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EC number: 407-000-3 | CAS number: 127519-17-9 CGL 384; TINUVIN 384
Bioaccumulation: aquatic / sediment
Administrative data
Link to relevant study record(s)
Description of key information
The substance does not significantly accumulate in organisms.
Key value for chemical safety assessment
Additional information
According to Annex XI of Regulation (EC) 1907/2006 substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or “category” of substances. Application of the group concept requires that physicochemical properties, human health effects and environmental effects or environmental fate may be predicted from data for reference substance(s) within the group by interpolation to other substances in the group (read-across approach). The similarities may be based on (1) a common functional group, (2) the common precursors and/or the likelihood of common breakdown products via physical and biological processes, which result in structurally similar chemicals or (3) a constant pattern in the changing of the potency of the properties across the category.
The read-across substance (EC 400-830-7) consists of two major components: (1) a monoester component present at 51 w/w% and (2) a diester component present at 35.4 w/w%. Both the read-across compound and EC 407-000-3 share the same phenolic benzotriazole core structure with a hydroxyl group at position 2 and a tertiary butyl group at position 3 of the phenyl group. At position 5 of the phenyl ring a CH2-CH2-COO group is connected to a (C2H4O)n group (n is typically in the range of 2 to 10). Both the monoester and the diester are highly similar to EC 407-000-3, especially the phenolic benzotriazole core structure which is identical in the respective compounds. The only structural difference is the side chain connected to the carboxylic moiety. Due to the carboxylic moiety and the ester linkage to the side chain the compounds are susceptive to hydrolysis and further degradation processes. The primary degradant of both the diester and the monoester are therefore highly similar/identical to the degradant of EC 407-000-3.
Although the water solubility of the monoester (monoester: 1.74 mg/L; diester: <0.2 mg/L) differ from the solubility of EC 407-000-3 (0.018 mg/L) it can be stated that both substances have low solubilities. The logKow values of the read-across substance and EC 407-000-3 indicate that the compounds have a bioaccumulative potential (logKow values: monoester: 5.9; diester: 4.6; EC 407-000-3: 9.2).
In summary, taking into account the common functional core structure as well as the common breakdown product via physical and biological processes a read-across from EC 400-830-7 to EC 407-000-3 is regarded as suitable. To further support the read-across strategy QSAR estimations of the parent as well as the degradation product have been performed to allow a solid assessment of the bioaccumulative potential of EC 407-000-3.
In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met. Furthermore according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort.
According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.
For the assessment of EC 407-000-3 (Q)SAR results were used for bioaccumulation. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.
Therefore, and for reasons of animal welfare, further experimental studies on bioaccumulation are not provided.
To conclude on the bioaccumulation behaviour of the test substance an weight of evidence approach was applied according to Reach
Annex XI, section1.2
For this approach the following data were used:
1. Bioconcentration and bioaccumulation data
2 . Biodegradation data on the test substance
3. Data on the major degradation product identified in the degradation study
1. Bioconcentration and bioaccumulation data
- The potential to bioaccumulate was investigated in a bioconcentration study on the carp Cyprinus carpio [Ciba Geigy, 1991] with the substance EC 407 -000 -3. At the end of an 8-week exposure period, the measured BCF values were below three.
- Calculations of the BCF with standard QSARs (EPISuite 4.11) for the substance (EC 407 -000 -3) resulted in moderate BCF values (BCFBAF v3.01, regression based estimate: BCF = 427 L/kg; Arnot-Gobas method (including biotransformation rate estimates: BCF 17.6 L/kg). A calculated BAF value indicates low accumulation properties (BCFBAF v3.01, Arnot-Gobas method, including biotransformation rate estimates, upper trophic: BAF 141.5 L/kg).
- Read-Across to similar substance (EC 400-830-7):
Two bioconcentrations studies according to OECD 305 (Ciba Geigy 1987, Nihon Ciba Geigy 1986) performed with a similar substance (EC 400 -830 -7) gave BCF values of 26 -34 and < 0.24- < 2.4, respectively. In both studies the concentration of the test substances were analytically monitored. No potential for bioaccumulation was identified.
- Conclusion of toxicokinetic assessment for mammals: No bioaccumulation hazard is expected. (see section 7, 7.1 of IUCLID)
2. Degradation studies according to OECD 308 show a fast primary degradation of substance EC 407 -000 -3 in aquatic sediment systems .
Under aerobic conditions the substance migrated rapidly from the water phase into the sediment, with a half-life of about a day. In the sediment a mean half-life of about 8 days was calculated. Several degradation products were determined. The main degradation product resulted from ester hydrolyses of the substance to carbonic acid.
The carbonic acid amounted to concentrations of about 60% of the applied radioactivity and degraded with a half-life of about 40-64 days. A part of the test item got stably bound to the immobile humin fraction.
Under anaerobic conditions similar results occur. The parent compound disappeared rapidly from the aquatic systems (half-life of 20.4 days) to form carbonic acid and bound residues.
Therefore, the substance EC 407-000-3 is unlikely to accumulate to a significant extent in biota. Additionally, due to the fast primary degradation, bioaccumulation of the substance is not likely to occur in the environment.
Assessment of the major degradation product:
The major degradation product formed by hydrolysis of the ester to give the corresponding carboxylic acid was found to be eliminated rapidly in the aquatic phase and incorporated in organic matter of the sediment as shown in the simulation studies with substance EC 407 -000 -3 according to OECD 308.
Calculations of the BCF with standard QSARs (EPISuite 4.11) for the major degradation product resulted in low BCF values (BCFBAF v3.01, regression based estimate: BCF = 3.16 L/kg; Arnot-Gobas method (including biotransformation rate estimates: BCF 109.3 L/kg). A calculated BAF value indicates low accumulation properties (BCFBAF v3.01, Arnot-Gobas method, including biotransformation rate estimates, upper trophic: BAF 109.3 L/kg).
It can be expected that the ability to cross biological membranes and to bioaccumulate is additionally hindered due to the charge of the carboxylic acid group.
Furthermore, the logKOW of 3.3 calculated with KOWWIN 1.68 indicate that the degradation product does not meet the bioaccumulation criteria according to REACH.
Conclusion:
Due to the presented available data and the fast primary degradation and elimination, bioaccumulation of the substance is not likely to occur in the environment.
Therefore, EC 407-000-3 is unlikely to accumulate to a significant extent in biota.
For further assessments a BCF of < 500 is used.
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