Ametryn

Long-term toxicity to aquatic invertebrates

Description of key information

Ametryn was reported to have a 21-day EC50 of > 1.4 mg/L in Daphnia magna based on a lack of immobilization at the highest measured concentration tested. Effects on reproduction were reported to occur at concentrations between 0.32 and 0.74 mg/L, and therefore the maximum acceptable toxicant concentration (MATC) was determined to be 0.49 mg/L.  Based on the reproductive effects reported, the NOEC = 0.32 mg A.I./L under the conditions of the study.
Daphnia magna: EC50 (21-day): > 1.4 mg/L
Daphnia magna: MATC (21-day): 0.49 mg/L
Daphnia magna: NOEC (21-day): 0.32 mg/L

Additional information

The long-term toxicity of ametryn in aquatic invertebrates was determined in Daphnia magna (McNamara, 1989). The study was conducted according to OECD Guideline 211 with the following exceptions: the temperature varied from 18 to 21°C (a variation of 3°C instead of 2°C), dissolved oxygen dropped below 60%, and 10 daphnia were housed per vessel instead of 1 daphnid per vessel. The test also followed EPA OPP 72-4 guidelines. Ametryn was reported to have a 21-day EC50 of >1.4 mg/L, based on a lack of immobilization at the highest concentration tested. It was established that the adverse effect on reproduction was the most sensitive indicator of the toxicity of Ametryn Technical to Daphnia magna. Based on these data, the Maximum Acceptable Toxicant Concentration (MATC) of this test material to daphnids was estimated to be ≥ 0.32 mg a.i./L and ≤ 0.74 mg a.i./L (geometric mean MATC = 0.49 mg a.i./L). Based on the reproductive effects reported, the NOEC = 0.32 mg A.I./L under the conditions of the study.