Tea Tree Oil
Also: Melaleuca alternifolia oil · melaleuca oil · TTO · tea tree essential oil
Use sparingly — same case-series concern as lavender; fine occasionally for spot acne use, less ideal as a daily-use shampoo ingredient.
Testosterone & hormonal load
Tea tree oil was identified in the same NEJM case series as lavender in prepubertal gynecomastia reports (Henley et al. 2007). NIEHS cell studies confirmed that multiple tea tree oil components (eucalyptol, 4-terpineol, dipentene/limonene) inhibit androgen receptor activity and activate estrogen receptors. Daily use as a primary shampoo ingredient creates repeated exposure. Occasional spot application for acne is a different risk profile than a daily-wash product.
Found in.
Two jurisdictions, two different verdicts.
Permitted cosmetic ingredient. Certain components must be declared as fragrance allergens above threshold concentrations.
Generally regarded as safe as a cosmetic ingredient. No restrictions.
The receipts.
- [01]Henley et al. 2007 — Prepubertal gynecomastia linked to lavender and tea tree oils (PubMed)pubmed.ncbi.nlm.nih.gov/17267908/
- [02]Ramsey et al. 2019 — Lavender products associated with premature thelarche and prepubertal gynecomastia (PubMed)pubmed.ncbi.nlm.nih.gov/31393563/
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