Hop, Humulus lupulus, ext., isomerized, potassium salt

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."

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

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.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Reference 1

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."

Reference 2

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Reason / purpose for cross-reference:

data waiving: supporting information

Reference 3

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch no. DB EXP 9

Irritation parameter:

other: Percentage of viability

Value:

ca. 2.8

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects / acceptance of results:

Notes from study report:
Provided that the assay acceptance criteria are met:

• A test item is considered as “No Category”, i.e. not requiring a warning label in the European chemical classification systems for eye irritation or serious eye damage (UN GHS No Category), if the eye model viability after exposure and post-treatment incubation is >60%.

• If the mean percent tissue viability after exposure and post-exposure incubation is ≤60%, no prediction can be made.

The percentage of viability obtained with test item Potassium salt of hop iso-alpha acids, resin form was 2.831 %, therefore no prediction can be made.
During the study, the required preliminary test confirmed that the test item did not interfere with MTT or solvent.
During the study, it was observed that the resinous test item was not fully removed using the standard rinsing procedures. The outcome of this is that the test item remained on the surface of the tissues for more than the standard 6 hours application time. The total exposure time was 24 hours and this should be taken into account when regarding the data presented below. The potential effect of the prolonged exposure time could be reduced tissue viability.

Interpretation of results:

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

Conclusions:

Notes from study report: During the study, it was observed that the resinous test item was not fully removed using the standard rinsing procedures. The outcome of this is that the test item remained on the surface of the tissues for more than the standard 6 hours application time. The total exposure time was 24 hours and this should be taken into account when regarding the data presented below. The potential effect of the prolonged exposure time could be reduced tissue viability.


The test item is a naturally sticky resin and so the laboratory issues were reasonable. Inspection of the results, especially Graph 1 (see the attached results under "Attached background material") show that the test gave a considerably lower viability than the positive control. Together with weight of evidence from skin irritation and skin corrosion studies, an eye damage category 1 classification is reasonable.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)