Health Effects of Pesticides

Pesticides are chemicals used for preventing, destroying, repelling, or mitigating pests. They include herbicides that are used to kill weeds and insecticides, which destroy insects, as you might have guessed. And in the U.S., we use them a lot.

About one billion pounds of conventional pesticides are used each year in the United States to control weeds, insects, and other pests, according to the United States Geological Survey (USGS). While the benefits of this pesticide use are immediate and obvious—green lawns and smooth playing fields—its hazards are not.

Too often left unnoticed are the costs that come with those chemically laden fields. The effects of toxic persistent pesticide exposure on human health have been well-researched and documented, yet most people are not aware of the risks. It’s an “aha moment” for many communities when they find out the risks that children in particular are exposed to as they play on soccer fields or picnic in the local park.

General Health Risks

Back in 2004, a National Cancer Institute-led report concluded that, “evidence clearly suggests that at current exposures pesticides adversely affect human health.” Many pesticides can pose risks to people, depending on their level of exposure, according to the United Stated Environmental Protection Agency (EPA). Some concerns include:

Cancers – In 2015, the International Agency for Research on Cancer (IARC), a division of the World Health Organization, found that there was sufficient evidence to classify both glyphosate and 2,4-D as human cancer-causing agents. Glyphosate was labeled “probably carcinogenic to humans” and 2,4-D as “possibly carcinogenic.”

In reviewing a decade of scientific studies on pesticides, the National Cancer Institute found an association between herbicide exposure and the following types of cancer: non-Hodgkin lymphoma, leukemia, multiple myeloma, prostate cancer, pancreatic cancer, lung cancer, ovarian cancer, and soft-tissue sarcoma.

Endocrine System Disruption – According to the Environmental Protection Agency (EPA), both 2,4-D and glyphosate have been linked to the disruption of the endocrine system, which regulates the body’s hormone production. Endocrine disruption has been linked to infertility, low sperm count, birth defects, early puberty, and hormone-dependent cancers, like testicular, breast, and prostate.

Parkinson’s Disease – A 2013 meta-analysis of over 100 studies found that pesticides and solvents are associated with an elevated risk of developing Parkinson’s disease, a neurodegenerative disorder.

Kidney & Liver Disease – Herbicides like glyphosate tend to concentrate in the liver and kidneys, putting these organs at risk for long-term diseases.

Children’s Health Risks

Are children at greater risk than adults to pesticide exposure? Yes, they are at much greater risk, due to their stage of growth and development. Their natural behaviors, such as when babies crawl on the floor, or when kids play in the dirt, also up the ante. The National Academy of Sciences, in its 1993 groundbreaking report on pesticide exposure, said it best: “Children are not just little adults.”

What determines the nature and level of risk and harm to any given person depends on the timing, dose, and toxicity of the pesticide exposure.

  • TIMING: When the exposures occur (e.g., when a woman is pregnant, early in a child’s life, during adulthood, or when a person is fighting a virus or a chronic illness)
  • DOSE: What the level, frequency, and duration of the exposure was
  • TOXICITY: The toxicity and properties of the specific herbicide

In his new book Children and Environmental Toxins*, Dr. Philip Landrigan, pediatrician, epidemiologist, and pioneer in children’s environmental health, explains why timing is critical when it comes to pesticide exposure during childhood. According to Landrigan, the greatest overall danger is that children are undergoing rapid growth, and their delicate developmental processes are easily disrupted.

During childhood, there are “windows of vulnerability” when exposure to even minute amounts of toxic chemicals (which wouldn’t affect the average adult) can result in lifelong injury to the brain, immune system, and other organ systems.

Children experience the world in ways that are fundamentally different from adults. For example:

  • They breathe in much more air than adults, pound for pound.
  • They are lower to the ground, breathing in pesticide residues in the air, on the floor and carpets, on clothing and shoes, or by household pets.
  • Children also have more permeable skin than adults, and they have more skin surface area in comparison to their overall body weight than someone fully grown.
  • They taste, touch, and mouth everything they can get their hands on, putting them at greater risk of ingesting toxic material.
  • Their metabolic pathways are immature. Studies show that since their internal organs are still developing, they aren’t as good at detoxifying chemicals. It is only at late adolescence that the liver, kidney, and GI tract are fully functional.

Pesticide exposure is real. In its March 2018 report of biomonitoring data on exposures to chemicals, the Centers for Disease Control (CDC) found that children ages 6-11 had significantly higher levels of multiple pesticide residues in their urine than adults. Public health experts and epidemiologists have been warning of possible health impacts from pesticide exposure for decades. Well-documented pesticide-induced increases in certain childhood cancers (such as leukemia), and neurological disorders and/or loss of IQ have deepened the concern.

Exposure from athletic/playing fields, schools, and playgrounds is of particular concern because of the number of hours children spend on or around such areas. Understanding the potential impacts of these toxic chemicals is a great start to avoiding them in the future.

[*With the authors’ permission, some material has been excerpted from the book, Children and Environmental Toxins by Philip J. Landrigan and Mary M. Landrigan.]