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.
What you can do / Other evidence
Going from 50 to 75 or 100 grams of baking soda per kilogram of food waste added little extra odor reduction in this experiment, so the lowest tested dose did nearly as well.
Weak evidence: Single bucket per dose per day, so differences between doses cannot be separated from bucket-to-bucket variation; values about, read from Fig. 2a.
Source: Qamaruz-Zaman 2015, Waste Management Link to this fact
What you can do / Other evidence
If a rash matches the exact shape of a bandage or first-aid product, stop using it, check the label for benzalkonium chloride, and ask a dermatologist about patch testing.
Weak evidence: Advice from a single case report; most bandage rashes have other causes.
What you can do / Other evidence
If a rash does not improve or worsens on a prescribed cream, check the inactive ingredients for benzyl alcohol and ask a dermatologist about patch testing with your own products.
Weak evidence: Advice for people with suspected contact allergy, not for the general public.
Source: Zheng et al. 2026, ACDS Allergen of the Year (Cutis), Cutis Link to this fact
What you can do / Other evidence
If a rash or blisters appear in the exact outline of a splint or cast, tell the clinician early: in this case it was first treated as infection (cellulitis) and worsened until the cast was removed.
Weak evidence: One case; the authors argue allergy must be distinguished from cellulitis because treatment differs.
Source: Wong and Watson 2001, Australasian Journal of Dermatology Link to this fact
What you can do / Other evidence
If you have stubborn hand, face or eyelid dermatitis, ask a dermatologist about patch testing that includes methylisothiazolinone and benzalkonium chloride, and check liquid soaps, sanitizers, eye products and moisturizers for those ingredients.
Weak evidence.
Caveats
A patch-test positive is not proof of cause; weak reactions may be irritant; relevance to a product must be confirmed. The advice is our inference from the positivity data; the paper gives no consumer guidance.
Source: [[src-2018-trends-patch-testing-mayo-clinic-standard-series|Veverka 2018]], Dermatitis® Link to this fact
What you can do / Other evidence
After a spill, release or accidental chemical mixing, such as bleach with acid, leave the area and get airflow testing (spirometry, reversibility or an airway reactivity test) if cough or wheeze persists.
Weak evidence: Advice inferred from case reports; the review gives no doses or incidence for household mixing.
Source: Walters 2020, Occupational Medicine Link to this fact
What you can do / Other evidence
The CHRC says a scent-free policy should list the types of products to avoid, be flexible, be mentioned in a letter of offer, and that an employee with environmental sensitivities who must leave because of a trigger should not suffer negative impacts.
Weak evidence: Guidance for federally regulated employers; no evidence on effectiveness, and a person outside that sector cannot rely on it as a legal entitlement.
Source: [[src-2019-chrc-environmental-sensitivity-scent-free-policies|CHRC 2019]] Link to this fact
What you can do / Other evidence
The ASEQ-EHAQ appeal asked readers to follow a link to a GoFundMe page, to report "healthy, affordable housing in the Toronto area" to the charity, and to share the post.
Weak evidence: Describes what the page asked; it does not say what donations would pay for. That purpose appears only on the separate fundraiser page.
Source: [[src-2022-aseq-ehaq-urgent-help-save-sophias-life|ASEQ-EHAQ 2022]] Link to this fact
What you can do / Other evidence
CTV reported that the woman wrote that she had applied for and now qualified for MAID, and CTV reported friends raised a fundraiser ("approximately $12,000") to try to find her better housing.
Weak evidence: Quoted from her letter and from CTV's figure; for the fundraiser total, see the GoFundMe page. Subject matter is a death by MAiD; add 988 line in published use.
Source: CTV News, April 2022 (via Smoke-Free Housing BC; redacted copy), CTV News (news article) Link to this fact
What you can do / Other evidence
CTV's April 2022 figure of "approximately $12,000" collected by a friend's fundraiser and the GoFundMe page's displayed $10,220 (as of 2026-10-21) were measured at different times and may not describe the same total.
Weak evidence.
Caveats
Different dates of measurement are the likely explanation; whether CTV's figure refers to this campaign alone is not confirmed. Partial capture ending before the campaign description; the figure is a 2026-10-21 snapshot.
Source: GoFundMe campaign page, "Save Sophia's Life!" (2022; captured 2026-10-21; redacted, partial) Link to this fact
What you can do / Other evidence
Inclusion Canada argues that because the law requires counseling on alternatives to relieve suffering, safe housing free of smoke and chemical infiltration matters; it says her doctors found such housing would have improved her health and quality of life.
Weak evidence: Advocacy post by an organization, written a year later; not independent reporting. Attribute to Inclusion Canada. The post does not say whether counseling occurred in her case.
