Environmental toxins

The air you breathe and the everyday products you put on your skin show up in your bloodstream and on your epigenetic clock. The interventions that actually work are unglamorous — a bedroom air filter, fewer scented products, decent water filtration and, cheapest of all, a radon test — and while non-persistent chemicals clear within days, heavy metals and "forever chemicals" linger for years.

A large share — but not the overwhelming majority — of how long you live is environmental and modifiable rather than inherited. Classic twin studies put the heritability of lifespan at only 20–25%, and some large pedigree studies as low as 6%; a 2026 reanalysis argues those figures are deflated by accidents and infections and that heritability of intrinsic ageing is "above 50%" once such extrinsic deaths are stripped out (evidence: moderate).^[1] Either way, environment and behaviour move a big, addressable fraction. Air pollution is the second-leading global mortality risk factor — ~8.1 million premature deaths a year — and the dose-response runs through chronic disease, not acute toxicosis.^[2] Cadmium, lead, arsenic, phthalates, bisphenols, and perfluoroalkyl substances (PFAS) all show up in human serum and all accelerate biological-aging clocks at population scale. Two categories behave very differently, and conflating them is a common mistake: non-persistent compounds (phthalates, bisphenol A, parabens, most volatile organic compounds) clear within days to weeks once you stop the input, whereas bioaccumulative persistents — PFAS (serum half-life of years), cadmium (kidney half-life of decades), lead (stored in bone for years), and dioxins/PCBs — do not.

The exposome — environmental load as an aging input

The exposome is the cumulative environmental exposure an individual has from conception to death — air, water, chemicals in consumer products, dietary contaminants, and psychosocial stressors. It's now one of the dominant frameworks for explaining aging variance that genetics doesn't.^[3]

The mechanism is mostly oxidative-stress-driven: pollutants raise reactive oxygen species, which damage DNA, accelerate telomere attrition, and impair autophagy. This shows up on epigenetic clocks before it shows up clinically.

What the epigenetic clocks pick up

Two of the more useful clocks for exposome work:

GrimAge / GrimAge2 — predicts time-to-death using surrogate plasma proteins; highly responsive to heavy metals and persistent organics.
DunedinPACE — a "speedometer" measuring biological years aged per chronological year; built from longitudinal data and particularly sensitive to recent exposures and interventions.^[4]

A 2025 NHANES analysis of 2,346 US adults aged 50–84 found per-standard-deviation increases in measured biomarker exposure produced striking accelerations:^[5]

Exposure	Source	Epigenetic acceleration per SD
Cadmium (serum)	Tobacco smoke, polluted air, contaminated soils	+1.23 yr GrimAge, +1.27 yr GrimAge2
Cotinine	Active or second-hand smoke	+1.40 yr GrimAge2
Lead, PCBs, dioxins	Legacy industrial, processed food chains	Significant DunedinPACE acceleration

A separate machine-learning analysis of 78 simultaneous chemical exposures identified urinary benzophenone-3 (a sunscreen filter) and toluene as nonlinear PhenoAge accelerators on top of the classic heavy metals.^[6]

The single-substance regulatory model under-counts real-world risk. The European HBM4EU biomonitoring data found only 4% of children exceeded the guidance value for any individual phthalate, but 17% were above the safe threshold once mixtures of phthalates with shared biological pathways were summed.^[7]

Psychosocial exposome

The exposome includes social stressors too. A 2026 PNAS analysis found each additional chronic-stress relationship ("hassler") in someone's close social network was associated with ~1.5% faster biological aging by DunedinPACE, on top of all chemical exposures.^[8] See Stress and Purpose.

Air: filter what you breathe

People in industrialised countries spend ~90% of their lives indoors, and indoor concentrations of fine particulate matter (PM2.5) and volatile organic compounds (VOCs) are routinely higher than outdoor levels — pulled in from traffic and wildfire smoke, then added to by gas stoves, scented products, and off-gassing furniture.

PM2.5 is the clearest harm. Particles smaller than 2.5 µm cross the alveolar barrier into systemic circulation and have been recovered from coronary plaques, brain tissue, and placenta. Cohort linkage of US health-record data with air-quality index (AQI) scores shows a measurable mortality reduction for every step-down in chronic PM2.5 exposure.^[9] The pooled European ELAPSE analysis put numbers on this: each 5 µg/m³ of long-term PM2.5 raised natural-cause mortality by about 13%, and — crucially — the association persisted and even steepened below the WHO, EU, and US limits, so there is no clean "safe" threshold (evidence: strong).^[10] A contrarian minority disputes the causal reading on statistical grounds, but quasi-experimental and within-person designs support causation.

