α,α,α-trifluoro-4-nitro-m-cresol

Endpoint summary

Description of key information

Fish (Channel catfish): LC50 (96 hours): 0.632 mg/L.

Daphnia: Chironomus tentans: LC50 (96 hours): 0.534 mg/L

Algae (Nitzschia sp.): EC50 (96 h): 1.2 mg/L

Microorganisms: EC50 value (3h): 48.6 mg/L (95% confidence limits: 42.2–56.3 mg/L). NOEC: 10.24 mg/L.

Additional information

Fish:

In a static test the effect of the test item on the mortality of Rainbow trout (Salmo gairdneri) was tested. At pH 6.5 an a temperature of 12 °C the LC50 value was determined to be 1.10 mg/L after 96 hours with a 95 % confidence interval of 0.744 - 1.63 mg/L.

In a static test the effect of the test item on the mortality of Channel catfish (Ictalurus punctatus) was tested. At pH 6.5 an a temperature of 12 °C the LC50 value was determined to be 0.632 mg/L after 96 hours with a 95 % confidence interval of 0.584 - 0.684 mg/L.

Daphnia:

As the test item is registered since 1964 for limited use in tributaries of the Great Lakes in the US for control of the parasitic sea lamprey, numerous studies on aquatic invertebrates are available. Only the most important studies are presented here: The test with the lowest LC50 (Chironomus tentans) and two standard species for the endpoint (Daphnia magna and Gammarus pseudolimnaeus). No guidelines were available in 1975 and in the publications the description of the methods are insufficient. But as all results are in the same range (LC50: 0.5 – 29 mg/L) they are considered valid. Additionally they match with the data given in the RED document of the test item of EPA (Reregistration Eligibility Decision, United States Environmental Protection Agency, November 1999, 7508C) where a LC50 of 3.8 - 22.3 mg/L is given.

Algae:

As the test item is registered since 1964 for limited use in tributaries of the Great Lakes in the US for control of the parasitic sea lamprey, numerous studies on aquatic algae are available. Only the most important study presented here: The test with the lowest EC50 (Nitzschia sp.) and two additional species for the endpoint (Pseudokirchneriella subcapitata and Anabaena cylindrica). No guidelines were available in 1975 and in the publications the description of the methods are insufficient. For all three species the field grade test item (35.7 %) showed lower EC50 values based on the active ingredient. As all results are in the same range (EC50: 1.2 – 8.6 mg/L) they are considered valid. Additionally they match with the data given in the RED document of the test item of EPA (Reregistration Eligibility Decision, United States Environmental Protection Agency, November 1999, 7508C) where an EC50 of less than 10 mg/L is given.

Microorganisms:

The purpose of the 3-hour test was to evaluate the influence of the test item on the activity of the activated sludge by measuring the respiration rate under defined conditions according to OECD 209. The respiration rates (total, heterotrophic and nitrification oxygen uptake rates) of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours. Based on the preliminary information about the test item caused effect on the activated sludge inoculum, the test item was investigated at the nominal concentrations of 4.1, 10.24, 25.6, 64 and 160 mg/L. Defined amounts of the test item were added directly into the test vessels. In parallel with the test item treatments 3,5-dichlorophenol as positive reference control in a concentrations of 2, 7 and 24.5 mg/L; furthermore blank (inoculum) control and nitrification controls were investigated. The main test was performed without abiotic controls, based on the results of the preliminary test where abiotic controls were tested at the test item concentration of 1000 mg/L and no remarkable abiotic oxygen consumption was noticed. The test was performed without pH adjustment. All validity criteria of the study were met. The inhibition of the oxygen consumption rates showed clear dose-related tendency in the whole examined concentration range 4.1-160 mg/L. At the lowest examined concentration of 4.1 mg/L inhibition was not noticed, at 10.24 mg/L 4.0 % inhibition, at 25.6 mg/L 29.5 %, at 64 mg/L 63.2 % inhibitions were calculated. At the highest examined concentration of 160 mg/L 86.2 % inhibition was obtained. Based on the available data the 3-hour EC10, EC50 and EC80 values and their 95% confidence limits were calculated by Probit analysis using IBM® SPSS® Statistics software. The values are the following: EC10: 13.9 mg/L (10.8–17.0), EC50: 48.6 mg/L (42.2–56.3), EC80: 110.6 mg/L (92.3–138.6). The specific respiration rates were compared with the blank control values using Dunnett t-test (α=0.05). Consequently the NOEC can be statistically and biologically determined as 10.24 mg/L.