Source: Inclusion Canada: Remembering Sophia (advocacy post, Feb 22, 2023; redacted copy), Inclusion Canada blog post Link to this fact
What you can do / Other evidence
A friend with MCS says people with the illness cannot easily get justice because the available tribunals take years, and that recognition of MCS as a disability is rarely enforced.
Weak evidence: Personal view of one person with MCS; compare the survey evidence on accommodation refusals before generalizing.
Source: Chemical Sensitivity Podcast ep. 101, 2026 Link to this fact
What you can do / Other evidence
Urine MEP was highest 3-6 hours after cologne use (about 2.8-fold versus use more than 8 hours earlier), suggesting the fragrance-product signal in the body is short-lived.
Weak evidence: Small subgroups; secondary analysis; the authors call power limited.
Source: Duty 2005, Environmental Health Perspectives Link to this fact
What you can do / Other evidence
Women who used anti-aging facial cream in a Mexican study had about 2.5 times the median monoethyl phthalate of nonusers (178 vs 71 ug/g creatinine); perfume users showed a similar-sized but statistically uncertain difference.
Weak evidence: Only 11 and 19 users, unadjusted rank-sum tests with about 80 product-metabolite comparisons, so a chance finding is plausible; perfume's own MEP difference was not significant.
Source: Romero-Franco 2011, Environment International Link to this fact
What you can do / Other evidence
The authors argue prevention of EDC exposure would bring large societal benefits, but the costs are modeled from expert judgments and extrapolated slopes, so cite them as estimates, not measured bills.
Weak evidence: Authors' advocacy-adjacent framing; funders include foundations; phthalates carry no IQ cost in this model and fragrance ingredients are not costed.
Source: Bellanger et al. 2015, J Clin Endocrinol Metab, The Journal of Clinical Endocrinology & Metabolism Link to this fact
What you can do / Measured in people or real products
The study's mixture analysis (four methods) found no combined effect of prenatal parabens, triclosan, benzophenone-3, bisphenols and pentachlorophenol on early cognition in a high-tobacco-exposure South African cohort.
Weak evidence.
Caveats
Null in one cohort with modest power cannot show safety; paraben and triclosan exposure remains a reasonable thing to ask about in pregnancy but this paper does not support avoidance advice for cognition.
Source: Zhou 2025, Environmental Research Industry-funded 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
The 2025 review says fatty, acidic, heated or long-stored packaged foods and drinks pick up more plasticizer from packaging, and suggests not reusing packaging, following label temperature limits and favoring fresh home-prepared food.
Weak evidence: Recommendations are drawn from migration studies and are not tested for health benefit in this review.
Source: Gorini 2025, Toxics Link to this fact
What you can do / Other evidence
Doubling outdoor air from 20 to 40 cfm/person raised average decision-making scores by about 25% in this office-lab study, so ventilating beyond the minimum and using low-emitting materials may help thinking at work.
Weak evidence: One small, fixed-order, industry-gift-funded lab study; effect on real offices untested.
Source: Allen 2016, Environmental Health Perspectives Industry-funded Link to this fact
What you can do / Other evidence
Among migraine patients who linked odors to attacks, the places most often named were offices (55.4%) and homes (40.6%); 42% wore masks and 16.8% moved away from the odor.
Weak evidence: Self-report from one clinic; coping measures were not tested for benefit.
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 / Other evidence
Smelling lavender oil five times from a bottle is not shown to sharpen your thinking: the one small EEG study that says so had no comparison odor and no blinding.
Weak evidence: Absence of a control is a design limit, not proof of no effect.
Source: Afghan 2024, Journal of Medical Signals & Sensors Link to this fact
What you can do / Other evidence
Running 222 nm lamps in a room with strong terpene sources such as deodorizer screens, air fresheners or terpene cleaners adds an ozone source to those emissions; the authors also suggest fragrance formulation labeling would let people avoid reactive terpenes.
Weak evidence: Inference and authors' suggestion from one room; no consumer testing.
Source: Link 2024, Environmental Science: Processes & Impacts Link to this fact
What you can do / Other evidence
In the final model, only 5 of about 40 predictors reached p<0.05 for cosmetic adverse reactions; the abstract's claim that younger age, higher education, allergy history and frequent use predict reactions is not supported by that model.
Weak evidence: Cross-sectional self-report; reference categories not stated; text mixes bivariable and multivariable results.
Source: AlBlooshi 2026, Frontiers in Toxicology Link to this fact
What you can do / Other evidence
The survey's statement that allergy testing is protective rests on a model in which every testing frequency, including never testing, has an odds ratio below 1 against an unstated reference, so the result more likely reflects the reference group than a protective effect.
