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.
Health effects / Review of other studies
Doctors have published detailed reports of 12 young children (8 boys, 4 girls) whose breasts began to grow while they used lavender or tea tree oil products such as colognes, baby bath soap, or hair gel; in every case the growth went away within months of stopping.
Weak evidence: Case reports only; no rechallenge; this kind of breast growth often regresses on its own; the review itself concludes causation is not shown.
Source: Braunstein & Braunstein 2023, touchREVIEWS in Endocrinology Industry-funded Link to this fact
Health effects / Review of other studies
Dermatologists judge that the allergy seen in a small proportion of children given aluminum-containing vaccines does not outweigh the benefit of vaccination for almost all children.
Weak evidence: Authors' opinion citing FDA and CDC positions; the paper presents no benefit-risk analysis of its own.
Source: Novack 2022, Cutis Link to this fact
Health effects / Other evidence
Children living in New York homes with median perchloroethylene near 340 micrograms per cubic meter showed subtle vision effects in a 2010 state health department study, as relayed by the county.
Weak evidence: One relayed study; primary not read here; cross-sectional and for homes above dry cleaners, so other exposures cannot be excluded.
Source: SCDHS 2018 Link to this fact
Health effects / Other evidence
Only one study in the EPA review looked at a clinical ADHD diagnosis: in a Norwegian cohort of 802 children, higher mid-pregnancy urinary DEHP metabolites went with 1.5 times the odds of ADHD (CI 1.1 to 1.9), while DEP, DBP, DIBP and DINP showed no higher odds.
Weak evidence: One study, association only, single urine sample; DEHP is a plastics and food-contact phthalate, not a fragrance one; EPA still rated the DEHP-behavior evidence 'slight'.
Source: Radke 2020, Environment International Link to this fact
Health effects / Other evidence
The review reports a meta-analysis of 27 mostly Chinese cross-sectional studies of children drinking fluoride-rich water, with an average IQ difference of about 7 points, while the authors say the dose-response needs further characterization.
Weak evidence: Cross-sectional studies in high-fluoride areas, not studies of fluoridated water in the US or Europe; the authors themselves ask for better dose-response data.
Source: Grandjean & Landrigan 2014, Lancet Neurology, The Lancet Neurology Link to this fact
Health effects / Other evidence
In CHAMACOS, prenatal sums of high-molecular-weight and DEHP phthalate metabolites went with lower IQ in boys and higher IQ in girls (interaction p = 0.01), but the boys' intervals included zero and the all-children results were null.
Weak evidence.
Caveats
Exploratory sex-stratified analysis; DEHP and other HMW phthalates are plastics and food-contact chemicals, not fragrance; the supplement carries more detail; the abstract and text differ slightly on one girls' CI.
Source: Hyland 2019 (CHAMACOS), Environmental Health Perspectives Link to this fact
Health effects / Review of other studies
A 2022 European scoping review that tallied other authors' reviews, without grading study quality, put lead, phthalates and BPA in its 'moderate to high' tier for association with ADHD in children.
Weak evidence.
Caveats
Counts review conclusions rather than appraising evidence; the authors state they did not evaluate evidence quality; heavy overlap between included reviews; contrast US EPA's graded review, which rated phthalate-ADHD evidence slight or indeterminate.
Source: Moore 2022 Link to this fact
Health effects / Measured in people or real products
Higher prenatal pentachlorophenol (a wood preservative) was linked to lower cognitive scores only among children of non-smoking mothers (-2.17 points, 95% CI -3.83 to -0.51), not among children whose mothers had tobacco exposure.
Weak evidence: Exploratory interaction (p = 0.012) among 36 tests, no correction; only 113 non-smokers; direction opposite to the usual expectation; not a personal-care or fragrance chemical.
Source: Zhou 2025, Environmental Research Industry-funded Link to this fact
Health effects / Measured in people or real products
In 1,297 European children aged 6 to 11, higher urinary methyl-paraben and the phthalate metabolites MEHP, oh-MiNP and oxo-MiNP went with slightly more variable reaction times on a computer attention test (about 2 to 4% higher on the log scale for a 10th-to-90th percentile rise).
Weak evidence.
