Butyl ethyl ether

Endpoint summary

Description of key information

There is no study available elucidating the skin sensitisation potential of butyl ethyl ether (target substance). Therefore, a skin sensitisation study conducted with di-n-butyl ether was used in a read-across approach. It was shown in this study, which was conducted equivalent to OECD testing guideline 406, that the source substance is considered not sensitising to the skin.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

The source compound di-n-butyl ether (EC 205-575-3, CAS 142-96-1) is considered a suitable read across partner for butyl ethyl ether (EC 211-055-7, CAS 628-81-9). Both structures are short chain, linear alkyl ethers. The only difference in the structure is a C1-shorter (asymmetric) side chain in the butyl ethyl ether (C3-O-C4) compared to dibutyl ether (C4-O-C4).
Both ethers have similar physico-chemical properties. Both are water soluble (300 mg/L vs 2.88 g/L). Di-n-butyl ether has a slightly higher log Kow (3.35 vs 2.03), similar boiling points (140 °C vs 92.3 °C), melting point (-95 °C vs 124 °C), and self-ignition temperature (194 °C vs 180 °C) compared to butyl ethyl ether.
Based on the comparable log Kow and sufficing water solubility, it can be concluded that both compounds penetrate the skin to a similar extend, which would be a pre-requisite to elicit an immune response in the skin. From the structural similarity, it can also be concluded that both compounds have a similar behaviour in binding to proteins in the skin Therefore, it was concluded that the negative results from a skin sensitisation study in di-n-butyl ether can be used to predict the negative outcome in a skin sensitisation study with butyl ethyl ether. This assumption is further supported by the negative results in the OECD QSAR toolbox profiler (version 4.2). The profiler for Protein binding by OASIS and OECD predict “no alert found”, the Protein binding potency profiler for Cys and Lys predict “DPRA less than 9%”, and the endpoint specific profiler “Protein binding alerts for skin sensitisation according to GHS” or “[..] by OASIS”, as well as the “Protein binding potency h-CLAT” did not identify any alerts.

Reason / purpose for cross-reference:

read-across source

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100%

No. with + reactions:

4

Total no. in group:

5

Clinical observations:

Erythema

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

100%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

Edema

Group:

negative control

Remarks on result:

not measured/tested

Group:

positive control

Remarks on result:

not measured/tested

Interpretation of results:

GHS criteria not met

Conclusions:

The test item was tested negative for skin sensitisation.

Executive summary:

The present study explored the quantitative dermal exposure requirements for dermal sensitization in the guinea pig in relation to the concentration required for dermal response at challenge.

In this dermal sensitisation study (equivalent to OECD 406) guinea-pigs of the Hartley strain were tested. Test animals were challenged 5 days after induction. n-Butyl ether was used as vehicle. To exclude any reactions induced by n-butyl ether, a vehicle control was included in the test design (0.0 % test substance). At the 24-h reading no dermal reactions were seen in the vehicle application. Based on the results, n-butyl ether is not a dermal sensitiser.

This information on n-butyl ether is used in a read-across approach in the assessment of the substance to be registered.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No data is available for butyl ethyl ether (target substance). Thus, available data from the suitable read-across partner di-n-buthyl ether (source substance) was used to assess the sensitising potential of the target substance. Di-n-butyl ether was tested negative in a dermal sensitisation study conducted equivalent to OECD 406. Based on the results from the read-across partner, the target substance butyl ethyl ether can be considered as not sensitising to the skin.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In a dermal sensitisation study conducted equivalent to OECD 406 a suitable read-across partner was tested negative for skin sensitisation. Based on the results from the read-across partner, no classification of butyl ethyl ether is warranted.