The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has evaluated the developmental toxicity of 4‐tert‐octylphenol [140‐66‐9]. In 2015, the maximum concentration at the workplace (MAK value) for 4‐tert‐octylphenol was set at 0.5 ml/m3 (4.3 mg/m3).
In a screening study in rats with gavage administration, litter size and body weight of the progeny at postnatal day 4 was reduced at 500 mg/kg body weight and day, accompanied by maternal toxicity. A NOAEL for foetotoxicity of 250 mg/kg body weight and day was derived, corresponding to a concentration of 28.5 ml/m3 at the workplace. In a 2‐generation feeding study in rats, foetotoxicity was not observed until postnatal day 13. At 111–369 mg/kg body weight and day, vaginal opening or preputial separation of the F2 progeny was delayed. A NOAEL of 10.9–32.6 mg/kg body weight and day was derived for postnatal developmental toxicity in rats, corresponding to 1.2–3.7 ml/m3. Because adequate studies of prenatal developmental toxicity over the complete period of organogenesis are lacking, data are not sufficient for classification and 4‐tert‐octylphenol is assigned to Pregnancy Risk Group D.