Palladium monoxide

Endpoint summary

Description of key information

Palladium monoxide was not irritant in a limited (pre-GLP) study, involving 24-hr occluded application to the intact and abraded skin of 6 male rabbits (Campbell et al., 1975).
According to an expert review of an unpublished eye irritation study, conducted to US guidelines (CFR 21, part 191 12), a single instillation of palladium monoxide (100 mg) to the eyes of six rabbits produced no signs of irritation.

No relevant respiratory tract irritation data were identified.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not stated in paper, but submitted for publication in 1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Although the study is not conducted to a modern protocol and is somewhat limited, it is nevertheless fairly well documented and scientifically acceptable

Qualifier:

no guideline followed

Principles of method if other than guideline:

Dermal irritancy asessed using male albino rabbits using procedures and evaluation criteria adopted from those in use by the National Institute for Occupational Safety and Health, ... a modification of the official Food and Drug Administration procedure [1973]"

GLP compliance:

no

Remarks:

prior to GLP

Species:

rabbit

Strain:

other: albino

Details on test animals or test system and environmental conditions:

no data

Type of coverage:

occlusive

Preparation of test site:

other: Pairs of test sites, each 2 cm x 2 cm, on the closely clipped dorsolaterals aspects of each animal, one side abraded and the other side intact

Vehicle:

water

Remarks:

0.1 ml

Controls:

yes, concurrent vehicle

Amount / concentration applied:

0.1 g

Duration of treatment / exposure:

24 hours

Observation period:

skin reactions scored immediately on removal of patch and 48 hours later

Number of animals:

Total of 6 rabbits, with up to 7 pairs of test sites each, used to test 14 test substances, some substances tested more than once

Details on study design:

Pairs of test sites, each 2 cm x 2 cm, on the closely clipped dorsolaterals aspects of each animal, one side abraded and the other side intact; Test substances in solid (powder) state were mixed with water (0.1 g quantity mixed with 0.1 ml deionised water) and spread over each site; after application of test substances [several probably tested simultaneously on each animal], test sites occluded; 24 hours later, coverings removed and test sites gently washed with soap, rinsed and dried; skin reactions scored immediately and 48 hours later; evaluation on a grading scale from 0 to 4 [similar to Draize scale]

Irritation parameter:

overall irritation score

Basis:

mean

Remarks:

single test rating or average of two or three

Time point:

other: 24 and 72 hours

Score:

0

Max. score:

4

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

Average skin reaction for 24 and 72 hours after the start of treatment calculated for intact and abraded skin. No individual scores or any further information presented in paper, but the data confirm that a score of 0 was obtained for each of the 6 test animals.

Interpretation of results:

GHS criteria not met

Remarks:

evaluation criteria adopted from those in use by the National Institute for Occupational Safety and Health

Conclusions:

Palladium monoxide was not irritant in a limited (pre-GLP) study, involving 24-hr occluded application to the intact and abraded skin of 6 male rabbits.

Executive summary:

In a pre-GLP study, the dermal irritancy of 14 materials, including palladium monoxide, was assessed in albino rabbits. Test materials, mixed with water, were applied to intact and abraded skin of 6 male albino rabbits as 24-hour occluded patches. Coverings were then removed and sites scored immediately and 48 hours later, using a scale from 0 (non-irritant) to 4 (corrosive).

Palladium monoxide failed to give any indication of irritation (score 0) on both intact and abraded skin (mean of reactions at 24 and 72 hours).

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:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: US CFR guideline study, pre-GLP, with limited reporting.

Qualifier:

according to guideline

Guideline:

other: CFR 21, part 191 12 (revised as of April 1, 1973)

Deviations:

no

GLP compliance:

no

Remarks:

(prior to GLP)

Species:

rabbit

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Albino rabbits with no known ocular abnormalities.

