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.
Children and pregnancy / Measured in people or real products
In 34 California childcare centers, the chemicals at the highest levels in the air children breathed came from cleaning and personal-care products: a silicone ingredient called D5 (median 51 µg/m³) and the citrus-scent chemical limonene (median 33 µg/m³).
Strong evidence: Single-day samples; upper values capped by calibration (underestimates).
Children and pregnancy / Review of other studies
Children exposed to household chemical/cleaning products before birth or in their first year wheeze more often, now replicated in four independent prospective birth cohorts. The founding ALSPAC cohort (UK, n=7,019, Sherriff et al. 2005) found that an 11-product, frequency-weighted prenatal household chemical (TCB) score was significantly associated with persistent wheeze through 3.5 years (adjusted OR 1.06 per unit increase; top-vs-bottom-decile adjusted OR 2.3), but not with transient early or late-onset wheeze; this is the same ALSPAC cohort and composite-score methodology that both Casas 2013 and Mikeš 2019 name as their model. In the Canadian CHILD cohort (n=2,022), frequent use in early infancy was linked to higher odds of recurrent wheeze (adjusted OR 1.35) and asthma diagnosis (adjusted OR 1.37) by age 3, but not isolated skin-prick allergy (adjusted OR 1.14, ns), though wheeze combined with allergy was itself raised (adjusted OR 1.49). In the Czech ELSPAC-CZ cohort (n=3,411), each 1-SD increase in an 18-product household chemical exposure score at 6 months raised the odds of intermediate-onset transient, intermediate-onset persistent, and early-onset persistent wheeze phenotypes through age 5 (adjusted OR 1.23-1.36), and those persistent phenotypes carried 5-8x higher odds of doctor-diagnosed asthma at age 7 (pediatrician records, not self-report). In the pooled Spanish INMA cohorts (n=2,292), prenatal (third-trimester) use of cleaning sprays raised the odds of both wheezing (OR 1.37) and lower respiratory tract infection (OR 1.29) in the first year of life, with solvents raising wheezing odds (OR 1.30) and air fresheners raising LRTI odds (OR 1.29); bleach, ammonia, and non-spray cleaners showed no association.
Strong evidence.
Caveats
All four cohorts are observational and use self-reported product-use frequency, not measured indoor air chemistry. The ALSPAC/Sherriff 2005 and ELSPAC-CZ signals are specific to persistent-type wheeze phenotypes, not wheeze in general; ALSPAC found no association with transient early or late-onset wheeze. The 'not atopy' finding remains single-cohort (CHILD only); ELSPAC-CZ's atopic-rash variable is a covariate, not an outcome, and Casas 2013 measured neither atopy nor a physician asthma diagnosis, only maternal-reported LRTI and any-wheezing through 12-18 months, so it neither confirms nor refutes the atopy finding; ALSPAC/Sherriff 2005 did not assess atopy or asthma at all. Casas 2013 is the only cohort among the three post-2010 cohorts with genuinely prenatal (rather than early-postnatal) exposure measurement, but ALSPAC/Sherriff 2005 is also prenatal and its composite score behaved like CHILD's and ELSPAC-CZ's (significant), not like Casas's (null) — evidence against prenatal timing per se explaining the Casas null. Casas 2013's own summed cleaning-product-count score was NOT a significant predictor, unlike ALSPAC's, CHILD's, and ELSPAC-CZ's frequency-weighted composite scores — an open methodological tension (register entry C262) that means 'more products used' is not yet a uniformly replicated exposure metric across all cohorts, even though several specific products (sprays consistently, plus solvents and air fresheners) are.
Source: Salonen 2024, Environment International Link to this fact
Children and pregnancy / Measured in people or real products
In a national Canadian birth cohort (n=2,022), infants in homes with more frequent use of household cleaning products at 3–4 months of age had higher odds of recurrent wheeze (adjusted OR 1.35 per interquartile increase in use) and of an asthma diagnosis (adjusted OR 1.37) by age 3, but no higher odds of isolated allergic sensitization (skin-prick positivity).
Strong evidence.
Caveats
Observational; the authors explicitly state their results do not prove causation. Recurrent wheeze combined with atopy was itself significantly increased (adjusted OR 1.49), so isolated atopy — not allergic sensitization in general — is what showed no association.
