The aquatic toxicity of dibenz(b,f)-1,4-oxazepine (CR) was examined using organisms from three trophic levels. The compound is a peripheral sensory irritant which produces an immediate irritation of the eyes, nose, mouth, skin, and respiratory tract in man. The compound is comprised of a double benzene ring with a shared oxygen molecule and a doublebonded carbon, nitrogen group. The intended use of the compound is for the control of civil disturbances. Acute bioassays were performed using Ankistrodesmus falcatus, Daphnia magna, and Pimephales promelas. A 21-day static renewal test was performed using D. magna.

A 24-h EC₅₀ of 1.48 mg/L and 48-h EC₅₀ of 0.94 mg/L were calculated for daphnids. Significant differences in reproductive output and body length were observed at 0.50 mg/L using ANOVA in the 21-day chronic assay with D. magna. The 96-h algal growth inhibition test yielded an IC50 in the range of 1.95 to 3.55 mg/L. An LC₅₀ of 2.6 to 2.8 mg/L was determined for the fish. An enhancement compared to controls in reproductive output was observed for both the algae and daphnia at low concentrations of CR. Dose response curves and comparisons of linear and exponential regressions are presented for several of the toxicity tests.