reaction mass of dipentarythritol and 3-mercaptopropionic acid

Endpoint summary

Description of key information

Based on read across from PETMP, Di-PETMP is considered not irritating to skin.

Based on read-across from PETMP, Di-PETMP is considered not irritating to eyes.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Currently, do data on toxicokinetics/metabolism is available for this category. Based on structural features (e.g. sterical hindrance) it is however assumed, that ester cleavage would not be fast and complete, especially since the substances contain up to 6 ester functions, which are in addition sterically shielded. Therefore, it seems more reasonable to base the category hypothesis on structural similarity.
In addition, it is not clear yet, whether the strength of the effects vary in a predictable manner, or if no relevant variations occur. However, there are variations in structure (number of ester bonds and consequently number of free -SH groups) and physicochemical properties (especially water solubility and log Kow). It is assumed that these variations will also be reflected by variations in effect levels. Therefore, scenario 4 is the working hypothesis for the time being.
More data points within the category are needed to further strengthen the category hypothesis (refer to Data matrix toxicity endpoints (systemic effects)). The scenario selection will be re-evaluated after the studies are finished.
This currently selected scenario covers the category approach for which the read-across hypothesis is based on structural similarity. For the REACH information requirement under consideration, the property investigated in studies conducted with different source substances is used to predict the property that would be observed in a study with the target substance if it were to be conducted. Similar properties are observed for the different source substances; this may include absence of effects for every member of the category.
There are expected to be differences in strength of the effects forming a regular pattern. The prediction will be based on a worst-case approach. The read-across is a category approach based on the hypothesis that the substances in this category share structural similarities with common functional groups. This approach serves to use existing data on acute toxicity, repeated-dose toxicity, and reproductive toxicity endpoints for substances in this category.
The hypothesis corresponds to Scenario 4 of the RAAF. The substances GDMP, TMPMP, PETMP, and Di-PETMP are esters of a common acid, 3-mercaptopropionic acid (3-MPA). The key functionality of the substances within this category is the presence of free SH-groups. It is hypothesised that the strength of effects correlates with the number of SH-groups. In addition, differences in bioavailability are expected to influence the strength of effects.
For details, please refer to the category document attached to Iuclid section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

Species:

rabbit

Irritation parameter:

erythema score

Basis:

mean

Remarks:

3 animals

Time point:

24/48/72 h

Score:

0

Max. score:

3

Irritation parameter:

edema score

Basis:

mean

Remarks:

3 animals

Time point:

24/48/72 h

Score:

0

Max. score:

4

Interpretation of results:

GHS criteria not met

Conclusions:

Based on QSAR prediction and read-across from PETMP, Di-PETMP is considered not irritating to skin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Currently, do data on toxicokinetics/metabolism is available for this category. Based on structural features (e.g. sterical hindrance) it is however assumed, that ester cleavage would not be fast and complete, especially since the substances contain up to 6 ester functions, which are in addition sterically shielded. Therefore, it seems more reasonable to base the category hypothesis on structural similarity.
In addition, it is not clear yet, whether the strength of the effects vary in a predictable manner, or if no relevant variations occur. However, there are variations in structure (number of ester bonds and consequently number of free -SH groups) and physicochemical properties (especially water solubility and log Kow). It is assumed that these variations will also be reflected by variations in effect levels. Therefore, scenario 4 is the working hypothesis for the time being.
More data points within the category are needed to further strengthen the category hypothesis (refer to Data matrix toxicity endpoints (systemic effects)). The scenario selection will be re-evaluated after the studies are finished.
This currently selected scenario covers the category approach for which the read-across hypothesis is based on structural similarity. For the REACH information requirement under consideration, the property investigated in studies conducted with different source substances is used to predict the property that would be observed in a study with the target substance if it were to be conducted. Similar properties are observed for the different source substances; this may include absence of effects for every member of the category.
There are expected to be differences in strength of the effects forming a regular pattern. The prediction will be based on a worst-case approach. The read-across is a category approach based on the hypothesis that the substances in this category share structural similarities with common functional groups. This approach serves to use existing data on acute toxicity, repeated-dose toxicity, and reproductive toxicity endpoints for substances in this category.
The hypothesis corresponds to Scenario 4 of the RAAF. The substances GDMP, TMPMP, PETMP, and Di-PETMP are esters of a common acid, 3-mercaptopropionic acid (3-MPA). The key functionality of the substances within this category is the presence of free SH-groups. It is hypothesised that the strength of effects correlates with the number of SH-groups. In addition, differences in bioavailability are expected to influence the strength of effects.
For details, please refer to the category document attached to Iuclid section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across source

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Number of animals or in vitro replicates:

1+2

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

3

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritant / corrosive response data:

Only very slight conjunctival reactions, including very slight chemosis (grade 1), very slight redness of the conjunctiva (grade 1) and clear discharge, were observed in all animals on day 1.
No other ocular reactions were observed during the study. Mean scores calculated for each animal over 24, 48 and 72 hours were 0.0, 0.0 and 0.0 for chemosis, redness of the conjunctiva, iris lesions and corneal opacity.

Interpretation of results:

GHS criteria not met

Conclusions:

Based on read-across from PETMP, Di-PETMP is considered not irritating to eyes

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

PETMP was not irritating to skin in an in-vivo test in rabbits according to OECD 404. This result is expected to be representative for the other category members due to the structural similarity.

Justification for classification or non-classification

Based on read across from PETMP, Di-PETMP is considered not irritating to skin and not irritating to eyes.