Experimental contact sensitization with 3,4,5-trichloropyridazine.

The potential of 3,4,5-trichloropyridazine to induce contact sensitization was assessed in the guinea pig maximization test of Magnusson and Kligman and also in the closed patch test described by Buehler. The test material was a 1% solution of 3,4,5-trichloropyridazine in a highly refined mineral oil. The test material elicited moderate to severe irritation when diluted in mineral oil to concentrations of 15-25% and minimal irritation at concentrations of 1-3%. Both tests clearly indicated that 3,4,5-trichloropyridazine was a contact sensitizer to guinea pigs, although the response was stronger in the maximization test. Sensitization was distinguished from irritation by the use of concurrent irritation control groups.