Glycine

Endpoint summary

Description of key information

-primary skin irritation study in rabbits was conducted with the read-across substance beta-alanine (4 hour-exposure, according to OECD 404, Draize scheme; GLP): not irritating to the skin

-eye irritation study was conducted with the read-across substance beta-alanine (equivalent to OECD 405; GLP, Draize score): not irritating to the 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:

refer to analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

other: mean over 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Irritation parameter:

edema score

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Irritation parameter:

edema score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Irritant / corrosive response data:

No evidence of skin irritation was noted during the study.

Interpretation of results:

GHS criteria not met

Conclusions:

Glycine is considered to be not irritating to skin as the source and target substance are considered to have similar skin irritating potential.

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:

refer to analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Irritation parameter:

iris score

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

2

Reversibility:

other: reversibility: not applicable

Irritation parameter:

iris score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

2

Reversibility:

other: reversibility: not applicable

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours

Score:

0.33

Max. score:

3

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: conjunctival redness was observed at 1 hour observation

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours

Score:

0.33

Max. score:

3

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: conjunctival redness was observed at 1 hour observation

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

other: 24, 48 and 72 hours

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: conjunctival redness was observed at 1 hour observation

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

4

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: conjunctival redness was observed at 1 hour observation

Interpretation of results:

GHS criteria not met

Conclusions:

Glycine is considered to be not irritating to eye as the source and target substance are considered to have similar eye irritating potential.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

For glycine, no data on skin and eye irritation potential is available. Therefore, data on skin and eye irritation of the read-across substance beta-alanine was considered for hazard assessment of these endpoints. The read-across was justified based on inclusion and exclusion rules, a concept developed at or in cooperation with the German Bundesinstitut für Risikobewertung (BfR). Inclusion rules are based on structural alerts and exclusion rules are based on physico-chemical parameters. Inclusion rules are met neither for skin nor for eye irritation/corrosion for both, beta-alanine and glycine. Physico-chemical parameters of both substances are similar and due to the melting point, log Pow and lipid solubiliy, glycine is less likely to be a skin irritant than beta-alanine. Furthermore, dermal absorption coefficients of glycine and beta-alanine are similar and very low for both substances. For details on read across approach see rationale and justification.

A GLP study was performed to assess the irritation potential of beta-alanine to the skin of 2 New Zealand White rabbits. The method was designed to meet the following requirements: OECD Guidelines for the Testing of Chemicals No. 404 “Acute Dermal Irritation/Corrosion” (adopted 24 April 2002); Method B4 Acute Toxicity (Skin Irritation) of Commission Regulation (EC) No. 440/2008. A single 4-hour semi-occluded application of the test material to the intact skin of two rabbits produced no evidence of skin irritation. No corrosive effects were noted. The test material produced erythema score and oedema scores of 0.0 and was classified as non-irritant to rabbit skin according to the Draize classification scheme. 

In order to assess the irritation potential of the test material an in vivo eye irritation test was performed on 2 New Zealand White rabbits. The study method was designed to meet the requirements of the following: OECD Guidelines for the Testing of Chemicals No. 405 “Acute Eye Irritation/Corrosion” (adopted 24 April 2002); Method B5 Acute Toxicity (Eye Irritation) of Commission Regulation (EC) No. 440/2008. A volume of 0.1 mL of the test material was placed into the conjunctival sac of the right eye, formed by gently pulling the lower lid away from the eyeball. The application of the test material to the non-irrigated eye of two rabbits produced moderate conjunctival redness (Draize Score 1 for 1 animal and 2 for the second animal), which was reversible with 48 hours.

 

Justification for selection of skin irritation / corrosion endpoint:

Hazard assessment is conducted by means of read-across from a structural analogue. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substance and overall quality assessment (refer to the endpoint discussion for further details).

Justification for selection of eye irritation endpoint:

Hazard assessment is conducted by means of read-across from a structural analogue. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substance and overall quality assessment (refer to the endpoint discussion for further details).

Justification for classification or non-classification

The available data on skin and eye irritation do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.