p-Chloroaniline – Derivation of a BAR

Assessment Values in Biological Material – Translation of the German version from 2026

Isabell Schönrath¹
Gabriele Leng²
  Hans Drexler³ (Head of the working group “Assessment Values in Biological Material” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
  Andrea Hartwig⁴ (Chair of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft)
  MAK Commission<sup>5

1</sup> Currenta GmbH & Co. OHG, CUR-SIT-ABG-GS-BLM – Institute for Biomonitoring, 51368 Leverkusen, Germany
² 40699 Erkrath, Germany
³ Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute and Outpatient Clinic of Occupational, Social, and Environmental Medicine, Henkestraße 9–11, 91054 Erlangen, Germany
⁴ Institute of Applied Biosciences, Department of Food Chemistry and Toxicology, Karlsruhe Institute of Technology (KIT), Adenauerring 20a, Building 50.41, 76131 Karlsruhe, Germany
⁵ Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area, Deutsche Forschungsgemeinschaft, Kennedyallee 40, 53175 Bonn, Germany

Abstract

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area evaluated the data for 4-chloroaniline [106-47-8] to derive a biological reference value (BAR). p-Chloroaniline is an intermediate in organic synthesis and is used in the manufacture of pharmaceuticals, plant protection products and dyes. As a potent inducer of methaemoglobin formation, the hazards regarding its acute toxicity surpass the carcinogenic potential. Hence, several accidents with a consecutive cyanosis are reported. Besides the methaemoglobin level, two other, more specific biomarkers are known: p-chloroaniline set free from the haemoglobin adduct and p-chloroaniline in urine. p-Chloroaniline after hydrolysis represents the sum of all N-conjugated phase II metabolites which are then back-converted to their mother compound. Based on studies of the general population, a BAR of 1 µg p-chloroaniline (after hydrolysis)/l urine has been derived. The smoking status did not influence the urinary levels of p-chloroaniline.

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