Magnesium hydroxide sulfate (Mg6(OH)10(SO4)), hydrate (1:3)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

performed between 29 August 2006 and 12 September 2006.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 30/08/05; Date of signature: 14/11/06

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

483-390-9

EC Name:

-

Cas Number:

12508-61-1

Molecular formula:

H16Mg6O17S

IUPAC Name:

hexamagnesium(2+) trihydrate decahydroxide sulfate

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: B & K Universal Ltd, Hull, UK.
- Age at study initiation: eight to twelve weeks
- Weight at study initiation: 15 to 23 g
- Housing: suspended solid floor polypropylene cages furnished with softwood woodflakes.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least five days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25°C
- Humidity (%): 30 to 70%,
- Air changes (per hr): approximately fifteen changes per hour
- Photoperiod (hrs dark / hrs light): twelve hours continuous light (06.00 to 18.00) and twelve hours darkness.


IN-LIFE DATES: From: Day 1 To: Day 6

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Concentration:

Vehicle control group (0% w/w)
2.5% w/w
5% w/w
10% w/w

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: 10% w/w
- Irritation: None observed.
- Lymph node proliferation response: None


MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local lymph node assay
- Criteria used to consider a positive response: The test material will be regarded as a sensitiser if at least one concentration of the test material results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test material failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitiser".


TREATMENT PREPARATION AND ADMINISTRATION:
Test material administration
Groups of four mice were treated with the test material at concentrations of 2.5%, 5% or 10% w/w in dimethyl formamide. 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 (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, GE Healthcare UK Ltd) giving a total of 20 µCi to each mouse.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

Not stated in report.

Results and discussion

Positive control results:

Concentration (% v/v) in
dimethyl formamide: 5 , 10 and 25

Stimulation Index : 2.81, 4.82 and 13.15

Stimulation index: Negative, Positive, Positive

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.62

Test group / Remarks:

2.5 %

Results 2

Key result

Parameter:

SI

Value:

1.78

Test group / Remarks:

5 %

Results 3

Key result

Parameter:

SI

Value:

1.72

Test group / Remarks:

10 %

Results 4

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: Please refer to the table in the Remarks on results including tables and figures section.

Any other information on results incl. tables

Concentration (% w/w) in dimethyl formamide	dpm	dpm/Node^a	Stimulation Index^b	Result
Vehicle	4324.76	540.60	na	na
2.5	7006.60	875.83	1.62	Negative
5	7685.40	960.68	1.78	Negative
10	7448.24	931.03	1.72	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

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test material was considered to be a non-sensitiser under the conditions of the test.

Executive summary:

Introduction:

A study was performed to assess the skin sensitisation potential of the test material in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The method was designed to meet the requirements of the following:

§        OECD Guideline for the Testing of Chemicals No. 429 "Skin Sensitisation: Local Lymph Node Assay" (adopted)

§        Method B42 Skin Sensitisation (Local Lymph Node Assay) of Commission Directive 2004/73/EC

Methods:

Following a preliminary screening test, three groups, each of four animals, were treated with 50 µl (25 µl per ear) of the test material as a suspension in dimethyl formamide at concentrations of 2.5%, 5% or 10% w/w. A further group of four animals was treated with dimethyl formamide alone.

Results:

 The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows:

Concentration (% w/w) in dimethyl formamide	Stimulation Index	Result
2.5	1.62	Negative
5	1.78	Negative
10	1.72	Negative

Conclusion. The test material was considered to be a non‑sensitiser under the conditions of the test.