# Anilin: MAK-Begründung, Nachtrag

## TL;DR

This paper evaluates if the current workplace limit for aniline protects unborn children from health risks.

## Contribution

The paper re-evaluates aniline's developmental toxicity and assigns it to Pregnancy Risk Group B based on MetHb levels.

## Key findings

- Aniline's MAK value of 2 ml/m³ may not protect unborn children from adverse effects.
- Newborns are more sensitive to MetHb formers than adults due to lower MetHb reductase activity.
- Aniline is classified in Pregnancy Risk Group B, similar to dichloromethane and carbon monoxide.

## 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 developmental toxicity of aniline [62-53-3]. Relevant studies were identified from a literature search. An occupational exposure limit value (maximum concentration at the workplace, MAK value) of 2 ml/m3 was previously set for aniline to maintain methaemoglobin (MetHb) levels below 5%, above which adverse effects are expected. This addendum evaluates whether the MAK value also protects the unborn child. There are no studies available on the effects on newborns exposed to maternal MetHb levels of up to 5% in utero. MetHb levels of up to 2% are considered to be within the physiological range for pregnant women. Newborns are significantly more sensitive to MetHb formers than adults. MetHb reductase activity in erythrocytes is 5 to 10 times as high in rats and mice as in humans. Thus, as the reduction of MetHb is much slower in humans they are more sensitive to MetHb formers than rodents. Therefore, developmental toxicity should not be assessed using data from these species. A risk to the unborn child cannot be ruled out at the MAK value for aniline of 2 ml/m3 and aniline has therefore been assigned to Pregnancy Risk Group B. This is supported by the assignment of dichloromethane and carbon monoxide to Pregnancy Risk Group B at a CO-Hb value of 5%. It was not possible to establish a concentration in air that would allow aniline to be classified in group C because there are no data to derive an aniline concentration that would not increase the MetHb levels above the range of fluctuation. However, reference is made to the justification of the requirement for Pregnancy Risk Group C for an aniline concentration in urine.