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Description of key information

The substance needs to be classified as a skin sensitizer based on human work experience (laboratory and production plant).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
other: U.S. EPA Pesticide Assessment Guidelines Subdivision F, Part 81-6
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The study was conducted in 1993 and can be used as a surrogate for a LLNA.
Species:
guinea pig
Strain:
other: Hartley Dunkin Pirbright White
Sex:
not specified
Route:
intradermal and epicutaneous
Vehicle:
other: Intradermal: paraffin oil. Epicutaneous: petrolatum.
Concentration / amount:
Concentration of test material and vehicle used at induction:
a) Primary induction (intradermal): 0.2% in paraffin oil
b) Secondary induction (topical): 1% in petrolatum (gauze)

Concentration of test material and vehicle used for each challenge:
0.005% in petrolatum (gauze).
Route:
other: topical
Vehicle:
other: Intradermal: paraffin oil. Epicutaneous: petrolatum.
Concentration / amount:
Concentration of test material and vehicle used at induction:
a) Primary induction (intradermal): 0.2% in paraffin oil
b) Secondary induction (topical): 1% in petrolatum (gauze)

Concentration of test material and vehicle used for each challenge:
0.005% in petrolatum (gauze).
No. of animals per dose:
Number of animals in test group: 22
Number of animals in negative control group: 22
Positive control substance(s):
no
Reading:
rechallenge
Hours after challenge:
48
Group:
test chemical
Dose level:
0.005%
No. with + reactions:
0
Total no. in group:
22
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
24
Group:
test chemical
Dose level:
0.005%
No. with + reactions:
0
Total no. in group:
22
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
24
Group:
positive control
Dose level:
0.025 % dilution in vaseline
No. with + reactions:
22
Total no. in group:
22
Remarks on result:
positive indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
48
Group:
positive control
Dose level:
0.025 % dilution in vaseline
No. with + reactions:
22
Total no. in group:
22
Remarks on result:
positive indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
24
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
22
Remarks on result:
no indication of skin sensitisation
Reading:
rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
0
No. with + reactions:
0
Total no. in group:
22
Remarks on result:
no indication of skin sensitisation

Signs of irritation during induction:

During the first induction, the Draize score was lower for the groups that were injected with the vehicle without test substance than in the group injected with the test substance.

Evidence of sensitisation of each challenge concentration:

While the sensibilized animals did not exhibit a reaction during the challenge, a slight reaction was observed in the animals in the control group after 48 hours.

The reaction to the first challenge was read at 48 hrs only, while the reaction to the rechallenge was read at 24 hrs only. No additional information is available.

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Remarks:
Migrated information
Conclusions:
It was conluded that GST does not cause any primaty sensittization in guinea-pigs using the Magnusson-Kligman method.

However, the substance needs to be classified as potential skin sensitizer based on human experience in one production plant According to Annex VI of CLP (1272/2008/EC)
Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

The skin sensitising potential of 2,3 -bis((2 -mercaptoethyl)thio)-1-propanethiol was evaluated in a study performed under GLP and according to U.S. EPA Pesticide Assessment Guidelines, Subdivision F, Part 81 -6, similar to the Guinea Pig Maximisation Test of Magnusson and Kligman (Mitsui 1993, SNIF#001-4.1.70 -01). No skin effects were observed in the animals challenged with the test substance. Therefore, 2,3-bis((2 -mercaptoethyl)thio)-1-propanethiol is not considered to be sensitising under the test conditions.

However, observations with the test substance at the production plant reported by the manufacturer lead us to conclude that there is evidence that the substance could be a skin sensitiser in humans.


Migrated from Short description of key information:
There is sufficient information from experience in humans that DMPT could be a skin sensitiser. This is in contrast to the guinea pig maximisation test conducted in 1993.

Justification for selection of skin sensitisation endpoint:
Key study

Justification for classification or non-classification

According to Annex I of DSD (67/548/EC), the available data on 2,3-bis((mercaptoethyl)thio)-1-propanethiol are sufficient for classification.

According toAnnex VI of CLP (1272/2008/EC), the available data on 2,3-bis((mercaptoethyl)thio)-1-propanethiol are sufficient for classification.