnant women. Store pesticides in dry, secure containers in areas that are not accessible to children. Follow recommended disposal and clean-up procedures. Do not burn pesticide containers. Be watchful about pesticide drift caused by wind or other environmental factors. And always be aware that children and pregnant women are at greater risk of harm from low-dose pesticide exposures than others in the population.
♦ Best Practice 7
Don’t bend the rules. Those who do not follow best practices regarding pesticide safety increasingly run the risk of being reported to regulatory authorities or the criminal justice system. Hikers, bikers, fishermen, and hunters sometimes report people who are not properly applying or storing pesticides. More and more people are moving into areas formerly populated only by farmers, foresters, and other rural residents and have less tolerance for pesticide misuse.
Conclusion
Rural residents place a high level of trust in their physicians’ advice about pesticide safety. Physicians with patients who use pesticides can easily and quickly make a difference by promoting universal precautions in handling them. In doing so, physicians not only will help prevent possible long-term adverse health effects among those patients but also can protect the health of their families, neighbors, and communities, as well as the environment. In addition, physicians can contribute tremendous public health and ecological benefits by persuading their patients who administer pesticides to follow responsible standards of care in their work. MM
Neal Holtan is medical director for the Environmental Resource Council in Anoka, Marion Warwick is a medical consultant to the council, and Bruce Bomier is the council’s board chair.
The Environmental Resource Council and the Minnesota Institute of Public Health conducted surveys, gathered information, and produced education materials referred to in this article through a grant from the Archibald Bush Foundation. There were no other sources of funding. The authors wish to give special thanks to Minnesota’s Commissioner of Agriculture, Gene Hugoson, who encouraged them to find common ground between agriculture and public health during the project.
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