Caveats
Cross-sectional with a pooled two-sample urine reflecting about one day; 4 nominal hits among 21 chemicals with no multiple-comparison correction reported; oh-MiNP lower CI is 0.001; effects are small.
Source: Fabbri 2025 (HELIX), Environmental Research Link to this fact
Health effects / Measured in people or real products
In the same children, many chemicals (BPA, ethyl-paraben, MEHP, oh-MiNP, oxo-MiNP, methyl-paraben and some pesticide metabolites) went with higher urinary cortisol, cortisone and corticosterone production, with BPA largest (about 0.26 to 0.29 on the log scale).
Weak evidence.
Caveats
Cross-sectional; hormones from the night urine and chemicals from a different pooled sample; no multiplicity correction; mechanism (e.g. 11-beta-HSD2 inhibition) is from in-vitro work cited by the authors.
Source: Fabbri 2025 (HELIX), Environmental Research Link to this fact
Health effects / Other evidence
A 2025 narrative review says BPA, PBDEs, PCBs, PFAS, phthalates, perchlorate, pesticides and metals can disturb thyroid hormone production, transport or metabolism, but much of that rests on lab, animal or small hormone-level studies rather than proof of harm to children.
Weak evidence: No systematic methods; mechanisms for phthalates cited from a PBDE review and a 1983 in vitro paper.
Source: Eraslan Aydemir & Sahin 2025, Turk J Med Sci, Turkish Journal of Medical Sciences Link to this fact
Health effects / Measured in people or real products
Among all children in this ECHO analysis, the only single-compound result with a confidence interval excluding zero was a lower sleep-impairment score (about 4.8 T-score points) in the middle methylparaben exposure tertile versus the lowest, with no dose-response in the top tertile.
Weak evidence.
Caveats
One of about 24 single-compound comparisons with no multiple-comparison correction; the paper's own Results wrongly describe it as 'per unit increase'; direction is opposite to the authors' hypothesis, so it is not evidence of harm or benefit.
Source: Geiger 2025, Frontiers in Pediatrics Link to this fact
Health effects / Review of other studies
In this review the most developed thyroid-to-brain chain is for PCBs: in rats, developmental PCB exposure lowers thyroxine and causes hearing and motor deficits, and thyroxine replacement attenuates them; for phthalates it cites only an exposure-thyroid association in preschool children, with no mediation test.
Weak evidence: Rat data for PCBs (not a fragrance ingredient); the phthalate thyroid link is one association and Engel 2018's null mediation result is not cited.
Source: Jocsak 2026, Frontiers in Behavioral Neuroscience Link to this fact
Health effects / Other evidence
In a small German clinic study of 60 children and adolescents, unmedicated children with ADHD detected a rose-like odorant (2-phenylethanol) at lower concentrations than matched healthy children (a large difference, Cohen's d 1.27), while telling odors apart and naming them was normal.
Weak evidence.
Caveats
One single-center study with 20 per group, no replication in our evidence base; it measures lab odor detection of one non-irritant odorant, not reactions to fragrance or chemical intolerance.
Source: Romanos 2008, Biological Psychiatry Link to this fact
Health effects / Other evidence
Children with ADHD who were taking methylphenidate did not differ significantly from healthy controls on odor detection, but this compares separate groups of 20, not the same children before and after treatment.
Weak evidence: Cross-sectional between-group comparison; medication was not randomized; dopamine mechanism is a hypothesis from animal work.
Source: Romanos 2008, Biological Psychiatry Link to this fact
Health effects / Other evidence
Because ADHD is strongly familial (siblings of affected children have about nine times the risk), studies linking parents' exposures or traits to child ADHD can partly reflect shared genes unless parental genetics are controlled.
Weak evidence: This is our inference from the review, not a finding of the review; whether specific chemical studies are affected has to be checked paper by paper.
Source: Faraone 2019, Molecular Psychiatry Link to this fact
Health effects / Other evidence
Studies of urinary parabens and attention in children and teens disagree in direction: a Dutch adolescent cohort found better ratings with methylparaben, while a six-country child cohort found worse attention with methylparaben.
