MAK Value Documentation for Dipropylene glycol
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the work place (MAK value) for dipropylene glycol has been set at 100 mg/m3 for the inhalable fraction, considering the endpoints respiratory tract irritation and systemic toxicity as well as absorption through the skin. A 2‐year drinking water study with rats shows a NOAEL for focal inflammation of the liver in males of 115 mg/kg body weight and day and a NOAEL for olfactory epithelium degeneration in males and females of 470 and 530 mg/kg body weight and day, respectively. This raises the question, whether the olfactory epithelium could also be a local target tissue after inhalation. Inhalation studies with dipropylene glycol are not available. The substance shows very slight irritation of skin and eyes, if any. Thus, there are no indications of a potential local irritative effect to the upper airways. Therefore, the MAK value of 100 mg/m3 derived from systemic effects is validated. As systemic effects are critical, the assignment to Peak Limitation Category II and the excursion factor of 2 are retained. A recent in‐vitro study with human skin shows that skin contact does not contribute significantly to systemic toxicity and the former designation with an “H” notation is withdrawn.