Endocrine-Disrupting Chemicals and Cancer

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Endocrine disruptors or endocrine-disrupting chemicals (EDCs) are substances in the environment that can interfere with the actions of hormones in our bodies. Through a number of mechanisms, endocrine disruptors have been linked to several cancers, including those of the thyroid, breast, and prostate. For those who are living with cancer, there is also some concern that exposures could enhance the progression or metastasis of tumors. It's thought that chronic low dose exposure to a combination of these chemicals is most concerning.

While learning about a potential connection between substances we encounter each day and medical conditions (ranging from cancer to decreased IQ in children) can be disconcerting, knowledge can truly be power in this setting. Fortunately, having an awareness of where these chemicals hide, and making simple changes to your lifestyle, may not only reduce your health risks due to exposure, but could be aesthetically pleasing and benefit your budget as well.

Definition

Endocrine disruptors are defined as "exogenous" chemicals that may interfere with the actions of hormones in our bodies. The term exogenous means that they come from outside of the body.

When evaluating chemicals in the environment with regard to health, the conventional approach is to look at the effect of high doses over a short period of time. What we've learned with endocrine-disrupting chemicals, however, is that low dose exposure over an extended period of time (and to the combination of a number of these chemicals) is of greater concern—a concern that many researchers believe has been largely underestimated.

Where Are They Found?

Endocrine-disrupting chemicals can be found throughout our homes and lives. Examples include:

  • Metal food cans (the liner)
  • Many personal care products
  • Food
  • Cosmetics
  • Cleaning products
  • Plastic bottles
  • Children's toys
  • Medical devices
  • Cash register receipts
  • Hand sanitizer

What Chemicals Are Considered Endocrine Disruptors?

The following list contains some of the chemicals classified as endocrine disruptors, meaning that they can interfere with the actions of hormones in the body in some way, but it's important to focus on the whole rather than specific chemicals. Looking at exposure to this group of chemicals as a whole is similar to the approach researchers have recently adopted with air pollution. When air was evaluated for specific compounds that may be causing lung cancer, there was not a strong association. But looking at air pollution (particulate matter) as a whole made the true risk much clearer. Particulate matter in the air is now classified as a human carcinogen.

Examples of endocrine-disrupting chemicals include:

  • Bisphenol A
  • Phthalates (such as BBP, DBP, DEHP, DEP, DiDP, DiNP, DnHP, and DnOP)
  • Dioxins
  • Parabens (such as methylparaben, ethylparaben, propylparaben, and butylparaben)
  • Pesticides
  • Polychlorinated biphenyls
  • Polybrominated diethyl ethers

Mechanism

While endocrine disruptors are commonly thought of as being chemicals that mimic the effects of natural hormones in the body, this is but one mechanism. Some of these mechanisms may explain why EDCs have been implicated even in cancers that are not considered to be hormone-sensitive.

A 2020 review lists specific ways by which endocrine disruptors could have an effect in our bodies:

  1. Receptor agonist: In this method, the chemical may mimic the effect of a natural hormone in the body (such as estrogen or thyroid hormones) by directly binding to the receptor (for example, estrogen receptors).
  2. Receptor antagonist: Instead of binding to the receptor for a hormone and mimicking its actions, the chemical may bind to the receptor so that the natural hormone cannot.
  3. Receptor expression: The chemical may alter the expression (number of receptors) present for natural hormones. For example, BPA appears to affect the expression of estrogen receptors in the brain.
  4. Signal transduction: There are many signaling pathways involved in the endocrine system. A chemical may act by interfering with or disrupting a wide variety of signaling pathways in the body involving hormones.
  5. Epigenetic alterations: Non-genetic changes that affect the way that DNA is "read" may result, and this has been seen with ovarian cancer cells in the lab.
  6. Hormone synthesis: The production of hormones in the body could be affected in many ways, leading to an increase or a decrease of many hormones.
  7. Hormone transport
  8. Blood levels of hormones
  9. Breakdown of hormones in the body (and removal from the body): A chemical may affect the metabolism of the hormone in the liver so that either a hormone is not broken down as fast as usual, or is broken down more rapidly.
  10. Proliferation/differentiation/apoptosis

There are not only a number of different ways that these substances could have an effect on the body, but this effect can vary depending on the age of a person, sex, and even changes in the season or time of day (circadian rhythms) that exposure occurs.

