Every fact on this site, with its evidence grade, its caveats, and a link to the source.
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 / Review of other studies
The main BPA exposure routes this review names are ingestion of food and beverages from polycarbonate plastic containers and epoxy-lined cans, plus dermal or inhalation contact with BPA in thermal receipt paper and household dust, rather than fragranced personal-care products specifically.
Moderate evidence: Sourced from the review's introduction, which itself cites general BPA exposure literature rather than PCOS-specific measurements.
What you can do / Measured in people or real products
If you test positive for oxidized linalool specifically, it may be worth asking your dermatologist to test more broadly for cosmetic-related allergens (preservatives, colophony, other fragrance-mix ingredients), since concurrent allergy to several of these was common in this study's linalool-HP-positive group.
Moderate evidence: Based on patch-test association data from one Swedish clinic; not a clinical practice guideline.
Source: Sukakul 2024, Contact Dermatitis Industry-funded Link to this fact
What you can do / Government agency
HUD's own 1991-92 guidance gives two concrete examples of reasonable accommodation for chemically sensitive tenants: (1) a tenant sensitive to pesticides can ask for advance notice before the building is fumigated and for boric acid to be substituted for the chemicals normally used; (2) an applicant sensitive to carpet chemicals can ask the housing provider what type of carpeting is used throughout the building before deciding whether to rent.
Moderate evidence.
Caveats
These are HUD's own worked examples from internal guidance, not a binding regulation with a fixed list of required accommodations; HUD explicitly says reasonableness depends on the individual's circumstances and is bounded by undue financial/administrative burden.
Source: HUD guidance (1991) Link to this fact
What you can do / Government agency
After a 1993 ADA complaint over municipal-employee perfume use, San Francisco voluntarily adopted a policy requiring public meeting notices to ask attendees to refrain from wearing perfume or other scented products, to let people with environmental illness or multiple chemical sensitivity attend.
Moderate evidence: One city's voluntary accommodation, reported secondhand in DOJ's own letter; not evidence the policy was enforced or effective, and not a legal requirement.
Source: DOJ Civil Rights Division 1993 (TAL 383) Link to this fact
What you can do / Measured in people or real products
A typical application of lipstick is very small (median 5 mg, mean 10 mg), a typical application of body lotion is about 3.5-4.4 g, and a typical application of face cream is about 0.8-1.2 g, based on a two-week diary-and-weighed-container study of over 300 regular US users of each product.
Moderate evidence.
Caveats
From a women-only, US-only sample of already-regular product users given a substitute prototype product (not their own brand) for two weeks; the amounts are ratio estimates from total container weight change, not measured per application.
Source: Loretz 2005, Food and Chemical Toxicology Industry-funded Link to this fact
What you can do / Self-reported survey
When people apply body lotion, they put it on their hands far more often than anywhere else, followed by arms, then legs and feet, with the back getting the fewest applications.
Moderate evidence: Based on diary self-report of application site from about 300 regular US body-lotion users over two weeks with a substitute prototype product.
Source: Loretz 2005, Food and Chemical Toxicology Industry-funded Link to this fact
What you can do / Measured in people or real products
A single spray of perfume puts about a quarter gram of product on the skin (median 0.23 g per application), and a single hairspray application puts on about two grams from an aerosol can or three-and-a-half grams from a pump, based on a two-week diary-and-weighed-container study of regular users.
Moderate evidence.
Caveats
From a women-only sample of already-regular product users who were given the product free; the study's own authors say the design likely overestimates rather than underestimates use.
Source: Loretz 2006, Food and Chemical Toxicology Industry-funded Link to this fact
What you can do / Government agency
Because no federal rule requires air fresheners to disclose their full ingredients, a consumer cannot rely on an 'all-natural' or 'unscented' label to rule out the presence of phthalates or other undisclosed fragrance constituents.
Moderate evidence.
Caveats
Applies to the 2007 dataset and to the current absence of a federal labeling mandate reported elsewhere in our evidence base (FDA, EPA Safer Choice pages); does not mean every unlabeled air freshener contains phthalates today.
