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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Significant accumulation in organisms is not to be expected.
The applied QSAR models calculated a BCF (log BCF) in a range between 5 L/kg (0.7) and 272 L/kg (2.43). Therefore, these estimated results indicate that alpha-Tocopherol (CAS 59-02-9) is not to be expected to accumulate in organisms (estimated BCF <500 L/kg).

Key value for chemical safety assessment

Additional information

QSAR-disclaimer

 

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.

 

Read across to bioaccumulation assessment of DL-alpha-Tocopherol

In order to assess the bioaccumulation behaviour of alpha-Tocopherol (CAS 59-02-9) reference is made to a bioaccumulation assessment of the structural isomer DL-alpha-Tocopherol (CAS 10191-41-0), which was performed based on several QSAR models. Due to the structural similarity of the isomers it is justified to take over the conclusion for the DL-alpha-Tocopherol (CAS 10191-41-0) to alpha-Tocopherol (CAS 59-02-9).

 

 

Bioaccumulation assessment of DL-alpha-Tocopherol

For the assessment of DL-alpha-Tocopherol (Q)SAR results were used for aquatic 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 aquatic bioaccumulation are not provided.

Assessment of bioaccumulation potential:

In accordance with REACH Annex XI, the bioaccumulation test in aquatic species does not need to be conducted. As the substance is highly insoluble, it will not be significantly bioavailable and no significant exposure of aquatic organisms is expected. DL-alpha-Tocopherol (CAS 10191-41-0) as well as alpha-Tocopherol (CAS 59-02-9) is commonly used as food additive (Vitamin E supply) and is therefore considered being not bioaccumulative in organisms.

In support of this conclusion, a bioaccumulation assessment of DL-alpha-Tocopherol (CAS 10191-41-0) was performed based on several QSAR models. Based on the chemical properties of the substance (mainly the high log Kow), the substance was outside of the applicability domain of the available models. Therefore the estimated BCF values may be less accurate. A weight-of-evidence approach was selected to evaluate the estimated BCF values.

 

-The QSAR model BCFBAF v.3.01 of EPISUITE v.4.11 calculated a BCF of 38.6 L/kg (log BCF: 1.59) based on a log Kow of 12.18 (BASF SE, 2014).

The obtained BCF value indicates that significant accumulation in organisms is not to be expected (log Kow <1; calculated BCF 1-100). The substance was not within the applicability domain of the model.

 

- The US EPA T.E.S.T package v.4.1 calculated the BCF on different sets of molecular descriptors. According to this strategy, the substance has a BCF of 272 L/kg (log BCF: 2.43) using the Consensus Method based on 5 modelling results.

However, based on the mean absolute errors (MAE’s) of these models the confidence in the predicted results is low.

 

- Three QSAR models (CAESAR v.2.1; Meylan v.1.0.2, Read-across v.1.0.2) implemented in the VEGA tool v.1.0.8 estimated the BCF at:

         -CAESAR: 5 L/kg (log BCF: 0.7; BASF SE, 2014)

-Meylan: 39 L/kg (log BCF: 1.59; BASF SE, 2014)

-Read-Across: 155 L/kg (log BCF: 2.19: BASF SE; 2014)

 

 In all cases the substance was out of the applicability domain of the estimation models.

-UBA (2011), collection of 13 log Kow regressions: the estimated log Kow of 12.18 from KOWWIN v1.68 (implemented in EPISUITE v.4.11) was not within the recommended range of the models.

 

In conclusion, the applied QSAR models calculated a BCF (log BCF) in a range between 5 L/kg (0.7) and 272 L/kg (2.43). Therefore, these estimated results indicate that DL-alpha-Tocopherol (CAS 10191-41-0) and consequently also alpha-Tocopherol (CAS 59-02-9) is not to be expected to accumulate in organisms (estimated BCF <500 L/kg).

 

Several publications provide supplementary information, indicating that bioaccumulation of Vitamin E (DL-alpha-Tocopherol) is not to be expected in organisms, due to its well-known, essential function as a lipid soluble, chain-breaking antioxidant:

 

- Feeding studies with e.g. commercial broilers (Cobb 500; Bottje et al., 1997) and Korean rockfish (Sebastes schlegeli,; Bai & Lee, 1998) showed a dose response concerning the concentration of alpha-Tocopherol in liver tissue.

 

- In addition, Hsu & Shiau (1999) outline several feeding studies with DL-alpha-Tocopheryl acetate, demonstrating DL-alpha-Tocopherol to be the major form of Vitamin E “stored” in the liver of Hybrid Tilapia (Oreochrimis niloticus x O. aureus) and of Rainbow Trouts (from Hung et al. 1998). Metabolized to alpha-Tocopheryl-acetate, Vitamin E is furthermore the major form found in blood or muscle tissue of Hybrid Tilapia and also shrimp (Penaeus monodon).

 

- Such findings are supplemented by the fact that the antioxidant activities of tocopherols are imparted by their ability to donate their phenolic hydrogen atoms to lipid free radicals by converting to tocopheryl-acetate (Burton & Ingold 1989). In addition, Vitamin E directly effects positive growth performance of e.g. muscle tissue and enhances the stability of erythrocytic membranes (Paul et al. 2004).

 

Taken together, these results indicate Vitamin E to be stored after ingestion in the liver, which is known to be the central metabolic organ of higher vertebrates. Over time Vitamin E is successively metabolized and deposited by the respective organism.

Therefore, the studies strongly suggest that bioaccumulation of Vitamin E in organisms is not to be expected. 

 

References:

- S.-C. Bai & K.-J. Lee (1998) "Different levels of dietary DL-alpha-tocopheryl acetate affect the vitamin E status of juvenile Korean rockfish, Sebastes schlegeli"; Aquaculture 161: 405 - 414

- W. G. Bottje, G. F. Erf, T. K. Bersi, S. Wang, D. Barnes & K. W. Beers (1997) "Effect of Dietary dl-alpha-Tocopherol on Tissue alpha- and gamma-Tocopherol and Pulmonary Hypertension Syndrome (Ascites) in Broilers."; Poultry Science 76: 1506 -1512

- G. W. Burton & K. U. Ingold (1989) "Mechanisms of antioxidant action: preventive and chain-breaking antioxidants" (in) J. Miquel, A. T. Quintanilha, & H. Weber (es.), Handbook offree radicals and antioxidants in biomedicine (Vol. 2, pp. 29). Boca Raton, FL, CRC Press.

- T. S. Hsu & S. Y. Shiau (1999) "DL-alpha-Tocopheryl Acetate is Not the Only Tissue Storage Form of Vitamin E in Tilapia Fed Dietary

DL-alpha-Tocopheryl Acetate."; Fisheries Science 65: 959 - 960

- S. S. O. Hung, T. W. Moon, J. W. Hilton & S. Slinger (1982) "Uptake, Transport and Distribution of DL-alpha-Tocopheryl Acetate compared to

DL-alpha-Tocopherol in Rainbow Trout, Salmo gairdneri."; J. Nutr. 112: 1590 -1599

- B. N. Paul, S. Sarkar, S. N. Mohanty (2004) "Dietary Vitamin E requirement of mrigal, Cirrhinus mrigala, fry."; Aquaculture 242: 529 -536