2025/01/01 by Hartwig, Andrea, MAK Commission
Biochemistry, Genetics and Molecular Biology · Environmental Science · Immunology and Microbiology · #1 #1-Dimethylethanol #2-Methyl-2-propanol #2-Methylpropan-2-ol #571.95 Toxicology #571.95 Toxikologie #616.9803 Betriebs- und Arbeitsmedizin #616.9803 Industrial and occupational medicine #Carcinogens and Genotoxicity Assessment #Effects and risks of endocrine disrupting chemicals #Entwicklungstoxizität #Immunotoxicology and immune responses #Luft #MAK value #MAK-Wert #Trimethyl carbinol #Trimethylcarbinol #air #developmental toxicity #maximale Arbeitsplatzkonzentration #maximum workplace concentration #tert-Butylalkohol #tert‐Butanol #tert‐Butyl alcohol
paper · doi:10.34865/mb7565e6418_w
openalex publication_date 2025/01/01 · openalex created_date 2025/12/13 · openalex updated_date 2026/07/01
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the Pregnancy Risk Group of tert‐butyl alcohol [75‐65‐0]. In rats, fetal weights were reduced at 2000 ml/m3, the LOAEC for developmental toxicity after inhalation. A 95% lower confidence limit of the benchmark dose for developmental toxicity of 1600 ml/m3 was calculated. After now considering the increased respiratory volume at the workplace (see List of MAK and BAT Values, Sections I b and I c) this concentration corresponds to 800 ml/m3 at the workplace. The difference to the MAK value of 20 ml/m3 is still sufficient so that damage to the embryo or foetus is unlikely when the MAK value is observed. tert‐Butyl alcohol remains assigned to Pregnancy Risk Group C. In a screening study based on OECD guideline 421 the NOAEL for fetotoxicity is 400 mg/kg body weight and day in rats. After toxicokinetic scaling this dose corresponds to a concentration of 230 ml/m3 at the workplace. The difference between the NOAEL for fetotoxicity for rats and the MAK value of 20 ml/m3 confirms the assignment to Pregnancy Risk Group C. For mice, no NOAEL for developmental toxicity was obtained. At the LOAEL for developmental toxicity after gavage of 1600 mg/kg body weight and day, increased numbers of resorptions and reduced litter size, but no malformations occurred. After toxicokinetic scaling this dose corresponds to a concentration of 520 ml/m3 at the workplace. The difference between the LOAEL for developmental toxicity for mice and the MAK value does not contradict the retention of the assignment to Pregnancy Risk Group C, particularly as a bolus administration (gavage) is considered to be a worst case compared with a continuous exposure at the workplace.