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Description of key information

OECD 406; GLP; no skin sensitisation was observed in guinea pigs; reliability = 2. [CAS# 121-91-5]

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
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
This study is used for read-across and therefore has been assigned a reliability of 2 (reliable with restrictions). The study, if used in support of isophthalic acid, has a reliability of 1 (reliable without restriction).
Justification for type of information:
The test substance rapidly hydrolyses to isophthalic acid (IPA). Therefore, the study with IPA is being used to fulfil this data requirement. Additional documentation, provided within the IUCLID Assessment Reports section, supports the read-across approach.
Reason / purpose for cross-reference:
read-across: supporting information
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
no
GLP compliance:
yes
Type of study:
Buehler test
Justification for non-LLNA method:
Data from an in vivo sensitsation study in guinea pigs are available.
Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 6 weeks
- Weight at study initiation: 281-370 g
- Housing: individually in stainless steel cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C
- Humidity (%): 63%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
0.3 mL of a 30% (w/w ) test substance/DMSO
Route:
epicutaneous, occlusive
Vehicle:
DMSO
Concentration / amount:
0.3 mL of a 30% (w/w ) test substance/DMSO
No. of animals per dose:
3 groups of ten males
Details on study design:
MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 30
- Exposure period: 2 weeks
- Test groups: 10
- Vehicle Control group: 10
- Sham Control group: 10
- Site: Upper left quadrant of the backs
- Frequency of applications: once/week
- Duration: 3 weeks
- Concentrations: 0.3 ml of a 30% (w/w) test article/DMSO solution (Test group) or undiluted DMSO (Vehicle control), Nothing (Sham group)


B. CHALLENGE EXPOSURE
- No. of exposures: 30
- Exposure period: 6 hours
- Test groups: 10
- Control group: 10
- Sham Control group: 10
- Site: lower left quadrant of the backs
- Concentrations: 0.3 ml of the 30% (w/w) test article/DMSO (Test group and Sham group), Vehicle control guinea pigs each received a challenge dose of 0.3 ml of a 70% aqueous DMSO solution
- Evaluation (hr after challenge): 24 hours and 48 hours

-OTHER
Approximately 24 and 48 hours after application of the first induction dose and of the challenge dose, the test sites were scored for erythema according to the method of Draize. To facilitate scoring, all animals were shaved immediately prior to scoring during the induction phase, while all of the guinea pigs were depilated with hair remover approximately 2 hours prior to the 24-hour scoring during the challenge phase.
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.3 ml of 30% (w/w) test substance/DMSO
No. with + reactions:
1
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
0.3 mL of 30% (w/w) test substance/DMSO
No. with + reactions:
0
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
other: vehicle control
Dose level:
0.3 mL of 70% aqueous DMSO
No. with + reactions:
0
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
other: vehicle control
Dose level:
0.3 mL of 70% aqueous DMSO
No. with + reactions:
0
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0.3 mL of 30% (w/w) test substance/DMSO
No. with + reactions:
0
Total no. in group:
10
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0.3 mL of 30% (w/w) test substance/DMSO
No. with + reactions:
0
Total no. in group:
10
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Remarks on result:
other: not reported
Interpretation of results:
GHS criteria not met
Conclusions:
The findings indicate that dermal sensitisation did not result from repeated dermal application of test substance.
Executive summary:

The test substance was applied once a week at a dose of 0.3 ml of a 30% (w/w) solution in dimethyl sulfoxide (DMSO) to the shaved backs of ten male guinea pigs during an induction period of three weeks. Another group of 10 male guinea pigs served as a vehicle control and was similarly dosed with 0.3 ml of undiluted DMSO. A third group of ten sham control guinea pigs was handled in the same manner, but was not treated with test article or vehicle. Two weeks following application of the third induction dose, the treated and sham control guinea pigs each received a challenge dose of 0.3 ml of the 30% (w/w) test article/DMSO solution; the vehicle control guinea pigs each received a challenge dose of 0.3 ml of a 70% (w/w) aqueous DMSO solution. All guinea pigs were scored for erythema approximately 24 and 48 hours following application of the first induction dose and the challenge dose. Positive erythema reactions (i.e., a score > 2) were observed in only one test article-treated guinea pig, compared to no vehicle or sham control guinea pigs during the challenge phase. Thus, the primary effect of treatment (treated vs. control) and the secondary effect of time of scoring (24 hr vs. 48 hr) were not statistically significant. These findings indicate that dermal sensitisation did not result from repeated dermal application of test substance.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

The test substance did not produce skin sensitisation in laboratory animals.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Not specifically tested for this endpoint. However, no adverse respiratory tissue effects observed in acute inhalation study.

Justification for classification or non-classification

The test substance did not produce skin sensitisation in laboratory animals, and there were no observations of respiratory sensitisation during inhalation exposures. The substance does not need to be classified for sensitisation according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.