Pesticides 101

Pesticides are defined as “Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.” Insecticides, herbicides, and fungicides are all examples of pesticide products.

Pesticides harm health – A growing body of evidence in scientific literature shows that pesticide exposure can adversely affect endocrine systems neurological, immune, and respiratory systems in humans, even at low levels.

Pesticides contribute to disease – Of the most commonly used pesticides, 19 are linked with cancer or carcinogenicity, 21 with reproductive effects, 13 are linked with birth defects, 26 with liver or kidney damage, 15 with neurotoxicity, and 11 with disruption of the endocrine or your hormonal system.

Children are more vulnerable than adults – Children are especially sensitive to pesticide exposure as they are smaller and busy developing… Children take in more pesticides relative to their smaller body weight, are more physical in their environment, running, touching and playing outdoors, and their bodies are still developing.

Pesticides move from the application site – Pesticides do not stay put after application and can be transported over long distances fairly rapidly through wind and rain. Scientific studies show that 2,4-D applied to lawns drifts and is tracked indoors where it settles in dust, air and surfaces and may remain for up to a year in carpets.

Pesticides are not safe after application even when dry – Pesticide residues will remain where it was sprayed even when it is dry. Both inhalation and dermal exposures are considered major routes of exposure for pesticides.

One 2014 analysis of 129 preschool children, ages 20 to 66 months, found that children were exposed to indoor concentrations of pyrethroids, organophosphates and organochlorines pesticides which were detected in soil, dust and indoor air.

Samples from 120 Cape Cod homes, where elevated incidence of breast, colorectal, lung, and prostate cancers are reported, find high indoor air and dust concentrations of carbaryl, permethrin, and 2,4-D.

We are not exposed in isolation – Exposure to multiple pesticides, multiple pesticide ingredients or other toxic chemicals can change the way we are affected by them.

Multiple exposures can have a magnified effect greater than the individual chemical effects added together. This is called a synergistic effect, or synergistic toxicity.

When you go to the doctor, they always ask what other medications you are taking. That’s because your doctor knows that chemicals can interact and become more intense, or less effective depending on what other drugs you are exposed to. So when you think about the spray drift of the weed killer, combined with the neighbors spraying for termites and ants – the combination of these chemicals will react in ways that can be very harmful when the exposures occur together.

“Impacts from multiple chemicals may simply add up, amplify one anothers effects,” – David Bellinger, professor of neurology at Harvard Medical School

“The major challenge with showing that a chemical causes cancer in humans [as opposed to animals] is that the cancer typically develops many years after exposure.” Dr. Bruce Blumberg, PhD. UCI Professor of Developmental and Cell Biology, and Professor of Pharmaceutical Sciences has stated.

Pesticide exposures in the real world are not isolated incidents. Rather, they are a string of incidents marked by combinations of exposures. As a result, scientists have argued for years that toxic exposures to pesticides should be measured as they would normally occur, in combination with one another. Yet, current federal law does not require this type of testing for pesticides on the market, except in very limited instances.

Dose, as well as frequency, duration of exposure, sequence and timing are all factors in how a pesticide exposure may effect someone. Not all people are effected the same. Individual susceptibility varies but is influenced by age, gender, health status, genetics, and lifestyle. Children and elderly people often have an increased susceptibility to chemicals.

EPA registration – Any pesticide legally used in the USA must be registered with the Environmental Protection Agency (EPA) before it goes into commerce. The EPA’s main function is to register the pesticides, not to ensure safety. The EPA has registered over 85,000 different chemicals and often once it is determined to be detrimental to human or the environment it takes many many many years before and if the product is pulled out of the market. Registration does not constitute safety or an approval rating by the EPA, in fact the EPA is clear that a pesticide manufacture cannot state that a pesticide is safe by Federal Law. Registration with the EPA does not even guarantee that the chemicals have been fully tested for environmental and human health effects.

A child in a household using home and garden pesticides is 6.5 times more likely to develop leukemia than in a home that does not. Obviously, EPA approval is not a guarantee of safety; in fact, EPA believes that no pesticide can ever be considered perfectly “safe.”


Pesticide-Induced Diseases Database

Health effects of 30 commonly used pesticides

Children and Pesticides Don’t Mix

Wade, T., et al. 2001. Atmospheric Deposition of PAH, PCB and Organochlorine Pesticides to Corpus Christi Bay. Texas A&M Geochemical and Environmental Research Group. Presented at the National Atmospheric Deposition Program Committee Meeting.

Nishioka, M., et al. 1996. “Measuring lawn transport of lawn-applied herbicide acids from turf…” Env Science Technology, 30:3313-3320; Nishioka, M., et al. 2001. “Distribution of 2,4-D in Air and on Surfaces Inside Residences…”Environmental Health Perspectives 109(11).

Morgan, M, Wilson, N, and Chuang C. 2014. Exposures of 129 Preschool Children to Organochlorines, Organophosphates, Pyrethroids, and Acid Herbicides at Their Homes and Daycares in North Carolina. Int. J. Environ. Res. Public Health, 11(4),3743-3764

Rudel, Ruthann, et al. 2003. “Phthalates, Alkylphenols, Pesticides, Polybrominated Diphenyl Ethers, and Other Endocrine-Disrupting Compounds in Indoor Air and Dust.” Environmental Science and Technology 37(20): 4543-4553.

Lawns and Landscapes Chemical Lawn Care FAQ

National Institute of Health. Chemicals guide. Lesson 4.