2-Methoxyethanol: MAK-Begründung, Nachtrag

TL;DR

This paper updates the occupational exposure limit for 2-methoxyethanol based on its developmental toxicity and its metabolite's effects on embryos and fetuses.

Contribution

The paper re-evaluates and retains the MAK value for 2-methoxyethanol based on new toxicokinetic and developmental toxicity data.

Findings

The MAK value of 1 ml/m³ was retained based on extrapolation from methoxyacetic acid's biological tolerance value.

A lower concentration of 0.15 ml/m³ is proposed for Pregnancy Risk Group C based on rabbit studies.

2-methoxyethanol remains in Pregnancy Risk Group B due to potential fetal risks at the MAK value.

Abstract

The German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) re-evaluated the data for developmental toxicity and the derivation of the occupational exposure limit value (maximum concentration at the workplace, MAK value) for 2-methoxyethanol [109-86-4]. The MAK value was derived in analogy to the BAT value (biological tolerance value) for the metabolite methoxyacetic acid of 15 mg methoxyacetic acid/g creatinine. This concentration was extrapolated to a 2-methoxyethanol concentration in air using the findings of a volunteer study and toxicokinetic considerations. The MAK value of 1 ml/m3 was retained based on these results. The substance remains classified in Pregnancy Risk Group B because a risk for the developing foetus cannot be ruled out at exposure to the MAK value of 1 ml/m3. This was concluded based on embryo-/foetotoxic and teratogenic effects induced by the metabolite methoxyacetic acid in rats, mice, rabbits and monkeys. A 2-methoxyethanol concentration of 0.15 ml/m3 was derived for the workplace from the lowest NOAEC (no observed adverse effect concentration) of 3 ml/m3 for developmental toxicity induced in rabbits by 2-methoxyethanol; damage to the embryo or foetus is unlikely at this concentration (the prerequisite for assignment to Pregnancy Risk Group C).

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