National Toxicology Program

National Toxicology Program

Abstract from Report IMM89007 on Benzethonium Chloride

The Assessment of Contact Hypersensitivity to Benzethonium Chloride in Female B6C3F1 Mice (CAS No. 121-54-0)

The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009. The findings and conclusions for this study should not be construed to represent the views of the NTP or the U.S. Government.


Benzethonium chloride is used as an antiinfective, in veterinary medicine as a topical antiseptic, and as a cationic detergent. Cationic detergents are used agriculturally in herbicides and in antiseptics, spermicides, astringents, germicides, disinfectants, and preservatives. Hypersensitivity reactions have been reported in 12 of 42 individuals treated with a topical preparation containing benzethonium chloride (Acta Otolaryngol. 100: 414, 1985).


Benzethonium chloride (lot # W0061/01) was obtained from Rohm and Haas, Inc. (Philadelphia, PA) and was > 98% pure as determined by high-performance liquid chromatography. The material was prepared in 95% ethanol, which also served as the vehicle. A 0.5% solution of 1-fluoro-2,4-dinitrobenzene (Sigma Chemical Corp., Lot No. 87F-3777; > 99.0% pure as determined by HPLC) was used as the positive control. In the primary irritancy studies, a 10% concentration of benzethonium chloride was not significantly irritating, therefore, 20% was chosen as the challenge concentration. For the hypersensitivity test, B6C3F1 mice were divided into 7 treatment groups of 8 mice/group and administered the test compound at the concentrations shown in Table 1. The irritancy response was determined by monitoring the extravasation of 125I-bovine serum albumin into the testing area. The contact hypersensitivity response was determined by monitoring the infiltration of 125I- iododeoxyuridine labeled cells into the challenge site.

Table 1. Study Design: Contact Hypersensitivity Study with Benzethonium Chloride

Group (n) Description Sensitization Challenge
1 (8) Vehicle Vehicle Vehicle,
2 (8) Baseline Control Vehicle 20% BZ
3 (8) Experimental 1% BZ 20% BZ
4 (8) Experimental 3% BZ 20% BZ
5 (8) Experimental 10% BZ 20% BZ
6 (8) DNFB Positive Control 0.5% DNFB 0.5% DNFB
7 (8) DNFB Negative Control Vehicle 0.5% DNFB

BZ = benzethonium chloride DNFB = 1-fluoro-2,4-dinitrobenzene


There were no treatment-related effects on survival or body weights. The Hypersensitivity Index values obtained with benzethonium chloride sensitization at 1%, 3%, and 10% were not significantly different from the baseline control value. The positive control group (6) produced a statistically significant hypersensitivity response at a sensitizing and challenge concentration of 0.5% DNFB.


Under these experimental conditions, no statistically significant group or dose-dependent contact hypersensitivity responses to benzethonium chloride were observed in mice by dermal exposure.

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