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Description of key information

3 -Isocyanatomethyl-3,5,5 -trimethylcyclohexyl isocyanate was tested in aquatic acute toxicity studies:

 In a static acute 96-hour fish toxicity limit test according to Directive 92/69/EEC with Danio rerio (Bayer AG, 2000) no mortalities or abnormal swimming were observed. The analytical test concentration, which was determined daily by DOC measurements, was 72.3 mg/l.

In a static 48h-study with Daphnia magna (Hüls AG, 1995) according to EU method C.2 five concentrations ranging from 5.2 to 73 mg/L the EC50 was determined as 27 mg/L. In another 96 h-study with the marine crustacea Chaetogammarus marinus (Adema 1982) the EC50 was determined as 4.0 mg/L.

In a 72h-study with the algae Scenedesmus subspicatus (Bayer AG, 2000) according to EU method C.3, seven concentrations of Isophorone diisocyanate ranging from 1.1 to 70.0 mg/L were tested. The EC50 (72 hours, growth rate) was determined as >70 mg/L and the NOEC as 4.4 mg/L.

The effects of isophorone diisocyanate on the inhibition of the respiration rate of activated was investigated (Bayer AG, 2000) according to EU method C.11. The EC50 (3 hours contact time) was determined as 263 mg/L, the EC10 (3 hours contact time) was 106 mg/L.


Chronic studies with 3 -Isocyanatomethyl-3,5,5 -trimethylcyclohexyl isocyanate were not conducted due to the chemical properties of the substance and due to exposure consideration (substance-tailored exposure driven testing).

Additional information

3 -Isocyanatomethyl-3,5,5 -trimethylcyclohexyl isocyanate hydrolyses upon contact with water. The diisocyanate groups of the substance react by forming amines (i.e. 3-aminomethyl-3,5,5-trimethylcyclohexylamine) and CO2. The amines formed may react further with unreacted diisocyanate groups of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate resulting in oligo- and subsequently polyurea components.

Test substance solutions of 3 -isocyanatomethyl-3,5,5 -trimethylcyclohexyl isocyanate were prepared at nominal concentrations that were some orders of magnitude higher than the maximum water solubility. The solutions were stirred for 18 to 24 hours and insoluble particles were filtered off. Substance concentrations were determined as DOC/TOC and were backcalculated to the parent compound. Therefore, results should be treated with caution when considering effect concentrations as it is not clear whether effects are caused by the parent substance or by the hydrolysis products 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl amine or polyurea.

The lowest toxicity values were derived for the aquatic invertebrates Daphnia magna and Chaetogammarus marinus. The EC50 was 27 mg/L for Daphnia magna (parent substance) and 4.0 mg/L for Chaetogammarus marinus.