Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Toxicological information

Skin sensitisation

Currently viewing:

Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
30 June 2016 - 12 August 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
Minor environmental fluctuations, not considered to have impacted the outcome of the study or interpretation of the study results.
Qualifier:
according to guideline
Guideline:
EU Method B.6 (Skin Sensitisation)
Deviations:
yes
Remarks:
Minor environmental fluctuations, not considered to have impacted the outcome of the study or interpretation of the study results.
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Deviations:
yes
Remarks:
Minor environmental fluctuations, not considered to have impacted the outcome of the study or interpretation of the study results.
GLP compliance:
yes (incl. QA statement)
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The GPMT method (OECD 406) was preferred above LLNA (OECD 429) since previous experience with various rare earth compounds learned that there is an increased risk for false positive results when performing the LLNA. Additionally, insoluble inorganic substances, such as dysprosium oxide, are often not able to penetrate the skin.

Test material

Constituent 1
Chemical structure
Reference substance name:
Didysprosium trioxide
EC Number:
215-164-0
EC Name:
Didysprosium trioxide
Cas Number:
1308-87-8
Molecular formula:
Dy2O3
IUPAC Name:
dysprosium(3+); oxygen(2-)
Test material form:
solid: particulate/powder
Details on test material:
Name of the test material (as cited in the report): didysprosium trioxide
Physical state: solid
Appearance: (pale) yellow powder
Further information on test item confidential.
Specific details on test material used for the study:
No correction was made for the purity/composition of the test item.

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Remarks:
Albino guinea pigs, LAL/HA/BR
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: male albino guinea pigs, LAL/HA/BR; LAB-ÁLL Bt., Budapest, 1174 Hunyadi u. 7., Hungary
- Age at first dosing (Day 1): young adult, ~ 9 weeks old
- Weight at randomisation (Day-1): 423-529 g
- Housing: Animals were housed in Macrolon cages size IV, with up to 5 animals/cage to allow socialisation, “Lignocel ® 3/4-S Hygienic Animal Bedding” produced by J. Rettenmaier & Söhne GmbH+CO.KG (D-73494 Rosenberg, Germany) was available to the animals during the study.
- Diet (e.g. ad libitum): Ad libitum, Cunigra Diet for Rabbits (produced by Bonafarm-Bábolna Takarmány Ltd., Hungary).
- Water (e.g. ad libitum): Ad libitum, tap water from municipal supply as for human consumption, containing at least 50 mg/100 mL ascorbic acid. The drinking water is routinely analysed and is considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.
- Acclimation period: 33 days before start of treatment under laboratory conditions. Animals were examined on arrival and only healthy animals were used for the test. The health status was certified by the veterinarian.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.4-24.9°C
- Humidity (%): 36-84%
- Air changes (per hr): 15-20 air exchanges/hour
- Photoperiod (hrs dark / hrs light): 12/12, light from 6.00 a.m. to 6.00 p.m.

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal
Vehicle:
other: 1% methyl cellulose
Concentration / amount:
concentration: 5% (w/v)
volume: 0.1 mL per injection
Day(s)/duration:
day 1 of treatment
Adequacy of induction:
highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Remarks:
dampened with saline
Concentration / amount:
amount: 0.5 g
Day(s)/duration:
day 8 of treatment; 48 hours of exposure
Adequacy of induction:
non-irritant substance, but skin pre-treated with 10% SDS
Challengeopen allclose all
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
unchanged (no vehicle)
Remarks:
dampened with saline
Concentration / amount:
amount: 0.5 g
Day(s)/duration:
day 22 of treatment; 24 hours of exposure
Adequacy of challenge:
highest non-irritant concentration
No.:
#1
Route:
epicutaneous, occlusive
Vehicle:
other: 1% methyl cellulose
Concentration / amount:
volume applied: 0.5 mL
concentration: 50% (w/v)
Day(s)/duration:
day 22 of treatment; 24 hours of exposure
Adequacy of challenge:
other: safeguard dose
No. of animals per dose:
Preliminary test: 8 animals
Main test: 10 in the test group, 5 in the control group
Details on study design:
RANGE FINDING TEST
- A day prior to the test, the hair was removed from the right and left sides of the animals (approximately 5x5 cm). The hair removal was performed carefully to ensure animals are closely shaven.
- A series of test item concentrations were tested to identify the primary irritation following intradermal injection and dermal application: 0.05, 0.1, 0.5, 1, 2.5 and 5% (w/v) concentrations in 1% methyl cellulose were used for intradermal injection and 25, 50, 75% (w/v) and 100% (as supplied, dampened with saline) for dermal application. Local effects were examined and scored 1, 24, 48 and 72 hours after the treatment or after patch removal. Skin effects were scored for erythema and oedema; any other observations of changes to the skin were recorded.
- For the intradermal application, 0.1 mL per concentration was injected intradermally into the hair free skin of the animals. Two concentrations were injected on the right side and another two concentrations on the left side of the animals. The highest concentration (5%) was also used in a 1:1 mixture (v/v) of Freund's Complete Adjuvant and physiological saline solution. Each concentration was injected in duplicate. Two animals were used per concentration. The highest concentration (5%) formulated in the vehicle or in FCA:saline caused no more than mild-to-moderate erythema (score 1 or 2) during the observation period, therefore this concentration could be used in the main study.
- For the topical application, the volume of the concentrations was 0.5 mL. For the 100% (undiluted) treatment, 0.5 g test item was dampened with saline, and then applied to the skin. A closed patch exposure was performed by means of an occlusive bandage using similar treatment procedures as for the main study. The time of exposure for the dermal application was 48 hours. One concentration was used on the right side and another concentration on the left side of animals. Two animals per concentration were used. It was found that all the dermal treatments at the tested concentrations produced no reaction on the skin of guinea pigs.

