1,3,3-trimethyl-N-(2-methylpropylidene)-5-[(2-methylpropylidene)amino]cyclohexanemethylamine

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

The substance itself and its degradation products are not PBT and vPvB since they do not fulfill the criteria.

Although not readily biodegradable, the substance itself showed a biodegradation rate of 34% in a manometric respirometry test. Furthermore, hydrolysis occurs rapidly: the substance is hydrolyzed completely within 2.4 hours at 50 °C and pH 4, 7, and 9 each. Hydrolysis half-lives below 30 min under these test conditions correspond to half-lifes below five hours at 25 °C. Main degradation products are isophorone diamine and isobutyraldehyde. Thus, the persistence criterion is not fulfilled.

Aquatic toxicity tests showed that E(L)C50 values for fish, daphnids and algae were in the range of 14.7 mg/L to 73.6 mg/L based on measured DOC values.The screening criterion for toxicity is an E(L)C50 value below 0.01 mg/L which is not fulfilled.

One of the degradation products is Isobuturaldehyde (CAS 78 -84 -2) which can be regarded as not PBT/vPvB based on the data available from the dossier. The substance is readily biodegradable as shown in a modified MITI test according to OECD 301C. 90% degradation was observed after 14 days. The log Kow was determined to be 0.77 (measured) and 0.74 (calculated), this indicates a low potential for bioaccumulation. The toxicity test results varied from minimum 23 mg/L (96h, fish) to maximum 277 mg/L (48h, daphnia) thus the toxicity criterion is not fulfilled.

The second degradation product is isophorone diamine (CAS 2855-13-2). The substance was assessed as not readily biodegradable, but abiotic degradation occurs. Half-life in fresh water is below 12 hours, half-life of the hydrolysis product 3-aminomethyl-3,5,5-trimethylcyclohexylamine is >120 d; the substance has to be considered as persistent. QSAR calculations resulted in a BCF value of 910 for the parent substance and 3.16 for the main hydrolysis product which indicates a low potential for bioaccumulation. The lowest aquatic toxicity test results were 72h-NOEC for algae (4.4 mg/L, Bayer AG 2000) and a long-term NOEC (Daphnia reproduction) for hydrolysis product (3-aminomethyl-3,5,5-trimethylcyclohexylamine) with 3.0 mg/L showing that the substance and its degradation products do not fulfill the toxicity criterion.