MAK Value Documentation for Phosphorus oxychloride
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) of phosphorus oxychloride of 0.2 ml/m3, considering the endpoints local and systemic toxicity as well as developmental toxicity. Available publications are described in detail. Phosphorus oxychloride is corrosive to eyes and skin and hydrolyses in water to hydrogen chloride and phosphoric acid, similar to phosphorus trichloride. There is not enough data for phosphorus oxychloride to set a MAK value because valid inhalation studies with repeated exposure are missing. Therefore, the MAK value of phosphorus oxychloride is derived by using a read‐across to phosphorus trichloride for which a MAK value of 0.1 ml/m3 has been set based on a 28‐day inhalation study. Considering the fivefold higher NOAEC of phosphorus trichloride for sensory irritation in volunteers and rats the MAK value for phosphorus oxychloride is lowered accordingly to 0.02 ml/m3. The assignment to Peak Limitation Category I, because local effects are critical, and the excursion factor of 1 are confirmed. The assignment to Pregnancy Risk Group C is retained as damage to the embryo or foetus is unlikely when the MAK value is observed.