A streamlined stack of supplements designed to meet your most critical needs - Adapt Naturals is now live. Learn more

Environmental Toxins: The Elephant in the Room?


Published on

Toxins from our environment are ubiquitous and almost impossible to avoid. If you are taking steps to limit your exposure, should you be worried about the low levels that are still undoubtedly in your system? The answer is: it depends. Read on to find out how the traditional view of toxicity is outdated, what factors influence one’s susceptibility to a toxin, and what else you can do to decrease your body’s toxic burden.

Environmental toxicity is all over - not just in the places we think it is.
Pollution such as the smoke from this factory is not the only environmental toxin we need to be concerned about. istock.com/azgek

We are exposed to thousands of environmental toxins, whether they are inhaled, applied to our skin, ingested with our food, or injected. Common exposures include substances found in:

  • health and beauty products, which I covered in a series of articles
  • pesticides and herbicides
  • industrial pollutants
  • mold
  • preservatives and flame retardants
  • petrochemical fuels and solvents
  • plastics and cookware

There is no denying that toxic chemicals are IN us. The Environmental Working Group (EWG) reported that the average person carries 91 toxic chemicals in his or her blood and urine. Another EWG study found 232 different toxins in the umbilical cord blood of 10 newborn babies. Do we fully understand how these chemical cocktails might be affecting our health?

Low Doses of Toxins Can Be Harmful

Traditional studies for toxicity aim to find the lowest observed adverse effect level (LOAEL) and no observed adverse effect level (NOAEL). In other words, a level of a toxin that is known to cause harm is experimentally lowered until the toxic effects disappear. Toxicity studies usually test large doses to determine far-off endpoints like cancer and death, while ignoring small doses and subtle effects like endocrine disruption and immunotoxicity. Furthermore, most studies assume that everyone responds the same. No consideration is made for fetuses, young children, those in puberty, or people with chronic diseases.

However, a growing body of research indicates that chronic, low doses of many toxins can also be very harmful. Frogs that were given a mixture of nine pesticides at 10 to 100 times below EPA standard safe levels had slowed growth and higher levels of corticosterone and were more likely to be infected with a common pathogen, highlighting the shortcomings of regulatory studies that only look at an isolated chemical in large doses (1). In 2002, the National Toxicology Program reported adverse effects from low-dose exposure to common endocrine disruptors, including bisphenol A (BPA), genistein (an isoflavone derived from soy), methoxychlor (an insecticide), nonylphenol (an industrial chemical that can be found in drinking water), and vinclozolin (a fungicide), mostly in rodent studies (2). Ten years later in a large review, more adverse effects were confirmed for low doses of plasticizers, pesticides, phytoestrogens, industrial chemicals, preservatives, surfactants, flame retardants, and more (3). These researchers also explored how study design choices, such as animal strain selection and statistical methods, can skew results.cdx

Endocrine disruptors, which can mimic and interfere with the body’s natural circulating hormones, are especially concerning (4). BPA is the endocrine disruptor that gets the most press, but a wide range of substances is continually being added to the list, including dioxins, PCBs, and some pesticides. When you look at BPA levels that have been found in human serum—we’re talking nanograms per milliliter, which is analogous to less than a teaspoon of water in an olympic-sized swimming pool—they may appear too small to be significant (5). However, circulating blood estrogen levels in young girls are 100 times smaller, at under 15 picograms per milliliter. From this perspective, it is easy to see how very “low” doses of toxins can have huge effects when they far outnumber naturally circulating hormones.

Some Toxins Show Different Responses at High Doses Compared to Low Doses

Even more concerning is that low doses of a toxic substance can sometimes act differently in the body than high doses.
For these chemicals, what happens to the body at high doses cannot be used to predict what will happen at low doses, a phenomenon called a non-monotonic dose response (6).

Because regulation is designed to test a high toxic dose and keep decreasing it until the no observed adverse effect level (NOAEL) is found, many low-dose effects are completely missed and not reported.

Is there really such a thing as a safe “low-level exposure” for an environmental toxin?

Substantial evidence of non-monotonic effects has been found in everyday environmental toxins. In mice, fetal exposure to low doses of diethylstilbestrol resulted in prostate enlargement, but the opposite effect was found at high doses (7). Another mouse study showed that DEHP (a phthalate) increased fetal and maternal testosterone levels at low doses but not at high doses (8).  

