13
Jul
Deadly Pesticide Poses an Increased Risk of Hormone-Associated Reproductive Cancers in Women
(Beyond Pesticides, July 13, 2023) A study published in Environmental Science and Pollution Research finds exposure to p-Dichlorobenzene (p-DCB), a chlorophenol compound with uses as an insecticide, disinfectant, repellent, fumigant, fungicide, and deodorizer, can increase the risk of common endocrine (hormone)-mediated reproductive cancers (i.e., breast, uterine, and ovarian) in women. P-DCB or paradichlorobenzene has carcinogenic (cancer-causing) properties and the chemical has been banned in the European Union (EU) since 2005 for air fresheners and 2008 for mothballs. Being a chlorinated aromatic hydrocarbon (with benzene) compound (chlorobenzene), in addition to its cancer-causing properties, p-DCB can cause acute illnesses like headaches, numbness, sleepiness, nausea and vomiting and chronic effects like nervous system disorders leading to depression, and impact on the brain, birth outcomes, reproductive system, liver, and kidneys.
Pesticides have a long history associated with endocrine-disrupting properties that induce various molecular changes, prompting disease development. Adding to the science, a similar review published in Environmental Exposure, Biomonitoring, and Exposure Assessment highlights how specific estrogen-mimicking pesticides increase the risk of disease, particularly hormone-related cancers among women (e.g., breast, ovarian, and endometrial cancer) and men (i.e., testicular, prostate cancer).PDCB, also known as para-dichlorobenzene, contains the carcinogen benzene and is chlorine-based (a chlorinated aromatic hydrocarbon compound), which in December 2019 gained it the status of EPA’s “High-Priority Substance for Risk Evaluation” under the Toxic Substances Control Act. It is long-lasting in the environment. According to EPA, the chemical is mainly used as a fumigant for the control of moths, molds, and mildews, and as a space deodorant for toilets and refuse containers. Importantly, it is also used as an intermediate chemical in the production of other chemicals, including those for tree-boring insects, and in the control of mold in tobacco seeds. It shows up in ambient air testing, in drinking water, and in factories producing or processing the product.
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 cancer, among other health issues.
The study “provides insights on the potential role of environmental exposures in the etiology of gynecological cancers. Further exploration of the epidemiological and pathophysiological interactions between p-DCB exposure and endocrine-related female cancers is warranted to expand upon these findings.”
Exposure to p-DCB can disrupt metabolic and endocrine effects associated with endocrine-related female cancers (breast, ovarian, and uterine cancers). Using the U.S. National Health and Nutrition Examination Survey from 2003 to 2016, the study analyzed the urinary components of 4,459 women aged 20 years or older for concentrations of 2,5-dichlorophenol (2,5-DCP), the primary metabolite of p-DCB, to determine the association between p-DCB exposure and widespread endocrine-related cancers. Of the participants, 202 women have an endocrine-related reproductive cancer diagnosis with a significantly higher urinary concentration of 2,5-DCP than women without these cancers. Additionally, women experiencing moderate and high exposure to p-DCB have urinary concentrations of 2,5-DCP significant enough to increase the risk of endocrine-related reproductive cancers compared to low-exposure groups.
Endocrine disruptors are chemicals that can disrupt normal hormonal function, even at low exposure levels. 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. Overall, endocrine disruption can negatively impact reproductive function, nervous system function, metabolic/immune function, hormone-related cancers, and fetal/body development. Thus, the connection between cancers and EDCs has a historical establishment. 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. However, the variations in EDC exposure levels and duration can make it challenging 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. In addition to cancers, exposure to EDCs has links to infertility, early puberty, other reproductive disorders, diabetes, cardiovascular disease, obesity, attention deficit hyperactivity disorder (ADHD), Parkinson’s, Alzheimer’s, and more. EDCs can also wreak havoc 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.
This study adds to the little scientific literature concerning the probable link between p-DCB exposure and female reproductive cancers via endocrine disruption. Although endocrine-related cancers have genetic and behavioral components, the environmental components, like chemical exposure, are also essential to understand, especially since there is an incomplete understanding role the endocrine system plays in the development of these cancers has incomplete understanding. As an endocrine disruptor, p-DCB causes a dose-dependent increase in estrogenic activities, directly affecting the size and function of reproductive organs. Additionally, the International Agency for Research on Cancer (IARC) categorizes p-DCB as a possible human carcinogen (Group 2B), warranting further investigations into the carcinogenic potential of this chemical to humans upon chronic exposure.
Studies directly link obesity with an increased risk of hormone-regulated endocrine cancers in women, finding an association between obesity/metabolic disorders and increased 2,5-DCP concentrations. This finding is unsurprising as p-DCB is a compound with lipophilic properties, accumulating in adipose (fatty) tissue. Like other EDCs and hydrocarbons, p-DCB may impair fatty acid metabolism and lipid synthesis, indicating a potential underestimation of toxicity effects on human, animal, and environmental health. Considering products in the U.S. containing p-DCB are frequently used in households and workplaces, the potential risk to the metabolic and endocrine system among individuals is infinite.
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.
EPA has been severely criticized for its failure to evaluate pesticides in wide use for their endocrine-disrupting properties. See Inspector General Rips EPA for Failure to Test Pesticides for Endocrine Disruption. For a deeper dive into EPA’s failure to meet its statutory responsibility to evaluate pesticides for endocrine disruption fully, see While France Bans a Common Endocrine Disrupting Pesticides, EPA Goes Silent: EPA ignores statutory mandate to review pesticides that cause deadly illnesses at minute doses, defying classical toxicology.
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.
Source: Environmental Science and Pollution Research
