10
Jan
Pesticides’ Role in Lower Sperm Counts and Reproductive Harm in Men Again in Science Literature
(Beyond Pesticides, January 10, 2024) Exposure to endocrine-disrupting chemicals (EDCs) negatively impacts testicular function and may cause sperm count declines over time, according to a 2022 review published in Endocrine. The findings indicate that this occurs regardless of whether exposure is prenatal (before birth) or postnatal (after birth). More recent work from October 2023 confirms the connection between male reproductive health and exposure to organophosphate and carbamate insecticides and the weed killer glyphosate—as many pesticide products containing these chemicals are classifiable as endocrine disruptors (ED). Just last year, a meta-analysis from researchers at Mount Sinai Medical Center, the Hebrew University of Jerusalem, and the University of Copenhagen, among others, finds that the drop in global sperm count is accelerating, dropping by 51.6 percent from 1973 through 2018.
The U.S. regulatory system, under the authority of the U.S. Environmental Protection Agency (EPA), has not kept pace with the science and does not fully evaluate pesticides in wide use for endocrine disruption, despite a requirement in 1996 law (the Food Quality Protection Act) to begin that testing and evaluation nearly three decades ago. In 2021, Beyond Pesticides reported that the Office of the Inspector General (OIG) for EPA issued a damning report on the agency’s progress in protecting the population from potentially damaging endocrine disruption impacts of exposure to synthetic chemical pesticides (and other chemicals of concern). For more context on EPA’s failure to regulate endocrine-disrupting pesticides, see When France Bans Common Endocrine Disrupting Pesticide, EPA Goes Silent. For more background, see here.
Endocrine disruptors are xenobiotic (i.e., chemical substances like toxic pesticides foreign to an organism or ecosystem). Many reports demonstrate that exposure to endocrine-disrupting chemicals can adversely affect human, animal—and thus environmental—health by altering the natural hormones responsible for conventional reproductive, physical, and mental development. Scientists and health officials already associate pesticide exposure with a decrease in male fertility, including reduced sperm count, quality, and abnormal sperm development. Furthermore, Beyond Pesticides has long highlighted the relationship between reproductive anomalies and toxic pesticides, particularly the role of endocrine-disrupting (ED) compounds. Therefore, reviews like this emphasize the importance of understanding how chemical exposure threatens reproductive health, not just for the current generation but for future generations, as these reproductive harms can prompt genetic changes.
The researchers reviewed animal and human studies on the effects of EDC exposure on testicular development, spermatogenesis (sperm production and development), malformations of the male genital tract, testicular tumors, and the mechanisms involved in testicular damage mediated by EDCs. After reviewing the scientific literature, the review confirms that EDCs harm the male reproductive system, ultimately compromising male fertility. The study notes explicitly that EDCs can bind to hormone receptors, dysregulating hormone receptor expression, disrupting the production and metabolism of the steroid hormone (steroidogenesis), and altering the epigenetic (heritable traits) mechanisms. The resulting reproductive outcomes from EDC exposure include poor semen quality, increased sperm DNA fragmentation, increased gonadotropin levels, a slightly increased risk of hereditary malformations (e.g., cryptorchidism and hypospadias), and testicular tumor development. Regarding prenatal exposure, maternal exposure to EDCs increases the predisposition for testicular tumor development, as well.
The ubiquity of pesticides in the environment and food supply is concerning, as current measures restricting pesticide use and exposure do not adequately detect and assess total environmental chemical contaminants. The scientific literature demonstrates pesticides’ long history of severe adverse human health effects (i.e., endocrine disruption, cancer, reproductive/birth problems, neurotoxicity, loss of biodiversity, etc.). Most concerning is exposure to past and current-use pesticides, as these chemicals display endocrine-disrupting effects. The World Health Organization (WHO), European Union (EU), and endocrine disruptor expert (deceased) Theo Colborn, Ph.D., classify over 55 to 177 chemical compounds as endocrine disruptors, including various household products like detergents, disinfectants, plastics, and pesticides. Endocrine disruption can lead to several health problems, including hormone-related cancer development (e.g., thyroid, breast, ovarian, prostate, testicular), reproductive dysfunction, and diabetes/obesity that can span generations. Therefore, studies related to pesticides and endocrine disruption help scientists understand the underlying mechanisms that indirectly or directly cause infertility, among other health issues.
Like this review, other studies highlight many pesticides can impact male sperm production (and reproduction broadly) through endocrine disruption. This disturbance may happen in several ways, including mimicking a natural hormone and fooling the body into over-responding to a stimulus, responding at inappropriate times, blocking the effects of a hormone from specific receptors, and/or directly stimulating or inhibiting the endocrine system, cause over- or under-production of hormones. The National Institutes of Health explainer says that exposures to ED chemicals can cause “deleterious effects on human reproductive health by interfering with the synthesis and mechanism of action of sex hormones. Any change during the synthesis or action of the sex hormones may result in abnormal reproductive functions, which includes developmental anomalies in the reproductive tract and decline in semen quality.”
In addition to the downward trend in sperm quality, the evidence highlighted by this review is sufficient enough to cause concern. Moreover, science has recognized for years the significant role pesticide exposures likely play in degraded sperm quantity and quality and impaired reproductive functions. Pesticides are ubiquitous — they are found in many industrial products and consumer products, such as plastics, furniture, clothing, canned food, water bottles, toys, cosmetics, electronics, food packaging, fertilizers, and pesticides. People are exposed to pesticides through these products, occupationally and dietarily.
Although this study explicitly evaluates EDCs’ impacts on male fertility, it is not the first to demonstrate the sex-specific effect of pesticide exposure. In 2017, scientists presented a study at the 99th meeting of the Endocrine Society, showing instances of early onset puberty in boys after exposure to common pyrethroid insecticide, which exhibits endocrine-disrupting properties that interfere with the proper regulation of the human body’s hormonal system. Furthermore, a 2021 study demonstrates that exposure to current-use pesticides, like organophosphates, poses a greater health risk to women. In addition to impacts on fertility, the study warns, “Testicular GJIC and connexin dysregulation, especially during critical early stages of development, could partly participate in the etiopathology of human subfertility and infertility and testicular cancer.”
Pesticides and other chemicals undermine the ability of reproduction. Furthermore, studies regarding pesticides reveal mechanisms that show how specific chemical toxicants can alter fertility, including endocrine disruption. Therefore, advocates urge that policies strengthen pesticide regulations and increase research on the long-term impacts of pesticide exposure. Beyond Pesticides tracks the most recent studies related to pesticide exposure through our Pesticide Induced Diseases Database (PIDD). This database supports the clear need for strategic action to shift away from pesticide dependency. For more information on the multiple harms of pesticide exposure, see PIDD pages on Sexual and Reproductive Dysfunction, Endocrine Disruption, Body Burdens, and other diseases.
The ubiquity of pesticides in the environment and food supply is concerning, as current measures restricting pesticide use and exposure do not adequately detect and assess total environmental chemical contaminants. For instance, 90 percent of Americans have at least one pesticide biomarker (including parent compound and breakdown products) in their body. However, one way to reduce human and environmental contamination from pesticides is to buy, grow, and support organic. Numerous studies find that levels of pesticides in urine significantly drop when switching to an all-organic diet. Furthermore, given the wide availability of non-pesticidal alternative strategies, families, from rural to urban, can apply these methods to promote a safe and healthy environment, especially among chemically vulnerable individuals or those with health conditions. For more information on how organic is the right choice for consumers and the farmworkers that grow our food, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Endocrine
