Registration Dossier

Administrative data

Endpoint:
acute toxicity: oral
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
2000-11-22 to 2000-12-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Zircon, cadmium yellow is a zircon-type oxide/pigment with the main structural element ZrSiO4 (Zr in an dodecahedral O environment) which forms a strong and inert matrix. Zr and Si are the main components with percentages of ~46% w/w and 15% w/w respectively. The amount of Cd as component is about 2% w/w.

The read-across substance Silicic acid, zirconium salt, cadmium pigment encapsulated is a zircon-type pigment as well with an identical crystallographic structure and a very similar composition. Zr content is ~46% w/w and the Si content is ca. 14% w/w. Cd is present in about 4.7% w/w. Minor amounts of Se and S (1.53 and 1.04% w/w, respectively) are present as well.

Besides the obvious structural analogy the solubility of both pigments in aqueous and physilogical media are as follows (determination of Zr and Cd):

Solubility of Cd from the pigment Zircon, cadmium yellow in physiological media was in a range of 0.180 µg/L (PBS) and 0.398 µg/L (ALF) after 2 hours. After 24 hours a dissolution range from 0.140 µg/L (GMB) - 0.722 µg/L (GST) was measured.

Solubility of Zr from the pigment Zircon, cadmium yellow in physiological media was in a range of below LOD and 0.812 µg/L (ALF) after 2 hours. After 24 hours a dissolution range from below LOD (ASW) - 1.44 µg/L (ALF) was measured.

The read-across substance Silicic acid, zirconium salt, cadmium pigment encapsulated afforded after 2 hours a solubility for the element Cd in range of 0.07 µg/L (GMB) 2.58 µg/L (GST) and after 24 hours a solubility of 0.07 µg/L (GMB) to 6.13 µg/L (GST).

Solubility of Zr from the pigment Silicic acid, zirconium salt, cadmium pigment encapsulated in physiological media was in a range of below LOD and 0.52 µg/L (ALF) after 2 hours. After 24 hours a dissolution range from below LOD - 1.25 µg/L (ALF) was measured.

T/D testing of the pigment Zircon, cadmium yellow afforded the following solubility at 1mg loading after 28 days:
Cadmium: below LOD (<0.0048) and 0.2077 ± 0.0993μg/L at pH 8 and pH 6, respectively
Zirconium:
T/D testing of the read-across substance Silicic acid, zirconium salt, cadmium pigment encapsulated afforded the following solubility at 1mg loading after 28 days:
Cadmium: 0.34 ± 0.09 μg/L and 0.86 ± 0.39 μg/L at pH 8 and pH 6, respectively
Zirconium:
In sum, the two zircon type pigments are structurally identical with very similar composition and both show a very low solubility in different artificial and aqueous media. In fact, the read-across substance Silicic acid, zirconium salt, cadmium pigment encapsulated shows slightly higher dissolution and bioaccessibility without showing any signs of systemic or local toxicity in various studies (acute inhalation, skin/eye irritation, sensitisation). No toxicity on algae, fish and invertebrates could be observed in respective studies.
Hence, read-across to Silicic acid, zirconium salt, cadmium pigment encapsulated is fully justified.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 401 (Acute Oral Toxicity)
Version / remarks:
1987-02-24
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
signed 2000-08-02
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
- Name of test material (as cited in study report): Inclusion pigment
- Physical state: pink, solid, powder
- Odour: none
- Water solubility: poorly watersoluble, insoluble in organic solvents
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature

Test animals

Species:
rat
Strain:
other: Crl: CD® BR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Deutschland GmbH, Sandhofer Weg 7, D-97633 Sulzfeld
- Age at start of adaptation: males: 34 days; females: 43 days
- Weight at study initiation: males: 171 - 193 g; females: 162 - 178 grams
- Fasting period before study: feeding was discontinued approx. 16 hours before administration; only tap water was then available ad libitum
- Housing: during the 14-day observation period the animals were kept in groups of 2 -3 animals in MAKROLON cages (type III); bedding material: granulated textured wood (Granulate A2, J. Brandenburg, D-49424 Goldenstedt)
- Diet (ad libitum, except for fasting period before study): Altromin 1324 (ALTROMIN GmbH, D-32791 Lage/Lippe
- Water (ad libitum): drinking water
- Acclimation period: at least 5 adaptation days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 °C ± 3 °C (maximum range)
- Relative humidity: 55 % ± 15 % (maximum range)
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: 0.8 % hydroxypropyl-methylcellulose gel
Details on oral exposure:
VEHICLE
- Source: Synopharm, Barsbüttel
- Batch no.: MM 96 100 910

MAXIMUM DOSE VOLUME APPLIED: 20 mL/kg bw
Doses:
2000 mg/kg bw
No. of animals per sex per dose:
5 males / 5 females
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days.
- Frequency of observations and weighing: observations were performed before and immediately, 5, 15, 30 and 60 min, as well as 3, 6 and 24 hours after administration. During the follow-up period, clinical signs were observed at least once a day until all symptoms subsided , thereafter each working day. Observations on mortality were made at least once daily with appropriate actions taken to minimize loss of animals during the study. Individual body weights were recorded before administration of the substance and thereafter in weekly intervals up to the end of the study, and at death. Changes in weight were calculated and recorded.
- Necropsy of survivors performed: yes, at the end of the experiments all surviving animals were sacrificed, dissected and inspected macroscopically. All pathological changes were recorded. From animals which survive 24 hours or longer a microscopic examination of all organs which showed evident lesions was performed, if necessary. Autopsy and macroscopic inspection of animals which died prematurely were carried out as soon as possible after exitus.
Statistics:
The LD50 could not be calculated because no lethality occurred in this limit test.

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Mortality:
No mortality occurred.
Clinical signs:
Under the present test conditions a single oral administration of 2000 mg Inclusion Pigment/kg bw to rats revealed no toxic symptoms.
Body weight:
The animals gained the expected weight through the test exposure period.
Gross pathology:
No abnormalities were noted at necropsy.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
LD50 (male and female rats) > 2000 mg/kg bw
According to the Regulation (EC) No 1272/2008 and subsequent adaptations, the substance is not acutely toxic via the oral route.