DEET: The Active Ingredient in Common Insect Repellents
Insect repellents remain an essential tool for preventing insect-borne diseases worldwide, especially for protecting vulnerable populations from serious illnesses. However, growing concerns surrounding the use of DEET, an active ingredient commonly found in insect repellents, within those same vulnerable populations have led to increased scrutiny of its safety profile. Developed in 1946 by the US Army and used as a pesticide, DEET was registered for use by the general public in 1957.1 It is a fully man-made chemical designed to make it difficult for biting insects to detect humans, rather than killing the insects. Formulations registered for direct application to human skin contain anywhere from 5 to 99% DEET. Higher DEET concentrations do not necessarily increase effectiveness, but instead extend the duration of protection. It is estimated that 30% of the US population uses repellents containing DEET and that approximately 1800 tons of DEET are used annually in the US.2
The last safety review of DEET performed by the US Environmental Protection Agency was in 2014, and since then, a number of scientific studies have been performed raising questions about potential long-term safety effects of DEET usage. It has been shown that “DEET and its metabolites are detected in human urine, serum, semen, and cord serum, and an estimated 84% of the US population has detectable concentrations of DEET metabolites in their urine”.2 The National Center for Environmental Health and the Agency for Toxic Substances and Disease Registry, both smaller organizations compared to the EPA and with much smaller national impacts, have discussed reports of potential neurotoxic effects associated with high or prolonged DEET exposure, including impaired cognitive functioning, agitation, and aggressive behavior in humans.3 Some early studies researching the effects of DEET showed that high doses of DEET to the skin of pregnant female rats showed an increase in embryo mortality, decreased birthweight, delayed development, and high postnatal death rate.2 These specific studies never gained much attention or follow-up in human studies, and there remains to be very little data on the effects of DEET exposure on human reproductive health.
Given that DEET exposure is so prevalent throughout society, concerns about its safety have risen in recent years, and have led to notably two studies in 2024 and 2025 demonstrating devastating implications of DEET usage in children and pregnant women.
Effect of DEET on Children’s Health
A study published in 2025 in the Journal of Advanced Research found that “DEET exerts a detrimental effect on bone health by interfering with sex hormones in children and adolescents, warranting heightened public concern.” The researchers in this study, knowing that children and adolescents are particularly susceptible to endocrine (hormone) disrupting chemicals that could cause age-related underdevelopment, were concerned that DEET could have a significant effect on children’s endocrine systems. Indeed, the researchers found that DEET does in fact have a detrimental effect on children’s health, with their in-depth analysis revealing an increased DEET exposure was associated with decreased levels of sex hormones and bone mass among participants younger than 12 years old and non-overweight children. In basic terms, the research suggests DEET usage in children leads to a disrupting their ability to create sex hormones, which in turns lowers bone density, potentially affecting normal growth and bone development, as well as other long term health defects.
This study offered some of the first evidence of the potential for DEET to disrupt hormone production and bone mass. The researchers noted that “the report by the EPA indicated that no significant associations have been established between DEET exposure and endocrine disruption. However, this conclusion is primarily derived from toxicological (how substances cause harm) data, as there is a scarcity of epidemiological (real-world patterns of disease in populations) studies available to substantiate the potential endocrine-disrupting effects of DEET.”3 This eye-opening study demonstrates how little research has been done on real-world and long-term consequences of DEET usage effects on vulnerable populations, especially children in this case.
DEET Exposure Effecting Women’s Fertility
Another significant study showing negative effects of DEET usage was published in 2024 in the iScience journal. Scientists in this study were concerned that DEET usage in the first trimester of human pregnancy had not ever been studied. They developed a study assessing the effects of DEET directly on female meiosis (the development of eggs for human sexual reproduction). Female meiosis occurs during the fetal stage of development; human females are born with all of the eggs they will ever have in their lifetime, as contrasted to human males who constantly perform meiosis throughout their adult lives through sperm production. The researchers in this study used a model of C. elegans, a type of worm that is highly predictive of mammalian reproduction, and provides many advantages for the study of meiosis, including sharing the same biochemical pathways as humans, as well as a rapid life cycle (developing from an egg into an adult in 3 days). The scientists found that DEET exposure led to altered gene expression, resulting in increased stress and altered chromatin structure in the eggs, thereby compromising the integrity of the eggs and increasing fetal lethality. Therefore the worm study showed that DEET exposure was associate with abnormalities in egg development and reduced fertility in C. elegans.2
Monica Colaiacovo, professor of genetics at Harvard Medical School, the researcher behind the study, discussed her worm findings study with a journalist, outlining the implications of her findings. She said that her lab initially screens various environmental chemicals for their effects on meiosis, and DEET was one of the highest scorers, leading to their full study. Colaiacovo said in the interview, “DEET was one of our top hits in terms of chromosomes not separating properly, so eggs end up with abnormal numbers of chromosomes. In humans, this can cause miscarriage, still birth, infertility, and genetic conditions such as Down syndrome.” She noted that their work is very important for pregnant women, because female meiosis begins in the developing fetus in the womb. DEET exposure while pregnant could potentially lead to that pregnant woman’s daughter being born already infertile. With this study being only performed in C. elegans and not humans, the researchers noted that these findings may warrant further investigation into how DEET exposure could affect human reproductive development during pregnancy.4
The findings in this significant study underscores the need for further research into how specifically DEET effects human fertility. Nevertheless, this study and other emerging ones emphasize that there are risks associated to DEET usage in vulnerable populations, such as pregnant women and women planning on becoming pregnant.
A Safe Alternative to DEET
As emerging data show increased risk for negative effects of DEET usage, alternative insect repellents with higher safety ratings are rising in popularity. The active ingredient IR3535®, widely regarded as a more natural repellent compound with a well-established history of safety, is now being used in repellents that are proven effective against biting insects. Used across Europe for over 20 years with no substantial adverse effects, IR3535® has demonstrated a strong safety profile for use among pregnant women and children.5 IR3535® is a technical grade synthetic biochemical pesticide, meaning designed to mimic natural mechanisms and to be effective while minimizing risk to humans and the environment. Developed by Merck KGaA in the 1980s, IR3535® is structurally similar to the naturally occurring amino acid b-alanine (a component of Vitamin B5). It is designed to inhibit an insect’s sense of smell and taste, impeding their interest in feeding off of human hosts. Repellents using IR3535® as their active ingredient, being odorless and less greasy, are more acceptable among safety-conscious consumers and for cosmetic use.6
IMPEDE is one such safe insect repellent alternative, using IR3535® as its active ingredient instead of DEET. While the active ingredient IR3535® plays a central role in IMPEDE’s safety, other aspects of the formulation further support its suitability for use among vulnerable populations, like pregnant women and children. The IMPEDE lotion is hypoallergenic and dye-free, making it gentle on skin. Using the patented STAYTEC™ technology, IMPEDE is designed to keep the active ingredient on the surface of the skin, minimizing absorption. STAYTEC™ gives IMPEDE a protection time of up to 14 hours, reducing the need for frequent reapplication. Safe for daily use, travel, outdoor activities, and extended exposure, IMPEDE offers consistent, long-lasting protection, ideal for any family excursion. Manufactured with premium ingredients and consistent quality standards, IMPEDE is built with safety, reliability, and family use in mind.
As understanding of long-term chemical exposure continues to expand, the future of insect repellents may increasingly depend on formulations that prioritize both public health protection and ingredient safety. Therefore, choose IMPEDE: tough on bugs, gentle on you.