Reaction mass of 5-[(Disubstituted-dihydrocarbopolycyclyl)diazenyl]-6-hydroxy-4-methyl-2-substituted-1-propyl-1,2-dihydropyridine-3-carbonitrile and 1-Butyl-5-[(disubstituted-dihydrocarbopolycyclyl)diazenyl]-6-hydroxy-4-methyl-2-substituted-1,2-dihydropyridine-3-carbonitrile

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

At the test item concentration of 1000 mg/L, a part of the test item was suspended in the test medium. Thus, the test concentration was clearly above the water solubility limit of FAT 41039/A under the present conditions of the test.

The test item had no significant inhibitory effect (<15%) on the respiration rate of activated sludge after the incubation period of 3 hours at the test item concentration of 1000 mg/L.

Thus, the 3-hour NOEC (EC15) of FAT 41039/A to activated sludge microorganisms was at least 1000 mg/L. This value might even be higher but concentrations above 1000 mg/L were not tested. The 3-hour EC20, EC50, and EC80 could not be calculated but were clearly higher than 1000 mg/L.

Results with reference substance (positive control):

The 3-hour EC50 of the reference item 3,5-dichlorophenol (positive control) was calculated to be 18 mg/L (the 95% confidence limits were not calculable). The 3-hour EC50 is within the guideline-recommended range of 5-30 mg/L, confirming the suitability of the activated sludge used.

The oxygen consumption rates of the two controls (run at the start or at the end of the test) differed by 1.0% (guideline-recommended maximum variation: 15%).

Validity criteria fulfilled:

yes

Conclusions:

The EC50 for FAT 41039/A, a structural analogue of FAT 41048, was found to be greater than 1000 mg/L.

Executive summary:

The inhibitory effect of FAT 41039/A, a structural analogue of FAT 41048, 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, and the OECD Guideline for Testing of Chemicals, No. 209.

In accordance with EU Commission Directive 92/69/EEC (C.1, C.2, and C.3) and OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, a limit test was performed testing one nominal concentration of FAT 41039/A of 1000 mg/L to demonstrate that the test item has no toxic effect on activated sludge microorganisms up to and including this test concentration.

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 the suitability of the activated sludge and the method used.

The test item FAT 41039/A had no significant inhibitory effect (<15%) on the respiration rate of activated sludge after the incubation period of 3 hours at the test item concentration of 1000 mg/L.

Thus, the 3-hour NOEC (EC15) of the test item to activated sludge microorganisms was at least 1000 mg/L. This value might even be higher but concentrations above 1000 mg/L were not tested. The 3-hour EC20, EC50, and EC80 could not be calculated but were clearly higher than 1000 mg/L.

Description of key information

The 3 hr EC50 of FAT 41039/A, a structural analogue of FAT 41048, is greater than 1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The inhibitory effect of FAT 41039/A, a structural analogue of FAT 41048, 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, and the OECD Guideline for Testing of Chemicals, No. 209. 

The test item FAT 41039/A had no significant inhibitory effect (<15%) on the respiration rate of activated sludge after the incubation period of 3 hours at the test item concentration of 1000 mg/L.

Thus, the 3-hour NOEC (EC15) of the test item to activated sludge microorganisms was at least 1000 mg/L. This value might even be higher but concentrations above 1000 mg/L were not tested. The 3-hour EC20, EC50, and EC80 could not be calculated but were clearly higher than 1000 mg/L.