Don’t take our word for it. Here’s every fact on this site, with its evidence grade, its caveats, and a link to the source, so you can check us.
We start you on the strong ones: findings that have been replicated or come from one large, well-controlled study. Moderate and weak facts are here too, labeled for what they are. Use “Link to this fact” to share a single card.
Hidden ingredients / Other evidence
Several store-brand and name-brand antibacterial bandages (including Care Band, Curad, CVS, Equate, Top Care, Up & Up, Urgo, Walgreens) and Hansaplast wound spray are reported to contain benzalkonium chloride.
Weak evidence: Brand list is the authors' and reflects 2018; formulations change.
Hidden ingredients / Other evidence
A commercial product database (SkinSAFE) lists 10,998 skin care products containing benzalkonium chloride or a related quaternary ammonium compound such as benzethonium chloride, all liquids such as moisturizers, liquid soaps, shampoos and conditioners.
Weak evidence: Authors' relay of one commercial database; not independently counted; product list not given.
Source: [[src-2018-trends-patch-testing-mayo-clinic-standard-series|Veverka 2018]], Dermatitis® Link to this fact
Hidden ingredients / Other evidence
The only fragrance-solvent marker in this study, urinary MEP (from diethyl phthalate), was folded into a five-metabolite 'personal care product' phthalate sum that was not significantly associated with ADHD-type behavior overall (RR 1.16, 0.98-1.37).
Weak evidence.
Caveats
The sum is dominated by dibutyl-type metabolites; MEP was not analyzed alone in the PDF; hyperactivity subset 1.25 (1.07-1.47) was nominally significant; cannot separate DEP from the fragrance mixture it rides in.
Hidden ingredients / Other evidence
Pools and wastewater treatment can chlorinate or brominate phenolic personal-care ingredients such as parabens, bisphenols and UV filters, creating derivatives that are not on any label; the authors call for toxicity work on these emerging products.
Weak evidence: The paper tested lab-made derivatives and cites environmental and urine levels from the authors' own earlier review; it did not measure any in consumer products.
Indoor air / Review of other studies
During ordinary house cleaning with bleach, chlorine gas concentrations can peak at up to about 0.5 parts per million, and trichloramine is thought to reach similar concentrations when bleach reacts with ammonia or other nitrogen-containing substances.
Weak evidence: This is the authors citing a separate domestic-cleaner cohort study (their own ref. 15) as background, not a measurement made on the children or homes in this study.
Source: Nickmilder, Carbonnelle & Bernard 2007, Pediatric Allergy and Immunology Link to this fact
Indoor air / Other evidence
In a 1996 Hong Kong pilot, five freshly dry-cleaned garments stored in a poorly ventilated, carpeted bedroom wardrobe pushed bedroom perchloroethylene (PCE) to 494 micrograms per cubic meter on the first day, against outdoor readings below about 1 microgram.
Weak evidence.
Caveats
One bedroom per ventilation condition (3 total), no randomization, 24-h tube samples; ventilation not measured during the tests; government-commissioned (no industry funding); not children or health outcomes.
Source: Chao 1998, Building and Environment Link to this fact
Indoor air / Other evidence
Hot, dry car cabins shift the particles from a spray smaller: at 25 degrees C the driver-seat nanoparticle share reached about 81% (versus about 65% at 10-20 degrees C).
Weak evidence: Single SUV and spray; the humidity explanation is the authors' interpretation; text and abstract disagree on the size of the rise (25.3 +/- 0.4% vs +/- 3.2%).
Source: Lee 2024, Science of The Total Environment Link to this fact
Indoor air / Other evidence
EPA's 2006 assessment found modeled inhalation margins for home mopping, wiping, trigger spray, aerosol deodorizer and carpet spray at 820 to 50,000 against a target of 100.
Weak evidence: Modeled with surrogate exposure data, an oral rabbit study as the inhalation endpoint, and judgment-based amounts handled; EPA itself called for confirmatory exposure data.
