2‐Isopropoxyethanol

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the workplace (MAK value) and the Pregnancy Risk Group of 2‐isopropoxyethanol [109‐59‐1]. As 2‐isopropoxyethanol is irritating to rabbit skin and eyes an irritating potential for the respiratory tract of humans has to be assumed. In a poorly documented three‐week inhalation study in rats, nasal irritations at 1000 ml/m3 are reported, but the nose is not histopathologically investigated in any of the inhalation studies. A MAK value of 10 ml/m3 for 2‐isopropoxyethanol is derived by analogy with 2‐butoxyethanol (ethylene glycol monobutyl ether) which shows a similar irritation potency. For rats, the critical effect in a 28‐day inhalation study is the concentration dependent haemolytic anaemia at 100 ml/m3 and above. The NOAEC is 30 ml/m3. As humans are less sensitive than rats for this effect, which does not increase with prolonged exposure, the MAK value of 10 ml/m3 should provide sufficient protection from haemolytic anaemia. Since a local effect is critical, Peak Limitation Category I is designated. By analogy with 2‐butoxyethanol and 2‐propoxyethanol an excursion factor of 2 is set. The NOAEC for developmental toxicity in rats is 600 ml/m3 and after considering the increased respiratory volume at the workplace because the blood:air partition coefficient of 2‐isopropoxyethanol is > 5 (see List of MAK‐ and BAT Values, Sections I b and I c) the difference to the MAK value is sufficient. Therefore, damage to the embryo or foetus is unlikely when the MAK value is observed and 2‐isopropoxyethanol remains assigned to Pregnancy Risk Group C.