Effect differences at low and high doses have also been reported for many other common toxins, including BPA (9, 10), atrazine (an herbicide) (11), pyrethroid (an insecticide) (12), and more.  

Like what you’re reading? Get my free newsletter, recipes, eBooks, product recommendations, and more!

Toxicity Susceptibility Is Highly Individual

What determines “toxicity”? A variety of factors is important, including:

  • level of exposure
  • duration of exposure
  • frequency of exposure
  • synergistic relationships (chemicals together producing an effect that is more than additive)
  • timing (in utero, during puberty, while ill)
  • the least studied and understood of all, human variability

The liver is the major organ responsible for detoxification, a process divided into three phases. The first phase begins to process the toxins through oxidation, reduction, and/or hydrolysis (13). In Phase 2, conjugation pathways further break down the toxin byproducts into water-soluble compounds that can be excreted. Phase 3 involves cell membrane proteins that control the modified products’ elimination (14). Sometimes, the products at the end of Phase 1 are more toxic than the beginning toxin, as with the conversion of ethanol (alcohol) to acetaldehyde. If Phase 2 isn’t functioning properly due to nutrition deficiency or disease, toxic byproducts from Phase 1 can linger in the body with deleterious effects.

Susceptibility to toxicity is highly individual and dependent on one’s ability to biotransform and excrete toxins through detoxification. Many factors can influence this process, and I am going to briefly summarize some of the research on several of them below.

Nutrition status and diet. Eating a variety of nutrient-dense, whole foods can help reduce the chances of toxicity. A 2014 review laid out the evidence that diets rich in fruits and vegetables, probably due to their innate antioxidant and anti-inflammatory properties, can help protect against environmental toxic stressors (15). Good intake of essential minerals reduced the uptake of heavy metals (16). Dairy products were associated with lower levels of lead from occupational exposure, possibly due to calcium–lead interaction (17). On the flip side, inflammatory diets, such as those high in omega-6 fatty acids, can increase the vascular toxic effects of PCBs (18).

Genetics. As with other body processes and disease progressions, genetic makeup can impact your body’s detox ability. Even as early as 1985, researchers knew that chronic toxicity studies should include multiple strains of mice to account for genetic variations (19). In pharmacology, drug metabolism, which often occurs through detoxification pathways, is highly dependent upon genetics (20). Certain genetic variations, such as single-nucleotide polymorphisms (SNPs), can influence one’s risk of toxicity following radiation therapy (21). Furthermore, being male vs. female can influence your toxicity susceptibility (22, 23, 24).

Gut health. As I have argued before, you’re only as healthy as your gut. Research has shown that air pollution, heavy metals, and other toxins can all negatively impact the gut microbiome in mice and humans (25, 26, 27, 28, 29). In the pharmaceutical world, the gut is an important player in drug metabolism, efficacy, and toxicity (30, 31), and it looks like all those beneficial gut bacteria can help digest other toxic invaders, too. Probiotic supplementation reduced mercury and arsenic levels in pregnant women and children (32), and in a laboratory setting, probiotics were shown to decrease pesticide accumulation (33). Compared to “germ-free” rats, rats with normal gut microbiomes showed decreased toxicity to an herbicide (34).  

Epigenetics. We now know that our DNA sequence doesn’t determine everything about us. Epigenetics studies the different mechanisms that change how and when our genes are turned on or off, and some of these effects can be transgenerational. Epigenetics is one explanation for the differences in people’s susceptibility to toxicity (35). Nematodes whose parents were exposed to silver showed 10 times increased sensitivity to this heavy metal, and these effects were present for 10 generations (36). BPA’s effects on human fertility are also thought to be transgenerational (37).

Methylation. Methylation is a simple yet important biochemical reaction that occurs billions of times in our bodies. In liver detoxification, methylation is one of the conjugation reactions in Phase 2 that helps break down toxins (38). Glutathione, which requires methylation, is a major molecule in the detox cycle, especially in heavy metal detox (39, 40). If your methylation status is impaired, through genetics and/or lifestyle, your ability to detox can be similarly limited.