Role in Cancer

The precise relationship of endocrine-disrupting chemicals and cancer is still not known, and we may never how important they are in the cause or progression of the disease. It's simply not ethical to expose one group of people to a chemical (or a chemical cocktail) to see what happens. Instead of prospective studies such as this, most of our information comes from retrospective studies—studies that look back in time and compare two groups of people. Unfortunately, retrospective studies are much less accurate.

Several of these chemicals have been evaluated in the laboratory and/or in animal studies, but these studies do not necessarily translate to humans. The signaling pathways involved in the endocrine system cannot be replicated in a dish, and we know from the past that some exposures that are safe in animals are unsafe in humans, and vice versa.

While endocrine-disrupting chemicals have been linked to low sperm counts, lower IQ in young boys born to exposed mothers, obesity, and much more, the connection with cancer can be more challenging to study. For example, exposure during pregnancy resulting in changes in young children or sperm counts is easier to monitor. An overall exposure that occurred over a period of time decades earlier (due to the latency period of cancer) is more difficult to analyze.

Overall Endocrine-Disrupting Chemical Exposure

The majority of studies that have looked at the potential for endocrine disruptors to induce or cause the progression of cancer have focused on specific chemicals, for example, BPA or dioxins. Yet, we are learning from other research that overall exposure may be of greatest concern. A 2019 study looked at maternal exposure to endocrine-disrupting chemicals and the effect on intelligence in children at age 7 who were born to these mothers. Boys who had a higher than average exposure to a mixture of 26 different endocrine disruptors during the first trimester had an average drop in IQ of 1.9 at age 7. The chemical that was associated most strongly with exposure was bisphenol F, a chemical often found in food packaging. In fact, with the recent trend to go "BPA free," many people may now be exposed to more bisphenol F.

Types of Cancer and Endocrine Disrupting Chemical Exposure

Studies looking at specific endocrine-disrupting chemicals to date have focused on the potential effect of these chemicals on hormone-sensitive cancers. Intuition tells us that cancers such as breast cancer, prostate cancer, uterine cancer, ovarian cancer, testicular cancer, and thyroid cancer could be influenced by chemicals that mimic the effects of hormones in the body.

That said, and looking at the mechanisms above, there is concern that some cancers that are not considered hormone-sensitive could be either caused or affected by EDCs. While BPA has primarily been linked to hormone-sensitive cancers in the past, it also appears to be associated with non-hormonal sensitive cancers such as bone cancer (osteosarcoma), cervical cancer, lung cancer, and meningioma.

Cancer That is Already Present and Endocrine Disruptors

Not only have endocrine disruptors been associated with the development of some cancers, but they may play a role in the progression or spread of cancers already present. Again this is challenging to study outside of the lab, but a few concerns have been noted.

In the lab, exposure to low doses of endocrine disruptors has been found to cause changes in cancer cells that can lead to progression. In breast cancer cells, overall exposure to low dose EDCs resulted in the proliferation of breast cancer cells, as well as activation of aromatase. Aromatase is an enzyme that converts androgens to estrogen in the tissues after menopause. For women who have had breast cancer and are menopausal, taking an aromatase inhibitor has been found the cut the risk of recurrence in half.

Similarly, studies evaluating ovarian cancer cells have found that exposure to endocrine-disrupting chemicals causes changes in the way that DNA is read (epigenetic changes) that are associated with progression, spread, and resistance to treatment.

Some people have commented that after a cancer is diagnosed, it is too late to be concerned about the environment. Looking at cancer biology, the reason this belief is wrong is clear. Cancerous tumors aren't simply an abnormal clone of cells that is unchanging. Tumors continuously change and develop new mutations. This is, in fact, the reason that resistance develops to many treatments. And since cancer cells tend to divide more rapidly than normal cells, there may be more potential for damage related to environmental exposures.

Reducing Exposure

It can be frightening, and sometimes maddening, to think about your potential exposure to endocrine-disrupting chemicals in daily life. Many people who study this area find themselves irritated that they did not know about the potential exposures, and wonder why there are not more policies in place protecting the public. It can be helpful to realize that all of life poses risk, and the best way to protect yourself from EDCs and other potential harms in your path is to be your own advocate.

