Environmental Toxins and Cancer Risk
7 min read
The chemicals in our water, air, and food, the materials in our home, and non ionizing radiation present cancer risks.
Researchers have identified several mechanisms by which most cancer-producing toxins disrupt our body’s defense systems.
How Toxins Produce Cancer
While we once thought of “cancer” as a single devastating disease, we now recognize that a range of cells, in various tissues, can undergo “malignant transformation” to become cancer.
In fact, the body’s natural defenses are repeatedly inhibiting processes involved in cancer development through a series of targeted responses, much like a nation’s security forces.
On occasion, however, a precancerous or malignant cell slips through all of those defenses and may proceed to start a tumor.
In the worst case, the tumor can release tiny clumps of malignant cells that spread cancer to distant parts of the body. Metastatic cancer is almost always a predictor of death as a result of the disease.
Despite the vast number and diversity of cancer types, there are a relatively small number of events that typically occur in the progression from healthy cell to malignancy. Toxic environmental chemicals, electromagnetic fields, and ionizing radiation may initiate and/or promote malignancy, operating along a number of mechanisms. Some of these mechanisms include:
- DNA damage,
- Liver detoxification impairment,
- Immune impairment,
- Endocrine disruptors, and
- Loss of apoptosis.
DNA Damage
The first way toxins may lead to cancer is by breaking DNA strands. Damage to DNA is a major initiating factor in cellular transformation to cancer. DNA damage can be caused by toxins that break DNA strands (such as pro-oxidant chemicals or ionizing radiation). Such damage can induce mutations in the DNA that trigger cancer. That is why nutrients that prevent DNA damage, or ones that promote its repair, are so potent in protecting against cancer.
Given the role of oxidative stress in causing such damage, nutrients that reduce DNA damage (i.e. vitamins C and E and the trace mineral selenium), are often considered as a first line of defense.
Surprisingly, probiotics, which are normally associated with improved gastrointestinal function, have been found to be effective at reducing DNA damage specifically in the colon. This may help to prevent colon cancer, the third cause of cancer-related deaths in the US.
And, while sunlight exposure can boost vitamin D levels, such exposure also raises DNA skin damage, but vitamin D supplementation can protect against DNA damage throughout the body.
Liver Detoxification Systems
The second way environmental toxins cause cancer is through their detrimental impact on liver detoxification systems. Liver detoxification systems play a major role in managing ingested toxins because blood from the digestive tract goes to the liver before being pumped around to the remainder of the body.
The liver has two major detoxification pathways: Phase I and Phase II. Phase I enzymes convert toxic chemicals into compounds that may be more toxic than the parent compound.64 Unfortunately, if the toxic load is too heavy, it can cause overactivity of Phase I enzymes, which can have the reverse effect of converting relatively harmless substances into potential DNA-damaging carcinogens.
Making matters worse, the worst offenders of overactive Phase I enzymes are substances some people encounter on a daily basis, including alcohol, saturated fats, and exhaust fumes, among others.
In Phase II detoxification, the liver adds another substance to the toxic chemical in order to make it more water soluble. This allows your body to excrete the toxin through bile or urine, helping remove the potentially carcinogenic substance from the body.
For these reasons, cancer-preventive nutrients that influence liver metabolism are generally those that regulate toxin-enhancing Phase I reactions, promote toxin-neutralizing Phase II reactions, or, in many cases, do both. Nutrients that regulate these liver detoxification systems come largely from dietary plants and their extracts.
Several nutrients have this dual action on liver enzymes, including curcumin, folic acid, and garlic, among others. Research suggests this may have a positive impact on preventing some of the most common and deadly cancers.
Immune Surveillance
The third way environmental toxins can cause cancer is through their impact on immune surveillance. Immune surveillance refers to the immune system’s continual search for cells bearing signs that they have become cancerous.92 A number of environmental toxins can suppress immune surveillance, raising the risk that a malignant cell will slip under the radar, form a tumor, and successfully spread to other parts of the body.
Nutrients that enhance immune surveillance are only now being recognized as powerful contributors to the body’s lifelong fight against cancer. These nutrients boost those components of the immune system that are responsible for recognizing the unique tumor “markers” displayed on the surface of malignant cells, and then destroying those cells.
Nutrients that enhance immune surveillance may stimulate growth and proliferation of tumor-detecting lymphocytes, promote a vigorous attack on tumor cells by so-called “natural killer cells,” and/or stimulate antibody production, which aids in immobilization and destruction of malignant cells.
