The European Union (EU) has raised concerns about tea tree oil, suggesting it may affect fertility and proposing its classification as a presumed human reproductive toxicant. This classification stems from studies where high doses of tea tree oil were administered to rats, resulting in lower sperm counts but no significant effects on female fertility. However, human studies and pharmacovigilance data have shown no evidence of reproductive toxicity associated with tea tree oil use. The concentrations of tea tree oil in cosmetics are deemed safe, with limits of 2.0% in shampoo, 1.0% in shower gel, and 0.1% in face cream. Importantly, humans metabolize tea tree oil differently from rats, producing only trace levels of harmful byproducts. The UK's Health and Safety Executive has also concluded that tea tree oil is not a reproductive toxicant. Overall, while initial concerns raised by the EU were alarming, subsequent evaluations suggest that tea tree oil is safe when used as directed.