Magnesium thiosulphate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Comparable to guideline study reliable with restrictions. Minor deviations with no effect on the results: - Purity and stability was missing - According to guideline, observations should be made at 30-60 minutes and at 24, 48, and 72 hours after patch removal and not 24 hours, 48 hours and 8 days after start of exposure. -The narrative desciption of the degree and nature of irritation observed is missing

Justification for type of information:

The basis for the read-across concept for this project is the equilibrium between sulfites, hydrogensulfites, and metabisulfites in aqueous solutions depending on pHvalue which is clearly described in published literature and summarised in the following equations:[1],[2]
           SO2+ H2O <->`H2SO3´         H2SO3<->H++ HSO3-<->2H++SO32-    2HSO3-<->H2O +S2O52-
As the nature of the cation should make no significant difference in this case concerning toxicity and solubility (all substances are very soluble in water), only the chemical and biological properties of the anion are considered relevant. Based on the described equilibrium correlations, we propose unrestricted read-across between the groups of sulfites, hydrogensulfites and metabisulfites.

Additionally, it is known that sodium dithionite disproportionates in water to form sodium hydrogen sulfite and sodium thiosulfate (equation II) so that this substance can also be added to the read-across concept.[2],[1]It is expected for this case that the substance is not stable enough under physiological conditions to fulfil the requirements of study guidelines and so the products of decomposition have to be considered.
       2 S2O42-+ H2O→2HSO3-+ S2O32 -
 
Not completely included in this read-across concept is the substance class of thiosulfates. Although thiosulfates may also disproportionate in aqueous solution to form polythionic acids and SO2(HSO3-), the required conditions are somewhat different (more acidic) and are therefore not strictly comparable with physiological conditions, except for the case of oral application where read-across should be considered unrestricted due to the strongly acidic conditions in the stomach:
       HS2O3-+ H2S2O3→HS3O3- + SO2+ H2O
Nevertheless, read-across for all other routes (dermal, inhalation) should also be considered.
The proposed read-across concept only applies to toxicological and ecotoxicological/environmental fate endpoints.
[1]Hollemann Wiberg, Lehrbuch der Anorganischen Chemie, 101.Auflage
[2]Handbook of Chemistry and Physics, Ed. Lide, DR, 88thedition, CRC Press

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1981

Report date:

1981

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

, adopted 1981-05-12

Deviations:

yes

Remarks:

, see "rationale for reliability"

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium sulphite

EC Number:

231-821-4

EC Name:

Sodium sulphite

Cas Number:

7757-83-7

IUPAC Name:

disodium sulfite

Constituent 2

Reference substance name:

sodium sulfite

IUPAC Name:

sodium sulfite

Details on test material:

- Name of test material (as cited in study report):Natriumsulfit wasserfrei Z
- Expiration date of the lot/batch: September 1983
No further information on the test substance was stated.

Test animals

Species:

rabbit

Strain:

Vienna White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Firma Gaukler; 6050 Offenbach/Main
- Weight at study initiation: Mean weight males: 3.03 kg; mean weight females: 2.80 kg (Individual weights of the test animals: 3.26 kg (male); 2.98 kg (female); 2.79 kg (male); 2.62 kg (female))
- Housing: The animals were housed individually; Cage made of stainless steel with wire mesh walk floor, floor area: 40 cm x 51 cm; No bedding in the cages; sawdust in the waste trays
- Diet: Ovator Solikanin 4 mm; Muskator-Werke, 4000 Düsseldorf, FRG (about 130 g per animal per day)
- Drinking water: About 250 ml per animal per day: fully demineralized water (Monday - Friday), tap water (Saturday/Sunday)
- Acclimatization period: About 8 days before the beginning of the study in the skin laboratory; same housing conditions as during the study.

ENVIRONMENTAL CONDITIONS
- Temperature: 20 - 26°C
- Relative humidity: approx. 30 - 70%
- Photoperiod (hrs dark / hrs light): 12/12
No further information on the test animals was stated.

Test system

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

water

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Applying an approx. 0.5 mm thick layer of the 50 % solution of the test substance (comparable to 0.5 g of the test substance).
No further information on the amount/concentration applied was stated.

Duration of treatment / exposure:

4 hours

Observation period:

8 days; Readings at 30-60 minutes after application as well as at 24 hours, 48 hours and 8 days after start of application

Number of animals:

2 males / 2 females

Details on study design:

TEST SITE
- Area of exposure: The fur of the rabbits was clipped at least 15 hours before the beginning of the study. The application area was 2.5 cm X 2.5 cm on the upper third of the back or flanks. The test patch was covered with the test substance. In order to prepare the solution distilled water was used. The untreated skin sites of the same animals was used as negative control.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): The test substance was removed with lutrol and lutrol/water (1:1).
- Time after start of exposure: At the end of the exposure period

SCORING SYSTEM: Draize scoring system
No further information on the study design was stated.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #1

Time point:

other: 24,48,and 72 hours

Score:

0.33

Max. score:

1

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (erythema = 0).

Results 2

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #1

Time point:

other: 24, 48, and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (oedema = 0).

Results 3

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #2

Time point:

other: 24,48, and 72 hours

Score:

0.33

Max. score:

1

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (erythema = 0).

Results 4

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #2

Time point:

other: 24, 48, and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (oedema = 0).

Results 5

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #3

Time point:

other: 24, 48, and 72 hours

Score:

0.33

Max. score:

1

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (erythema = 0).

Results 6

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #3

Time point:

other: 24, 48, and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (oedema = 0).

Results 7

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #4

Time point:

other: 24, 48, and 72 hours

Score:

0.33

Max. score:

1

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (erythema = 0).

Results 8

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #4

Time point:

other: 24, 48, and 72 hours

Score:

0

Max. score:

0

Remarks on result:

other: In the raw data no observation for 72 hours was included. Since at the 48 hours reading no skin irritation was observed, it was concluded that it could be safely assumed that no skin irritation was present at the 72 hour reading (oedema = 0).

Irritant / corrosive response data:

At the 8 day reading no erythema or oedema werte observed.

Other effects:

No data

Any other information on results incl. tables

Results:

Readings	Animal	Erythema	Edema	Additional findings
24 h	1	1	0
	2	1	0
	3	1	0	overlapping erythema
	4	1	0
48 h	1	0	0
	2	0	0
	3	0	0
	4	0	0
8 d	1	0	0
	2	0	0
	3	0	0
	4	0	0
mean 24 - 48 h	1	0.5	0.0
	2	0.5	0.0
	3	0.5	0.0
	4	0.5	0.0
mean		0.5	0.0

Applicant's summary and conclusion

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Sodium sulphite is not an skin irritant.
According to the criteria specified by Directive 67/548/EEC and subsequent regulations, the test item is not classified as skin irritant.
According to the EC Regulation No. 1272/2008 and subsequent regulations, the test item is not classified as skin irritant.