Endocrine - Disrupting Chemicals and Breast Cancer

Introduction:

Endocrine-disrupting chemicals are exogenous chemicals that can interfere with the synthesis, release, transportation, breaking down (metabolism), binding with the target receptor, action, or elimination of natural hormones from the body. These hormones are responsible for maintaining homeostasis in the body (a steady internal, physical, and chemical state of the body). These external agents can mimic the natural hormones and interfere with endocrine functions. Certain endocrine-disrupting chemicals have structures and properties similar to estrogen, which is a female sex hormone responsible for the regulation of the female reproductive system and the development of secondary sexual characteristics. When a female is exposed to endocrine-disrupting chemicals with estrogenic properties, especially at an early stage of life, she is at a higher risk of developing breast cancer.

What Are Endocrine-Disrupting Chemicals (EDCs)?

Endocrine-disrupting chemicals or EDSs are chemicals present in the environment like food products, water supply, medicines, self-care products, industrial chemicals, etc. These EDCs interfere with the normal functioning of the endocrine system in the human body by mimicking and acting as the natural hormones of the endocrine system. These EDCs either confuse the body into thinking they are hormones or prevent natural hormones from working properly. Certain EDCs can affect how hormones are made, broken down, or stored in our systems, causing hormone levels in our blood to rise or fall. Other EDCs can also change the body's sensitivity to different hormones. Some EDCs are potentially harmless on their own, but when present along with another EDC, they become harmful. Every endocrine axis is vulnerable to the effects of EDCs, including the hypothalamus-pituitary-thyroid axis, hypothalamus-pituitary-gonadal axis, hypothalamus-pituitary-adrenal axis, etc. EDCs have several ways to contaminate the human body. The most common sources of exposure are inhalation, food consumption, and direct touch.

What Are Some of the Common Endocrine-Disrupting Chemicals?

Some of the common endocrine-disrupting chemicals are

• Bisphenol A or BPA.

• Dioxins.

• Perchlorates.

• Perfluoroalkyl or polyfluoroalkyl substances or PFAs.

• Phthalates.

• Phytoestrogens.

• Polybrominated diphenyl ethers.

• Triclosan.

• Polychlorinated biphenyls.

• Pesticides.

• Dichlorodiphenyltrichloroethane or DDT.

• Dichlorodiphenyldichloroethylene or DDE.

• Atrazine.

• Parabens.

• Polybrominated diphenyl ethers or PBDEs.

• Levonorgestrel and Ethinyl estradiol.

• Mycotoxins.

What Are the Various Sources of Endocrine-Disrupting Chemicals?

Common sources of various endocrine-disrupting chemicals are

• BPA - Plastics, packaged food cans, resins, etc

• Dioxins - Industrial solvents and lubricants, waste burning, and wildfire byproducts.

• Perchlorates - The byproducts of medicine industries, aerospace, and weapons.

• PFAs - Textile coating, non-stick pans, etc.

• Phthalates - Toys, children’s products, plastic containers, cosmetics, etc.

• Phytoestrogens - Soy and soy products.

• Polybrominated diphenyl ethers - Flame retardants used for furniture and carpets.

• Triclosan - Skincare products.

• DDT and DDE - Those accumulated along the food chain in meat, fish, and dairy products.

• Atrazine - Agricultural herbicides.

• Parabens - Preservatives in food, beer, sauces, jams, skincare products.

• Mycotoxins - Naturally occurring toxins produced by certain fungi.

• Levonorgestrel and Ethinyl estradiol - Oral contraceptive pills.

• Pesticides - Agricultural produce.

What Are the Common Effects of Endocrine-Disrupting Chemicals in the Body?

Endocrine-disrupting chemicals' effects are divided into three categories; hormone-disrupting, obesity-related, and cancer-related. Common symptoms or effects of EDCs are:

• Change in behavior and mood.

• Neurological alterations.

• Stress and stress handling issues.

• Anxiety.

• Depression.

• Obesity.

• Diabetes mellitus (type 2).

• Thyroid gland dysfunction.

• Pituitary gland dysfunction.

• Adrenal gland dysfunction.

• Reproductive dysfunction.

• Infertility in men and women.

• Precocious or delayed puberty.

• Congenital disabilities (birth defects) in babies like low birth weight.

• Reduced immunity.

• Cancers like; prostate and breast cancer.

What Is Breast Cancer?

Abnormal and uncontrollable growth of the breast cells is known as breast cancer. Breast cancer affects women, and in very rare cases, it can also occur in men. The hallmark symptom of breast cancer, which is also usually the chief complaint of the patient as well, is the development of a lump in the breast. Apart from a breast lump, individuals affected by cancer may also complain of nipple discharge, pain in the breast, uneven size of both breasts, etc. In more advanced cases, where breast cancer spreads to distant parts of the body, symptoms include; unusual weight loss, pain in the joints and bones, yellowness of skin, swollen lymph nodes, etc. Breast cancer is the most common cancer in women globally, and it affects 1 in every seven women. Endocrine-disrupting chemicals (EDCs) are known to play a key role in the development of breast cancer.

How Do Various Endocrine-Disrupting Chemicals Cause Breast Cancer?