Air pollution and the ageing brain

The best-evidenced ageing endpoint for air pollution is dementia, not the lungs. A 2025 meta-analysis of 32 studies covering some 26 million people found each 5 µg/m³ of long-term PM2.5 raised incident-dementia risk by about 8%, with smaller but consistent signals for nitrogen dioxide and for black carbon (traffic soot); certainty was moderate, limited by high between-study heterogeneity and the possibility of residual socioeconomic confounding (evidence: moderate).^[11] The 2024 Lancet Commission on dementia now lists air pollution among 14 modifiable risk factors, attributing roughly 3% of global dementia cases to it.^[12] This is the mechanism that ties the HEPA and ventilation advice below to a healthspan outcome, not just a lung one.

A widely shared 2024 headline claimed wildfire smoke sharply raised dementia risk; it was retracted and replaced in 2025 after a coding error was found, and the corrected effect was smaller and not statistically significant overall (evidence: weak-preliminary).^[13] Treat wildfire-specific dementia claims cautiously; the general PM2.5 signal above is the solid one, and an N95 respirator during heavy smoke or an air-quality index above 100 is a sensible precaution.

HEPA in the bedroom

The intervention with the cleanest RCT data is a single, properly-sized HEPA (high-efficiency particulate air) portable air cleaner running in the bedroom overnight. In a four-week double-blind crossover trial of low-income elderly adults living near major US highways, the active filter dropped indoor bedroom PM2.5 from 8.3 to 1.3 µg/m³, with corresponding reductions in 24-hour personal exposure and home blood pressure.^[14] A systematic review of 63 indoor-air-quality experiments converges on the same picture: filtration improves heart-rate variability, blood pressure, and pulmonary function, with associated reductions in cardiovascular and respiratory event rates.^[15]

True HEPA is rated to remove ≥99.97% of particles ≥0.3 µm. It is not effective against gaseous pollutants — VOCs, ozone, NO₂. For gases, the only option in a portable unit is a dense activated-carbon bed; thin "carbon-coated" pre-filters in standard consumer units saturate quickly and provide little protection.

What about VOCs?

The intuition that you can "purify" gases away tends to fail in practice.

A 2021 MIT study found consumer "air-cleaning" devices using oxidation chemistry (plasma, photocatalysis, UV-PCO) were actively producing VOCs themselves — the partial-oxidation reactions intended to destroy formaldehyde generated more formaldehyde and other carbonyls than they removed.^[16] Ozone-generating "ionizers" carry the same problem at the residential scale.

The honest VOC playbook is source control plus ventilation, not chemical destruction:

Stop using aerosolised synthetic fragrances, plug-in air fresheners, and scented candles. Most "fragrance" is undisclosed phthalate-carrier mix (more on this below).
Cook on an exhaust fan vented outdoors. Gas stoves are a substantial NO₂ and PM2.5 source even when off.
Open windows for cross-ventilation when outdoor air is reasonably clean. Cracking a window for 10 minutes typically clears more VOCs than an hour of any consumer device.
Use a HEPA filter for particulate matter and accept that VOC removal is a separate, harder problem.

The houseplant myth

A persistent claim, repeatedly debunked, is that houseplants meaningfully clean indoor air. The original 1989 NASA study used hermetically-sealed chambers; the dynamics don't translate to actual rooms.^[17] Real-world ventilation dilutes VOCs faster than plant stomata can absorb them. To match the clean-air delivery rate of a basic mechanical filter you'd need on the order of 10–1,000 plants per square metre of floor.^[18] Houseplants are nice. They are not air filters.

Endocrine-disrupting chemicals in personal care products

Endocrine-disrupting chemicals (EDCs) — phthalates, bisphenols, parabens, triclosan, certain glycol ethers — interfere with hormone synthesis, transport, and signalling at sub-toxicological doses, often violating the monotonic dose-response assumed in classical toxicology. They saturate cosmetics, deodorants, lotions, plastic food packaging, and stain-resistant or non-stick coatings. Adult women applying a typical daily makeup and skincare routine put on 13 products containing 100+ unique chemical entities, mostly absorbed dermally.

