Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked

Endpoint summary

Description of key information

The acute toxicity of the test item Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked to fish (zebrafish) was determined according to OECD-Guideline for Testing of Chemicals No. 203 (1992). A semi-static limit test with daily renewal of the test media was performed with the saturated solution of nominal 3.9 mg/L. The duration of the test was 96 h. Seven test organisms were exposed to the saturated solution and the control. The determination of the test item was carried out via LC-MS/MS from the saturated solution and the control from freshly prepared media after and 72 h and from 24 h aged test media after 24 h and 96 h. The values were 397 and 896 µg/L (freshly prepared media) and 227 and 563 µg/L (in 24 h aged test media), respectively. All effect levels are given based on the geometric mean measured concentrations of the test item.

In this study Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked was found to cause no toxic effects to Zebrafish after 96 hours when tested with the saturated solution. The LC50 after 96 hours is > 462 µg/L. All effect levels are given based on the geometric mean measured concentration of the test item.

The acute toxicity of the test substance to Daphnia magna was studied under static conditions according to OECD TGD 202 and EU method C2. Daphnids were exposed to the test item at one concentration (highest soluble concentration) for 48 h. No effects were observed up to the water solubility limit (0.63 mg/L) indicating that the test substance does not pose a significant hazard to aquatic invertebrates.

The toxicity ofCyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked to the unicellular freshwater green algaPseudokirchneriella subcapitatawas determined according to the principles of OECD 201.The aim of the study was the determination of NOEC, LOEC, EC₁₀- , EC₂₀- and EC₅₀- values of growth rate and yield over a period of 72 hours.

The study was conducted under static conditions with a saturated solution* (i.e. 100 %) and further four dilution levels of 9.96 - 17.7 - 31.6 - 56.2 % of the saturated solution, corresponding to geometric mean measured test item concentrations of 226 - 399 – 638 – 1268 – 2088 µg/L.

The concentrations of the test item were analytically verified by LC-MS/MS analysis at test start and test end of all dilution levels and the control. The measured concentrations at test start were in the range of 180 – 2154 µg/L. The measured concentrations at the end of the test were in the range of 283 – 2024 µg/L. All effect values given are based on the geometric mean measured concentrations of the test item.

In this study the test item was not found to inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata significantly, when tested with the saturated solution and further dilution levels. The effect values after 72 hours (geometric mean measured test item concentrations) were: The EC50-values with 95 % confidence intervals for inhibition of specific growth rate (ErC50) and yield (EyC50) after 72 hours were > 2088 µg/L for both endpoints. The NOEC-values for inhibition of specific growth rate and yield after 72 hours were 2088 µg/L (highest test concentration) for both endpoints.

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 (2010) was carried out with the test item Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked. Test system was activated sludge of a municipal treatment plant. The test was carried out under static conditions with the limit concentration of 1000 mg/L. The respiration rates of the control, reference and test item replicates were measured after a contact time of three hours by means of oximeter immediately after transferring the solution to the measuring cell and the oxygen depletion was recorded for at least 3 minutes on a flat bed recorder.

The inhibitory effects of the test and reference item were determined in comparison to the control respiration rate. The inhibition of respiration for the test item replicates ranged from -9 to -7 %.The NOEC of the test item Cyclohexane, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethyl-, homopolymer, acetone oxime-blocked is 1000 mg/L.