Source: Parks et al. 2020, CMAJ (Canadian Medical Association Journal) Link to this fact
Children and pregnancy / Measured in people or real products
Childcare air had about three times more limonene than new California homes (33 vs 11 µg/m³), which the authors link to frequent cleaning.
Moderate evidence: Comparison with a different study (Offermann 2009); daytime vs 24-h sampling.
Children and pregnancy / Self-reported survey
Mothers who use cleaning sprays during pregnancy have infants with higher odds of both a lower respiratory tract infection (29% higher, OR 1.29) and wheezing (37% higher, OR 1.37) in their first year of life, in a pooled analysis of four Spanish birth cohorts (n=2,292); prenatal solvent use also raised wheezing odds (30% higher) and prenatal air freshener use raised LRTI odds (29% higher).
Moderate evidence.
Caveats
Single research group/dataset (pooled INMA cohorts, all Spanish, one study design), self-reported exposure and outcome by mothers, and only 12-18 month follow-up (no atopy or physician-diagnosed asthma measured). Consistent in direction with two other independent cohorts (Parks 2020, Canada; Mikeš 2019, Czech Republic) that measured early-postnatal rather than prenatal exposure, which is why the combined three-cohort claim is graded strong elsewhere while this single-paper prenatal-specific finding stays moderate.
Source: Casas 2013, International Journal of Public Health Industry-funded Link to this fact
Children and pregnancy / Self-reported survey
In a random sample of Swedish teenagers aged 13-19, about 1 in 6 (15.6%) said they were bothered by strong odors such as perfume, cleaning agents, or flower scents, most often affecting the nose.
Moderate evidence: Single-item self-report; general odor sensitivity, not fragranced-product-specific; one Swedish town.
Source: Andersson 2008, International Journal of Hygiene and Environmental Health Link to this fact
Children and pregnancy / Measured in people or real products
The protective association between bleach cleaning and reduced allergy/asthma risk was abolished in households with parental smoking; in that subgroup, bleach use was instead linked to a higher rate of recurrent bronchitis (adjusted OR for the smoking-by-bleach interaction, 2.03, 95% CI 1.12-3.66).
Moderate evidence: Subgroup/interaction analysis from a single cross-sectional study; the recurrent-bronchitis outcome is parent-reported, not medically confirmed.
Source: Nickmilder, Carbonnelle & Bernard 2007, Pediatric Allergy and Immunology Link to this fact
Children and pregnancy / Self-reported survey
In a Dutch birth cohort of 2,333 adolescents (age 14), a composite score for household use of 10 types of cleaning agents was not associated with asthma, rhinitis, or eczema, even at the highest exposure quartile: adjusted OR (95% CI) 0.95 (0.56, 1.63) for asthma, 1.23 (0.83, 1.82) for rhinitis, and 0.95 (0.56, 1.63) for eczema, comparing highest to never/seldom use.
Moderate evidence.
Caveats
Cross-sectional, single cohort, parent-reported exposure and outcomes; adolescents are not the ones doing the cleaning, so this speaks to a low-exposure life stage rather than ruling out effects at higher exposure (e.g. prenatal/infancy).
Source: Bukalasa et al. 2019, Environment International Link to this fact
Children and pregnancy / Self-reported survey
A sensitivity analysis restricted to the 988 adolescents (42% of the cohort) reported to be sometimes or mostly present at home during cleaning activities again found no association between the composite cleaning-agent-use score and asthma, rhinitis, or eczema, confirming the main null result.
Moderate evidence.
Caveats
Smaller subsample (n≈988) with wider confidence intervals; one rhinitis point estimate for the low-exposure category rose to adjusted OR 2.14 (95% CI 1.04, 4.41) without a dose-response pattern across categories, which the authors do not treat as a real effect.
Source: Bukalasa et al. 2019, Environment International Link to this fact
Children and pregnancy / Self-reported survey
Household ammonia use was the only one of 10 individual cleaning agents (out of 30 agent-outcome comparisons) significantly associated with an outcome in this study: adolescents in homes where ammonia was ever used had lower odds of rhinitis, adjusted OR 0.60 (95% CI 0.44, 0.82), than those in homes that never used it.
Weak evidence.
Caveats
The study's own authors call this a likely chance finding given the number of associations tested and their limited statistical power to explore it further; not a basis for claiming ammonia protects against rhinitis.
Source: Bukalasa et al. 2019, Environment International Link to this fact
Information, not medical advice. See also: myths we won’t tell you.