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.
Children and pregnancy / Measured in people or real products
In 130 Danish and Finnish mothers, phthalate breakdown products were reported in essentially every breast milk sample (95-100% for each of the six measured) — but an independent, more contamination-controlled US study (Hines 2009) found the analogous class of monoester phthalate metabolites in under 10% of milk samples from a separate cohort, and declined to report its own milk hydrolytic-monoester data (which would include MEP) as likely contamination-inflated.
Weak evidence.
Caveats
1997-2001 samples; composite home-collected milk; phosphoric acid was not added at collection 'due to logistics' (this page's own Methods/limitations), a known contamination risk for hydrolytic monoesters. Hines 2009 (EPA/CDC, tighter contamination controls) found the analogous metabolite class in <10% of milk samples and withheld its own milk hydrolytic-monoester data on contamination grounds. US EPA systematic review (Radke 2018) separately excluded this study's milk data as a critically deficient exposure matrix.
Source: Main 2006, Environmental Health Perspectives Link to this fact
Children and pregnancy / Measured in people or real products
Baby boys whose mothers' milk contained more dibutyl phthalate had slightly lower free testosterone at 3 months (about 15% lower per 10-fold rise). For diethyl phthalate, the fragrance phthalate, the link was with higher SHBG, and its free-testosterone trend was not significant. These are correlations in 96 boys, not proof of harm.
Weak evidence.
Caveats
MBP–free T r = −0.22 (p = 0.033); mEP–free T r = −0.19 (p = 0.07, NS). US EPA review excluded this study (breast milk critically deficient as an exposure matrix for short-chain phthalates) and rated infant-testosterone evidence indeterminate (Lin 2011: MEP r = −0.10). 46% of Danish mothers used breast pumps.
Source: Main 2006, Environmental Health Perspectives Link to this fact
Children and pregnancy / Measured in people or real products
In one early, small US study, boys in the highest phthalate group had about 4 to 10 times the odds (3.8-10.2) of a shorter-than-expected anogenital distance than the lowest group, depending on the phthalate. A larger (N=753) follow-up by the same group found much smaller effect sizes for the one phthalate class (DEHP) that replicated, and did not test comparable categorical odds ratios.
Weak evidence.
Caveats
Single small cohort with very wide CIs (MEP OR 3.8, 1.03-13.9); US EPA rated this cohort's AGD data (extended n=106) low confidence. The DEP (MEP) part did not replicate in three larger cohorts, including the same group's own N=753 TIDES follow-up (Swan 2015), which also found smaller continuous effect sizes for the metabolites that did replicate (DEHP: beta -1.12 to -1.43 in TIDES vs -3.50 to -5.13 in this cohort, per Swan 2015's Discussion), consistent with lower current-day exposure. Quote as one small study's result only; prefer the EPA review or Swan 2015 for general claims.
Source: Swan 2005, Environmental Health Perspectives Link to this fact
Children and pregnancy / Measured in people or real products
In a Danish–Finnish study (hormones measured in 96 of 130 baby boys), some phthalates in mothers' breast milk went with hormone changes at 3 months that point to weaker male-hormone action (higher SHBG; lower free testosterone for dibutyl phthalate only).
Weak evidence.
Caveats
Association; hormones in 96 boys; mEP (DEP) free-T link not significant (p = 0.07); 46% of Danish mothers used breast pumps; US EPA review excluded this study (milk critically deficient as exposure matrix) and rated infant testosterone indeterminate. Cite the primary, not the thesis, which inverted the direction.
Source: Main 2006 Link to this fact
Children and pregnancy / Other evidence
Prenatal exposure to phthalates in synthetic candle fragrance can promote permanent, irreversible changes to fetal immune-system development and contribute to childhood asthma and allergies.
Weak evidence: Secondhand citation of a general phthalate-immune mechanism paper, not a candle-specific exposure or outcome measurement; no dose given for candle-derived phthalate exposure.
Source: Singh 2023, Environmental Science & Technology Link to this fact
Children and pregnancy / Review of other studies
Studies of pregnant women's phthalate exposure and their children's later weight disagree in direction: one study linked higher maternal DEHP and DINP metabolites to a greater chance of excess infant weight gain, while another found children born to mothers with the highest DEHP exposure actually had slightly lower body fat at birth than those with the lowest exposure.
Weak evidence.
Caveats
Results vary by specific phthalate compound, child sex, and study design; the direction of effect (more fat vs. less fat) is inconsistent across the available prospective cohorts, so no reliable direction of effect can be claimed for maternal phthalate exposure and infant body composition.