Vehicle:

not specified

Controls:

other: The left eye of each animal served as a control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 mg (deposited on the eye surface)

Duration of treatment / exposure:

Presumably the observation period

Observation period (in vivo):

3 days

Number of animals or in vitro replicates:

6

Details on study design:

REMOVAL OF TEST SUBSTANCE: Not removed

SCORING SYSTEM: No data

TOOL USED TO ASSESS SCORE: No data

Irritation parameter:

other: Number of animals showing irritant reactions

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

6

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

other: Number of animals showing irritant reactions

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

6

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

other: Number of animals showing irritant reactions

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

6

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

other: Number of animals showing irritant reactions

Basis:

animal #4

Time point:

24/48/72 h

Score:

0

Max. score:

6

Reversibility:

other: Not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

other: Number of animals showing irritant reactions

Basis:

animal #5

Time point:

other: 48 hours

Score:

0

Max. score:

6

Reversibility:

other: Not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

other: Number of animals showing irritant reactions

Basis:

animal #6

Time point:

other: 72 hours

Score:

0

Max. score:

6

Reversibility:

other: Not applicable

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

No corrosive conjunctival lesions or severe inflammation of the cornea and anterior chamber of the eyes

Other effects:

In one animal, the test material was still present in the conjunctival sac at the end of the observation period, but was completely covered with a thick mucous material.

Interpretation of results:

GHS criteria not met

Conclusions:

According to an expert review of an unpublished eye irritation study, conducted to US guidelines (CFR 21, part 191 12), a single instillation of palladium monoxide (100 mg) to the eyes of six rabbits produced no signs of irritation.

Executive summary:

According to an expert review of an unpublished eye irritation study, conducted to US test guidelines (CFR 21, part 191 12), palladium monoxide (100 mg) was instilled into one eye of each of six rabbits. The other eye remained untreated and acted as the control. The treated eye was then assessed for ocular inflammation 24, 48 and 72 hr after application. No reaction was noted in any of the six animals, indicating that the test material was not irritating.

 

Based on the results of this study, palladium monoxide should not be classified for eye irritation according to EU CLP criteria (EC 1272/2008).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No relevant irritation/corrosion human data were identified. No in vitro skin or eye irritation studies were identified, or are required, as reliable in vivo studies are already available.

 

In a pre-GLP study, the dermal irritancy of 14 materials, including palladium monoxide, was assessed in albino rabbits. Test materials, mixed with water, were applied to intact and abraded skin of 6 male albino rabbits as 24-hour occluded patches. Coverings were then removed and sites scored immediately and 48 hours later, using a scale from 0 (non-irritant) to 4 (corrosive).

 

Palladium monoxide failed to give any indication of irritation (score 0) on both intact and abraded skin (mean of reactions at 24 and 72 hours) (Campbell et al., 1975). No classification for skin irritancy is required according to EU CLP criteria (EC 1272/2008), based on the results of this study.

 

According to an expert review of an unpublished eye irritation study, conducted to US test guidelines (CFR 21, part 191 12), palladium monoxide (100 mg) was instilled into one eye of each of six rabbits. The other eye remained untreated and acted as the control. The treated eye was then assessed for ocular inflammation 24, 48 and 72 hr after application. No reaction was noted in any of the six animals, indicating that the test material was not irritating (Hysell et al., 1974). Based on the results of this study, palladium monoxide should not be classified for eye irritation according to EU CLP criteria (EC 1272/2008).

 

No respiratory tract irritation data were identified. A new study was not conducted as it is not a REACH Standard Information Requirement. Further, the compound is not expected to reach the lungs in appreciable quantities (based on respiratory tract deposition modelling data). Thus, inhalation will not be a significant route of exposure.

Justification for selection of skin irritation / corrosion endpoint:
US Guideline study, pre-GLP, and the only skin irritation study available.

Justification for selection of eye irritation endpoint:
US Guideline study, pre-GLP, and the only eye irritation study available.

Justification for classification or non-classification

Based on the results of the available skin and eye irritation studies with palladium monoxide (both in vivo), there is no requirement to classify palladium monoxide for skin or eye irritation according to EU CLP criteria (EC 1272/2008).