Abstract
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) of 5 ml/m3 for methyl acrylate [96‐33‐3] considering the endpoints local and developmental toxicity as well as genotoxicity. Available publications and unpublished study reports are described in detail. The critical effect in a two‐year inhalation study with rats was reserve cell hyperplasia with loss of ciliated and olfactory cells in the transitional nasal epithelium at the lowest concentration of 15 ml/m3. In a two‐generation reproduction toxicity study with a NOAEC of 5 ml/m3, degeneration with regeneration of the olfactory epithelium, hyperplasia of the transitional epithelium as well as hyperplasia and hypertrophy of the goblet cells were observed. A lower confidence limit of the benchmark dose for an extra risk of 5% increase of the critical effect incidence (BMDL05) of 6.8 ml/m3 as a substitute for a NOAEC was calculated from the data of the two‐year inhalation study. Since 2014, the Commission uses an empirical approach to set MAK values for substances with critical effects on the upper respiratory tract or the eyes. According to this approach, the MAK value for methyl acrylate has been lowered to 2 ml/m3. As local effects are critical, the assignment to Peak Limitation Category I and the excursion factor of 2 are confirmed, in analogy to ethyl acrylate. The NOAECs for developmental toxicity in rats and rabbits are sufficiently high so that damage to the embryo or foetus is unlikely when the MAK value is not exceeded. Thus, methyl acrylate is classified in Pregnancy Risk Group C. The substance is clastogenic in vitro but not in vivo and was not carcinogenic in a 2‐year inhalation study in rats. There are only a few cases of contact sensitization in humans but there is a positive result in a local lymph node assay. Data on airway sensitization are still not available. Methyl acrylate remains designated with “Sh”. Skin absorption was calculated to contribute significantly to the systemic toxicity and methyl acrylate is designated with an “H”.
Hartwig, A