Several EDCs are directly and indirectly associated with breast cancer development. These EDCs are present in various environmental and other sources, some of which are unavoidable and readily available for contamination. Pesticides, plasticizers, pharmacological agents, personal care items, food goods, and packaging are all examples of EDCs. EDCs may alter the formation or progression of breast cancer and, as a result, lead to lifetime adverse health implications, according to growing epidemiological evidence, especially when humans are exposed early in life. EDCs are prevalent in the environment, and evidence suggests that EDCs' ability to mimic estrogen may be responsible for the rising breast cancer incidence. Because EDCs disrupt the endocrine system's ability to regulate growth and differentiation, young women or girls nearing puberty will be more susceptible to cancer if they are regularly exposed to environmental toxicants such as EDCs, even at low concentrations. The effects of various EDCs are

• Pesticides: Pesticides are the strongest environmental factor associated with breast cancer. Pesticides are enormously used in farming, and their exposure is almost unavoidable. Chemicals, including agricultural pesticides and herbicides, such as p,p’-dichlorodiphenyltrichloroethane (DDT), p,p’-dichlorodiphenyldichloroethylene (DDE), atrazine, etc., have estrogenic properties which can lead to breast cancer development. DDT and DDE are two EDCs that are extremely persistent in the environment. They can accumulate along the food chain and can be found in breast milk as well as fat tissues. Since it was known that DDT has endocrine-disruptive qualities and causes birth abnormalities in humans and animals, most countries have banned its usage.

• Atrazine: The use of atrazine was prohibited due to the widespread and unavoidable contamination of water and soil by the chemical. Atrazine can be discovered in crops used as cattle feed, milk, and meat. This indicates that they are persistent in nature. Atrazine is active and harmful even at low levels; however, its mechanism of action is unknown.

• Dioxins: Dioxin is a byproduct of combustion and manufacturing chemicals, and they are classified as EDCs because they bind to the aromatic hydrocarbon receptor to produce estrogenic or antiandrogenic effects. Dioxins are carcinogenic in nature and found abundantly in milk, poultry, meat, eggs, etc.

• Bisphenol A or BPA: BPA is a chemical used in the production of polycarbonate plastics used to make storage cans for food and beverages. It is considered a weak EDC because of its low affinity to binding to estrogen receptors. However, BPA is capable of triggering cellular responses to initiate breast cancer even at low levels. It is believed that a higher prevalence of infertility, genital tract abnormalities, and breast cancer may be linked to BPA exposure during the early stages of development.

• Phthalates: These EDCs contaminate food packaging materials and substances used during the processing and storage of food. They are carcinogenic or known to cause cancer due to their possible endocrine disruptive capabilities, which include their ability to interfere with the breaking down (metabolism) and actions of androgen (male sex hormones), thyroid hormones, and glucocorticoid hormones.

• Per- and Polyfluoroalkyls Substances (PFAS): These are the EDCs that contaminate the water, enter the food chain, and get consumed through packaged food and contaminated soil. Because PFAS can imitate fatty acids and accumulate in adipose tissues, exposure to these chemicals can have detrimental health effects. PFAS binds to plasma proteins, which can be passed down through the placenta and breast milk to the baby. These cause endocrine disruption by binding and activating the peroxisome proliferator-activated receptor signaling pathways, raising hepatic aromatase and estrogen levels.

• Parabens: Parabens are synthetic preservatives used in food products (beer, jams, sauces, etc.), personal care products, cosmetics, and skincare products. These preservatives are considered carcinogens (cancer-causing agents) and endocrine disruptors because they can mimic estrogen and cause hormonal imbalances in the body. During several types of research, parabens have been detected in normal breast cells, breast milk, and maternal urine. These researches suggest that parabens' estrogenic qualities may disrupt the mechanism of normal breast cells, contributing to their aberrant proliferation and increasing the risk of breast cancer.

• Oral Contraceptive Pills: Some oral contraceptive pill that contains both Levonorgestrel (synthetic hormone similar to progesterone) and Ethynyl estradiol (synthetic steroid hormone similar to progesterone) are considered endocrine-disruptors because they interfere with normal reproductive functioning and mimic the action of estrogen in the body and prevents the production of normal estrogen in the body. These contraceptive pills have been associated with an increased risk of breast cancer. The duration of taking these pills also plays a role in the development of breast cancers.

• Phytoestrogens: Certain naturally occurring chemicals can cause endocrine disruption and interfere with the production and functioning of normal endogenous hormones. Phytoestrogens are estrogens that exist naturally in plants and are abundant in them. Phytoestrogens are thought to be helpful in treating or preventing breast cancer in some cases. However, phytoestrogens have been linked to serious side effects. Long-term exposure to estrogenic substances, particularly during critical phases of development, can have serious long-term complications, such as the development of cancers and a variety of reproductive system disorders.

Conclusion:

To summarize, exposure to these EDCs through food appears to be unavoidable, and this can have harmful long-term consequences for human health and well-being, particularly in pregnant women, developing babies in the womb, and young children, who are often considered to be particularly vulnerable to EDC exposures. Moreover, because several EDCs coexist in the environment, further research is needed to accurately assess the human risk of breast cancer as a result of exposure to combinations of EDCs.