What question did this study set out to answer?

The research aims to summarize data for establishing occupational exposure limits for hydrotreated heavy naphtha.

April 1, 2026Open Access

Naphtha (petroleum), hydrotreated heavy

Key Points

The research aims to summarize data for establishing occupational exposure limits for hydrotreated heavy naphtha.
Identified relevant studies through literature search.
Included unpublished study reports.
Conducted a 13-week study in rats.
Performed a behavioral toxicity study in volunteers.
Confirmed no need to change the MAK value of 50 ml/m3 based on neurotoxic effects.
Retained assignment to Peak Limitation Category II with an excursion factor of 2.
Found no evidence that juvenile animals are more sensitive to neurotoxic effects compared to adults.
Maintained categorization of pregnancy risk as Group D.

Abstract

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 Relevant studies were identified from a literature search and also unpublished study reports were used.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).

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