2,2,6,6-Tetramethylpiperidin-4-yl dodecanoate

Endpoint summary

Additional information

Short-term toxicity to fish

In a semi-static acute toxicity test,Brachydanio reriowas exposed to the test item for 96 hours according to OECD Guideline 203. The effect concentrations are based on the measured concentration (geometric mean) as follows: NOEC = 0.03 mg/L, LOEC = 0.09 mg/L and LC50 = 0.26 mg/L.

Short-term toxicity to aquatic invertebrates

In a semi-static acute toxicity test, youngDaphnia magna(< 24 h old) were exposed to the test item for 48 hours according to OECD 202. The effect concentrations are based on the measured concentration (geometric mean) as follows: NOEC = 0.15 mg/L, LOEC = 0.315 mg/L and EC50 = 0.383 mg/L. In addition, a supporting study was performed to evaluate the acute toxicity of the test substance with a low level of humic acid. The effect concentrations are based on the nominal concentrations as follows: NOEC = 0.95 mg/L and EC50 > 1.90 mg/L.

The screening study towardsDaphnia magnawith the addition of a low level of humic acid (equivalent to 1 mg/L total organic carbon) was conducted to get a clearer picture of the environmental impact of the test item under more realistic conditions. Usually, a range of 10 to 20 mg/L of humic acid has been suggested as a suitable level for aquatic testing [1, 2]. Thus, the concentration of humic acid in the present study represents clear worst case exposure conditions but still a first approximation of the environmental behavior of the test item in natural surface waters. The study clearly shows that humic acid equivalent to only 1 mg/L total organic carbon reduces the toxic potential of the test item towardsDaphnia magna. It can be expected that humic acid concentrations of 10 to 20 mg/L suggested by the US EPA and the OECD [1, 3] have an even higher impact on the toxicity of the test item. It is therefore expected that under natural conditions the toxic potential of the compound will be significantly lower than the experimental studies suggest.

[1] Organization for Economic Cooperation and Development (OECD) 2000, Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, OECD Series on Testing and Assessment, No. 23, OECD Publishing.

[2] Hamilton, JD., Reinert, KH., and Freeman, MB. (1994) Aquatic Risk Assessment of Polymers. Environ. Sci. Technol., 28 (4): 186A-192A.

[3] United States Environmental Protection Agency, Ecological Effects Test Guidelines OPPTS 850.1085 Fish Acute Toxicity Mitigated by Humic Acid.

Toxicity to aquatic algae and cyanobacteria

In a static toxicity test, the test organisms (Pseudokirchneriella subcapitata) were exposed to the test item for 72 hours according to OECD 201. The effect concentrations are based on the initial measured concentration as follows: EC10 = 0.27 mg/L and EC50 = 0.626 mg/L.

During the toxicity studies on fish (OECD guideline 203),Daphnia magna(OECD guideline 202), and algae (OECD guideline 201) it was observed that the test substance concentrations declined in the test media. This phenomenon is probably due to adsorption to the test vessels and/or the test organisms. Due to the semi-static test design in the fish and Daphnia study with 24h test media renewal periods the concentration of the test substance did not drop below the limit of detection at the end of the renewal periods but remained at around 30 to 45% of the initial values. Therefore the resulting effect concentrations were generated with the geometric mean measured concentrations. However, the algae study according to OECD guideline 201 does not allow a semi-static or even flow-through test design and was therefore conducted as static test with an exposure time of 72h. Test substance verification was performed at the beginning of the exposure period and at test termination. After the exposure period of 72h the test substance concentration was below the limit of detection of the analytical method of 0.005 mg/L. This level of detection was used in the calculation of the geometric mean which resulted in artificially low effect concentrations. According to the OECD guideline for the testing of chemicals, freshwater alga and cyanobacteria, growth inhibition test (201) the alga growth inhibition test is a more dynamic test system than most other short-term aquatic toxicity tests. As a consequence, the actual exposure concentrations may be difficult to define, especially for adsorbing substances tested at low concentrations. In such cases, disappearance of the test substance from solution by adsorption to the increasing algal biomass does not mean that it is lost from the test system. Therefore, it seemed appropriate to base the analysis of the results on the initial measured concentrations and not the artificially low geometric mean measured concentrations.

Toxicity to aquatic plants other than algae

The growth ofLemna gibbaexposed to the test item was investigated in a 7 day semi-static test according to the OECD Guideline for the Testing of Chemicals No. 221 (2006). The endpoint values were determined based on the nominal test item concentrations. However, since the determined concentrations of the test item were not stable under the test conditions in a period between daily renewals, the endpoint values were also determined based on the time-weighted mean of the measured concentrations of the test item. The determined endpoint values based on time weighted mean concentrations based on frond number as primary measurement (according to ECHA's Guidance and information requirements and chemical safety assessment, chapter R.7b) were as follows: The ErC50/7 d > 1.02 mg/L, the ErC10/7 d > 1.02 mg/L. The LOEC/7 d = 0.40 mg/L and the NOEC/7 d = 0.17 mg/L.

This test was additionally conducted to avoid the analytical difficulties of the algae study. As semi-static test with 24h renewal periods of the test media the decrease of test substance is not as severe as in the 72h algae test which cannot be conducted as semi-static of even flow-through test.

Toxicity to microorganisms

In a static respiration inhibition test, the microorganisms from a domestic activated sludge were exposed to the test item for 3 hours according to OECD Guideline No 209. The effect concentrations are based on nominal concentrations as follows: EC10 is equal to 95 mg/L and EC50 is equal to 400 mg/L.