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Administrative data

Link to relevant study record(s)

Reference
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.
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
Radiolabelling:
no
Species:
rabbit
Strain:
not specified
Sex:
not specified
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.
Signs and symptoms of toxicity:
no effects
Dermal irritation:
yes
Key result
Time point:
24 h
Dose:
2000 mg/kg bw
Remarks on result:
other: no indication of absorption in acutely toxic amounts

Response remarks:

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

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).

Description of key information

When the skin of 2 rabbits was exposed to a dose level of 2000 g 3,5-xylenol per kg body weight for 24 hours, there was no indication of absorption through the skin in acutely toxic amounts.

Key value for chemical safety assessment

Absorption rate - oral (%):
100
Absorption rate - dermal (%):
50
Absorption rate - inhalation (%):
100

Additional information

Default values for absorption rates are proposed according to ECHA Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7c, Endpoint specific guidance: Toxicokinetics (Version 3.0, June 2017). A dermal absorption rate of 50% is set as data on acute dermal and oral toxicity of the analogue 3,5-xylenol suggest that the substance may not completely be absorbed through the skin.

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).