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Ecotoxicological information

Long-term toxicity to aquatic invertebrates

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Description of key information

NOEC(21d): 1.1 mg/L (Daphnia magna, OECD 211) 
NOEC(21d) >= 0.5 mg/L (Daphnia magna, OECD 211)
Calculation with ECOSAR v1.00 (EPIWIN software by US-EPA), Chronic Value for daphnids: 0.00121 mg/L

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
1.1 mg/L

Additional information

The chronic toxicity of m-tolylidene diisocyanate to aquatic invertebrates was investigated in two experiments with Daphnia magna according to OECD Guideline 211(key and supporting information). Furthermore, a QSAR prediction of 2,4,6 -triisopropyl-m-phenylene diisocyanate was performed.

In the experiment performed by Cerbelaud et.al. (1997), young female daphnids (less than 24 hours old) were exposed to nominal test concentrations of 0.28, 0.55, 1.10, 2.20 and 4.40 mg/L for a test duration of 21 days. Analysis of 2,4- and 2,6-TDA was carried out using High Performance Liquid Chromatography (HPLC). The NOEC for the test substance was defined as 1.1 mg/L. Conversion of TDI to TDA was incomplete in all the experiments, with yields shown to be between 57 and 69 % in the initial test solutions at the beginning of the tests. The TDA analysis indicates a derived NOEC for TDA of 0.5 mg/L.

In the supporting study, the test material was stirred into the medium for 1 h prior to sampling and the medium was renewed thrice weekly (Caspers et al., 1986). At each renewal of the test medium, activated sludge extract from a domestic sewage treatment plant (final COD concentration in the test water: 5 mg/L) was added to assure maximum reproduction rates under control conditions. This limit test was conducted with test concentrations of 0.05, 0.16 and 0.50 mg/L. No effect observed at highest concentration tested, therefore the EC50, LOEC and NOEC values were determined as greater or equal to 0.50 mg/L. Due to the rapid hydrolysis of TDI this test essentially measured the toxicity of hydrolysis products. Preparations were found to be heterogeneous with much insoluble product.

The prediction for long-term toxicity for aquatic organisms of the substance 2,4,6 -triisopropyl-m-phenylene diisocyanate was determined by the computer program ECOSAR v1.00 (EPIWIN software) by US-EPA (Chemservice S.A., 2011). The program uses an extensive set of structure-activity relationships (SARs) to estimate the toxicity of chemicals discharged to water. For daphnids a Chronic Value (ChV) of 0.00121 mg/L was predicted.