How to Reduce Your Toxic Burden

We know that even low levels of toxins can be harmful and that your body’s individual ability to bioprocess and excrete toxins is difficult to fully assess. So what can you do?  Some amount of exposure may be out of your control, but you can certainly strive for change:

  • Limit environmental toxins that are within your control. Be particular about which beauty, health, and other personal products you buy, and even consider making your own. Controlling room humidity can prevent indoor mold growth. Change any plastic food storage containers to glass or stainless steel, and use safer cookware. Consuming organic produce and animal products will greatly reduce your pesticide exposure. Consider installing a reverse osmosis water filtration system for drinking water and a filter for your shower head, as toxins can aerate when heated.
  • Improve liver detox. For liver detoxification to work properly, a wide variety of macronutrients, micronutrients, cofactors, and more is required. Milk thistle is commonly used to help support detoxification, and other supplements are also available. I recommend working with a functional medicine practitioner to help optimize any detox improvement protocol.
  • Improve gut health. If at all possible, avoid antibiotics, which can destroy the gut microbiome. Increase your intake of fermented vegetables like sauerkraut and, if tolerated, yogurt and raw dairy. Resistant starches like green bananas or cooked-and-cooled starchy tubers also boost gut health. And keep drinking that bone broth.
  • Improve overall nutrition. Our bodies require nourishing, nutrient-dense whole foods as part of a Paleo lifestyle. Eliminate processed foods and refined sugars, which can increase inflammation and susceptibility to toxins.
ADAPT Naturals logo

Better supplementation. Fewer supplements.

Close the nutrient gap to feel and perform your best. 

A daily stack of supplements designed to meet your most critical needs.

Chris Kresser in kitchen
Affiliate Disclosure
This website contains affiliate links, which means Chris may receive a percentage of any product or service you purchase using the links in the articles or advertisements. You will pay the same price for all products and services, and your purchase helps support Chris‘s ongoing research and work. Thanks for your support!


Join the conversation

  1. The constant exposure that we have to toxins in modern life makes maintaining our toxic burden a necessity. It really does come down to limiting the environmental toxins that we can limit and eating more healthily, just as you said, Chris. The food we eat and the supplements we take support our body’s ability to detoxify, or even follow a detox program. (My personal favorite is this 14-day program from Designs for Health: https://store.ecobeautica.com/productvariation/detox-original-14-day-program-vanilla-purepea™) But sometimes we need to take it a step further by really discovering the kind and amount of toxins in our system. Once we do that, we can know the best way to support our bodies.

  2. This may seem insignificant to some, but I really believe having many house plants can help “detox” the air inside our homes.

  3. Chris, I always find your posts so vital to my ongoing healing journey. Thank you so much!!

  4. I take an Epsom salt bath once a week. It has 3 major benefits for me. I relax and eliminate stress while sweating to detox and the Epsom salts are packed with magnesium that my body absorbs.

  5. Okay so, I’m taking a little side note on this topic. Knowing that the presence of free radicals are right just EVERYWHERE, I think it’s also time for us to be MORE responsible in maintaining or improving our body’s natural defenses.
    It’s really hard that upon knowing this dark truth, we still opt to do more harm that worsens our vitality.
    Let’s just take the example of the choices of food that we take. Isn’t it frightening that apart from the harmful hazards we get exposed and breathe in everyday, we are also doing harm in our body internally?

  6. Recently my nutritionist tested heavy metals when he did my blood test and my nickel level came back above normal. Normal the lab said was 10 mcg/l or less and I came back 17 mcg/l blood serum. Does anyone know anything about nickel toxicity and if 17 is really that high that I would need to consider something like a IV Chelation? Also does anyone have any idea what could have made my blood serum so high for nickel? I live in New York City in an old apartment building (100 years old) with old pipes and I do drink the water out of the faucet with a Brita. I don’t know if it could have came from the water in the pipes but I work a regular nine-to-five job in a building so it’s not like I’m in some kind of Factory or construction site or something and the only other thing I could think of is I have a really old air conditioner that’s like over 20 years old and probably has Freon in it but it makes the room so amazingly cold in the summer. I don’t know if there could be some kind of chemicals coming out of that into the air that could have caused this? If anyone has any ideas please feel free to respond here and also let me know if there’s any natural oral supplements I could try versus chelation or if anybody knows if 17 isn’t really considered that high or dangerous that I don’t really have to worry about it? Thank you so much in advance for any help that anyone can give me with this, I really appreciate it 🙂

  7. Is reverse osmosis water better than natural spring water?

    Do you drink reverse osmosis water?