Weak evidence: Reverse causation (people who reacted before test more) is acknowledged by the authors for label reading and plausible here.
Source: AlBlooshi 2026, Frontiers in Toxicology Link to this fact
What you can do / Other evidence
In the perfume rat study, oral vitamin E (40 mg/kg/day) lessened many of the changes (blood pressure, heart rate, serum MDA, CYP1A1/CYP1A2 induction) without normalizing creatinine, troponin or PO2.
Weak evidence.
Caveats
Rat oral dose, five animals per group, no human test; the printed serum MDA for the vitamin E group is identical to the control value, suggesting a transcription error; statistical letters show partial effects only.
Source: Al-Sowayan 2026, Frontiers in Pharmacology Link to this fact
What you can do / Other evidence
Aromatherapy claims that lavender sharpens thinking rest on small before-and-after studies like this one, where everyone knew they were smelling lavender and no one smelled a dummy scent, so they are leads rather than proof.
Weak evidence: Applies to this one study; other controlled lavender-cognition studies exist and are not assessed by this paper.
Source: Afghan 2026, Journal of Medical Signals & Sensors 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
Methylparaben, the most common paraben, produced no significant methylation hit in this study; the signals came from the less common butyl-, isobutyl- and isopropylparaben, which the EU restricted or banned in cosmetics after the study period.
Weak evidence: Lower-abundance compounds with fewer detections (isopropylparaben 8%); suggestive only; association with a marker, not a health effect.
Source: Mäkinen 2026, Environment International Link to this fact
What you can do / Other evidence
If painting or renovating during pregnancy, ventilate and keep away from fresh paint; the EPA's source-control advice stands, and one mouse study now adds an animal warning signal.
Weak evidence: Animal study; the advice itself is standard EPA guidance, not derived from this paper's data.
Source: Sun 2026, Journal of Hazardous Materials Link to this fact
What you can do / Other evidence
The authors recommend adequate ventilation; this chamber study did not test whether keeping ventilation up on high-ozone days or avoiding terpene-scented products or ozone generators reduces particle formation indoors, so that advice is an inference from the chemistry.
Weak evidence: Chamber study of one ventilation range (0.52-0.76 h-1); the ventilation recommendation is the authors' and the rest is inferred; no health outcome.
Source: Wainman 2000, Environmental Health Perspectives Link to this fact
What you can do / Other evidence
A parent who wants to limit synthetic food colors and sodium benzoate in a young child's diet can read ingredient lists; the 2004 Isle of Wight trial suggests a small parent-noticed difference, but this is precaution under uncertainty, not a treatment and not a fragrance recommendation.
Weak evidence.
Caveats
Rests on a single parent-rated outcome in one trial; the European regulator later called the closely related McCann 2007 evidence 'limited' and left acceptable daily intakes unchanged.
Source: Bateman 2004, Archives of Disease in Childhood 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
What you can do / Other evidence
In the model, more air exchange with ozone-containing outdoor air raises how fast indoor VOCs are oxidized, but product levels depend on rate divided by air exchange, so ventilation is not a simple fix for oxidation products.
Weak evidence: Model only; product concentrations were not computed; the authors' first-order rule is for generic products.
Source: Waring & Wells 2015, Atmospheric Environment Link to this fact
What you can do / Other evidence
The OEHHA review concludes that the basis of the ADIs for Red 3, Red 40, Yellow 5 and Yellow 6 may not be adequate to protect neurobehavior in susceptible children, and calls for re-evaluating children's exposure and more research.
Weak evidence: A precautionary recommendation by a state agency; not all children react and no individual dye except tartrazine is isolated in trials.
What you can do / Other evidence
Anxiety and depression were far more common in adults who reported an ADHD diagnosis (62.6% and 50.5%) than in screen-positive adults without a diagnosis (30.3% and 15.2%) or low-symptom adults (7.7% each), so group comparisons of sensory traits must account for mood diagnoses.
Weak evidence: Self-reported diagnoses; mood status entered as a single yes/no covariate; confounding by unmeasured factors remains possible.
Source: Aljuhani 2026, Frontiers in Psychiatry Link to this fact
What you can do / Other evidence
In a chamber at a very high ozone level (about 6.5 ppm), ozone starts the reaction that turns product terpenes into particles; by that chemistry, keeping indoor ozone low and ventilating during heavy use of scented sprays and cleaners should limit this aerosol, but the study did not test ozone or ventilation changes.
Weak evidence: The study only varied products, not ozone level or ventilation; the action is inferred from the chemistry, and no health effect was measured.
Information, not medical advice. See also: myths we won’t tell you.