The fourth way environmental toxins can cause cancer is through their impact on endocrine disruptors. Endocrine disruptors are chemicals that interact with sex hormones and/or their receptors to promote cancer development.
Not surprisingly, nutrients that inhibit endocrine disruptors show promise in preventing hormone-dependent cancers such as those of the breast, uterus, and prostate. Although scientists don’t yet fully know how these nutrients work to inhibit endocrine disruptors, it may involve enhanced excretion or reduced absorption of toxins from the intestinal tract.119,120
They appear to reduce the activity of estrogen-producing enzymes such as aromatase, thereby reducing overall sex hormone predominance and starving hormone-dependent tumors of their vital growth factors.
Loss of Apoptosis
Another way environmental toxins are associated with cancer is through inducing a loss of apoptosis, or programmed cell death. Loss of apoptosis refers to the “immortality” typical of cancer cells. Normal body cells are programmed to die off when appropriate.130 Cancer cells have lost this ability (often as a result of DNA damage), which allows them to reproduce essentially without limit.131 A number of chemical toxins, particularly aflatoxin, a potent inducer of liver damage, can switch off the gene responsible for producing apoptosis, which results in cancer promotion.
Nutrients that restore cells’ natural ability to die by apoptosis represent the final category in our listing of nutrients that help fight against cancers caused by environmental toxins. These nutrients typically act by modifying various signaling pathways. This means that they can activate genes that become suppressed when cells become cancerous, including genes that normally support the graceful death of a cell that is no longer useful or poses a threat.
By restoring the natural self-destruction program initiated by apoptosis genes, these nutrients put a sharp roadblock in the way of a developing tumor. This allows other anticancer mechanisms such as immune surveillance to clear the remainder of the battlefield.133
Nutrients known to promote apoptosis include coffee extract, quercetin, pine bark extract, and selenium. Research shows they have a positive impact on bladder, colon, and ovarian cancers, among others.
Sources of Cancer-Inducing and Cancer-Promoting Toxins
While it is impossible to avoid all cancer-causing environmental toxins, it is important to be aware of some of the most prominent sources. We have compiled a list of common toxins broken down by their environmental sources. As you’ll see from this list, these can be found in sources we interact with on a daily basis, including our food, water, plastic, cell phones, and even sunlight.
Aflatoxins are toxic chemicals produced by Aspergillus fungi growing on grains and peanuts, particularly those stored improperly. Chronic exposure induces cancer by multiple mechanisms.
Polycyclic aromatic hydrocarbons are chemical structures composed of carbon, hydrogen, and occasionally other atoms. They are products of fossil fuel combustion, particularly petrochemicals, and are a major source of cancer-causing chemicals in polluted air.
Bisphenol A (BPA) is one of the highest-volume toxic chemicals found worldwide.159 It is used in making all kinds of plastics and resins, including water bottles and food containers.
Heavy metals (including cadmium, arsenic, nickel, lead, and mercury) are naturally occurring components of the earth’s crust.160 Human exposure results from mining,161 smelting,162 and petroleum manufacturing,163 all of which release heavy metals into the air, water, and soil.
Pesticides and herbicides,164 especially those containing organic chemicals bonded to chlorine or bromine, are found in agricultural settings, where they make their way into the food chain. Sadly, even after the highly toxic dichlorodiphenyltrichloroethane (DDT) was banned, risks still abound, both because of persistent DDT in the environment and because newer compounds intended to replace DDT (such as methoxychlor) are turning out to have their own cancer-inducing properties.
Dioxins and dioxin-like chemicals such as polychlorinated biphenyls (PCBs) are commonly found in foods of animal origin (meat, dairy, and fish,165,166 depending on the country of origin).
Heterocyclic amines are chemicals that form when meat is cooked at high temperatures (e.g., grilled or broiled).
Ultraviolet radiation is a natural component of sunlight, but serves as a powerful source of many of the changes that lead to cancer.
Electromagnetic field radiation, especially the kind produced by cellular phones and their transmitting stations, are only now emerging as potential environmental threats. Such radiation is associated with DNA damage, potentially leading to cancer.
This is by no means an exhaustive listing of cancer-related environmental toxins. Toxins are ubiquitous, particularly in our highly industrialized society. They are, therefore, nearly impossible to avoid, but as we have read, we know that we are not helpless. We can arm ourselves with knowledge about natural products capable of offsetting much of the increased cancer risk posed by environmental toxins.
