Most of us aren’t trying to avoid every chemical on earth. That would be impossible, and honestly, a little exhausting to think about. But there is a difference between vague worry and actually understanding what you’re exposed to on a regular basis, and why some things matter more than others.
One note before we begin: “poison” is a strong word, and not every chemical on this list deserves that label equally. Some exposures warrant real caution, while others have reputations that go well beyond the evidence. Here is what current research and health guidance actually say.
Many of these exposures come from tap water, diet drinks, processed meat, personal care products, and dental fillings.
What’s Really in Your Water
Fluoride gets added to many public water systems in small amounts to help prevent tooth decay. The review did not find convincing evidence of harm at the fluoride concentrations used in typical U.S. community water fluoridation, about 0.7 to 1.0 milligrams per liter, but higher exposure, particularly above 1.5 milligrams per liter, the guideline threshold set by the World Health Organization, has been associated with concerns involving the developing brain, thyroid function, and bone health.(1) For most people drinking standard fluoridated tap water, this isn’t a reason for alarm. People using private well water may want to have it tested, since natural fluoride levels vary a lot by location. Parents should follow age-appropriate toothpaste guidance to limit swallowing in young children, and fluoride supplements should only be used if a dentist or doctor recommends them.
Chlorination byproducts are the real concern behind chlorinated water, not chlorine itself. Chlorine disinfection has done an enormous amount of good for public health by preventing waterborne disease. The tradeoff is that when chlorine reacts with organic material in water, it can form byproducts like trihalomethanes. A 2025 systematic review and dose-response meta-analysis of human studies found limited but suggestive evidence that higher long-term exposure to these byproducts is associated with an increased risk of bladder cancer.(2) This doesn’t mean chlorinated water is something to fear daily. If you choose a filter, check its independent certification and performance data to confirm it’s actually rated for the specific disinfection byproduct you want to reduce, rather than assuming any basic filter handles it.
Contaminants That Linger Longer Than You’d Expect
PCBs, or polychlorinated biphenyls, are industrial chemicals that were banned decades ago but still linger in soil, water, and the food chain, particularly in fatty fish. Occupational studies have reported higher rates of rare liver cancers and melanoma among workers with high PCB exposure.(3) Most people today have very low background exposure. If you eat a lot of fish from waters with known PCB advisories, that’s the main practical thing to pay attention to.
To learn more about how the liver metabolizes substances from food, medications, and the environment, read our guide to liver health.
The Sweeteners You Thought Were the “Healthier” Choice
Sugar substitutes get marketed as the smart swap, but the research is more nuanced than the packaging suggests.
Sucralose, a common tabletop sweetener, has generally been considered safe by regulators, but newer human research has started asking harder questions. A small controlled trial, 40 healthy adults over ten weeks, found that regular sucralose intake was associated with changes in gut bacteria along with shifts in glucose and insulin levels.(4) The findings are worth further study, but the trial was small and open-label, and it doesn’t establish what happens across different doses, products, or longer periods of use.
Aspartame, found in many “diet” products, went through a major evaluation in 2023 by the World Health Organization’s cancer research arm (IARC) and its food safety committee (JECFA). IARC classified aspartame as “possibly carcinogenic to humans,” based on limited evidence in human studies, largely tied to liver cancer. At the same time, JECFA reviewed the same evidence and kept the existing daily intake limit unchanged, citing evidence in humans that was inconsistent and not fully convincing.(5) In plain terms, there’s a flagged concern worth knowing about, but no consensus that typical consumption is dangerous.
High fructose corn syrup (HFCS) shows up in sauces, sodas, and packaged snacks. A controlled trial in young adults tested four different doses of HFCS-sweetened beverages over two weeks and found a dose-dependent pattern: higher intake was linked to a greater increase in liver fat and a greater drop in insulin sensitivity than lower intake.(6) The study tested daily HFCS-sweetened beverages over two weeks, so it doesn’t tell us much about someone consuming an HFCS-containing food occasionally. For most people, moderate intake is a more realistic goal than total avoidance.
What’s Curing Your Lunch Meat
Sodium nitrite is added to cured meats like deli ham, bacon, and hot dogs to prevent bacterial growth and preserve color. When nitrite is exposed to high heat or combines with certain compounds during digestion, it can form nitrosamines.(7) The World Health Organization’s cancer research arm has classified processed meat as a Group 1 carcinogen, based on sufficient evidence linking regular consumption to colorectal cancer.(8) Group 1 describes the strength of the evidence that something can cause cancer, not the size of the risk, so this puts processed meat in the same evidence category as tobacco, not the same risk level. Nitrite is only part of the picture, since heme iron, cooking method, and overall intake pattern matter too. Fresh, unprocessed meat is generally a lower-nitrite option, though products labeled “uncured” may still be cured using celery powder or other nitrate-rich ingredients, so the label alone doesn’t guarantee the product is free of nitrate or nitrite.