MAIN STUDY
The dose levels for the main study were selected based on the results of the preliminary test.
Control animals were treated similarly to test animals, except that during the induction phase, the test item was omitted.

A. INDUCTION EXPOSURE
A.1 INTRADERMAL INDUCTION EXPOSURE (day 1)
- No. of exposures: three pairs of intradermal injections (0.1 mL/site)
- Test groups (the first listed nearest the head): 2 injections of Freund's Complete Adjuvant and physiological saline solution in a 1:1 (v/v) mixture; 2 injections of 5% test item in 1% methyl cellulose; 2 injections of 5% test item, formulated in a 1:1 mixture (v/v) of Freund's Complete Adjuvant and physiological saline solution.
- Control group (the first listed nearest the head): 2 injections of Freund's Complete Adjuvant and physiological saline solution in a 1:1 (v/v) mixture; 2 injections of 1% methyl cellulose; 2 injections of 1% methyl cellulose, formulated in a 1:1 mixture (v/v) of Freund's Complete Adjuvant and physiological saline solution.
- Site: scapular region, on the day before treatment, an area approximately 5x5 cm on the scapular region of the animals was clipped free of hair and was carefully shaved.
- Frequency of applications: one application
- Skin reactions were observed and recorded as follows: 24 hours after the patch removal

A.2 DERMAL INDUCTION EXPOSURE (day 8)
- Since the undiluted test item was not skin irritant in the dermal dose range-finding study, the test area was painted with 0.5 mL of 10% sodium dodecyl sulphate in Vaseline 24 hours prior to the topical induction application, in order to create a local irritation.
- Site: The same scapular region that received the intradermal injections, was used for dermal induction exposure.
- Test groups: Seven days after the intradermal injections, the same hair-free scapular area was treated. 0.5g of the test item was placed on a 2.5x2.5 cm sterile gauze patch (4 layers of porous gauze pads) and dampened with saline, then applied over the injection sites. The gauze patches were kept in contact with the skin by a patch with a surrounding adhesive hypoallergenic plaster The treated areas were covered for 48 hours with a fully occlusive foil (Closed Patch Test). After the patch removal any remaining test item was removed with a wet gauze swab. Following the dermal induction treatment, the animals were left untreated for 14 days prior to challenge applications.
- Control group: The control group was treated with 1% methyl cellulose only.
- Frequency of applications: one application
- Skin reactions were observed and recorded as follows: 1, 24, 48 and 72 hours after patch removal

A.3 CHALLENGE EXPOSURE
Two weeks after the topical induction application, the animals were exposed to a dermal challenge dose. Approximately 24 hours before the treatment, the hair was removed from an area of approximately 5x5 cm on the left and right sides of each animal. 0.5 g of the test item was dampened with saline on a 5x5 cm patch of sterile gauze patch, then applied to the left side of all animals (both the test and the control). The right shaved side of all animals was treated with 50% dilution of the test item in 1% methyl cellulose. The volume of formulated test item was 0.5 mL. Treatment was performed as described for the Closed Patch Test (see dermal induction exposure). The time of exposure was 24 hours. After the patch removal any remaining test item was removed with a wet gauze swab.

Terminal animals were sacrificed under pentobarbital anaesthesia.

