Bis(2-ethylhexyl) carbonate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

For the assessment of the potential of Bis(2-ethylhexyl) carbonate to cause sensitisation several studies are available, which are used in a weight of evidence approach.

 

A Local Lymph Node Assay is available, which is considered to be invalid due to methodological deficiencies. In a dermal sensitisation study with Bis(2-ethylhexyl) carbonate (at minimum 99.9% a.i.) in acetone:olive oil, 4:1 (v/v) groups of 4 female CBA mice were tested using the LLNA method according to the draft Version of OECD Guideline 429, November 2000. Positive control substance was alpha hexyl cinnamic aldeyde, which gave a positive result (STIMULATION INDEX of 6.7) at a concentration of 25 % in acetone:olive oil, 4:1 (v/v).

STIMULATION INDICES of 4.1, 4.0 and 3.6 were determined with the test item at concentrations of 25, 50, and 75 % (w/w) in acetone:olive oil, 4:1 (v/v), respectively.

Although the stimulation indices at all tested concentrations was higher than 3, usually interpreted as demonstrating a sensitising potential, this result is most probably false positive because the test is considered to be unsuitable, because the results are likely to be due to the test substance´s irritating nature. The test substance is classified as a skin irritant with a cut off level of 25% and above.

This LLNA was performed in parallel with the skin irritation study. Hence, at the time of the conduct of the LLNA, there was no knowledge on the irritating properties of test substance. The lack of knowledge on irritation resulted in the choice of rather high test concentrations.

 

A second LLNA with lower concentrations was carried out to get a better understanding on the potency:

In a dermal sensitisation study with Bis(2-ethylhexyl) carbonate (at minimum 99.9% a.i.) in acetone:olive oil, 4:1 (v/v) groups of 4 female CBA mice were tested using the LLNA method according to the draft Version of OECD Guideline 429, November 2000. Positive control substance was alpha hexyl cinnamic aldeyde, which gave a positive result (STIMULATION INDEX of 6.7) at a concentration of 25 % in acetone:olive oil, 4:1 (v/v).

STIMULATION INDICES of 1.6, 1.4 and 1.7 were determined with the test item at concentrations of 5 %, 10 % and 15 % (w/w) in acetone:olive oil, 4:1 (v/v), respectively.

A test item is regarded as a sensitiser in the LLNA if the exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the STIMULATION INDEX.

Based on these criteria, the test item was found to be a non-sensitiser when tested up to 15 % (w/w) in acetone:olive oil, 4:1 (v/v). In this study, Bis(2-ethylhexyl) carbonate is not a dermal sensitiser.

 

To clarify if the irritating properties of the substance could have triggered the secretion of pro-inflammatory cytokines, which then in conjunction with TNF-alpha cells are able to stimulate the activation and migration of Langerhans cells from the epidermis resulting In their subsequent accumulation in the skin-draining lymph nodes, a Buehler test was conducted following the LLNA.

 

In a dermal sensitisation study with Bis-(2-ethylhexyl)carbonate (approx. 100% a.i.) in corn oil young adult Pirbright white guinea pig (10 male, 10 female) were tested using the BUEHLER method according to OECD Guideline 406, July 17, 1992 and EEC Directive B6, 29 December 1992.

Slight erythema and slight oedema were observed in most animals after the dermal application in the induction phase at the test article concentration of 50%. No allergic skin reactions were observed in test animals after the challenge exposure with the test article at a concentration of 25 %, assessed 24 and 48 h after patch removal. No findings were observed in control animals. The sensitisation rate, i.e. the number of animals showing an allergic response expressed as a percentage of the total number of animals, was determined 24 and 48 h after patch removal and was 0 % in test animals in each case. In this study, Bis(2-ethylhexyl) carbonate is not a dermal sensitiser.

 

In a dermal sensitisation study with Bis(2-ethylhexyl) carbonate (100% a.i.) in corn oil, young adult Albino Dunkin Hartley guinea pigs (15 males; 10 test and 5 control) were tested using the MAXIMISATION test method according to OECD Guideline 406, July 17, 1992 and EEC Directive B6, May 30, 2008.

The maximum compatible concentrations which led to slight irritation after intradermal and dermal application as well as the subirritative dose for the challenge application were determined in pretests. Corn oil was used as vehicle during induction and challenge. Based on the results of the pretests, for the intradermal and epicutaneous induction exposure test substance concentrations of 25% and 100% (undiluted) were used, respectively. The test article concentration for the challenge application was 5%. 

No allergic skin reactions were observed in test animals 24 and 48 hours after the challenge exposure. No findings were observed in control animals. The sensitisation rate, i.e. the number of animals showing an allergic response expressed as a percentage of the total number of animals, was 0%. In this study, Bis(2-ethylhexyl) carbonateis not a dermal sensitiser.

 

The Buehler test gave a 100% negative result (0% positive animals) following induction and challenge at very high concentrations (induction at clearly irritating concentration).

In addition, a GMPT was done to have good and robust data set to conclude that there are no risks to consumer concerning skin sensitisation from Bis(2-ethylhexyl) carbonate.

Likewise an unequivocal negative result (0% positive animals) following induction with 100% Bis(2-ethylhexyl) carbonate and 5% used for the challenge patch. The 5% concentration was the highest non-irritating concentration to be used for the challenge because the test substance proved to be clearly irritating (score 1) in the concurrent pretest at 10% and above. In both tests a positive control using hexyl cinnamic aldehyde demonstrated that the procedure showed an acceptable degree of sensitivity.

These unquestionable negative data from two valid sensitisation tests is further supported by one negative LLNA. This second LLNA has been performed with induction concentrations of 5%, 10% and 15% resulting in stimulation indices of less than 3 for all tested concentrations.

The results of the three valid tests (Buehler test, Maximisation test, LLNA) are in conflict with one LLNA, which is regarded as false positive.

There are strong indications, that the positive outcome of the first LLNA with high concentrations may have only shown cytotoxicity to the Langerhans cells which then reacted by releasing lymphocyte proliferating agents, resulting in the S.I. values of greater 3. This is supported by the decreased S.I. value for the highest concentration tested, which does not fit the expected dose response curve.

Skin irritation testing on rabbits clearly indicates that the test substance is irritating to the skin at concentrations of 25% and above resulting in Classification as skin irritating Category 2.

Furthermore, the dermal penetration of Bis(2-ethylhexyl) carbonate was found to be negligible in an in vitro test according to OECD guideline 428.

Based on a weight of evidence approach, Bis(2-ethylhexyl) carbonate is considered to be not sensitising to the skin.

 

No data are available to assess the potential for respiratory sensitisation of Bis(2-ethylhexyl) carbonate. However, due to its low vapour pressure and the nature of the products where it is used, inhalation is not a relevant route of exposure.

Migrated from Short description of key information:
Human data on skin sensitisation are not available.
Bis(2-ethylhexyl) carbonate was not sensitising in a Buehler test according to OECD Guideline 406, a Guine pig maximisation test OECD Guideline 406 as well as in a LLNA according to OECD guideline 429.

Justification for selection of skin sensitisation endpoint:
No single key study has been selected. All available data are considered in a weight of evidence approach.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

A classification of Bis(2-ethylhexyl) carbonate is not justified for skin sensitisation according to CLP, EU GHS (Regulation (EC) No 1272/2008) as well as the former European directive on classification and labelling Directive 67/548/EEC.

Results were taken from a weight of evidence approach considering all available data.