Weak evidence: Different ages, tests and designs, all cross-sectional single spot urines with no or limited multiplicity control. Not a fragrance result.
Health effects / Other evidence
The replacement plasticizer DEHTP was associated with lower infant composite and visual-reception scores (composite beta -0.11, 95% CI -0.21 to -0.01) but with a lower, not higher, risk of an ASD classification (RRR 0.50, 0.30-0.83) in the same children.
Weak evidence: Opposite directions in one dataset suggest chance or genetic-risk confounding in an enriched-risk cohort; DEHTP is not a fragrance ingredient.
Source: Sotelo-Orozco 2024, International Journal of Hygiene and Environmental Health Link to this fact
Health effects / Review of other studies
In six small case-control studies reviewed in 2026 (30 to 80 per group), children with ADHD had different gut bacteria on average (lower alpha diversity, fewer Lactobacillus and Bifidobacterium, lower fecal short-chain fatty acids), but no study measured chemical exposure, the microbiome and ADHD in the same children.
Weak evidence: Cross-sectional, heterogeneous methods; one tabulated study is itself a meta-analysis; effect sizes not reported.
Source: Wu 2026, Biological Psychiatry Global Open Science Link to this fact
Health effects / Other evidence
ADHD prevalence in the 2007 review was higher in boys than girls (about 10% vs about 4%) and in children than adolescents (about 6.5% vs about 2.7%).
Weak evidence: Values read from a chart, not printed; sex and age strata came from fewer than half the studies and were not in the adjusted model.
Source: Polanczyk 2007, American Journal of Psychiatry Industry-funded Link to this fact
Health effects / Review of other studies
A 2025 review's 'Schecklmann 2011' result of higher odor discrimination after stimulant washout comes from a different paper (children on and off methylphenidate), not this adult study, where discrimination did not differ (13.55 vs 13.21 of 16, p = 0.43).
Weak evidence: The J Psychiatr Res paper itself has not been read in this evidence base; attribution rests on its PubMed abstract.
Source: Schecklmann 2011, Neuropsychobiology Link to this fact
Health effects / Other evidence
Pooling five double-blind crossover trials, restriction (elimination) diets reduced ADHD symptoms by about 0.29 standard deviations, roughly a third of a stimulant effect, with a conservative estimate that about 33% of children with ADHD respond.
Weak evidence.
Caveats
Only a handful of old, small trials; the effect is not specific to food colors; the abstract and text give different confidence intervals (0.07-0.53 vs 0.16-0.52); one outlying study was excluded to resolve heterogeneity.
Source: Nigg 2012 Industry-funded Link to this fact
Health effects / Other evidence
Laboratory attention tests showed a reliable but small-sample effect of food colors (6 studies, 154 children, 0.27, 95% CI 0.07 to 0.47); the authors judge it too small and too old to support clinical or policy recommendations.
Weak evidence: Only 68 children in FDA-color-only studies; the colors-only result is vulnerable to single-study removal.
Source: Nigg 2012 Industry-funded Link to this fact
Health effects / Other evidence
The paper's estimate that about 8% of children with ADHD may have symptoms related to food colors multiplies a 24% color-reaction rate by a 33% diet-responder rate, and the authors say its confidence interval would be large and could not be computed.
Weak evidence: Rate comes from children preselected as diet responders; not a population prevalence.
Source: Nigg 2012 Industry-funded Link to this fact
Health effects / Other evidence
In a small Serbian clinic study, 24 children aged 7-14 with ADHD, all taking methylphenidate, named fewer familiar odors correctly than 26 healthy children (about 6.2 vs 8.9 of 14, p < 0.001).
Weak evidence: Single clinic, n = 24 vs 26, all ADHD children medicated, IQ not measured in controls, no covariate adjustment; a trait outcome, not a fragrance exposure.
Source: Vučinić et al. 2016, Engrami Link to this fact
Health effects / Other evidence
The same study found children with ADHD were slightly worse at telling odors apart (about 8.9 vs 9.8 of 16, p < 0.05), a borderline difference.
Weak evidence: Exact p value not given; from the printed means and SDs a t-test gives about p = 0.05; no multiplicity correction.
