Naphtha (petroleum), hydrotreated heavy: MAK Value Documentation, addendum - Translation of the German version from 2025.

The German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) summarized and re-evaluated the data for the derivation of the occupational exposure limit value (maximum concentration at the workplace, MAK value) for naphtha (petroleum), hydrotreated heavy [64742-48-9]. Relevant studies were identified from a literature search and also unpublished study reports were used. The critical effect is preclinical neurotoxicity. The results of a 13-week study with an isoparaffinic product in rats and a behavioural toxicity study in volunteers do not contradict the previous MAK value of 50 ml/m3. The assignment to Peak Limitation Category II with an excursion factor of 2 is retained. Additionally, there are no experimental data showing that juvenile animals are more sensitive to naphtha-induced neurotoxic effects than adults. Therefore, there is no evidence that would require changing the previous categorization from Pregnancy Risk Group D to Pregnancy Risk Group B (suspected).