Praseodymium trichloride

Endpoint summary

Description of key information

Skin irritation

The study of Haley et al. (1964) was considered as the key study for this endpoint. In this study, crystalline praseodymium trichloride was used unchanged for application in vivo in rabbits in intact as well as abraded skin. Based on the fact that no skin irritation was observed in intact skin after 24 h, it was concluded that the reference substance (i.e. anhydrous praseodymium trichloride) is not to be classified as skin irritant.

Eye irritation

Based on the results of an in vivo skin irritation study in rabbits performed with praseodymium trichloride (Haley et al., 1964), the substance would have to be classified as Eye irritant Cat. 2 under the CLP Regulation. However, because other rare earth chlorides (which already have been registered under REACH) have been classified consistently as Eye Damage Cat. 1 under the CLP Regulation, it is considered appropriate to classify praseodymium trichloride in this category as well, based on the precautionary principle, and without having to perform new studies. This is considered justified because these substances have a common mechanism for causing damage to the eye, which is driven by the release of hydrogen chloride when in contact with the ocular fluid. An overview of the available information for rare earth chlorides is attached to IUCLID Section 13. Because the classification was not based on the results of the study of Haley et al. (1964), this study (which was scored Klimisch 2, i.e. reliable with restrictions) was considered as supporting information and any new studies (in vitro or in vivo) have been waived.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1963

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

The method of Draize et al. (1944) was used to study skin irritation in rabbits.

GLP compliance:

not specified

Species:

rabbit

Strain:

not specified

Details on test animals or test system and environmental conditions:

No further data on test animals reported.

Type of coverage:

not specified

Preparation of test site:

other: intact and abraded skin

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

0.5 g

Duration of treatment / exposure:

Not entirely clear.

Observation period:

7 days (up to 35 days for animals exposed to the test chemical on abraded skin)

Number of animals:

6, sex not specified

Details on study design:

TEST SITE: no data reported

REMOVAL OF TEST SUBSTANCE: no data reported

OBSERVATION TIME POINTS: not reported, but observations are reported after 24 h, 7 days, and 35 days (the latter only for abraded skin)

SCORING SYSTEM: Draize scoring system

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

24 h

Score:

0

Max. score:

8

Remarks on result:

no indication of irritation

Remarks:

intact skin

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

24 h

Score:

8

Max. score:

8

Reversibility:

fully reversible within: 35 days

Remarks on result:

probability of severe irritation

Remarks:

abraded skin

Irritant / corrosive response data:

- Direct application of the test item to intact rabbit skin produced no irritation within 24 hours, and no delayed reaction after 7 days.
- On abraded skin, there was a severe reaction after 24 hours with a maximum irritation index of 8. No change in irritation index was observed over the following 14 days, but complete healing with scars of 25-30 mm in diameter occurred at 35 days.
- It was mentioned that the liberation of nascent hydrochloric acid from the test item by tissue fluids may explain the difference in response between intact and abraded skin.

Other effects:

No additional information.

Interpretation of results:

GHS criteria not met

Conclusions:

The test item was found to be irritating to abraded skin, but non-irritating to intact skin. Therefore, and considering the requirements of current test guidelines, the test substance is considered to be not classified according to the CLP Regulation.

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin irritation study does not need to be conducted because adequate data from an in vivo skin irritation study are available

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1963

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

The method of Draize et al. (1944) was used to study ocular irritation in rabbits.

GLP compliance:

not specified

Species:

rabbit

Strain:

not specified

Details on test animals or tissues and environmental conditions:

No further data on test animals reported.

Vehicle:

water

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 mL into the conjunctival sac of one eye of each rabbit
- Concentration (if solution): 1:1 aqueous solution

Duration of treatment / exposure:

not reported

Observation period (in vivo):

4 weeks total, post-application

Number of animals or in vitro replicates:

3, sex not specified

Details on study design:

REMOVAL OF TEST SUBSTANCE: no data

SCORING SYSTEM: Draize scoring system

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

other: 1 hour

Score:

20

Max. score:

20

Reversibility:

fully reversible within: > 1 week

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: 1 hour

Score:

0

Max. score:

80

Remarks on result:

no indication of irritation

Irritation parameter:

iris score

Basis:

mean

Time point:

other: 1 hour

Score:

0

Max. score:

10

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

No effects were observed on cornea or iris, however, increased blinking rate and a maximum irritation index of 20 on the conjunctiva were observed within 1 hour after application. The test item produced conjunctival ulcers which persisted for 1 week, after which complete healing occurred. Observations over the next 3 weeks did not disclose any residual damage to the eye structures.

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

The test item was found to produce conjunctival ulcers in rabbits, which persisted for one week but after that healed completely. No effect was observed on cornea or iris. Based on the results of this study, the test item praseodymium trichloride would have to be classified as Eye irritant Cat. 2, according to the CLP Regulation.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation

In the study of Haley et al. (1964), no skin irritation was observed in intact skin in rabbits after 24 h. However, in abraded skin, a severe irritant response was observed. It was reported that this might have been caused by the liberation of hydrogen chloride from the test item through contact with the tissue fluids from the abraded skin. Considering this likely mechanism of skin irritation, it is advisable to use dermal protection when handling both dry praseodymium trichloride, hydrated forms, and aqueous solutions. Also, registrants may classify their aqueous solutions for skin irritation.

Eye irritation

In the in vivo study of Haley et al. (1964) in rabbits, no effects were observed on cornea or iris. However, conjunctival ulcers were observed within 1 h after application, which persisted for 1 week and after that healed completely. The results of this study would result in classification as Eye irritant Cat. 2 under the CLP Regulation. However, it was decided (based on the common mechanism for causing damage to the eye) to classify the substance as Eye damage Cat. 1 in consistency with other rare earth chlorides. An overview of the available information for other rare earth chlorides is attached to IUCLID Section 13. The study of Haley et al. (1964) was therefore assigned supporting status and further studies (in vivo or in vitro) have been waived.

Justification for classification or non-classification

Skin irritation

The reference substance, i.e. anhydrous praseodymium trichloride, is not classified for local effects in skin.

Eye irritation

Praseodymium trichloride is classified as Eye damage Cat. 1 under the CLP Regulation, in consistency with other rare earth chlorides.