Source: EPA RED 2006 Link to this fact
Indoor air / Other evidence
The county quotes dry-cleaned-wool scenarios of perchloroethylene up to 240 milligrams per cubic meter in a sealed 3.4 m3 closet and 620 in a warm car, assuming all residual solvent vaporizes.
Weak evidence.
Caveats
Theoretical ceilings with no ventilation; the figures differ from the ppm values on our Sherlach 2011 page (about 50 and 126 ppm, roughly 340 and 850 mg/m3), so they are not reconciled; not measured exposure.
Source: SCDHS 2018 Link to this fact
The industry / Other evidence
The flavor trade association argues the Delaney Clause is 'antiquated science' that should be reformed, and it presents FDA's 2018 delisting of seven rodent-carcinogenic flavors, while also calling them safe at use levels, as proof.
Weak evidence: An advocacy position from FEMA authors in a review, not a finding; the petitioning NGOs and the statute's text take the opposite view.
Source: Hallagan 2020, Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Other evidence
The dye trade is still active: distributors were found for most of 60 listed hazardous dyes, up to 44 for some, mostly in China and India, including two IARC-suspected carcinogens.
Weak evidence: Rough lookchem.com search; shows availability, not use in textiles.
Source: Danish EPA 2014, Survey of Chemical Substances in Consumer Products No. 129 Link to this fact
The industry / Other evidence
EWG states it accepts no programmatic funding from food, household-cleaning, or personal-care companies, no funding for corporate-sponsored research, and no payment of any kind for inclusion or scoring in Skin Deep, Guide to Healthy Cleaning, or Food Scores.
Weak evidence: This is a policy statement by EWG itself; 'programmatic funding' is not defined and no audit of compliance is on the page.
Source: EWG Funding & Reports page, 2026, EWG website (web page) Link to this fact
The industry / Other evidence
At its March 2015 meeting a CIR panelist said the Panel does not consider carcinogen-containing ingredients safe in products, so polysorbates enhancing a carcinogen 'wouldn't be an issue'; other participants noted known carcinogens, including formaldehyde, still occur in some cosmetics.
Weak evidence: Transcript of oral discussion, not a finding; the final wording of the Discussion was left to editorial comment.
Source: CIR 2015 draft Industry-funded Link to this fact
The industry / Review of other studies
Major retailers have pledged to cut phthalates, for example Sephora aiming to reduce 8 phthalates by 50% over 3 years, and CVS, Walmart, Rite Aid and Loblaw working toward elimination in beauty and personal care products, which the authors cite as proof that elimination is feasible.
Weak evidence: Pledges as reported by the authors in 2020 from company announcements; delivery not verified here.
Source: Engel 2021, American Journal of Public Health Link to this fact
Laws and loopholes / Other evidence
In the EU, free formaldehyde in cosmetics is capped at 0.2% (0.1% in oral hygiene products) and products with formaldehyde or releasers must carry a 'contains formaldehyde' warning above 0.05%, whereas the authors say the US has no specific norms.
Weak evidence: Regulatory statement from a 2011 discussion citing a 1986 directive; rules have changed since (see the Goossens 2022 page) and the US statement is not checked here.
Laws and loopholes / Government agency
The CHRC says scent-free policies should apply to employees and non-employees alike, name the products to avoid, be flexible, and carry consequences for non-compliance, and that employers should stay open to other accommodation options.
Weak evidence: Policy-design advice with no cited evidence base (footnotes not captured).
Source: CHRC 2026 web Link to this fact
Laws and loopholes / Other evidence
Station wastewater treatment in Antarctica (biological treatment with UV or chlorine) is judged by the authors to be ineffective for personal-care chemicals, and one-third of permanent and two-thirds of summer stations have no treatment.
Weak evidence: Efficacy is asserted, not quantified for these compounds; the authors admit plant conditions differ too much to compare treatments.
Source: Balakrishna 2023 (review), Environmental Research Link to this fact
Skin allergy / Measured in people or real products
Once someone is sensitized, patch tests can trigger reactions at low ppm concentrations of oxidized terpene, but the specific 'as low as 1 ppm' figure is for Δ³-carene in older, narratively-reviewed occupational turpentine literature; for the two terpenes that dominate consumer exposure, modern peer-reviewed dose-response studies put the threshold one to two orders of magnitude higher (limonene hydroperoxides: ~24 ppm single patch application, ~140 ppm repeated realistic exposure, ED₁₀ ≈85 ppm; linalool hydroperoxides: ~560 ppm repeated realistic exposure).