OBSERVATIONS AND SCORING
- Body weight was recorded with a precision of 1 g at randomisation (Day -1), then at least weekly, including Day 25 prior to euthanasia. The mean values and the standard deviations were calculated and reported.
- Mortality/clinical signs: Daily recorded during the test.
- Detailed clinical observations were made on all animals outside the home cage in a standard arena before the first treatment (on the day of randomisation) and at least weekly thereafter. The dermal irritation scores (in case of dermal induction exposures) were evaluated according to the scoring system by Draize (1959).

- Erythema and eschar formation:
0 = No erythema
1 = Very slight erythema (barely perceptible)
2 = Well defined erythema
3 = Moderate to severe erythema
4 = Severe erythema (beef redness) to slight eschar formation (injuries in depth)

- Oedema formation:
0 = No oedema
1 = Very slight oedema (barely perceptible)
2 = Slight oedema (edges of area well defined by definite raising)
3 = Moderate oedema (raised approx. 1 mm)
4 = Severe oedema (raised more than 1 mm and extending beyond area of exposure)

After the challenge exposure, each animal was examined and scored 24 and 48 hours after the end of the exposure period.

Grading was performed according to the following system (classification of skin sensitisation):
0 = no visible change
1 = discrete or patchy erythema
2 = moderate and confluent erythema
3 = intense erythema and swelling
Challenge controls:
0.5 g of test item was dampened with saline on a 5x5 cm sterile gauze patch, then applied to the left side of all animals. The right shaved side of all animals was treated with 50% dilution of the test item (w/v) in 1% methyl cellulose.
Positive control substance(s):
yes
Remarks:
2-mercaptobenzothiazole

Results and discussion

Positive control results:
Challenge with reference item 2-mercaptobenzothiazole resulted in a positive response in test animals previously sensitised. The net response values at the 24 and 48 hours observations represented an incidence rate of 90% and 80% and net score values of 0.90 and 0.80 respectively. In the control animals no visible changes were found either at the 24 or 48 hours examinations following challenge with the reference item.

In vivo (non-LLNA)

Resultsopen allclose all
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
100% (undiluted, dampened with saline)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no visible changes
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
test chemical
Dose level:
100% (undiluted, dampened with saline)
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no visible changes
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
100% (undiluted, dampened with saline)
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
no visible changes
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
100% (undiluted, dampened with saline)
No. with + reactions:
0
Total no. in group:
5
Clinical observations:
no visible changes
Remarks on result:
no indication of skin sensitisation
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
50% w/v (2-mercaptobenzothiazole)
No. with + reactions:
9
Total no. in group:
10
Clinical observations:
discrete erythema (score 1) on the skin of the animals
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
2nd reading
Hours after challenge:
48
Group:
positive control
Dose level:
50% w/v (2-mercaptobenzothiazole)
No. with + reactions:
8
Total no. in group:
10
Clinical observations:
discrete erythema (score 1) on the skin of the animals
Remarks on result:
positive indication of skin sensitisation

Any other information on results incl. tables

The right shaved side of all animals was treated with a test item concentration of 50% (w/v) as a safeguard dose and no reaction was noted (test group and control group).

Clinical observations/mortality:

Slightly decreased activity, slight ataxia and piloerection were noticed in one animal (animal no. 1) on Day 8. After consultation with the clinical Veterinarian it was considered not to be serious and the animal could continue on the study; as a precaution, the animal was moved to a separated cage and special attention was paid to it. Ataxia disappeared two days later (Day 10) and piloerection five days later (Day 13), however the animal’s decreased activity remained. Therefore, the animal was kept separated until the end of the study. These symptoms were considered not to be test item related.

No signs of systemic or local toxicity were observed in the other animals.

No mortality was observed during the study.

Body weight:

One animal (animal no. 1) had distinguishably lower body weight from Day 7 until the end of the study. This animal also showed clinical symptoms (see above). The body weight loss of this animal was not unacceptable for inclusion in the study and was considered not to be test item related. The body weight of this animal was measured daily from Day 8 until the end of the study.

There were no notable differences between the test animal group and the control group, except one animal (animal no. 1).

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
Challenge with test item (didysprosium trioxide) evoked no positive responses in the test animals previously sensitised with the test item or in the control group. The net response value represented an incidence rate of 0% and a net score value of 0.00. In conclusion, under the conditions of the present assay, the test item didysprosium trioxide was shown to have no skin sensitisation potential and is consequently classified as a non-sensitiser, according to current EU-regulations.