National Toxicology Program

National Toxicology Program

Abstract from Report IMM95006 on Atrazine

Report on the Assessment of Contact Hypersensitivity to Atrazine in Female B6C3F1 Mice (Dermal Studies) (CAS No. 1912-24-9)

Report Date: October 1994

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 The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009.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.


Atrazine was selected for evaluation as a sensitizing agent for contact hypersensitivity in mice. Atrazine is a selective pre- and post-emergence herbicide. Occupational exposure occurs mainly by inhalation or topical exposure. Studies have shown ATZ to be mildly irritating to the skin and eyes and studies with guinea pigs have shown ATZ to be a skin sensitizing agent.

The objective of this study was to determine the sensitizing potential of Atrazine when applied dermally to female B6C3F1 mice. Concentrations to be used in the contact hypersensitivity assays were determined by irritancy testing. The doses of Atrazine tested were 10, 20, and 30% in acetone (99.8%) for sensitization, and 30% for challenge. DNFB (Sigma Chemical Co.) was used as the positive control at a concentration of 0.25% for sensitization, and 0.5% for challenge. Measurement of the contact hypersensitivity response was accomplished by the Mouse Ear Swelling Test, and the local lymph node assay.

These studies did not identify Atrazine as a sensitizer. In the MEST at concentrations of 10, 20, or 30% no statistically significant response was observed at either 24 or 48 hours post challenge. The LLNA did not detect a significant response at any concentration tested. The positive control, DNFB, showed a statistically significant (p<0.01) response in both assays.

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