November is for the Boys: Pesticide Chlorpyrifos May Affect Men’s Health


Article Author: Brooke Linnehan, Biology Major, Class of 2021, Protect Our Breasts Science Translator 

We often share about choosing organic products to avoid chemicals linked to breast cancer. November is for the boys, and while men can still be diagnosed with the disease, new research has exposed the effects of an often-used pesticide on male fertility, specifically sperm count.

Chlorpyrifos (CPF) is a pesticide used in agricultural, residential, and commercial settings to control insects. Primarily used on cotton, corn, almonds, and various fruits, the World Health Organization considers CPF moderately hazardous. People can be exposed to CPF through contact with the skin or eyes, inhalation, or from eating. Typically, CPF exposure is known for causing adverse outcomes in neural development. However, new research suggests it can affect epigenetics and male reproductive health.

Epigenetic changes affect the way genes are expressed. Epigenetics do not make any changes to the actual DNA sequence. One example of epigenetics is methylation, or when a small molecule called a methyl group attaches to the DNA and has a silencing effect on that gene, like an off switch for a light bulb. Just because the light bulb is turned off doesn’t mean that the light bulb’s electrical circuit is any different. Although the DNA still has the instructions for making that particular protein, it is just not being made when the DNA for that gene is methylated. It has simply been turned off.

A recent peer-reviewed article from August 2020 explored the epigenetic effects of chlorpyrifos (CPF) on male reproductive health. The researchers treated rats with CPF for 90 days and compared their DNA with untreated rats. They found 27,019 different regions where the methylation in the treated rats was different from the methylation in the untreated rats. The genes associated with these regions of the DNA were predicted to be involved in 113 biological pathways. Keeping the lights on is critical. Some of these pathways are essential for directing cell growth and division. Cell growth and division pathways are extremely important for ensuring a cell doesn’t become cancerous and begin to grow and divide uncontrollably. When studying the actual effects of CPF on male rat testis, the researchers found that CPF can significantly increase rates of sperm malformation, which leads to a lower sperm count.

The importance of avoiding toxins like pesticides whenever possible cannot be emphasized enough. A way to avoid exposure to CPF is to choose organic products, because organic certification guarantees synthetic pesticides have not been used in production.  Both men and women are exposed to chemicals, toxins, and EDCs in their everyday lives, but it is possible to reduce individual exposures by making conscious healthier, safer organic choices. 


Sai, L., Jia, Q., Zhang, Y., Han, R., Geng, X., Yu, G., … & Peng, C. (2020). Genome-wide analysis of DNA methylation in testis of male rat exposed to chlorpyrifos. Toxicology Research, 9(4), 509-518.

Sai, L., Li, X., Liu, Y., Guo, Q., Xie, L., Yu, G., … & Li, L. (2014). Effects of chlorpyrifos on reproductive toxicology of male rats. Environmental toxicology, 29(9), 1083-1088.

Disclaimer: The information provided herein is the author’s opinion. Our authors are not scientists. We are not providing medical advice, but simply sharing publicly available information. When we reference data and databases, we do so with the caveat that most are only as good as the data they are based on. While POB strives to make the information as timely and accurate as possible, we make no claims, promises, or guarantees about the completeness, or adequacy of the contents of any site that is shared, and expressly disclaims liability for errors and omissions in the contents of these sites.  POB goes to great lengths to avoid declaring shared products as “safe” as there is no legal definition of the word “safe” at this time.

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