Weak evidence.
Caveats
The 1 ppm figure applies to Δ³-carene in historical occupational patch testing, not to limonene or linalool, and its own study design (occlusion, participant numbers) is not given in the citing review. No limonene- or linalool-specific study supports reactions at ~1 ppm.
Source: Karlberg & Lepoittevin 2021, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
Healthcare workers (medicine, dentistry, nursing, veterinary) had the highest fragrance-mix allergy rate among the occupations the London authors analyzed, about 10-12%, which they link to frequent hand washing followed by moisturizers and fragranced medicaments.
Weak evidence.
Caveats
Small groups (154 men), clinic patients; the hand-barrier explanation is the authors' suggestion, not tested; occupation subset tables for retired persons and students contain apparent transcription slips.
Source: Buckley 2003, British Journal of Dermatology Link to this fact
Skin allergy / Other evidence
Health care workers appear more often sensitized to BAK: one cited study found 7.5% relevant BAK reactions in health care workers versus 2.3% in other patients, and another 23.8% of 223 nurses sensitized.
Weak evidence: Relayed from other studies of small, selected groups; a third cited study found only a slight excess (2.0% vs 1.6% control).
Skin allergy / Review of other studies
Shorter-chain ceramides make the skin's fat layers pack more loosely and leak more: in lab membranes, swapping a 24-carbon fatty acid for a 16-carbon one raised permeability.
Weak evidence: Artificial membranes and porcine skin, not human skin in use; chemical-specific penetration was not tested.
Source: Berdyshev 2024, Allergy, Asthma & Immunology Research Link to this fact
Skin allergy / Other evidence
The CIR draft records that polysorbate 60 and a polysorbate 60-based cream caused hives (urticaria) within 20 minutes on the forehead of test subjects, but its Summary and Discussion say polysorbate 60 at 100% was 'not dermally irritating'.
Weak evidence: The urticaria entry is a one-line summary of an old study with no n or amount; the conflict is within the draft's own text.
Source: CIR 2015 draft Industry-funded Link to this fact
Skin allergy / Other evidence
If a skin-care product or topical treatment seems to make rosacea worse, ask a dermatologist for patch testing that includes your own products and any eye drops or medicines you use.
Weak evidence: Recommendation from a small study; no rosacea flare occurred in any patch-test-positive patient.
Skin allergy / Measured in people or real products
Wet work of 2 hours or more a day (occupational plus domestic) was not significantly associated with hand eczema after adjustment in a car-industry case-control study (irritant hand eczema OR 1.62, 95% CI 0.78-3.37), although it was more common in irritant cases univariately (49.1% vs 31.7%).
Weak evidence: Underpowered for exposure effects by the authors' own account; workplace had strong skin-protection policy; a null here is not evidence wet work is harmless.
Source: Apfelbacher et al. 2010, Contact Dermatitis, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
36.4% of surveyed UAE women reported an adverse reaction to cosmetics in the past 2 years, mainly skin redness (20.6%), pimples (18.4%) and itching (16.9%); skincare (21.7%) and makeup (14.1%) were blamed far more often than perfume (5.2%).
Weak evidence.
Caveats
Open-link snowball sample of 461 women, mostly young and university-educated; self-report, no exposure measurement; not weighted, so not a UAE prevalence. Mixes fragrance-related and non-fragrance reactions (pimples, hair loss, pigmentation); attribution is the respondent's own.
Source: AlBlooshi 2026, Frontiers in Toxicology Link to this fact
What you can do / Measured in people or real products
Childcare rooms with more fresh-air exchange had lower levels of several of the chemicals measured.
Weak evidence: Bivariate correlations, 34 rooms.
What you can do / Review of other studies
Close fragranced products after use and discard them about a year after opening to limit exposure to oxidized allergens.