Rather than becoming fanatical about one chemical, and forgetting about others that could be equally or more dangerous, making simple, overall lifestyle changes may be key. After all, it may sometimes be the combination of EDCs, instead of a single chemical, that's the culprit. How can you begin?

Skip Plastics When Possible

Our world is filled with plastics, and they are hard to avoid. That said, most plastic food containers contain endocrine-disrupting chemicals, even products that do not contain BPA. There are a few simple steps you can begin today; steps that are healthy for the environment as well as your body.

  • Keep plastic out of the microwave and hot cars. Always.
  • Switch to glass storage containers for leftover food. Initially, it may seem more expensive, but in the long run, will probably cost you less.
  • Switch to metal water bottles instead of plastic.
  • Switch to wax paper or parchment paper instead of plastic wrap.
  • Skip the antibacterial soap in the kitchen and instead use soap and water.
  • Pick up lunch meat sliced from the butcher and wrapped in butcher paper. (This is also a way to reduce your exposure to other substances linked to cancer.)

Go Fragrance-Free

Fragrances are no longer found in perfume bottles alone, but in a vast number of products we use every day. Most fragrances contain endocrine-disrupting chemicals. That pleasant smell you associate with cleanliness may actually be the smell of phthalates.

Avoid Products That Promise "Ease"

Whether ease in your life means non-stick cookware or stain-resistant carpet and furniture, these tiny luxuries are a hefty source of endocrine disruptors. Fortunately, there are alternatives, and the old iron skillets your grandmother used are much easier to care for today.

Read Labels

While this tip could initially cost more—you may need to purchase a magnifying glass—reading labels is important, whether they are on your food, cosmetics, or a bottle of brass cleaner.

Label reading isn't just for items in cans and jars. You can check everything from your next shower curtain to your new flooring to see if it is labeled as PVC free.

There are some caveats. Not all chemicals may be listed, and those that are may go by several names. The point, however, is to not concentrate too hard on avoiding one specific exposure but to reduce your overall daily load of EDCs.

Shop the Periphery at the Grocery Store

Shopping the periphery of the grocery store might spare you from bringing your magnifying glass to the grocery store, and is often healthier in a number of ways. This is where most stores stock the fresh fruit, vegetables, and other whole foods or minimally-processed foods, while the processed and canned foods are in the central aisles. Keep in mind that most food cans are lined with plastics classified as endocrine disruptors.

Consider a Water Filter

Most people have heard that city water contains fluoride, but it also contains substances ranging from hormones to Prozac. Certainly, there are regulations in place, but nobody is quite certain what represents a "safe" exposure level to some of these substances. If you can afford it, a reverse osmosis system is ideal, but even a kitchen counter filter is better than doing nothing.

Skip the Paper Receipts

Receipts printed on thermal paper are a less known but significant source of endocrine disruptors.

Clean Cleanly

The products many people use to "clean" their homes introduce a number of EDCs at the same time. It seems we've forgotten that a product doesn't need to have a list of unknown words on the label to be effective. Try seeing how much of your home you can clean with only baking soda, vinegar, lemon juice, and olive oil. You may be surprised. In fact, not only may it be healthier, but it will free up space in your cramped cupboards and benefit your budget to boot.

Enjoy a Few Houseplants

Plants not only add joy to your home, but can be very effective in absorbing some indoor air chemicals according to research conducted at NASA.

A Caveat

To reduce your exposure to endocrine-disrupting chemicals you don't need to become a fanatic or threaten your relationship with loved ones who are less eager to change their lifestyle. In this setting, the stress hormones produced in your body might be more detrimental that the chemicals you touch, smell, and eat. Moderation is key. It's better to drink water from a plastic water bottle than to risk dehydration.

A Word From Verywell

The true effect of low dose exposure to endocrine-disrupting chemicals on the development and progression of cancer is unknown, but there is evidence showing a cause for concern. Fortunately, there are many simple changes people can make to reduce their exposure daily, and there may even be additional benefits to these changes with regard to the environment and your general sense of wellbeing.

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