28
Jul
296 Chemicals in Consumer Products Increase Breast Cancer Risk Through Hormone (Endocrine) Disruption
(Beyond Pesticides, July 29, 2021) New research published in Environmental Health Perspectives finds nearly 300 different chemicals in pesticides, consumer products, and contaminated resources (i.e., food, water) increase breast cancer risks. Breast cancer is the most common cancer among women, causing the second most cancer-related deaths in the United States. Past studies suggest genetic inheritance factors influence breast cancer occurrence. However, genetic factors only play a minor role in breast cancer incidences, while exposure to external environmental factors (i.e., chemical exposure) may play a more notable role. There are grave concerns over exposure to endocrine (hormone) disrupting chemicals and pollutants that produce adverse health effects.
Most types of breast cancers are hormonally responsive and thus dependent on the synthesis of either estrogen or progesterone. Hormones generated by the endocrine system greatly influence breast cancer incidents among humans. Several studies and reports, including U.S. Environmental Protection Agency (EPA) data, identify hundreds of chemicals as influential factors associated with breast cancer risk. Therefore, advocates point to the need for national policies to reassess hazards associated with disease development and diagnosis upon exposure to chemical pollutants. The study’s researchers note, “This study shows that a number of chemicals currently in use have the ability to manipulate hormones known to adversely affect breast cancer risk. […] So, we should be extremely cautious about chemicals in products that increase levels of these hormones in the body.”
Using high throughput screening (HTP) data from in vitro ToxCast assay (test) developed by EPA, researchers identified chemicals that increase estradiol (a type of estrogen) or progesterone production in H295R cells responsible for hormone synthesis. An increase in estrogen or progesterone is often indicative of breast cancer and other endocrine-related risks. Researchers organized the identified chemicals by order of activity (i.e., efficacy and potency). Lastly, researchers compared the result to in vivo studies/assessments of carcinogenicity and reproductive/developmental toxicity, demonstrating comparable hormone-increasing mechanisms.
The study results find 296 chemicals associated with an increase in estradiol or progesterone. 182 and 185 different chemicals cause an increase in estradiol and progesterone, respectively, while 71 chemicals are responsible for the increased synthesis of both hormones. Of the chemicals that increase hormone synthesis, only 30 percent are likely reproductive/developmental toxicants or carcinogens from in vivo assessments, while five to 13 percent are unlikely. However, most of the chemicals that increase hormone synthesis lack sufficient in vivo data to gauge health effects. The study finds 29 chemicals associated with an increase in estradiol or progesterone production also have links to mammary tumor development. The researchers find most sources of chemical exposure come from pesticides, consumer product ingredients, food additives, and drinking water contaminants.
The connection between pesticides and associated cancer risks is nothing new. Several studies link pesticide use and residues to various cancers, from more prevalent forms like breast cancer to rare forms like kidney cancer nephroblastoma (Wilms’ tumor). Sixty-six percent of all cancers have links to environmental factors, especially in occupations of high chemical use. Although the link between agricultural practices and pesticide-related illnesses is stark, over 63 percent of commonly used lawn pesticides and 70 percent commonly used school pesticides have links to cancer. U.S. National Institutes of Health’s National Cancer Institute also finds many cancer-causing substances are endocrine disruptors. The entire endocrine system directly affects traditional endocrine glands and their hormones and receptors (i.e., estrogens, anti-androgens, thyroid hormones). Hence, epidemiology studies find endocrine disruption has close ties to hormone-related cancers like breast cancer. For breast cancer, one and eight women will receive a diagnosis, and genetics can only account for five to ten percent of cases. Therefore, it is essential to understand how external stimuli—like environmental pollution from pesticides—can drive breast cancer development to avoid exposure and lessen potential cancer risks.
This study is one of the first to detect chemical activity using HTP assessments based on an increase in estrogen or progesterone production, rather than the ability to mimic estrogen. The results of the study may serve to encourage government and health officials to reevaluate chemical safety tests. Although researchers are unaware of how these chemicals increase estradiol and progesterone production, they caution that encountering multiple sources of daily exposure increases adverse health risks. The most potent, efficacious chemicals associated with increasing estradiol and progesterone levels displayed higher hormone concentrations and mammary gland effects (i.e., tumors, etc.), among other reproductive toxicities. In vitro assessments, like the one in this study, are vital additions to current toxicology assessments as they are not sensitive to mammary gland effects.
For decades, Beyond Pesticides has been arguing that the risk assessment process used by EPA for its pesticide registration process is substantially inadequate to protect human health. The study shows some chemicals that increase hormone synthesis are classifiable as “unlikely to have reproductive/developmental toxicity or carcinogenicity.” However, the cohort of “unlikely” chemicals may be smaller than previously thought as EPA fails to adequately consider exposure effects on mammary gland development in its review of animal studies related to pesticide impacts. Therefore, mammary gland tumor development has been improperly dismissed from consideration in the registration process, including pesticides cyfluthrin and 2,4-D precursor, 2,4-DCP. The study also notes that 112 chemicals in consumer products, food, pesticides, or drugs lack adequate carcinogenicity evaluations and urgently require research and exposure reduction methods.
The researchers conclude, “Exposure to many of these chemicals is likely ubiquitous, based on exposure prediction models. We conclude that these [endocrine disrupting chemicals] EDCs are priorities for biomonitoring and exposure reduction as well as for additional study to better understand potential effects on breast cancer and other reproductive and developmental effects.”
Cancer is a leading cause of death worldwide. Hence, studies concerning pesticides and cancer help future epidemiologic research understand the underlying mechanisms that cause cancer. Furthermore, it is essential to understand the effects endocrine-disrupting chemicals have on human health, especially for latent diseases like cancer. There is a serious deficiency in understanding the etiology of pesticide-induced diseases, including predictable lag time between chemical exposure, health impacts, and epidemiologic data. Therefore, advocates maintain that lawmakers and regulators should take a more precautionary approach before introducing these chemicals into the environment.
With far too many diseases in the U.S. associated with pesticide exposure, reducing pesticide use is a critically important aspect of safeguarding public health and addressing cost burdens for local communities. Beyond Pesticides’ Pesticide-Induced Diseases Database (PIDD) is a vital resource for additional scientific literature that documents elevated cancer rates and other chronic diseases and illnesses among people exposed to pesticides. 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 breast cancer, endocrine disruption, and other diseases.
Proper prevention practices, like buying, growing, and supporting organics, can eliminate exposure to toxic pesticides. Organic agriculture has many health and environmental benefits, which curtail the need for chemical-intensive agricultural practices. Regenerative organic agriculture nurtures soil health through organic carbon sequestration while preventing pests and generating a higher return than chemical-intensive agriculture. For more information on how organic is the right choice, see Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: The Tennessee Tribune, Environmental Health Perspectives