Chemicals You’re Absorbing Through Your Skin
This entry covers two related but distinct chemical classes found in personal care products: parabens and phthalates. Parabens are commonly used as preservatives, while certain phthalates are used in fragrance formulations, plastics, and other product components. A 2024 study of 303 pregnant women found that certain patterns of personal care product use were associated with differences in urinary biomarkers of phthalates and related chemicals.(9) A separate 2022 study of adolescent girls found that daily makeup users had higher urinary concentrations of a phthalate metabolite and two parabens compared with girls who rarely used makeup.(10) These findings show exposure, not necessarily harm, and the health significance of typical, everyday exposure is still being studied. Parabens are usually easy to spot on ingredient labels, often under ingredient names ending in “-paraben.” Phthalates may not always be listed individually, since fragrance ingredients can appear under umbrella terms such as “fragrance” or “parfum.” People trying to reduce exposure can look for products specifically labeled phthalate-free and consider using fewer fragranced products.
The Flavor Enhancer With a Bad Reputation It May Not Deserve
MSG has carried a reputation problem for decades, often tied to so-called “Chinese restaurant syndrome.” The FDA classifies MSG as safe, and Mayo Clinic notes that researchers have found no clear proof linking MSG to the symptoms it’s historically been blamed for, though a small number of sensitive individuals may experience mild, short-term reactions like headache or flushing after eating large amounts.(11) For most people, current evidence doesn’t support avoiding MSG for health reasons, though anyone who consistently notices symptoms after eating it may choose to limit it.
A Quick Word on Dental Fillings
Older “silver” dental fillings, technically called dental amalgam, contain mercury. Certain groups are advised to discuss alternatives with their dentist before getting a new amalgam filling: women who are pregnant or planning to become pregnant, nursing mothers, children especially under six, people with a known allergy or sensitivity to mercury, and people with neurological impairment or kidney dysfunction.(12) This guidance is about avoiding new amalgam fillings when possible for these groups, not about removing existing ones. For most adults, the FDA does not recommend removing an intact filling solely to prevent a health problem, since removal can temporarily increase exposure to mercury vapor and also removes healthy tooth structure.
Where This Leaves You
The most useful takeaway isn’t to eliminate every chemical mentioned here. It’s to focus on the exposures you can realistically reduce without overhauling your life. The body can process and eliminate many of these substances, though a few, like PCBs, are persistent and can accumulate over time, which is worth keeping in mind rather than assuming everything clears itself quickly.
A few practical places to begin include:
- Checking your water utility’s annual water quality report, and if you choose a filter, confirming it’s certified for the specific contaminant you’re concerned about
- Treating deli meat and other cured products as an occasional food rather than a daily one
- Treating diet sodas and sugar-free products as optional tools, not automatically the healthier choice
- Using fewer fragranced personal care products if reducing phthalate exposure is a priority for you
Across all of these, ingredient lists and independent certification information tend to be more reliable than front-label claims like “diet,” “uncured,” or “clean.”
Healthy eating, regular movement, adequate sleep, and limiting alcohol are the foundation of liver health. To learn more about one liver support option, see the product information here.
Sources
- Public Health Impacts of Water Fluoride: A Rapid Review. PMC, National Institutes of Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC12662105/
- Exposure to Drinking Water Trihalomethanes and Risk of Cancer: A Systematic Review of the Epidemiologic Evidence and Dose-Response Meta-Analysis (2025). Environmental Health Perspectives, PMC, National Institutes of Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC11750423/
- Health Effects of PCBs. U.S. Environmental Protection Agency. https://www.epa.gov/pcbs/health-effects-pcbs
- Ten-Week Sucralose Consumption Induces Gut Dysbiosis and Altered Glucose and Insulin Levels in Healthy Young Adults (2022). PMC, National Institutes of Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8880058/
- Aspartame Hazard and Risk Assessment Results Released (2023). Pan American Health Organization / World Health Organization. https://www.paho.org/en/news/14-7-2023-aspartame-hazard-and-risk-assessment-results-released
- The Dose-Response Effects of Consuming High Fructose Corn Syrup-Sweetened Beverages on Hepatic Lipid Content and Insulin Sensitivity in Young Adults (2022). PMC, National Institutes of Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC9030734/
- Nitrites in Cured Meats, Health Risk Issues, Alternatives to Nitrites: A Review (2022). PMC, National Institutes of Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC9654915/
- Cancer: Carcinogenicity of the Consumption of Red Meat and Processed Meat. World Health Organization. https://www.who.int/news-room/questions-and-answers/item/cancer-carcinogenicity-of-the-consumption-of-red-meat-and-processed-meat
- Personal Care Product Use Patterns in Association with Phthalate and Replacement Biomarkers Across Pregnancy (2024). PMC, National Institutes of Health. https://pmc.ncbi.nlm.nih.gov/articles/PMC11303244/
- Personal Care Product Use as a Predictor of Urinary Concentrations of Certain Phthalates, Parabens, and Phenols in the HERMOSA Study (2022). Journal of Exposure Science & Environmental Epidemiology. https://pubmed.ncbi.nlm.nih.gov/33619365/
- Monosodium Glutamate, Also Called MSG: Is It Harmful? Mayo Clinic (updated 2025). https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/monosodium-glutamate/faq-20058196
- Information for Patients About Dental Amalgam Fillings. U.S. Food and Drug Administration. https://www.fda.gov/medical-devices/dental-amalgam-fillings/information-patients-about-dental-amalgam-fillings