2,5-xylenol

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Some experimental details are not reported.

Justification for type of information:

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
Available data show that there is no significant variation in acute dermal toxicity between members of the category. Therefore, the general hypothesis for the category approach that xylenol isomers are characterised by similar toxicity effects and a closely related toxicokinetic behaviour applies for the endpoint "dermal absorption".

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL )
The acute dermal toxicity of 4 individual xylenol isomers was found to be low, with similar rat or rabbit LD50 values in the range from 1000 to 2400 mg/kg bw. See attached read-across justification for further information.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1961

Report date:

1961

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

2000 mg of the solid material per kg body weight along with 5 ml water were applied to the rabbit skin under a semi- occlusive coverage (cuff) for a 24-hour period.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

3,5-xylenol

EC Number:

203-606-5

EC Name:

3,5-xylenol

Cas Number:

108-68-9

Molecular formula:

C8H10O

IUPAC Name:

3,5-dimethylphenol

Test material form:

solid

Details on test material:

A sample from the raw material used in the Zectran process- State of aggregation:

- Crystal structure: Needle-like
- Colour. white
- Density:
- Melting point 68 °C
- Boiling point: 219.5°C @ 760 mmHg
- Molecular weight: 122.16
- Molecular formula: C8H10O

Radiolabelling:

no

Test animals

Species:

rabbit

Strain:

not specified

Sex:

not specified

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

water

Remarks:

5 mL of water was applied under the cuff along with the weighed amount of solid material

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per group:

2

Control animals:

no

Details on study design:

2000 mg of the solid material per kg body weight along with 5 ml water were applied to the rabbit skin under a semi- occlusive coverage (cuff) for a 24-hour period.

Results and discussion

Signs and symptoms of toxicity:

no effects

Dermal irritation:

yes

Percutaneous absorption

Key result

Time point:

24 h

Dose:

2000 mg/kg bw

Remarks on result:

other: no indication of absorption in acutely toxic amounts

Any other information on results incl. tables

Response remarks:

Moderate necrosis, edema and hyperemia with hard, black scab formation.

Applicant's summary and conclusion

Conclusions:

When the skin of rabbits was exposed to a dose level of 2000 mg 3,5-xylenol per kg body weight for 24 hours, there was no indication of absorption through the skin in acutely toxic amounts.

Executive summary:

A skin absoprtion study using the Cuff Technique was conducted according to generally acccepted scientific methods with sufficient documentation. In this test 2000 mg of 3,5-xylenol per kg body weight along with 5 ml water were applied to the skin of two rabbits under a semi-occlusive coverage (cuff) for a 24-hour period. None of the exposed rabbits died, concusively there was no indication of absorption through the skin in acutely toxic amounts.

This result can be transferred to the target test item 2,5-xylenol based on high structural similarities in the read-across category of xylenol isomers (see 'Read-across statement' in section 13.2).