The most useful clinical biomarker for tracking endocrine disruption is sex hormone-binding globulin (SHBG) — a hepatic protein that regulates how much testosterone and estradiol is bioavailable. EDC-driven hepatic stress and hyperinsulinemia suppress SHBG synthesis, releasing unbound androgens and estrogens; depressed SHBG correlates with non-alcoholic fatty liver disease (NAFLD), polycystic ovary syndrome (PCOS) phenotype, and metabolic syndrome.^[19]

What behaviour change actually does — the PERTH trial (Moderate)

The strongest interventional evidence is randomised. The PERTH trial (Nature Medicine 2026) gave participants combinations of plastic-free kitchenware, low-plastic personal-care products, and food sourced to minimise every plastic touchpoint from paddock to plate, against a no-intervention control, and measured urinary plastic-associated chemicals as the primary outcome.^[20] Holding daily energy intake constant, the dietary intervention cut urinary levels of:

Compound	Where it comes from	Reduction (95% CI)
Monobenzyl phthalate	Plasticiser, vinyl flooring, packaging	−53.5% (−72.7 to −20.6)
Bisphenol A (BPA)	Can linings, plastic food packaging, receipts	−59.7% (−82.5 to −6.9)
Mono-n-butyl phthalate	Plasticiser, some cosmetics	−37.5% (−55.6 to −12.0)

(The bracketed 95% confidence interval is the range in which the true reduction most plausibly lies; where it stays well below zero, as here, a real drop is unlikely to be a chance finding.)

Two findings matter for what you actually do. First, food was the dominant lever — the arms given food with minimal plastic contact showed the broadest reduction, and highly processed, plastic-packaged and canned foods were the important modifiable sources. Second, swapping personal-care products alone produced an independent drop in mono-n-butyl phthalate — so the cosmetics shelf is a real but smaller lever than the kitchen.

The point is the timescale. These chemicals are non-persistent in the body but continuously replenished from daily use. Cut the input and the urinary load falls within weeks. The trial is small (60 participants) and measured biomarkers, not health outcomes — it proves the exposure is modifiable, not that modifying it extends life.

A parallel French intervention (IRECO), in which reproductive-age women switched to products free of synthetic fragrance, parabens, and certain glycol ethers for five days, is widely reported to have cut urinary phenoxyacetic acid, parabens, and phthalate markers over the same short horizon. It points the same way as PERTH, but we have only been able to trace it through a secondary summary published by an advocacy organisation, not a peer-reviewed paper — so it is mentioned here for direction, not relied on for numbers.

At the population level, higher urinary phthalate metabolites track with about 14% higher all-cause mortality in US survey data, which the authors translate into roughly 100,000 excess deaths a year among older Americans (evidence: weak-moderate — this rests on single spot-urine snapshots, where reverse causation and residual confounding are hard to exclude; and, for balance against the chemical-industry conflicts flagged elsewhere on this page, the lead author's recent work is partly funded by anti-plastics advocacy).^[21]

EU regulators are catching up. Mandatory CLP classification of substances with endocrine-disrupting properties takes effect for existing-market substances in November 2026, and ECHA's SVHC Candidate List recently added bisphenol AF (a regrettable BPA substitute) and n-hexane.^[22] Until that reaches consumer products, individual mitigation is the only lever.

Where to actually act

In rough order of effect size for a midlife adult:

Drop synthetic fragrance. "Fragrance" or "parfum" on an ingredient list is a regulatory loophole that almost universally hides diethyl phthalate as a carrier. Plug-in air fresheners, scented candles, fabric refreshers, perfumed laundry detergents, and most colognes are the highest-yield items to remove. Fragrance-free or essential-oil-only alternatives exist for every category.
Get plastic out of food contact at heat or in fat. Phthalate and bisphenol leaching scales sharply with temperature and lipid content. Don't microwave in plastic, don't store fatty leftovers in plastic, don't drink hot liquids through plastic-coated cups. Borosilicate glass and stainless steel are inert. Cast iron, ceramic, and uncoated stainless replace PTFE/PFAS non-stick cookware; chipped or scratched non-stick pans should be retired.
Read cosmetic and personal-care labels. Watch for parabens (ethyl-, methyl-, propyl-, butyl-), triclosan, oxybenzone (benzophenone-3), and the umbrella term "fragrance." Long-wear waterproof cosmetics frequently contain PFAS and are worth replacing first.
Manage household dust. Persistent flame retardants and PFAS shed off treated furniture and carpeting and accumulate in dust — which then gets ingested via hand-to-mouth contact. A vacuum with true HEPA filtration plus ordinary handwashing with plain soap before meals does most of the work. Aerosolised antibacterial sprays and triclosan-containing soaps add to the load without measurable benefit.

Heavy metals — the strongest population evidence

If the air section has the largest headline death toll, heavy metals have the most solidly quantified one. These are bioaccumulative persistents: they stay in the body for years to decades, so the lever is preventing intake, never a "cleanse."