Source: EPA 2007 Link to this fact
What you can do / Government agency
A resident of HUD-assisted housing with a documented chemical sensitivity can cite this HUD exhibit directly when requesting advance notice before common-area cleaning and nonchemical cleaning products where practical, since HUD's own guidance names these as accommodations that are not an undue burden.
Moderate evidence.
Caveats
Applies specifically to HUD-assisted (Section 504-covered) multifamily housing; the same specific accommodations are not guaranteed at privately owned housing covered only by the Fair Housing Act, where the undue-burden analysis is done case by case.
Source: HUD Occupancy Handbook 4350.3 REV-1, Exhibit 2-6 (2007) Link to this fact
What you can do / Government agency
Anyone can report a safety problem with a consumer product to CPSC by filing on SaferProducts.gov, and CPSC publishes qualifying reports of harm or potential harm in the site's searchable public database, where businesses can also respond.
Moderate evidence: CPSC states it does not guarantee the accuracy, completeness, or adequacy of report contents, particularly those submitted by people outside CPSC.
Source: CPSC 2026 Link to this fact
What you can do / Government agency
Anyone can download CPSC's full set of recalls and unsafe-product reports through SaferProducts.gov's "Public Database Export" tool.
Moderate evidence.
Source: CPSC 2026 Link to this fact
What you can do / Government agency
The US EPA states that using a biocide such as chlorine bleach is not recommended as a routine practice during mold cleanup, reserving it for specific circumstances such as when immunocompromised people are present; the described default method is scrubbing with ordinary detergent and water.
Moderate evidence: Agency recommendation, not a controlled comparison of bleach vs. detergent-and-water efficacy.
Source: US EPA, "A Brief Guide to Mold, Moisture and Your Home" (accessed 2026-09-28) Link to this fact
What you can do / Government agency
EPA warns that dead mold can still cause allergic reactions in some people, so killing mold (with bleach or otherwise) is not enough; it must also be physically removed.
Moderate evidence: Assertion, no citation given.
Source: US EPA, "A Brief Guide to Mold, Moisture and Your Home" Link to this fact
What you can do / Government agency
EPA's criterion for when mold cleanup or remediation is finished is functional and inspection-based (water problem fixed, no visible mold or moldy odor, no signs of recurrence on a follow-up visit, people can occupy without health complaints), not a fixed number of days away from the area.
Moderate evidence: EPA itself calls this 'a judgment call; there is no easy answer'.
Source: US EPA, "A Brief Guide to Mold, Moisture and Your Home" Link to this fact
What you can do / Government agency
EPA's official framework for improving indoor air quality ranks three strategies in order: (1) source control (remove or reduce the pollutant source), (2) increased ventilation, and (3) air cleaners, which EPA says are far more effective for particles than for gaseous pollutants.
Moderate evidence: Agency guidance/assertion, not a controlled comparison of the three strategies.
Source: US EPA, "The Inside Story" Link to this fact
What you can do / Measured in people or real products
Choosing toothpaste, soap, and deodorant that do not list triclosan (or Irgasan) on the label is a reasonable way to lower plasma and breast-milk triclosan levels, though it will not eliminate all exposure.
Moderate evidence.
Caveats
This single study alone would be weak support for a what-you-can-do claim; strength here rests on corroboration from the independent HERMOSA 2016 intervention trial (different population, different design) rather than on Allmyr 2006 alone.
Source: Allmyr 2006, Science of The Total Environment Link to this fact
What you can do / Measured in people or real products
Per this study, there is currently no reliable way for a consumer to tell from 'nanotechnology-based' vs 'regular' labeling alone whether a spray product contains detectable nanoparticles or how much aerosol they will inhale from using it.
Moderate evidence: Based on a 10-product single-lab study; a larger product survey could find a stronger or weaker relationship.
Source: Nazarenko 2014, Environmental Science: Nano Link to this fact
What you can do / Measured in people or real products
If a constant smell at home or work has faded for you but a visitor still notices it, that is a normal habituation effect on your part, not proof the smell is gone or that the visitor is being oversensitive.
Moderate evidence: Based on general human olfactory-habituation evidence reviewed in this paper, not a study of visitor/resident comparisons specifically.