    • If you are concerned with the pH of your drinking water, you should avoid guess work and get your water tested with an accurate pH tester meter

  8. Despite some alarmism sometimes making it seem otherwise, we’ve always had toxins around, from mercury to arsenic to odd stuff people in the past put into their foods. I, for one, think Iodine supplement is the best way to go to remove most of them without worries. It can remove most heavy metals and other toxins very quickly (therefore it can make you sick at first), and it’s a nutrient hard to overdose on. Also one of the only things that can detox from fluoride. I hear chlorella is great as well, but I never tried it, it’s very popular in asian countries.

    • I wonder if that’s why the Tri-Iodine 3mg. made me feel strange. I was going to return it to where I bought it but maybe I should give it another try

      • Could be. It’s sometimes confused as a side-effect of Iodine itself, but most toxins start to get expelled within 24 hours of ingestion of iodine, so while they’re all running in your blood you can feel sick, have headaches, muscle pain and other general malaise symptoms afterwards. Just give your body time before the next dose if you feel too sick, how long will it take to not feel anything will depend on how much toxins you have in your body. You can also take/eat things that support your kidneys and liver afterwards to speed things up. Vitamin C and a pinch of salt in water can help ease the symptoms as well (I think Vit C is more obvious why, but the reason for salt is that chloride can help expel some toxins faster, such as bromide that is pretty common, so other foods with chloride may have the same effect).

        • OK, I’ll give the iodine another try before returning it.
          I had switched to Kelp which doesn’t bother me

  9. After trying Paleo AIP approximately 95% compliant for almost 2 years, and unable to add back any foods, I came upon salicylate sensitivity and have now gone on a low salicylate diet which seems to be calming down my heart and decreasing the number of night time bathroom visits I have. I have had the Cyrex food allergy test, and didn’t realize until recently, that many of the foods I reacted to were high salicylate foods, like olives, red wine, honey, vanilla, etc. I definitely have multiple chemical sensitivities also, so cutting down on salicylates in home care and personal care products is also helping with that. Weird thing is, after two weeks of being low sals, I have developed painful acne just under my jaw line, have never had that before:(

  10. I am a male and trying to avoid estrogens, have weight gain around my middle and lack of a sex drive so I started trying out Calcium-D-Glucarate, DIM Pro and iC3.
    Not sure which is best to take and which would give the fewest side effects.
    I’ve heard that DIM is safer than iC3 but both change the color of urine and I have Interstitial Cystitis so not sure if that could be harmful.
    I have read that Calcium Glucarate is safe so I’m considering just taking that if it’s good enough for that purpose by itself.
    I have been taking Milk Thistle for years and also added Schizandra plus Artichoke and Turmeric.
    I also want to clean out my Lymph System as I feel like it’s clogged, which could hinder detoxification. I tried one herbal product but it really flared my IC.
    Going to try LifeSpa Majintha soon and hope it doesn’t give me those side effects.

    • @Steve- how about body brushing for your lymph system instead of adding another supplement.

        • How would you know ? Brushing does have definite effect in increasing your circulation and thereby adding oxygen to your system.

      • The Lymph system is all over the body, draining toxins and waste. If it’s clogged and it does get clogged toxin elimination is thwarted and you will feel bad even after bowel cleansing

          • While I am not aware of a test that specifically tests the lymph system, I have had thermography done, and the results will suggest whether the lymph system needs support.

            • KD,

              Can’t a CT scan see the lymph system?
              Also what type of support can someone get?
              Medicine or some of these tea’s and other remedies?

            • KD,

              Can’t a CT scan see the lymph system?
              Also you mentioned support, what type of support can someone get?
              Medicine or some of these tea’s and other remedies?

        • I just spoke a friend with MS. She began drinking one gallon of alkaline water a day from a special machine. Within one day her skin began to exude a yellow discharge from her head, which she said was somewhat similar to the cradle cap that babies get. This detoxification went on for over a month. I told her that there is a lymph system in the head, which cleanses toxins.