Source: Dalamaga 2024, International Journal of Molecular Sciences Link to this fact
Fragrance is everywhere / Review of other studies
A 2022 review of 37 studies found that phthalates, parabens, aldehydes, and aluminum salts are the contaminants most often reported in perfumes, colognes, and related scented products.
Weak evidence: Non-quantitative review with factual slips; cite primary studies for numbers.
Source: Kazemi 2022, Journal of Environmental Health Science and Engineering Link to this fact
Fragrance is everywhere / Measured in people or real products
In the same 33 breastfeeding women, urinary MEP (the metabolite of DEP, the fragrance phthalate) was on average about 57 times higher in women who "often" used nail polish than in women who never did (2,874 vs. 50.5 micrograms per liter).
Weak evidence.
Caveats
Small pilot study (n=33); frequency-group sizes not reported; perfume/cologne use was not asked about, so fragrance products cannot be separated from nail polish as a source; the difference was significant only on untransformed means, and the authors themselves suggest nail-polish users may also use more perfume and other DEP-containing products.
Source: Hines 2009, Environmental Health Perspectives Link to this fact
Health effects / Hypothesis
A 2019 minireview proposes that frequent, long-term burning of scented candles in poorly ventilated rooms may increase bladder cancer risk, based on chemicals in candle emissions (PAHs, benzo[a]pyrene, formaldehyde, phthalates) that are separately linked to bladder cancer via occupational and other non-candle exposure routes.
Weak evidence.
Caveats
No case-control, cohort, or biomonitoring study has ever tested candle use against bladder cancer; the authors' own conclusion calls for that study to be done. This is a narrative minireview with no original data.
Source: Adamowicz 2019, Cancer Prevention Research Link to this fact
Health effects / Review of other studies
Higher urinary MEHHP (a DEHP phthalate metabolite) was correlated with increased urothelial cancer risk in patients with chronic kidney disease; phthalate esters have also been identified in synthetic candle fragrances.
Weak evidence: Single cohort restricted to chronic kidney disease patients, not the general population; not a candle-exposure study; secondhand citation of Huang & Chou 2018.
Source: Adamowicz 2019, Cancer Prevention Research Link to this fact
Hidden ingredients / Review of other studies
In a 2007 NRDC test of 14 US air fresheners, 12 (86%) — including some labeled 'all-natural' or 'unscented' — emitted phthalates at up to 7,307 ppm, and none listed a phthalate on the label.
Weak evidence.
Caveats
NRDC 2007 is gray literature (an advocacy-group test, not peer-reviewed) and is not itself in our evidence base; this relays it secondhand through a 2017 review. Only 14 products tested, almost 20 years ago, so 86% is not a figure for the current market or for air fresheners in general. Peer-reviewed testing (Dodson 2012) separately confirms air fresheners are among the highest-DEP product categories, but does not reproduce this specific percentage.
Source: NRDC 2007 (via Steinemann 2017), Building and Environment Link to this fact
Indoor air / Review of other studies
Diethyl phthalate (DEP), the phthalate most consistently tied to fragrance use, has been detected in household dust in a German study, alongside the plasticizer phthalates DEHP, DINP, and DBP.
Weak evidence.
Caveats
Relayed secondhand through Crinnion 2010, a narrative review in a naturopathic-medicine journal already flagged elsewhere in this evidence base for reproducing outdated/imprecise figures; the underlying German house-dust study itself is not in our evidence base and has not been checked directly. Presence in dust does not establish that fragrance products (rather than other DEP sources, e.g. plastics) are the dust's source, and does not establish an ongoing-exposure mechanism or a health effect.
Source: German house-dust study, via Crinnion 2010, Alternative Medicine Review Link to this fact
What you can do / Review of other studies
Because diet is the main route of human exposure to BPA and phthalates from food packaging, avoiding microwaving food in plastic, cutting back on canned food, and choosing glass, stainless-steel, or aluminum containers instead of plastic can reduce dietary exposure to these obesogenic chemicals.
Weak evidence.
Caveats
This reduces measured chemical exposure; no trial has tested whether making this switch actually changes body weight or obesity risk in people. The review infers this from exposure routes; it cites no intervention study measuring the reduction.
Source: Dalamaga 2024, International Journal of Molecular Sciences Link to this fact
Information, not medical advice. See also: myths we won’t tell you.