(Published January 2010)
This chapter focuses on pesticides, chemicals to which many individuals are exposed in their homes, workplaces, schools, and communities.
Synthetic pesticides are substances used to inhibit the growth of or kill unwanted organisms, such as insects, fungi, plants, and rodents.1 This monograph addresses only synthetic chemical pesticides or chemically derived pesticides.
Chemical pesticide formulations contain two types of ingredients: active and inert. Active ingredients are those that exert the desired pesticidal effect: inhibiting the growth of or killing the unwanted organisms. Inert ingredients support the function of the active ingredients. However, “inert” is not synonymous with “benign.”2,3 Some inert ingredients have been shown to be reproductive toxicants.
Exposures to Pesticides
Use of chemical pesticides is widespread in the United States. According to the Environmental Protection Agency, more than 1.2 billion pounds of the chemicals are used each year.4 Household use represents as much as 10 percent of the total amount used annually. In fact, pesticides are used in 78 million US households.4 They are often used for insect and rodent infestation, lawn and garden care, and protection against fleas and ticks.
Individuals are exposed to pesticides through a number of different sources: residue on food, contaminated tap water, occupational exposure, and community application of pesticides.5,6 They also are exposed from the use of insecticides, insect repellents, rodent traps, weed killers, and pet flea products within the home. In addition, individuals are exposed through contaminated dust in the home and pesticides tracked in from outdoors by pets and humans.5,6
Data on the Reproductive Health Effects of Pesticides
Data on the health effects of pesticides come primarily from animal studies and population-based epidemiological studies. Randomized clinical trials that study the effects of pesticide exposure on humans would be unethical. Table 3 shows some of the potential reproductive health effects of pesticides. An example of a known reproductive health effect in animals is decreased egg production and embryo viability in birds associated with exposure to atrazine, a chemical used to control grasses and weeds in cornfields.7 Examples of known reproductive effects in humans include early pregnancy loss associated with exposure to ethylene oxide, a chemical used as a sterilant to kill bacteria, mold, and fungi; impaired neurological development associated with exposure to organophosphates; and reduced male fertility associated with exposure to the herbicide dibromocholorpropane (DBCP).8 The effects in humans were found in several epidemiological studies that demonstrated fairly consistent associations and evidence of exposure-risk relationships after controlling for potential confounding factors.
|Table 3: Potential Reproductive Health Effects of Various Pesticides9-11|
Counseling Patients on Pesticide Exposure
Health care providers should educate patients about the many steps they can take to prevent exposure to pesticides at home. Providers also should advise patients who work in occupations such as pest control, landscaping, agriculture, gardening, or construction about limiting or mitigating pesticide exposure at the workplace. Providers can recommend the following points to reduce patients’ exposures to pesticides:12,13
Additional Provider Resources on Pesticides:
Additional Patient Resources on Pesticides:
Case Study: Kate
Kate is a 29-year-old woman who recently experienced a pregnancy loss at 10 weeks’ gestation. There were no signs of any problems with the pregnancy. She is currently working toward a degree in landscape design and works part-time at a plant nursery. She asks you whether pesticides could have caused the miscarriage.
The first step you take is to complete an environmental history to assess Kate’s exposure to pesticides and other reproductive toxicants. You ask Kate about other potential sources of pesticide exposure. She tells you that because of financial constraints while she’s in school, she and her husband now choose conventionally grown rather than organic produce. They use pesticides on their house plants to control aphids but don’t use any in their vegetable garden. They do not have any pets. You ask her to find out more about the specific chemicals she’s exposed to at home and at work.
Kate returns the next week and tells you that the nursery owner said they primarily use the herbicide propazine. At home, Kate and her husband use an insecticide to kill roaches.
You tell Kate that it is impossible to know what caused the pregnancy loss. You explain that as many as 40 percent of all conceptions end in pregnancy loss, many occurring before a woman realizes she is pregnant.15 However, there are some steps she can take to reduce her exposure to potentially harmful chemicals by addressing occupational exposures and pesticides in the home. You help Kate rank her options, first addressing occupational exposures, because these are probably the most significant, then reducing pesticide exposure in the home. You recommend the following:
To reduce workplace exposure, you recommend that Kate:
To reduce pesticide exposure in the home, Kate should:
This case study illustrates the need to consider all areas of potential pesticide exposure when conducting an environmental health assessment. Although the link between pesticide exposure and the pregnancy loss is not certain, it is prudent to recommend precautions to reduce exposure, especially during pregnancy.
- Environmental Protection Agency. About Pesticides: What Is a Pesticide? 2009. Available at: http://www.epa.gov/pesticides/about/index.htm. Accessed July 14, 2009.
- Cox C, Surgan M. Unidentified inert ingredients in pesticides: implications for human and environmental health. Environ Health Perspect. 2006;114(12):1803–6.
- Pesticide Action Network North America. Pesticide regulation in the U.S. Available at: http://www.panna.org/node/835. Accessed January 3, 2010.
- Kiely T, Donaldson D, Grube A. Pesticides Industry Sales and Usage: 2000 and 2001 Market Estimates. Washington, DC: US Environmental Protection Agency; 2004. Accessed October 15, 2009.
- Environmental Protection Agency. Pesticides. Available at: http://www.epa.gov/pesticides. Accessed November 15, 2008.
- National Pesticide Information Center. http://npic.orst.edu/index.html. Accessed November 15, 2008.
- Environmental Protection Agency. Decision documents for atrazine. 2006. Available at: http://www.epa.gov/oppsrrd1/REDs/atrazine_combined_docs.pdf. Accessed November 29, 2009.
- Wigle DT, Arbuckle TE, Turner MC, et al. Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants. J Toxicol Environ Health B Crit Rev. 2008;11(5-6):373–517.
- Figà-Talamanca I, Traina ME, Urbani E. Occupational exposures to metals, solvents, and pesticides: recent evidence on male reproductive effects and biological markers. Occup Med. 2001;51(3):174–88.
- Whorton MD, Krauss RM, Marshall S, Milby TH. Infertility in male pesticide workers. Lancet. 1977;2:1259–61.
- Bretveld RW, Thomas CMG, Scheepers PTJ, et al. Pesticide exposure: the hormonal function of the female reproductive system disrupted? Reprod Biol Endocrinol. 2006;4:30.
- University of California-San Fransisco, Program on Reproductive Health and the Environment. Toxic matters. Available at: http://www.prhe.ucsf.edu/prhe/index.html. Accessed December 26, 2009.
- Environmental Protection Agency. Do’s and don’ts of pest control. 2008. Available at: http://www.epa.gov/pesticides/controlling/dosanddonts.htm. Accessed December 27, 2009.
- Environmental Working Group. Shopper’s guide to pesticides. Available at: http://www.foodnews.org/. Accessed December 27, 2009.
- Michels TC, Tiu AY. Second trimester pregnancy loss. Am Fam Physician. 2007; 76:1341–-46.