Most women don’t think twice about putting on nail polish. Whether due to the perception of nails as inert objects or the belief that nails, unlike skin, don’t absorb certain compounds, people generally don’t take seriously what they apply to their nails.
A 2015 study by Duke University and the Environmental Working Group (EWG) found that… Researchers asked 26 women to paint their nails with polish containing triphenyl phosphate (TPHP), a common plasticizer and flame retardant also used in furniture foam.
The Key Finding
- Before painting: All participants already had low levels of DPHP (the metabolite of TPHP) in their urine.
- 10–14 hours after applying nail polish: DPHP levels in urine increased by an average of nearly 7 times (700%).
- Levels continued rising and peaked around 20 hours post-application.
Importantly, this increase happened through absorption — the chemical passed through the nail bed and skin (not primarily from inhaling fumes). Nails are somewhat porous, and solvents in the polish may help chemicals penetrate more easily.
What Is TPHP and Why Does It Matter?
TPHP is an endocrine-disrupting chemical. In lab and animal studies, it has been linked to:
- Hormone interference (thyroid, reproductive hormones)
- Potential effects on metabolism and weight regulation
- Reproductive and developmental concerns
Human health effects from typical nail polish use are not fully known, but frequent exposure (especially for nail technicians or heavy users) raises more concern. TPHP is found in many conventional polishes, even some labeled “3-free” (free of the classic “toxic trio”: toluene, formaldehyde, and dibutyl phthalate/DBP).
Other Potential Effects from Nail Polish Chemicals
Beyond the 10-hour TPHP spike, common ingredients can cause:
- Toluene — nervous system irritation, headaches, dizziness (largely phased out in better formulas)
- Formaldehyde/formaldehyde resin — skin irritation, allergic reactions, and classified as a carcinogen
- Phthalates (like DBP) — hormone disruption (also widely reduced or removed)
- Camphor — potential skin irritation or toxicity in high amounts
Gel polishes add extra risks from UV lamps (increased skin cancer risk on hands with frequent use) and sometimes stronger chemical formulations.
The Reality Check
- One application is unlikely to cause immediate harm for most healthy people.
- Repeated or frequent use (weekly manicures, etc.) leads to cumulative exposure.
- Many modern polishes are “10-free,” “17-free,” or “non-toxic,” but some still contain concerning ingredients. Always check labels or look for certifications (e.g., EWG Verified).
- Nail technicians face higher exposure risks due to daily inhalation and skin contact.
Safer Alternatives
- Choose TPHP-free or “clean” brands (e.g., some that explicitly test for it).
- Opt for water-based or truly non-toxic formulas.
- Take breaks between manicures and let nails breathe.
- Use gloves or ventilation if doing nails at home or professionally.
Bottom Line:
About 10 hours after applying nail polish containing TPHP, a metabolite of this endocrine-disrupting chemical can show up in significantly higher levels in your body (up to 7x increase). It gets absorbed through your nails and skin into your bloodstream. While occasional use is probably low-risk for most people, frequent application adds to your overall chemical load.
If you love painted nails, switch to cleaner formulas and give your nails regular breaks — your hormones and long-term health will thank you.
