p-Chloroaniline - Derivation of a BAR: Assessment Values in Biological Material - Translation of the German version from 2026.

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.