Lead. There is no safe threshold. A 2023 modelling study estimated that lead exposure caused about 5.5 million adult cardiovascular deaths in 2019 — roughly six times the previous global estimate and on the same order as fine-particle air pollution — at a cost near US$6 trillion, about 6.9% of global GDP (evidence: strong for the CVD link; treat the exact death count as uncertain — a separate Global Burden of Disease estimate is closer to 1.6 million).^[23] Lead drives hypertension, atherosclerosis, and — as the NHANES table above shows — epigenetic-age acceleration.
Cadmium. A meta-analysis of about 350,000 people across 37 countries found roughly a third higher cardiovascular-disease risk and a 70% higher stroke risk in the most-exposed, and US survey data link higher urinary cadmium to nearly double the cardiovascular-mortality rate (evidence: strong).^[24] Cadmium's kidney half-life is 10–30 years. The dominant sources are tobacco (the single biggest controllable one) plus organ meats, shellfish, leafy greens, and rice.
Arsenic. A dose-response meta-analysis found each doubling of drinking-water arsenic raised cardiovascular-disease incidence by about 9% and coronary-heart-disease mortality by about 16%, with harm appearing even below the WHO 10 µg/L guideline; arsenic is also an International Agency for Research on Cancer (IARC) Group 1 human carcinogen for lung, skin, and bladder cancer (evidence: strong).^[25] The main exposure is groundwater, especially private wells, plus rice.
Mercury. No distinctive cardiovascular signal; methylmercury from fish is chiefly a neurodevelopmental concern, so grade it lower for adult ageing endpoints.

The American Heart Association now formally classifies lead, cadmium, and arsenic as established cardiovascular risk factors.^[26] The mitigation is mundane and already on this page: filter your water (reverse osmosis for arsenic), test a private well, control household dust and soil, don't smoke — and, emphatically, not chelation (see below).

PFAS — the health-endpoint story

Water filtration for PFAS lives on the Water page; the health and regulatory picture belongs here. In 2023 IARC classified PFOA — one of the most-studied "forever chemicals" — as a Group 1 human carcinogen. The nuance matters: that top-tier rating rests mainly on animal and mechanistic data plus only limited human evidence (for testicular and kidney cancer), and an industry-linked commentary argues the working group overstated the case; the related compound PFOS was placed in the weaker "possibly carcinogenic" Group 2B (evidence: moderate, contested).^[27] A 2022 US National Academies review found the firmest evidence not for cancer but for reduced vaccine-antibody response, raised cholesterol, lower fetal growth, and kidney cancer; it judged the cardiovascular evidence insufficient.

Because PFAS half-lives run to several years — roughly 3–5 for PFOS and 3–4 for PFOA — they are the clearest counterexample to the "clears in days" rule and the main reason source reduction (and water filtration) beats any attempt to flush them out. One genuine removal intervention has randomised-trial support: in highly exposed firefighters, regular plasma donation modestly lowered serum PFOS over a year (evidence: weak-preliminary, biomarker-only, and study-funded by the fire service).^[28] This is a supervised medical option for the heavily exposed, not a wellness routine.

Pesticides — the glyphosate question

Glyphosate, the world's most-used herbicide, is where regulators openly disagree. IARC rates it "probably carcinogenic" (Group 2A), driven by non-Hodgkin lymphoma, and a meta-analysis found about 41% higher lymphoma risk among the most heavily exposed — mostly agricultural workers, where recall and healthy-worker biases apply.^[29] The US EPA, reviewing the same literature, found no carcinogenicity — a real regulatory split rather than a settled fact (evidence: moderate, contested). For a general adult the practical, low-grade steps are washing produce and choosing organic for high-residue items; the benefit is modest.

Radon — the cheapest high-yield test on this page

Radon is a colourless radioactive gas that seeps from soil into homes and is the second-leading cause of lung cancer after smoking, implicated in roughly 21,000 US deaths a year, with pooled residential studies showing about 16% higher lung-cancer risk per 100 Bq/m³ of exposure and no threshold (evidence: strong).^[30] For a never-smoker it is plausibly the single highest-yield environmental hazard on this page, and the fix is cheap: a test kit costs on the order of a restaurant meal, and remediation — where a test comes back high — is roughly the cost of a domestic appliance. It combines multiplicatively with smoking, so smokers benefit most of all.

Water: a separate, larger story

PFAS, microplastics, heavy metals, and disinfection by-products are all consequential aqueous exposures, but the filtration story (RO vs. UF, the demineralisation trap, why activated-carbon pitchers are unreliable for PFAS, what to do about microplastics in bottled water) is a larger subject in its own right.

→ See Water for the full treatment.

