The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration of 3‐iodo‐2‐propynyl butylcarbamate at the workplace (MAK value), considering the endpoints respiratory tract irritation and developmental toxicity. No new studies have been published since the supplement from 2011. 3‐Iodo‐2‐propynyl butylcarbamate is irritating to the skin, eyes and airways and has skin‐sensitizing effects.
In a 5‐day aerosol inhalation study, hyperplasia, squamous cell metaplasia and necrosis occurred in the larynx of rats at 1 mg/m3 with a NOAEC of 0.3 mg/m3. These effects were more pronounced in the 13‐week study with a NOAEC of 0.23 mg/m3. The systemic effect dose in long‐term feeding studies in rats and mice extrapolated to a concentration in air at the workplace is around 100 times higher.
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. Based on this approach, a MAK value of 0.005 ml/m3 (0.058 mg/m3) can be calculated from the 13‐week study. Since the critical effect is irritation, Peak Limitation Category I is retained. As this effect is immediate and not a form of sensory irritation , but a change to the tissue, and because the margin between the MAK value and the histological NOAEC of 0.3 mg/m3 is sufficiently large, the excursion factor of 2 has been retained.
There are no new data on prenatal toxicity available. Pregnancy Risk Group C has therefore been retained.