Tin dioxide

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 22nd February 2012 to 8th March 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study in compliance with international recognized guidelines.

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material:
2012-000203
- Expiration date of the lot/batch:
07/02/2013, W0167
- Purity test date:
> 99.9%, 23/01/2011

INFORMATION ON NANOMATERIALS
- Chemical Composition:
Tin Dioxide
- Density:
6.936 g/cm³
- Particle size & distribution:
10-100 nm; 78
- Specific surface area: 7.4293 ± 0.0132 m²/g

Species:

mouse

Strain:

other: CBA/CaOlaHsD

Sex:

female

Details on test animals and environmental conditions:

Test System
Species/strain: healthy CBA/CaOlaHsD mice
Source: Harlan Winkelmann, 33178 Borchen, Germany
Sex: female (nulliparous and non-pregnant)
Age at the beginning of the study: 8 — 9 weeks
Number of animals: 5 mice / group
3 mice / preliminary test
The animals were derived from a controlled full-barrier maintained breeding system (SPF). According to Art. 9.2, No. 7 of the German Act on Animal Welfare [8] the animals are bred for experimental purposes.


Housing and Feeding Conditions:
- Full harrier in an air-conditioned room
- Temperature: 22 ± 3 °C
- Relative humidity: 55 ± 10%
- Artificial light, sequence being 12 hours light, 12 hours dark
- Air change: at least 10 x / hour
- Free access to Altromin 1324 maintenance diet for rats and mice (preliminary test: lot no. 1145, main study: lot no. 1114)
- Free access to tap water, sulphur acidified to a pH value of approx. 2.8 (drinking water, municipal residue control, microbiological controls at regular intervals)
- The animals were kept in groups of 5 animals in IVC cages, type III, polysulphone cages on Altromin saw fibre bedding (preliminary test and main study: lot no. 110811)
- Certificates of food, water and bedding are filed at BSL BIOSERVICE
- Adequate acclimatisation period (at least five days) under laboratory conditions

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

Preliminary test: two animals were treated by topical application with the test item on three consecutive days at a concentration of 12.5% to the entire dorsal surface of each ear.
Based on the results observed in the preliminary test the following test item concentrations were selected for the main study:
3.125%, 6.25% and 12.5% (w/v)

No. of animals per dose:

5 mice / group
3 mice / preliminary test

Details on study design:

Topical Application:
Each mouse was treated by topical application of 25 µL of the selected solution to the entire dorsal surface of each ear.
Topical applications were performed once daily over three consecutive days.
Administration of 3H-Methyl Thymidine:
Five days after the first topical application all mice were dosed with 20 µCi 3H-methyl thymidine by intravenous injection (tail vein) of 250 µL of 3H-methyl thymidine, diluted to a working concentration of 80 µCi/mL.
Preparation of Cell Suspension:
Approximately 5 hours after the injection of 3H-methyl thymidine all mice were sacrificed by cervical dislocation. The draining “auricular lymph nodes” were excised, individually pooled for each animal (2 lymph nodes per animal) and collected in phosphate buffered saline (PBS). A single cell suspension of pooled lymph node cells was prepared by gentle mechanical disaggregation through polyamide gauze (200 mesh size). After washing the gauze with PBS the cell suspension was pelleted in a centrifuge. The supernatant was discarded and the pellets were resuspended with PBS. This washing procedure was repeated.
After the final wash each pellet was resuspended in approx 1 ml 5% TCA at approx. 4°C for approximately 18 h for precipitation of macromolecules. each precipitate was once washed again, resuspended in 1 ml 5% TCA and 7 ml scintillation fluid was added. Then this solution was transferred into scintillation vials stored at room temperature overnight.
Determination of incorporated 3H-Methyl Thymidine:
The 3H-Methyl Thymidine- incorporation was measured in a ß-counter and expressed as the number of disintegrations per minutes (DPM). Similarly background 3H-Methyl Thymidine levels were also measure (5% TCA). determination of redioactivity was performed individually for each animal.

Positive control substance(s):

other: p-phenylendiamine (CAS 106-50-3, purity >98%

Statistics:

no data

Positive control results:

The mean value (MV) of DPM for the positive control was : 13469.6 (SD= standard deviation 4123.9)
MV of DPM/Node of the positive control was: 6726.5 (SD 2062)
the Stimulation index of the positive control was: 10.9 (SD 3.3)

Key result

Parameter:

SI

Value:

0.9

Test group / Remarks:

At concentration of 3.125%

Remarks on result:

other: see data in "illustration" field.

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

At concentration of 6.25%

Remarks on result:

other: see data in "illustration" field.

Key result

Parameter:

SI

Value:

7

Test group / Remarks:

At concentration of 12.5%

Remarks on result:

other: see data in "illustration" field.

All animals survived throughout the test period without showing any clinical signs.

The proliferative response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (DPM/NODE) and as the ratio of 3H-methyl thymidine - incorporation into lymph node cells of test group animals relative to that recorded for control group animals (STIMULATION INDEX). Before DPM/NODE values were determined, background values were subtracted.

EC3 values, calculated concentrations which induce stimulation indices of three, are determined by linear interpolation, EC3=c+[(3-d)/(b-d)]x(a-c), between two points of the stimulation indices axis, one above (a,b) and one below (c,d) the stimulation index of three. If all measured points are above or below the stimulation index of three, no EC3 value can be stated.

A substance is regarded as a sensitiser in the LLNA if at least one concentration of the test item results in a 3-fold or greater increase in 3H-methyl thymidine - incorporation into lymph node cells of the test group animals, relative to that recorded for the lymph nodes of control group animals (Stimulation Index equal to or greater than 3.0).

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The EC3 value (derived by linear interpolation) could not be calculated as the stimulation indices of all concentrations were below 3.
Consequently, according to OECD 429 the test item Tin dioxide as described in this report is expected to have no sensitising properties and therefore should not be regarded as a dermal sensitiser.
According to CLP Regulation the test item Tin dioxide is not to be classified as skin sensitizer.

Reference 2

Endpoint:

skin sensitisation: in vitro

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

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

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The LLNA has been developed as an alternative method for the identification of skin sensitising test items and measures the proliferation of lymphocytes isolated from lymph nodes (auricular lymph nodes) draining the site of exposure (dorsal aspect of the ears) in mice. Lymphocyte proliferation is measured by determining the incorporation of 3H-methyl thymidine. The EC3 value (derived by linear interpolation) could not be calculated as the stimulation indices of all concentrations were below 3. Consequently, according to OECD 429 the test item Tin dioxide as described in this report is expected to have no sensitising properties and therefore is not ti be classified as skin sensitizer according to CLP.

Skin sensitisation (OECD 429): not sensitizing

Justification for selection of skin sensitisation endpoint:
GLP study in compliance with international recognized guidelines.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Migrated from Short description of key information:
Respiratory sensitisation: not tested

Justification for classification or non-classification

The available in vivo study on the notifiable substance indicates that tin dioxide NP is not sensitizing to skin. Thus, the data are conclusive but not sufficient for classification for skin sensitisation according to Official Journal of the European Union 1272/2008 (CLP) dated December 16^th2008