Source: Pellegrino 2017, Physiology & Behavior Industry-funded Link to this fact
What you can do / Government agency
People who want to minimize systemic absorption of chemical UV filters while the additional toxicology studies FDA has requested remain outstanding can choose mineral-only sunscreens with zinc oxide or titanium dioxide as the active ingredient, the two filters FDA's own review has found 'generally recognized as safe and effective,' or rely on protective clothing and shade alongside sunscreen.
Moderate evidence.
Caveats
This is not a claim that chemical-filter sunscreens are unsafe, and it is not advice to avoid sun protection; the paper explicitly says its results do not indicate people should refrain from sunscreen use.
Source: Matta 2019, JAMA Link to this fact
What you can do / Other evidence
Pump and trigger sprays put far less of the product into the lung-reaching respirable range than aerosol versions of the same product: recommended respirable-fraction ranges are 0-2% for hair, deodorant, body, sunscreen, and facial pump sprays, versus 2-35% for the equivalent aerosols.
Moderate evidence.
Caveats
These are industry-compiled default ranges for safety-assessment purposes, not a head-to-head measurement of the same formulation in both formats; actual respirable fraction depends on the specific product's nozzle, pressure and formulation.
Source: Steiling et al. 2025, Toxicology Letters Industry-funded Link to this fact
What you can do / Government agency
Consumers checking an EU cosmetic ingredient list for a specific fragrance allergen above 2026-2028 should expect to see roughly 80 possible individually-named substances rather than the older list of about 24-26, including many now-named essential-oil species.
Moderate evidence: This is a practical implication of the regulation's content and transition dates, not itself tested by a product-labeling survey of post-2023 EU products in our evidence base.
Source: Regulation (EU) 2023/1545 Link to this fact
What you can do / Measured in people or real products
If you want an accurate sense of how strong your own perfume or home's ambient scent really is, ask someone who was not continuously exposed, since your own nose will have adapted specifically to that scent while remaining normally sensitive to everything else.
Moderate evidence.
Caveats
Based on an 8-person controlled study; the general mechanism (odorant-specific adaptation) is well replicated, but this specific framing is a reasonable extrapolation, not a tested intervention.
Source: Dalton & Wysocki 1996, Perception & Psychophysics Link to this fact
What you can do / Review of other studies
If you have diagnosed fragrance or deodorant-ingredient allergy, ask your dermatologist about expanded patch testing (balsam of Tolu, fragrance mix 2, botanicals, lichen acid mix) if a standard fragrance screen is negative but suspicion remains, since the standard screen is estimated to miss a meaningful share of true fragrance allergy.
Moderate evidence: Practice recommendation from a narrative clinical review, not from an interventional study measuring whether expanded testing changes diagnostic outcomes.
Source: Zirwas & Moennich 2008, The Journal of Clinical and Aesthetic Dermatology Link to this fact
What you can do / Other evidence
Hairdressers, salon workers, and professional or domestic cleaners can reduce workplace asthma risk with ventilation, gloves, and lower-irritancy products or application methods where available, since this population-based cohort found both hairdressing and cleaning occupations, and reactive cleaning/disinfecting chemical exposure specifically, associated with higher adult-asthma risk.
Moderate evidence.
Caveats
The study cannot identify which specific chemicals within 'hairdressing' or 'cleaning/disinfecting' exposure are responsible, so this is general occupational-hygiene advice, not a product-specific recommendation.
What you can do / Other evidence
A 2006 Belgian consumer survey found people burn scented candles only about 7-10 times a month for roughly 2 hours at a time, mostly in the living room, which is why realistic exposure estimates come out far lower than worst-case continuous-exposure modeled estimates.
Moderate evidence.
Caveats
Single market-research survey of one country (Belgium, 2006), commissioned by a government health ministry but not independently replicated elsewhere or more recently; candle-use habits may differ by country or have changed since 2006.
Source: Petry 2014, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
What you can do / Other evidence
Ventilating a room during and after burning a candle is a reasonable precaution even when an industry-funded modeling study's exposure estimates look low, since those estimates depend entirely on which pollutants were tested for and how sensitive the test method was.
Moderate evidence: Inference drawn from comparing this paper's pollutant panel/detection limits to a later study's findings, not a recommendation stated by this paper itself.
