Silicic acid, calcium salt

Skin sensitisation

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:

key study

Study period:

The study was performed between 01 June 2010 and 24 June 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study performed according to GLP and internationally accepted guideline. Reliability reduced for read across

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Kieselguhr, soda ash flux-calcined

EC Number:

272-489-0

EC Name:

Kieselguhr, soda ash flux-calcined

IUPAC Name:

272-489-0

Constituent 2

Reference substance name:

Kieselguhr soda ash flux calcined

IUPAC Name:

Kieselguhr soda ash flux calcined

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Sponsor's identification: soda-ash flux calcined kieselguhr
Description : white powder
Lot number : 211184
Date received : 10 February 2010
Expiry date : 31 December 2013
Storage conditions: room temperature in the dark

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Ltd, Bicester, Oxon, UK
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 15 to 23 g
- Housing: Individually housed in suspended solid-floor polypropylene cages furnished with softwood woodflakes
- Diet: 2014 Tekland Global Rodent diet ad libitum
- Water: ad libitum


ENVIRONMENTAL CONDITIONS
- Temperature: 19 to 25°C
- Humidity: 30 - 70 %
- Air changes: Approximately 15 per hr
- Photoperiod: 12 hrs dark / 12 hrs light

Study design: in vivo (LLNA)

Vehicle:

propylene glycol

Concentration:

Groups of four mice were treated with the test material at concentrations of 10%, 5% or 2.5% w/w in propylene glycol

No. of animals per dose:

4 mice per dose

Details on study design:

PRELIMINARY SCREENING TEST:
Using available information regarding the systemic toxicity/irritancy potential of the test material, a preliminary screening test was performed using one mouse. The mouse was treated by daily application of 25 µl of the test material at a concentration of 10% w/w in propylene glycol, to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The mouse was observed twice daily on Days 1, 2 and 3 and once daily on Days 4, 5 and 6. Any signs of toxicity or excessive local irritation noted during this period were recorded. The bodyweight was recorded on Day 1 (prior to dosing) and on Day 6

MAIN STUDY:
Groups of four mice were treated with the test material at concentrations of 10%, 5% or 2.5% w/w in propylene glycol. The preliminary screening test suggested that the test material would not produce systemic toxicity or excessive local irritation at the highest suitable concentration. The mice were treated by daily application of 25 µl of the appropriate concentration of the test material to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test material formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.
A further group of four mice received the vehicle alone in the same manner.

3H-Methyl Thymidine Administration
Five days following the first topical application of the test material or vehicle (Day 6) all mice were injected via the tail vein with 250 µl of phosphate buffered saline (PBS) containing 3H methyl thymidine (3HTdR: 80 µCi/ml, specific activity 2.0 Ci/mmol, ARC UK Ltd) giving a total of 20 µCi to each mouse

Positive control substance(s):

other: Phenylacetaldehyde (90%)

Results and discussion

Positive control results:

A group of five animals was treated with 50 µl (25 µl per ear) of Phenylacetaldehyde (90%) as a solution in propylene glycol at a concentration of 2.5% v/v. A further control group of five animals was treated with propylene glycol alone

The Stimulation Index expressed as the mean radioactive incorporation for the treatment group divided by the mean radioactive incorporation of the vehicle control group was 18.43.

Phenylacetaldehyde (90%) was considered to be a sensitiser under the conditions of the test

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Remarks on result:

other: 2.5 %w/w; SI = 1.13 5 %w/w; SI = 0.97 10 %w/w; SI = 0.99

Results 2

Key result

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: The radioactive disintegrations per minute per lymph node are given in table 2.

Any other information on results incl. tables

Table 1: Clinical Observations, Bodyweight and Mortality Data – Preliminary Screening Test

Concentration (%w/w) in propylene glycol	Animal Number	Bodyweight (g)		Day
				1		2		3		4	5	6
		Day 1	Day 6	Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
10	S-1	19	20	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 2: Disintegrations per Minute, Disintegrations per Minute/Node and Stimulation Index

Concentration (%w/w) in propylene glycol	dpm	dpm/Node^a	Stimulation Index^b	Result
Vehicle	6210.33	776.29	na	na
2.5	7020.81	877.60	1.13	Negative
5	6047.51	755.94	0.97	Negative
10	6135.29	766.91	0.99	Negative

dpm=  Disintegrations per minute

a=      Disintegrations per minute/node obtained by dividing the disintegrations per minute value by 8 (total number of lymph nodes)

b=      Stimulation Index of 3.0 or greater indicates a positive result

na =    Not applicable

Table 3: Individual Clinical Observations and Mortality Data

Concentration (% w/w) in propylene glycol	Animal Number	Day 1		Day 2		Day 3		Day 4	Day 5	Day 6
		Pre-Dose	Post Dose	Pre-Dose	Post Dose	Pre-Dose	Post Dose
Vehicle	1-1	0	0	0	0	0	0	0	0	0
	1-2	0	0	0	0	0	0	0	0	0
	1-3	0	0	0	0	0	0	0	0	0
	1-4	0	0	0	0	0	0	0	0	0
2.5	2-1	0	0	0	0	0	0	0	0	0
	2-2	0	0	0	0	0	0	0	0	0
	2-3	0	0	0	0	0	0	0	0	0
	2-4	0	0	0	0	0	0	0	0	0
5	3-1	0	0	0	0	0	0	0	0	0
	3-2	0	0	0	0	0	0	0	0	0
	3-3	0	0	0	0	0	0	0	0	0
	3-4	0	0	0	0	0	0	0	0	0
10	4-1	0	0	0	0	0	0	0	0	0
	4-2	0	0	0	0	0	0	0	0	0
	4-3	0	0	0	0	0	0	0	0	0
	4-4	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

Table 4: Individual Bodyweights and Bodyweight Changes

Concentration (% w/w) in propylene glycol	Animal Number	Bodyweight (g)		Bodyweight Change (g)
		Day 1	Day 6
Vehicle	1-1	20	20	0
	1-2	20	21	1
	1-3	17	17	0
	1-4	18	17	-1
2.5	2-1	18	17	-1
	2-2	19	19	0
	2-3	19	19	0
	2-4	19	19	0
5	3-1	20	20	0
	3-2	20	19	-1
	3-3	18	18	0
	3-4	20	20	0
10	4-1	17	17	0
	4-2	21	20	-1
	4-3	18	18	0
	4-4	20	20	0

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Kieselguhr soda ash flux calcined is not classified as a skin sensitiser in accordance with CLP Regulation (EC) no. 1272/2008