Clinical Snapshot
Methemoglobinemia After Accidental Dermal Absorption of P-Chloroaniline
Noticing a blue-grayish skin discoloration of a 38-year-old chemical technician, his co-worker alerted the in-house emergency services. Initially, there was central cyanosis (Figure a), SPO2 was 84% (measured with a two-wavelength pulse oximeter) while the patient was receiving 16 L/min O2 (mask); the patient felt well at that time. The employee reported that he had carried out tasks involving p-chloroaniline and that skin contact occurred when he removed his protective clothing. The follow-up measurement with a 7-wavelength pulse oximeter showed a methemoglobin concentration of 18%. After decontamination of the skin with polyethylene glycol 400, the patient was treated with an intravenous dose of 300 mg toluidine blue and an oral dose of 1000 mg ascorbic acid; simultaneously, human biomonitoring was performed with his consent. This found 161 µg/L p-chloroaniline; when good occupational hygiene practices are followed, this value is <1 µg/L. The skin coloration returned to normal over time (Figure b). When using pulse oximetry to determine SPO2 levels, it is important to note that no meaningful results can be obtained if amounts of carboxyhemoglobin or methemoglobin are present and 2-wavelength pulse oximeters are used.
Dr. rer. nat. Dr. med. Bernd Herber, Leiter Kompetenzzentrum Arbeitshygiene, Biomonitoring, Pharmakovigilanz, Infraserv GmbH & Co. Höchst KG,
bernd.herber@infraserv.com
Conflict of interest: The author declares that no conflict of interest exists.
Translated from the original German by Ralf Thoene, M.D.
Cite this as: Herber B: Methemoglobinemia after accidental dermal absorption of p-chloroaniline. Dtsch Arztebl Int 2024; 121: 755. DOI: 10.3238/arztebl.m2023.0279