Weak evidence.
Caveats
Expert advice; no study tests whether it reduces dermatitis. The assumed mechanism (in-bottle oxidation during storage) has now failed two industry market surveys rather than one: Kern 2014 (fine fragrances, antiperspirants, 9 months accelerated storage) and Natsch 2019 (104 products including creams and lotions, two fine fragrances tracked 3-6 years at room temperature) both found no hydroperoxide accumulation with age or storage time. The advice may still be reasonable for essential oils and raw materials (which do carry hydroperoxide, e.g. lavandin ~220 ug/g), just not via this specific in-bottle mechanism for finished consumer products. Both studies are industry-funded (IDEA consortium: Givaudan, Firmenich, IFF, IFRA) and not independently replicated, and say nothing about essential oils, raw materials, or product categories outside fine fragrances/antiperspirants/creams/lotions. Kern 2014 and Natsch 2019 are both industry studies (Givaudan / IDEA consortium) with Natsch as a co-author on both, so they are not independent replications of each other.
Source: Pastor-Nieto 2021 (Klaschka 2010), Current Treatment Options in Allergy Link to this fact
What you can do / Other evidence
Because the association tracked frequency of use in a dose-response pattern, using fewer personal care products or using them less often is the lowest-regret step for someone concerned about a possible link to lung function.
Weak evidence: The study did not test whether reducing use reverses any effect; this is an inference from an observational dose-response pattern, not a tested intervention.
Source: Dales 2013, Annals of Epidemiology Link to this fact
What you can do / Measured in people or real products
Running an ozone-generating device (an ionizer, or some 'air purifiers') at the same time as using citrus- or terpene-scented cleaning or personal-care products creates the same class of reaction-product nanoparticles studied here; keeping the two apart in time, or ventilating, avoids generating them.
Weak evidence.
Caveats
This study alone did not find a significant health effect from the terpene+ozone arm; the precautionary action is supported by the wider ozonolysis-SOA literature in our evidence base (see transformation-products), not by this study's HRV result in isolation. Downgraded to weak 2026-09-28 (Jev audit): the action goes beyond what this paper itself tested.
Source: Hagerman et al. 2014, Atmospheric Environment Link to this fact
What you can do / Other evidence
Because leave-on skin products with large use amounts (body lotion, fine fragrance) drove the highest modeled fragrance-ingredient exposure in this industry model — not air-care products, which had the highest in-product concentrations but low exposure due to no skin contact — a reasonable consumer heuristic is that layering multiple fragranced skin products likely matters more for aggregate systemic fragrance exposure than using a scented candle or air freshener.
Weak evidence.
Caveats
Derived inference from a single industry model covering 8 ingredients; not validated against measured exposure; does not address inhalation health effects, only relative modeled systemic dose.
Source: Safford 2017, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
What you can do / Hypothesis
Unlike outdoor air pollutants such as vehicle exhaust, people can directly reduce their exposure to limonene at home by limiting use of strongly limonene-scented personal-care products and household cleaners.
Weak evidence: This is the authors' own inference from a cross-sectional association, not a tested intervention; no randomized avoidance trial has been done, though the authors call for one.
Source: Dales & Cakmak 2019, Environmental Pollution Industry-funded Link to this fact
What you can do / Advocacy group testing
This report recommends free consumer apps (Yuka, Tox Fox, Kemiluppen) and trusted ecolabels (Nordic Swan, EU Ecolabel) or fragrance-free certification labels (Asthma Allergy Denmark, Allergy Certified) as ways to identify or avoid suspected EDCs and allergens in personal care products.
Weak evidence: The report does not test whether using these apps or labels measurably reduces a person's chemical exposure or biomarkers.
Source: Tegengif 2022 Link to this fact
What you can do / Other evidence
People should use scented candles with caution in closed spaces and should refrain from using them around vulnerable groups such as pregnant women, children, the elderly, and people with pre-existing cardiopulmonary conditions.
Weak evidence: A precautionary recommendation, not based on a candle-specific dose-response or exposure-outcome study in any of the named vulnerable groups.
