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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Toxicological information

Endpoint summary

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Administrative data

Description of key information

Skin sensitisation (in vivo): Key study. Pyridine was tested by the U.S. National Institute of Environmental Health Sciences in their validation studies of the murine Local Lymph Node Assay (LLNA). Few details are available on the doses or methods used. The EC50 of pyridine in the LLNA is greater than 3; however, this is unexpected as pyridine was a very weak allergen in the human predictive test. Based on read across from the analogue pyridine, 4-methylpyridine could be considered as skin sensitiser according to the test result.


Three members of the category of pyridines, pyridine, 2-methylpyridine and 4-methylpyridine are listed in annex VI of Regulation (EC) No. 1272/2008 (harmonized classification) and none of these are classified as sensitisers.


Thus, 4-methylpyridine should not be considered as skin sensitiser according to CLP Regulation (EC) No 1272/2008 despite of the conclusion obtained in the test with pyridine.


 


 

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
The analogue substance pyridine which shares the same functional groups with the substance 4-methylpyridine also has comparable values for the relevant molecular properties.
See attached the reporting format.
Reason / purpose for cross-reference:
read-across source
Key result
Parameter:
SI
Value:
> 3
Test group / Remarks:
Test group 1
Key result
Parameter:
SI
Value:
> 3
Test group / Remarks:
Test group 2
Key result
Parameter:
SI
Value:
> 3
Test group / Remarks:
Test group 3
Key result
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: no data

Pyridine is a very weak allergen in the human predictive test and so the conclusion that pyridine is positive in the LLNA was unexpected. The conclusion that pyridine is a sensitiser is not clear.

Interpretation of results:
other: ambiguous
Conclusions:
The EC50 of pyridine in the LLNA is greater than 3; however, this is unexpected as pyridine was a very weak allergen in the human predictive test. Based on read across from the analogue pyridine, the substance should not be regarded as skin sensitiser despite the conclusion obtained in the test.
Executive summary:

Pyridine was tested by the U.S. National Institute of Environmental Health Sciences in their validation studies of the murine Local Lymph Node Assay (LLNA). Few details are available on the doses or methods used. The EC50 of pyridine in the LLNA is greater than 3; however, this is unexpected as pyridine was a very weak allergen in the human predictive test. Based on these results, the read-across approach was applied and despite the conclusion obtained the substance should not be regarded as skin sensitiser.

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

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Based on the available data, the substance is not classified for skin sensitization according to CLP Regulation no. 1272/2008.