Registration Dossier

Toxicological information

Skin sensitisation

Currently viewing:

Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Carbon disulphide is both a reagent in the manufacture, as well as a decomposition product of xanthates. Sodium isobutyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of sodium isobutyl xanthate. In addition, xanthates decompose on aging to form a number of byproducts, depending on the pH, temperature, etc. Risks associated with xanthate are, therefore, a function of the breakdown of the product or un-reacted raw materials remaining in the product.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid: compact
Details on test material:
Carbon disulphide is both a reagent in the manufacture, as well as a decomposition product of xanthates. Sodium isobutyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of sodium isobutyl xanthate.
In addition, xanthates decompose on aging to form a number of byproducts, depending on the pH, temperature, etc. Risks associated with xanthate are, therefore, a function of the breakdown of the product or un-reacted raw materials remaining in the product.
- Name of test material (as cited in study report): Carbon disulfide
- Synonym: Carbon disulphide
- CAS Number: 75-15-0
- Batch Number: 0600809041160, supplier: Akzo Nobel
- Purity: >99%
- Storage conditions of test material: At room temperature, under nitrogen, avoid vapour release and contact of vapour with open flame and/or hot surfaces
- Expiration date: 2011-09-19

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS: Mice, CBA/CaOlaHsd
- Source: Harlan Laboratories B.V., Postbus 6174, 5960 AD Horst / The Netherlands
- Age at study initiation: 8 - 12 weeks (beginning of treatment)
- Weight at study initiation: 18.3 - 23.3 g
- Housing:single caging
- Diet: pelleted standard diet (Harlan Laboratories B.V., 5960 AD Horst / Netherlands), ad libidum
- Water: tap water, (Gemeindewerke, 64380 Rossdorf), ad libitum
- Bedding: granulated soft wood bedding (Rettenmaier & Söhne GmbH + Co. KG, 73494 Rosenberg)
- Acclimation period: At least 5 days prior to the start of dosing under test conditions after health examination. Only animals without any visible signs of illness were used for the study

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2°C
- Humidity (%): relative humidity 45-65%
- Photoperiod (hrs dark / hrs light): artificial light 6:00 a.m. - 6:00 p.m.

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
The highest test item concentration which can be technically used was 100% of the undiluted test item. The dilutions were formulated in acetone/olive oil (4:1 v/v).
In the pre-test, two mice were treated with test item concentrations of 50 or 100%.
The test item in the main study was assayed at 25, 50, and 100%.
No. of animals per dose:
4
Details on study design:
RANGE FINDING TESTS:
- Compound solubility: The highest test item concentration which can be technically used was 100% of the undiluted test item. The dilutions were formulated in acetone/olive oil (4:1 v/v).
In the pre-test, two mice were treated by topical application to the dorsal surface of each ear with test item concentrations of 50 or 100% once daily each on three consecutive days. At those concentrations the animals did not show signs of systemic toxicity or local irritation.

MAIN STUDY:

TOPICAL APPLICATION:
Each test group of mice was treated by topical (epidermal) application to the dorsal surface of each ear (left and right) with different test item concentrations of 25, 50, and 100% (w/v) in acetone:olive oil (4:1). The application volume, 25 µl, was spread over the entire dorsal surface (~ 8 mm) of each ear once daily for three consecutive days. A further group of mice was treated with an equivalent volume of the relevant vehicle alone (control animals).
ADMINISTRATION OF ³H-METHYL THYMIDINE AND DETERMINATION OF INCORPORATED ³H-METHYL THYMIDINE

Five days after the first topical application, all mice were intraveneously injected into a tail vein with radio-labelled thymidine (³H-methyl thymidine). Approximately five hours after treatment with ³HTdR all mice were sacrificed and the draining lymph nodes were excised and pooled per group. Single cell suspensions lymph node cells were prepared from pooled lymph nodes, which were subsequently washed with phosphate buffered saline and incubated with trichloroacetic acid overnight. The proliferative capacity of pooled lymph node cells was determined by the incorporation of ³H-methyl thymidine measured in a ß-scintillation counter.

