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Toxicity to microorganisms

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Description of key information

The 3 hour NOEC (EC10) of Triquat Monomer to activated sludge microorganisms was determined to be at least 2000 mg/L.  

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
2 000 mg/L

Additional information

One reliable key study is available for this endpoint. The inhibitory effect of the test item Triquat Monomer on the respiration rate of aerobic wastewater microorganisms of activated sludge was investigated in a 3 hour respiration inhibition test, according to the EU Commission Directive 88/302/EEC, Part C.11, Commission Regulation (EC) No. 440/2008, Part C.11 and the OECD Guideline for Testing of Chemicals, No. 209. The study has been performed in accordance with the GLP.

The following nominal concentrations of Triquat Monomer were tested: 20, 64, 200, 640 and 2000 mg test item/L, which correspond to 10, 32, 100, 320 and 1000 mg test item dry matter/L (taking into account a water content of 50%).

In addition, two controls and three different concentrations of the reference item 3,5 dichlorophenol (5, 16 and 50 mg/L) were tested in parallel. The results of these treatments confirmed suitability of the activated sludge and the method used.

Up to and including the highest test concentration of 2000 mg test item/L, the inhibition of the respiration rates of activated sludge after the incubation period of three hours was in the range 3.9 to 13% compared to the controls, without any concentration-effect relationship. Thus, the 3 hour NOEC (EC10) of Triquat Monomer to activated sludge microorganisms was at least 2000 mg/L. The 3 hour EC20, EC50 and EC80 could not be calculated, but were clearly higher than 2000 mg test item/L.