1H-Pyrazole, 1,4-dimethyl-

Endpoint summary

Additional information

Short-term toxicity to fish:

As key study a static GLP-study according to OECD 203 and EU method C.1 regarding the acute toxicity to fish was identified. It was performed as an advanced limit test with two test concentrations of 50 and 100 mg/L plus control (BASF, 1995; project no. 17F0349/945078). After 96h of exposure a NOEC of 100 mg/L and a LC50 of > 100 mg/L was estimated, related to nominal concentration. The measured concentrations ranges between 96 - 102 % of the nominal concentrations. It can be concluded that the substance is with high probability not harmful to fish.

Short-term toxicity to aquatic invertebrates:

As key study a static GLP study following the method laid down in Directive 79/831/EWG, method C.2 using Daphnia magna to determine the toxicity of 1,4-Dimethyl-1H-pyrazole (CAS 1072 -68 -0) to aquatic invertebrates was identified (BASF, 1995). It was performed with four concentrations plus control ranging from 12.5 to 100 mg/L. The calculated EC50 (48h) value in this study was > 100 mg/L, related to the nominal concentration. Measured concentrations ranges from 96 - 102 % of the nominal concentration throughout the test. It can be concluded that the substance is with high probability acutely not harmful to aquatic invertebrates.

 

Toxicity to aquatic algae and cyanobacteria:

As key study a static GLP-study according to OECD 201 regarding the toxicity to Raphidocelis subcapitata (reported as Pseudokirchneriella subcapitata) was identified. It was performed with five test concentrations plus control ranging from 6.25 to 100 mg/L (BASF, 2016). After 72h of exposure a NOECr of 50 mg/L and an ErC50 of >100 mg/L was estimated, related to nominal concentrations. The results are based on nominal concentrations because the measured concentrations over the test duration ranges from 108.2 to 116.9 % of the nominal concentrations. It can be concluded that the substance is with high probability acutely not harmful to aquatic algae and cyanobacteria.

 

Toxicity to microorganisms:

In a GLP short-term respiration test according to OECD 209 conducted with1,4-Dimethyl-1H-pyrazole (CAS 1072-68-0) an EC10 (180 min) of 1.1 mg/L (3h EC50 = 10 mg/L) was obtained for nitrification inhibition (3h values of 1.9 mg/L (EC10) and 110 mg/L (EC50) were determined for total oxygen uptake). The test was performed using domestic activated sludge. The 3h EC10 value for nitrification inhibition (1.1 mg/L) was used for the derivation of the PNEC-STP. It is concluded thatdepending on local conditions and existing concentrations, disturbances in the biodegradation process of activated sludge are possible. The nitrification performance of activated sludge during the elimination via sewage treatment plants may be interfered.