25
May
New Viewpoint on the Historic Link between Endocrine Disrupting Chemicals and Cancer Discussed
(Beyond Pesticides, May 25, 2023) A review of scientific literature published in the Journal of Endocrinological Investigation demonstrates exposure to past and current-use endocrine-disrupting chemicals (EDCs), like pesticides, have a long history of severe adverse human health effects. Endocrine disruptors are xenobiotics (i.e., chemical substances like toxic pesticides foreign to an organism or ecosystem) present in nearly all organisms and ecosystems. 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. The review notes, “New evidence supports the role of other EDCs as possibly carcinogenic and pregnant women should avoid risk area and exposure. The relationship between EDCs and cancer supports the need for effective prevention policies increasing public awareness.”
The review examines the relationship between EDCs and various hormone-mediated various (i.e., breast, prostate, testicle, ovary, and thyroid) to determine the carcinogenicity of the chemicals and their impact on public health. Researchers performed a literature review of meta-analyses and human studies between 1958 and 2022, searching for articles on “endocrine-disrupting chemicals,” “EDCs,” “phthalates,” “TCDD,” “dioxin,” “polychlorinated biphenyls,” “PCB,” “bisphenol A,” “BPA,” “nitrate,” “nitrite” and “breast cancer” or “prostate cancer” or “thyroid cancer” or “ovarian cancer” or “testicle cancer” on Pubmed. Although the review finds many studies establishing a link between EDCs and cancers, there is a lack of current criteria to test new chemicals of endocrine disrupting potential and possible carcinogenic activity. The latent, adverse manifestation of cancers at varying ages makes it difficult to assess the full impact of human exposure to EDCs. For instance, evidence suggests that developing fetuses and neonates are most vulnerable to endocrine disruption, but cancer development manifestation needs more comprehensive research.
Endocrine disruptors are chemicals that can, even at low exposure levels, disrupt normal hormonal (endocrine) function. The endocrine system consists of glands (thyroid, gonads, adrenal, and pituitary) and the hormones they produce (thyroxine, estrogen, testosterone, and adrenaline). These glands and their respective hormones guide the development, growth, reproduction, and behavior of animals, including humans. Past research shows exposures to endocrine-disrupting chemicals can adversely impact human, animal—and thus environmental—health by altering the natural hormones responsible for conventional fertile, physical, and mental development. Research demonstrates that endocrine disruption is prevalent among many pesticide products like herbicides, fungicides, insecticides, and pesticide manufacturing by-products like dioxin (TCDD). EDCs can enter the body and interfere with normal bodily function by mimicking the action of a naturally produced hormone, such as estrogen or testosterone, thereby setting off similar chemical reactions in the body, blocking hormone receptors in cells, thereby preventing the action of natural hormones; or affecting the synthesis, transport, metabolism, and excretion of hormones, thus altering the concentrations of natural hormones.
Endocrine disruption is an ever-present, growing issue that plagues the global population. The connection between cancers and EDCs has a historical establishment. However, this review highlights new perspectives on mechanisms involved in EDC-mediated cancers outside estrogen-receptor pathways. Genetic instability Mutation of damaged (unrepaired) DNA (genetic instability) and changes in the way genes work influenced by behavior and the environment (epigenetic changes). The variations in EDC exposure levels and duration can make it difficult to investigate among humans. The U.S. Environmental Protection Agency (EPA) fails to evaluate the depth and scope of chronic health and environmental concerns regarding exposure to EDCs. Exposure to EDCs has links to infertility, early puberty, and other reproductive disorders, diabetes, cardiovascular disease, obesity, attention deficit hyperactivity disorder (ADHD), Parkinson’s, Alzheimer’s, and childhood and adult cancers. ED chemicals can wreak havoc not only on humans but also on wildlife and their ecosystems. Hence, advocates maintain that policies should enforce stricter pesticide regulations and increase research on the long-term impacts of pesticide exposure.
Overall, endocrine disruption can negatively impact reproductive function, nervous system function, metabolic/immune function, hormone-related cancers, and fetal/body development. The International Agency for Research on Cancer (IARC) and the U.S. National Toxicology Program (NTP) classify many EDCs as possible carcinogens based on epidemiological studies identifying instances of kidney, ovarian, testicular, prostate, and thyroid cancer, as well as non-Hodgkin lymphoma and childhood leukemia. Considering EDCs like organochlorines (e.g., DDT, lindane, heptachlor, etc.) are anatomically similar to fatty acids and may impair fatty acid metabolism and lipid synthesis in the liver, there may be an underestimation of toxicity effects on human, animal, and environmental health. Therefore, advocates say it is essential to avoid toxic chemical exposure to lessen potential acute and chronic health risks. The study concludes, “More studies are needed to clarify these associations, but, despite the uncertainties, the relationship between EDCs and cancer supports the need for effective prevention policies, paying attention to public awareness.”
The endocrine-disrupting effects of pesticides and other chemicals have extensive documentation that Beyond Pesticides tracks through our Pesticide-Induced Diseases Database (PIDD). This database supports the clear need for strategic action to shift from pesticide dependency. For more information on the multiple harms that pesticides can cause, see PIDD pages on Endocrine Disruption 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. 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 why 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.