Source: Vučinić et al. 2016, Engrami Link to this fact
Health effects / Other evidence
Studies of smell in children with ADHD disagree: a German study found better odor detection in unmedicated children, while this Serbian study found worse odor identification and discrimination in medicated children.
Weak evidence: Different subtests (threshold vs identification/discrimination) and medication status; both small single-center studies.
Source: Vučinić et al. 2016, Engrami Link to this fact
Health effects / Other evidence
In about 2,700 Barcelona schoolchildren aged 7-11, higher traffic-related air pollution measured at school (elemental carbon, NO2) went with about 7-8% higher parent-reported behavioral difficulty scores per interquartile range, and the pattern held after adjusting for classroom noise.
Weak evidence: Cross-sectional, 39 school-level exposure values, parent-rated only, small effect; not a causal estimate. Air pollution is not fragrance-related.
Source: Forns 2016, Environmental Health Perspectives Link to this fact
Health effects / Review of other studies
In this meta-analysis, pooled studies of pesticides, PCBs and trichlorophenol in children found no overall association with ADHD (odds ratio 0.99, 95% CI 0.96-1.02 in the text; 1.03 in Table 1), with very low to low certainty.
Weak evidence: Heterogeneous chemicals grouped for lack of studies; the authors say no specific conclusion can be drawn; publication bias flagged for this group.
Source: Nilsen and Tulve 2020, Environmental Research Link to this fact
Health effects / Other evidence
In the olfactory studies the review pooled, children with ADHD stopped from methylphenidate showed no difference from controls in odor threshold or identification in one study (p = 0.345 to 0.855), against a lower threshold in the other (p < 0.004).
Weak evidence: Two small German clinic studies (20 per group; 13-22 per group); the lower-threshold result is not replicated; trait measure on a rose-like odorant, not odor intolerance.
Source: Recarey-Rama 2025, Journal of Psychiatric Research Link to this fact
Health effects / Other evidence
The review's abstract says children on methylphenidate had worse odor discrimination than unmedicated children, but the one study that measured it found higher discrimination in the unmedicated (withdrawal) group than in controls (p = 0.009) and no significant difference from the medicated group (p = 0.068).
Weak evidence: The abstract summary is not supported by its own table; both groups are cross-sectional, different children.
Source: Recarey-Rama 2025, Journal of Psychiatric Research Link to this fact
Health effects / Other evidence
Children with ADHD not on methylphenidate reported less pain than controls (p = 0.015) in a German survey of 260 children, while medicated children did not differ from controls (p = 0.782).
Weak evidence: Single study with a self-constructed parent/child questionnaire; cross-sectional between-group comparison; opposite results in Turkish and US studies cited by the authors.
Source: Recarey-Rama 2025, Journal of Psychiatric Research Link to this fact
Health effects / Other evidence
Two French studies found worse postural control in children with ADHD that improved after about a month of methylphenidate, but a German study with methylphenidate plus atomoxetine did not replicate it.
Weak evidence: Small samples (14 to 38 per group); not an environmental or fragrance finding; mixed medication in the null study.
Source: Recarey-Rama 2025, Journal of Psychiatric Research Link to this fact
Health effects / Other evidence
A 2026 meta-analysis of 29 observational studies found children with higher exposure to traffic-type air pollutants had modestly higher odds of ADHD: about 1.3 times for PM2.5 per study-specific increment (OR 1.32, 95% CI 1.16-1.50) and 1.5 times for PM10 (OR 1.47, 1.15-1.87).
Weak evidence.
Caveats
Not fragrance-related: noise and outdoor air pollutants. Observational; I2 90-97%; increments differ by study; pooled effect carried by diagnosis-based studies; no familial or sibling designs; authors say association, not causation.
Source: Zhang 2026, Frontiers in Psychiatry Link to this fact
Health effects / Other evidence
E-cigarette use in pregnancy showed only sparse, unsystematic associations with child behavior scores in children aged 10 or younger (3.90% exposed), too imprecise to call safe or harmful.
Weak evidence: Subset; wide confidence intervals; authors call it preliminary.
Source: Marceau 2026 (ECHO), Development and Psychopathology Link to this fact
Information, not medical advice. See also: myths we won’t tell you.