INTERPRETATION OF RAW DATA

The proliferative response of lymph node cells is expressed as the number of radioactive disintegrations per minute per lymph node (DPM/node) and as the ratio of ³HTdR incorporated into lymph node cells of test lymph nodes relative to that recorded for control lymph nodes (stimulation index). Before DPM/node values were determined, mean scintillation-background DPM was subtracted from test and control raw data. A test item is regarded as a sensitiser in the LLNA if the following criteria are fulfilled:
- First, that exposure to at least one concentration of the test item resulted in an incorporation of ³HTdR at least 3-fold or greater than that recorded in control mice, as indicated by the stimulation index.
- Second, that the data are compatible with a conventional dose response, although allowance must be made (especially at high topical concentrations) for either local toxicity or immunological suppression.
OBSERVATIONS

In addition to the sensitising reactions the following observations and data were recorded during the test and observation period:
- Mortality / Viability: Once daily (week day) from experimental start to necropsy.
- Body weights: In the pre-test prior to the first application and prior to sacrifice; in the main experiment prior to the first application and prior to treatment with 3HTdR.
- Clinical signs (local / systemic): In the pre-test clinical signs were recorded within 1 hour and 24 ± 4 hours after each application as well as on day 7. In the main experiment clinical signs were recorded within 1 hour each application, and 24 ± 4 hours after the first and second application as well as on the day of preparation. Especially the treatment sites were observed carefully.
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
The mean values and standard deviations were calculated in the body weight tables.

Results and discussion

Positive control results:
Experiment performend in November 2009:
5, 10, and 25% alpha-hexyl cinnamic aldehyde in acetone:olibe oil (4:1) yielded a S.I. of 1.78, 2.54, and 4.88, respectively. The EC3 value calculated was 12.9%.
The positive control substance alpha-hexyl cinnamic aldehyde was found to be a skin sensitizer under the described conditions, demonstrating the validity of the study.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: see Remark
Remarks:
In this study Stimulation Indices of 1.22, 0.99, and 3.46 were determined with the test item at concentrations of 25, 50, and 100% in acetone/olive oil (4:1 v/v), respectively. A conventional dose response curve could not be established and an EC3 value was not calculated because of the odd dose response.
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: As depicted in the table below.

Any other information on results incl. tables

Calculation and results of individual data; Vehicle: acetone/olive oil (4:1 v/v)

Test item concentration % (w/v)

Group

Measurement DPM

Calculation

Result

DPM-BGa)

number of lymph nodes

DPM per lymph nodeb )

S.I.

---

BG I

17

---

---

---

---

---

BG II

17

---

---

---

---

---

1

3517

3500

8

437.5

---

25

2

4282

4265

8

533.1

1.22

50

3

3479

3462

8

432.8

0.99

100

4

12129

12112

8

1514.0

3.46

VIABILITY / MORTALITY

No deaths occurred during the study period.

CLINICAL SIGNS

No symptoms of local toxicity at the ears of the animals and no systemic findings were observed during the study period.

BODY WEIGHTS

The body weight of the animals, recorded prior to the first application and prior to treatment with 3HTdR, was within the range commonly recorded for animals of this strain and age.

 

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Based on the numerical values of the stimulation indices one of which is slightly above 3, the test item Carbon disulfide has to be considered a skin sensitizer under the test condidions of this study. However, a conventional dose-response curve could not be established. An EC3 value was not calculated because of the odd dose-response.These factors contribute also in determining whether a borderline result shall be deemed as positive. In the opinion of the applicant this is a false positive and CS2 cannot be considered as a skin sensitizer base don this study.
Executive summary:

In this study carbon disulfide dissolved in acetone/olive oil (4:1 v/v) was assessed for its possible contact allergenic potential. For this purpose a local lymph node assay according to OECD guideline 429 was performed using test item concentrations of 25, 50, and 100%. All treated animals survived the scheduled study period and no signs of systemic toxicity or local irritation were observed. A test item is regarded as a sensitiser in the LLNA if the exposure to one or more test concentration results in a 3-fold or greater increase in incorporation of ³HTdR compared with concurrent controls, as indicated by the Stimulation Index (S.I.). The estimated concentration of test item required to produce a S.I. of 3 is referred to as the EC3 value. In this study Stimulation Indices of 1.22, 0.99, and 3.46 were determined with the test item at concentrations of 25, 50, and 100% in acetone/olive oil (4:1). Based on the numerical values of these stimulation indices, the test item carbon disulfide has to be considered a skin sensitizer under the test conditions of this study. However, a conventional dose-response curve could not be established. An EC3 value was not calculated because of the odd dose-response. These factors contribute also in determining whether a borderline result shall be deemed as positive. In the opinion of the applicant this is a false positive and CS2 cannot be considered as a skin sensitizer base don this study.