Canadian water quality guidelines for deltamethrin

Canadian Water Quality Guidelines (CWQG) are numerical or narrative limits that protect designated water uses. Development of CWQG is based on review of deltamethrin's properties, uses, fate in the environment, ambient levels, accumulation in biota, and toxicity. Deltamethrin is a synthetic pyrethroid insecticide used against agricultural pests. Concentrations of deltamethrin in Canadian agricultural areas range between 10 and 1000 ng m−3 in air, 0.04 and 24.0 μg L−1 in water, 3 and 5 ng g−1 in sediments, 281 and 1375 ng g−1 in plants, and 3.0 and 50.0 ng g−1 in animals. In nature, deltamethrin can undergo volatilization, isomerization, and hydrolysis. Estimates of toxicity of deltamethrin to freshwater life range from 0.0001 μg L−1 (48- and 96-h EC0 for immobilization of Daphnia magna) to 1700 mg L−1 (EC50 for photoinhibition of Selanastrum capricornutum). Terrestrial life is affected by concentrations of deltamethrin ranging from 1.0 mg kg−1 (retardation of fetus development in mice) to 5000 mg kg−1 (LD50 for a rat). A full guideline of 0.4 μg L−1 is recommended for the protection of freshwater life. A full guideline of 2.5 μg L−1 is recommended for water used for livestock production. There were insufficient data to derive guidelines for recreation, irrigation, and industrial applications.