Reaction mass of (2,4,6-trioxo-1,3,5-triazine-1,3,5(2H,4H,6H)-triyl)tri-2,1-ethanediyl triacrylate and 2-Propenoic acid, 1,1'-[[dihydro-5-(2-hydroxyethyl)-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-diyl]di-2,1-ethanediyl] ester

Endpoint summary

Description of key information

Short-term toxicity data for algae and crustacean is based on the hypothesis for a read-across approach to data from TMPTA and THEICTA is the similarity of the chemical structures. Both the target substance (T) and TMPTA and Tris(2-hydroxyethyl) isocyanurate /S3) are triacrylates, which – if not subjected to UV-radiation - are rather stable molecules.

By the same registrant as THEICTA, TMPTA has recently undergone OECD testing in order to fulfil the Annex VIII information requirements for the substance, and thus updated data of high quality is available from this substance. Data on toxicity to invertebrates and algae is also available for THEICTA.

Furthermore, an OECD SIDS reports are available for Tris(2-hydroxyethyl) isocyanurate (S3), Methylacrylate (S4) and Trimethylolpropane (S5) with high quality data on the acute toxicity towards fish, invertebrates and algae. For S3 data on the chronic toxicity towards invertebrates is also available.

To support the experimental data and the read across hypothesis, a QSAR calculation has been made for each single substance: THEICTA, THEICDA, TMPTA, Tris(2-hydroxyethyl) isocyanurate, Methylacrylate and Trimethylolpropane. Calculations confirm that the toxicity of the target substance and the source substances (TMPTA (S2) and Methylacrylate (S4)) are within the same level and thus comparable. They also confirm that the toxicity of THEICTA and THEICDA are on the same level and that THEICTA is slightly more toxic to algae, invertebrates and fish than THEICDA. Therefore, in case of that toxicity data for THEICTA is available, it is justified to make a read-across of THEICTA toxicity to toxicity of the mixture of THEICTA and THEICDA.

Short-term toxicity data for fish exist for the substance, i.e. the mixture of THEICTA and THEICDA. It can here be emphasized that using the same read-across approach for fish result in a lower LC50 value than is measured. This support that the use of the read-across is sufficient conservative.

Additional information

Experimental data

A study on the actue toxicity of the registered substance (mixture of THEICDA and THEICTA) to fish is available resulting in a LC50=22.64 mg/L. Studies on the acute toxicity of TMPTA (S2) is available for fish (96h), invertebrates (Daphnia magna, 48h) and algae (72h, growth rate) showing an E(L)C50 of 0.87 mg/L, 19.9 mg/L and 18.8 mg/L respectively. This shows that the mixture of THEICDA and THEICTA apparently is less toxic to fish than TMPTA. For algae an EC10 (72h, growth rate) = 1.9 mg/L is also available.

Studies on the acute toxicity of THEICTA (part of the target substance) is available for invertebrates (Daphnia magna, 48h) and algae (72h, growth rate) showing an E(L)C50 of 158.3 mg/L and 25.7 mg/L. For algae an EC10 (72h, growth rate) = 12.9 mg/L is also available. QSAR calculations confirm that THEICTA is slightly more toxic than THEICDA – but also that the toxicity is on the same level.

Furthermore, an OECD SIDS report is available for Tris(2-hydroxyethyl) isocyanurate (S3). Data on the acute toxicity show an E(L)C50 >100 mg/L, >1000 mg/L and >1000 mg/L for fish, invertebrates (Daphnia magna) and algae respectively. Furthermore the OECD SIDS report has data on the chronic toxicity towards invertebrate showing an NOEC (21d)≥100 mg/L.

An OECD SIDS Report is available for Methylacrylate (S4). The ecotoxicity data reported for Methylacrylate are within the same level (E(L)C50: 1.1 mg/L, 2.6 mg/L and 3.55 mg/L for fish, invertebrates (Daphnia magna) and algae respectively) and thus comparable to the toxicity data reported for TMPTA (S2) - indicating that the toxicity of S2 is most likely caused by the methylacrylate groups.

An OECD SIDS Report is available for Trimethylolpropane (S5). The ecotoxicity data reported for Trimethylolpropan are lower (E(L)C50: >1000 mg/L, 13000 mg/L and >1000 mg/L for fish, invertebrates (Daphnia magna) and algae respectively) and not contributing to toxicity.

Thus, due to the close structural similarity of TMPTA (S2) and Methylacrylate to the target substance, the same level of acute toxicity towards aquatic organisms is expected for the reaction mass of THEICTA and THEICDA (T). The toxicity of the source substance S3 is much lower than the toxicity of source substance S2 and S4. Furthermore, the toxicity data for S2 and S4 are within the same range indicating that the toxicity of S2 is most likely caused by the attached acrylate groups.

Based on a conservative approach, and the output from the QSAR calculations, which indicated that the toxicity of the target substance is more comparable to the toxicity of S2 and S4, results from studies with S3 are considered as supporting studies and results from studies with S2 are considered as key studies in the risk assessment.

Overall: Acute toxicity data for the substance is preferable, however these are only available for short-term toxicity to fish. For the other short-term toxicity end-points, a read-across of environmental toxicity data for THEICTA (in case data exist) respectively for TMPTA to the target substance is justified. The strategy is use the toxicity data for THEICTA -if they exist – else to use the toxicity data for TMPTA.