The gut as a biotransformation organ

Persistent organic pollutants like PFAS were long assumed biologically inert — hence "forever chemicals." A 2025 Nature Microbiology paper from the University of Cambridge upended that. Specific human gut bacteria absorb PFAS molecules from the lumen and shuttle them out via faeces; in mice colonised with nine of these species, 25–74% of an ingested PFAS dose was sequestered and excreted within minutes.^[31]

The same direction of effect appears in early work on dietary fibre, which interrupts the enterohepatic recirculation of PFAS — fibre traps biliary-secreted compounds for faecal excretion and feeds the bacterial species that do the sequestration. A Canadian study piloted a fibre-based method for lowering serum PFAS alongside its main cohort analysis,^[32] and an oat-fibre intervention reduced PFAS body burden in mice.^[33] Read this as mechanistically promising and Weak in humans: these are pilots and animal work, not trials showing that eating more fibre meaningfully clears your PFAS load.

Heavy metals do the opposite. Chronic arsenic, lead, mercury, and cadmium exposure suppress beneficial commensal bacteria and promote pathobionts like Collinsella, degrading the gut barrier and amplifying systemic inflammation.^[34]

The honest read: this is mostly preclinical and pilot-level human data. It points in the same direction as everything else on the site that recommends fibre and a Mediterranean-pattern diet — and there's no downside to either. Don't take this as license to buy a "detox" probiotic stack. The dietary pattern carries the evidence; the specific strain cocktails do not yet.

→ See Dietary patterns and Fermented foods.

A practical environmental-toxin protocol

Ranked by evidence-to-effort:

HEPA air filter in the bedroom, sized for the room (clean-air delivery rate, CADR, ≥ 2/3 the room's volume in m³/h). Run it nightly. Skip plasma, ionizer, UV-PCO, and ozone-based "purifiers."
Test your home for radon. A cheap test kit, then remediation only if it reads high — among the best evidence-to-cost trades on this list, especially for never-smokers.
Reverse osmosis water filtration with remineralisation if your supply has any PFAS or industrial concern (reverse osmosis is also the fix for arsenic). Otherwise, a good ultrafilter is enough. Test a private well for arsenic and lead. Don't drink habitually from PET bottles.
Eliminate synthetic fragrance from your household and personal care. Single biggest dermal/inhalational EDC reduction available.
Remove plastic from food contact under heat or fat. Glass and stainless replace plastic for storage and reheating; cast iron and ceramic replace non-stick.
Audit cosmetics and personal care for parabens, triclosan, oxybenzone, and PFAS in long-wear formulations.
Source food with heavy metals in mind. Vary grains rather than leaning on rice (arsenic), go easy on organ meats and shellfish (cadmium), and prefer known-clean water for cooking.
High-fibre dietary pattern — Mediterranean / MIND with legumes, vegetables, and whole grains. Independent of toxins, this is already what the rest of this site recommends.
Vacuum and ventilate. True-HEPA vacuum, regular dusting, cross-ventilation when outdoor air is clean. Avoid antimicrobial sprays.
Don't smoke. Avoid second-hand smoke. Tobacco is the single largest controllable source of cadmium and the highest-impact item on this list for anyone still exposed.

What's overrated

Houseplants for air purification — pleasant, ineffective.
Plasma / ionizer / UV-PCO purifiers — generate secondary pollutants; some studies show net VOC increase.
Oral "detox" cleanses, juice fasts, chelation outside frank heavy-metal toxicity — no evidence base for healthy adults; some chelators are actively dangerous. The definitive test is now in: a 1,000-patient randomised trial of EDTA chelation in high-risk heart-attack survivors found that, despite genuinely lowering blood lead, it did not reduce cardiovascular events (evidence: strong).^[35] An earlier positive subgroup signal failed to replicate. Chelation carries real risks — hypocalcaemia, kidney injury, and reported deaths — and belongs to treating diagnosed poisoning, not wellness.
Activated-carbon pitcher filters as a standalone PFAS solution — Duke/NCSU testing of 76 point-of-use filters found highly inconsistent PFAS removal; some improperly maintained whole-house carbon systems increased PFAS in effluent.^[36]
Generic "anti-toxin" supplement stacks built around glutathione, NAC, milk thistle. There's a thin biomarker case for any of these in healthy adults; the evidence base is dietary pattern, not pills.

Cautions

Personal biomonitoring (serum PFAS, urinary phthalate metabolites) is increasingly available commercially. NASEM guidance flags PFAS serum >20 ng/mL as a level warranting medical follow-up.^[37] For most healthy adults the test is more interesting than actionable: the corrective measures are the same as the protocol above whether or not you measured.
Industrial occupational exposure (firefighting, semiconductor manufacturing, certain agriculture) is a different category — domestic mitigation does not substitute for occupational health monitoring.