Ametryn

Long-term toxicity to fish

Description of key information

The maximum acceptable toxicant concentration for Ametryn is reported to be 2.9 and 1.4 mg A.I./L based on significantly reduced larval growth.  The maximum acceptable toxicant concentration for this material and fathead minnows is estimated to be >0.7 mg A.I./L and <1.4 mg A.I./L (geometric mean). The MATC was determined to be 0.99 mg A.I./L.  The 7-day chronic value (ChV), no observed effect level (NOEC), and observed effect concentration (OEC) of Ametryn in Brachydanio rerio are reported to be 0.3162 mg/L, 0.1 mg/L, and 1 mg/L, respectively.  Based on larval growth, the NOEC = 0.7 mg A.I./L under the conditions of the study.
Fathead minnows: MATC = 0.99 mg A.I./L
Fathead minnows: NOEC = 0.7 A.I./L
Brachydanio rerio: ChV = 0.3162 mg/L
Brachydanio rerio: NOEC = 0.1 mg/L
Brachydanio rerio: OEC = 1 mg/L

Additional information

Two long-term toxicity studies were performed to assess the toxicity of ametryn to the freshwater fish species Pimephales promelas and Brachydanio rerio (Surprenant, 1989; Viana, 1993). The first study was conducted in Pimephales promelas (fathead minnows) according to OECD Guideline 210 with the following exceptions: measurements of heavy metals, major anions and cations, pesticides and total organic carbon were not taken, and the number of larvae hatchlings was not provided. This study also was conducted according to EPA OPP 72-4 guidelines (Surprenant, 1989). At termination of the study, data obtained on organism survival at hatch, larval survival and larval growth on day 35 were analyzed. Analyses were performed using the mean organism response in each replicate aquarium rather than individual response values. Based on the significantly reduced larval growth at concentrations of 2.9 and 1.4 mg A.I/L ametryn technical, the maximum acceptable toxicant concentration for this material and fathead minnows is estimated to be >0.7 mg A.I./L and <1.4 mg A.I./L (geometric mean). Based on larval growth, the NOEC = 0.7 mg A.I/L under the conditions of the study.

The 7-day chronic value (ChV), no observed effect level (NOEC), and the observed effect level (OEC) for Ametryn were reported to be 0.3162 mg/L, 0.1 mg/L and 1 mg/L in Brachydanio rerio, respectively (Viana, 1993). These values were based on the incidence of mortality among the test animals exposed to ametryn in a static freshwater system. The study did not follow GLP and was rated ‘3’ for reliability under Klimisch standards; however, the test was reported to follow the guidelines set forth in teste D.3.2. da Portaria no 349 de 14/03/90 do IBAMA.