α-Bitter acids, hop, hydrogenated, isomerized

Endpoint summary

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 431 (In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test Method)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch no. EXP 7

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Vehicle:

unchanged (no vehicle)

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Viability measured after 3 minutes

Value:

ca. 40.3

Positive controls validity:

valid

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Tissue viability measured after 1 hour

Value:

ca. 28.1

Positive controls validity:

valid

Interpretation of results:

Category 1 (corrosive) based on GHS criteria

Conclusions:

Notes from study report: "After 3 min and 1h exposure on the surface of EpiDermTM reconstructed human epidermis, the viability of the tissues was assessed and compared to a negative control.
The percentage of viability obtained was 40.3% after 3 min and 28.1% after 1h and therefore:
Potassium Iso-Alpha Resin was classified as Corrosive, optional sub-category 1B/1C to human skin."

Since tetrahydroisoalpha acids are simply hydrogenated, with two side chain C=C double bonds converted to CH-CH, then it is appropriate to read across the classification from iso-alpha acids.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch no. EXP 7

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Irritation / corrosion parameter:

% tissue viability

Value:

ca. 7.323

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

positive indication of irritation

Interpretation of results:

Category 1 (corrosive) based on GHS criteria

Conclusions:

After 60 ± 1 minute exposure on the surface of the EpiDermTM reconstructed human epidermis, and a 42 ± 4 hours post-exposure incubation time, viability of the tissues was assessed and compared to the negative control.
The percentage of viability obtained was 7.323 % and therefore:

Potassium Iso-Alpha Resin was classified as an Irritant to the skin.

Since tetrahydroisoalpha acids are simply hydrogenated, with two side chain C=C double bonds converted to CH-CH, then it is appropriate to read across the classification from iso-alpha acids. The classification is based on endpoint 001 following a corrosion study.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Justification for type of information:

An eye irritation study according to OECD test guideline 492 has been commissioned and an update will be made once results are available. The skin corrosion studies performed on this substance indicate that a preliminary classification of eye damage category 1 is appropriate, pending the results of the study planned.

Qualifier:

according to guideline

Guideline:

other: OECD 431: skin corrosion study used as supporting evidence for classification

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch no. EXP 7

Vehicle:

unchanged (no vehicle)

Irritation parameter:

other: % tissue viability 3 minutes

Value:

ca. 40.3

Negative controls validity:

valid

Positive controls validity:

valid

Irritation parameter:

other: % tissue viability 1 hour

Value:

ca. 28.1

Negative controls validity:

valid

Positive controls validity:

valid

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Conclusions:

An eye irritation study according to OECD test guideline 492 has been commissioned and an update will be made once results are available. The skin corrosion studies performed on this substance indicate that a preliminary classification of eye damage category 1 is appropriate, pending the results of the study planned.

Notes from study report: "After 3 min and 1h exposure on the surface of EpiDermTM reconstructed human epidermis, the viability of the tissues was assessed and compared to a negative control.
The percentage of viability obtained was 40.3% after 3 min and 28.1% after 1h and therefore:
Potassium Iso-Alpha Resin was classified as Corrosive, optional sub-category 1B/1C to human skin."

Since tetrahydroisoalpha acids are simply hydrogenated, with two side chain C=C double bonds converted to CH-CH, then it is appropriate to read across the classification from iso-alpha acids.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)