Source: Singh 2023, Environmental Science & Technology Link to this fact
What you can do / Other evidence
A structured home walkthrough that identifies and removes common VOC sources (mothballs, scented cleaning and personal-care products, candles, garage-stored chemicals) and separates stored chemicals from living space (e.g., moving gasoline/solvents/paints to detached storage) reduced measured indoor VOC levels in the homes studied.
Weak evidence.
Caveats
Professional testing and a trained team delivered this intervention over 5 visits across a year; the paper does not test which individual component (removal vs. substitution vs. new storage vs. counseling) drove the VOC reduction. Evidence is one small uncontrolled case series.
Source: Rincón et al. 2024, Primary Health Care Research & Development Link to this fact
What you can do / Review of other studies
The study's authors argue that reducing DEHP/plastic-related cardiovascular mortality requires regulation (banning or restricting DEHP in products, improving labeling), better waste management, and international cooperation such as the UN's Global Plastics Treaty negotiations, rather than relying on individual consumer avoidance alone.
Weak evidence: This is the authors' policy recommendation; no intervention was tested in this study.
What you can do / Government agency
Frozen and fatty packaged foods in printed cartonboard (frozen foods, jellies, savory snacks, high-fat items like chocolate) were the categories a UK FSA survey found most likely to carry benzophenone residue from printing-ink migration; fresh or non-printed-packaging foods are a lower-exposure alternative for anyone wanting to reduce incidental dietary intake.
Weak evidence.
Caveats
Based on one national survey's positive-detection rates by food category, not a dose-response health-outcome study Graded weak: what-you-can-do resting on one survey relayed through the IARC monograph.
Source: IARC 2013 Link to this fact
What you can do / Self-reported survey
People pursuing an MCS accommodation in Canada should ask healthcare providers to document functional limitation, not just a diagnosis, and should keep a written record of every accommodation request and outcome, since the legal duty to accommodate turns on function and this study found requests and refusals were often repeated five or more times.
Weak evidence.
Caveats
Drawn from one self-report survey's qualitative themes and the authors' own policy recommendations, not tested as an intervention; rests on a single small, advocacy-recruited study.
Source: Diallo 2026 Link to this fact
What you can do / Measured in people or real products
Before applying moisturizer to an infant's skin, wash hands thoroughly, and give careful consideration to both the frequency and the type of product used, per the study authors' own cautious recommendation.
Weak evidence.
Caveats
This recommendation rests on one observational cohort (plus a matching but non-significant RCT signal from BEEP); it is not established clinical guidance, and moisturizers remain first-line treatment for infants who already have eczema.
Source: Perkin 2021 (EAT cohort), Journal of Allergy and Clinical Immunology Link to this fact
What you can do / Measured in people or real products
Parents who want to reduce infant phthalate exposure can limit the number of infant care products used on their baby and avoid applying lotion or powder unless medically indicated.
Weak evidence: This is the study authors' own recommendation, not a tested intervention; it is based on the correlational findings in the same study.
Source: Sathyanarayana et al. 2008, Pediatrics Link to this fact
What you can do / Measured in people or real products
Because this study's own route argument points to prenatal (placental) transfer, not breastfeeding, as the main way synthetic musk fragrance chemicals reach a baby, choosing fragrance-free personal-care and laundry products during pregnancy specifically, not only while breastfeeding, is a plausible way to reduce an infant's earliest musk exposure.
Weak evidence.
Caveats
Inferred from pharmacokinetics (musks' short half-life) and matrix comparisons, not from measured product use or from an intervention study; no study has tested whether reducing a mother's product use lowers her infant's cord-blood or milk musk levels.
What you can do / Measured in people or real products
Because fragrance musk exposure has been linked to personal-care and laundry product use in other studies, choosing fragrance-free cosmetics and laundry products during pregnancy and breastfeeding is a plausible way to reduce a baby's prenatal and infant musk exposure.
Weak evidence.
Caveats
This paper collected no personal-care-product-use data itself; the action is inferred from sibling studies (Hutter 2009, Lignell 2008) that did test product use, not from this paper's own data.