Source: Petry 2014, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
What you can do / Other evidence
Splitting 'hair styling products' into its five actual types shows a 15-fold difference in modeled exposure between the highest (styling foam, 20.71 mg/kg bw/day at the 90th percentile for women 15-39) and lowest (styling wax, 1.41 mg/kg bw/day for the same group) — a single regulatory default of 5.74 mg/kg bw/day for 'hair styling products' hides that spread.
Moderate evidence: Exposure is modeled, not measured; reflects French usage patterns (frequency and amount) which may not generalize to other countries.
Source: Ficheux et al. 2016 (exposure assessment), Food and Chemical Toxicology Link to this fact
What you can do / Self-reported survey
65.5% of autistic adults would support a fragrance-free workplace policy and 77.2% would prefer fragrance-free health care facilities and professionals, compared with 46.1% and 45.8% support among non-autistic adults.
Moderate evidence: Stated preference, not an intervention study; self-report survey.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
What you can do / Measured in people or real products
Air change rate and indoor VOC concentration were strongly, negatively correlated across hotel spaces (R2=0.69): rooms and break/laundry areas with higher ventilation rates had markedly lower total VOC levels, and the hotel's existing ventilation (average 2.5 air changes/hour) was credited with keeping absolute VOC levels and health risks low despite multiple identified indoor sources.
Moderate evidence: Single hotel (Hotel 1) for the ACR-TTVOC correlation; one outlier excluded from the regression; ACR estimates from the CO2 decay method are approximate.
What you can do / Other evidence
Ventilating a bathroom or other small room during and right after cleaning (opening a window, running an exhaust fan) is likely to cut both the particle and VOC bump from cleaning, since the single biggest difference between a low-impact room and a high-impact room in this study was air change rate, not which cleaner was used.
Moderate evidence: Based on one study's four rooms, not a controlled ventilation experiment within one room; advice is directionally supported, not quantified for a specific home.
Source: Souza 2025, ACS Earth Space Chem, ACS Earth and Space Chemistry Link to this fact
What you can do / Other evidence
When only cleaning (not disinfecting a specific pathogen), wiping up a quats disinfectant promptly rather than letting it sit for several minutes keeps both PM2.5 and TVOC much lower; leaving it the full label-specified 10-minute disinfection dwell time in a bathroom raised PM2.5 by 68% and TVOC about 8-fold compared with a 2-3 minute wipe-off.
Moderate evidence.
Caveats
Single bathroom, small N (1-5 per condition); a shorter dwell time may not achieve the disinfection the label is written for, so this is a cleaning-vs-disinfecting tradeoff, not a free upgrade.
Source: Souza 2025, ACS Earth Space Chem, ACS Earth and Space Chemistry Link to this fact
What you can do / Measured in people or real products
Adult men who used hair-styling gel applied nearly twice as much per use (95th percentile 10.3 g, n=40) as adult women did (95th percentile 4.3 g, n=41), while men used noticeably less liquid shampoo and less aerosol hairspray per application than women — the amount of a given product type used per application varies substantially by gender, not in one consistent direction.
Moderate evidence.
Source: Ficheux et al. 2016 (amount data), Food and Chemical Toxicology Link to this fact
What you can do / Measured in people or real products
Hairdressers and salons should treat glove use during hair-dye mixing and application as a partial, not complete, exposure-reduction measure, since hand contamination in this study was still highest during the ungloved cutting and drying of just-dyed hair.
Moderate evidence: The study did not test gloves vs. no gloves within the same task; see the glove-efficacy contradiction.
Source: Hueber-Becker et al. 2007, Food and Chemical Toxicology Industry-funded Link to this fact
What you can do / Review of other studies
Whether an odor affects mood or physiology depends more on how pleasant a person finds it and what they expect it to do than on which specific plant or chemical produced it; hedonic (liking) ratings predicted physiological and psychological outcomes across most of the 18 studies reviewed.
Moderate evidence: Narrative synthesis across 18 heterogeneous studies using different odors, doses and measures; not a meta-analysis.
Source: Herz 2009, International Journal of Neuroscience Industry-funded Link to this fact
Information, not medical advice. See also: myths we won’t tell you.