Source: Zhang 2015, International Journal of Hygiene and Environmental Health Link to this fact
What you can do / Other evidence
If you have damaged hand skin from wet work, frequent hand washing, or hand eczema, take extra care with fragranced hand products: the London authors suggest that impaired hand skin barrier may make fragrance sensitization more likely.
Weak evidence: Mechanism is proposed in the discussion and not tested; the study shows an association of age and occupation with positive tests only.
Source: Buckley 2003, British Journal of Dermatology Link to this fact
What you can do / Other evidence
Because several dyes are mixed even for light colors and tights carry them, the reviewers say the best advice for dye-allergic people is to wear non-synthetic fibers, not just to avoid dark clothes.
Weak evidence: Expert opinion; no trial of fiber switching.
Source: Malinauskiene 2013, Contact Dermatitis Link to this fact
What you can do / Other evidence
One in five clinically relevant BAK allergy cases was a health care worker (four nurses, one surgeon, all with hand dermatitis), traced to hand sanitizer in three cases and disinfectant wipes in two.
Weak evidence: Five patients; no comparison of exposure in health care workers with non-workers in this dataset (the 7.5% vs 2.3% comparison is from a cited paper).
What you can do / Other evidence
In EPA's 2006 ADBAC assessment the thinnest modeled home-use margins were dermal: wiping 76 and carpet spraying 72 against a target of 10.
Weak evidence: Modeled using irritation (not systemic) endpoint and surrogate unit exposures; no gloves assumed.
Source: EPA RED 2006 Link to this fact
What you can do / Other evidence
Liquid carbon dioxide was the only non-water process the county gave green on both health and environment, because it vaporizes on release and the gas is reported to be an industrial by-product.
Weak evidence: Qualitative; no measurements of the cleaning detergents the CO2 process requires or of air emissions; the by-product claim is from Cal EPA and TURI, not verified here.
Source: SCDHS 2018 Link to this fact
What you can do / Other evidence
A positive skin test to sulfites does not automatically mean giving up sulfite-containing food; dermatologists say that is usually unnecessary unless there is lip inflammation or a systemic pattern, while people with immediate reactions (hives, swelling, anaphylaxis) should avoid sulfite foods and carry epinephrine.
Weak evidence: Expert opinion in a narrative review, not trial data; individual advice belongs with a clinician.
Source: Choi 2024, Cutis Link to this fact
What you can do / Review of other studies
The review advises pregnant women to use glass or steel food containers, avoid microwaving plastic, skip nonstick cookware and thermal receipts, and choose fragrance-free, phthalate-free personal care products.
Weak evidence: Advice is general; the review shows no thyroid outcome benefit from any single step, and only the phthalate/DEP advice touches fragrance.
Source: Eraslan Aydemir & Sahin 2025, Turk J Med Sci, Turkish Journal of Medical Sciences Link to this fact
What you can do / Other evidence
Parabens are preservatives in cosmetics and personal care products; the evidence on children's attention is inconsistent across cohorts, so avoiding them is precaution under uncertainty, not a demonstrated protective step.
Weak evidence: Allergy side differs: parabens are the least sensitizing common preservative.
Source: Tung 2024, Environment International Link to this fact
What you can do / Review of other studies
Several small randomized trials of probiotics or synbiotics in children with ADHD report symptom improvement, but none enrolled children selected for chemical exposure, so they do not show that gut bacteria carry chemical effects.
Weak evidence: Small trials, some without microbiome measurement; relayed by the review without risk-of-bias scores in the main text.
Source: Wu 2026, Biological Psychiatry Global Open Science Link to this fact
What you can do / Other evidence
The author suggests filtering ozone out of ventilation air (charcoal or impregnated filters) and limiting use of ozone-reactive products on high-ozone days, especially in schools, hospitals and childcare centers.
Weak evidence: A mitigation suggestion; no trial of health benefit is cited, and efficacy of the product-limiting advice is untested.
Source: Weschler 2006, Environmental Health Perspectives Link to this fact
Information, not medical advice. See also: myths we won’t tell you.