Ammonium iron bis(sulphate)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Differences of draining lymph node cell proliferation among mice, rats and guinea pigs following exposure to metal allergens

Author:

Y. Ikarashi, K. Ohno, T. Tsuchiya, A. Nakamura

Year:

1992

Bibliographic source:

Toxicology, 76, 1992, 283-292

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

This animal test determines the sensitization potential of a chemical by assessment of proliferative responses in lymph nodes draining the site of chemical application. Following exposure to metal salts lymph node cell (LNC) proliferative activity was assessed via determining the incorporation of [methyl-3H]thymidine by scintillation counting.

GLP compliance:

not specified

Type of study:

other: Local Lymph Node Assay in F344 rats

Test material

Test material information

Constituent 1

Reference substance name:

Iron sulphate

EC Number:

231-753-5

EC Name:

Iron sulphate

Cas Number:

7720-78-7

Molecular formula:

Fe.H2O4S

IUPAC Name:

iron(2+) sulfate

Specific details on test material used for the study:

Solutions of Iron(II) Sulfate in DMSO: Water (4:1)

In vivo test system

Test animals

Species:

other: rat

Strain:

other: F344

Sex:

female

Details on test animals and environmental conditions:

Female F344 rats, 6-8 weeks old

Study design: in vivo (LLNA)

Vehicle:

other: DMSO: water (4:1)

Concentration:

c(FeSO4) / (w/v%): 0.0, 0.5, 1.0, 2.5, 5.0

No. of animals per dose:

3

Details on study design:

Three animals (n = 3) were used per group. Rats received 100 µl of each concentration of the test chemical on the dorsum of both ears daily for 3 consecutive days. Control rats received an equal volume of vehicle alone. Animals were sacrificed 24 h following the final exposure. The draining auricular lymph nodes were excised and pooled and weighed for each experimental group. A single suspension of lymph node cells (LNC) was prepared. Cell suspensions (1×106 cells/200 µl) were seeded into 96-well tissue culture plate (5 wells per group) and cultured at 37°C in a humidified atmosphere of 5% CO2 in air with 0.5 µCi [methyl-3H]thymidine (3HTdR). After 18 h culture, LNC were harvested with an automatic cell harvester and 3HTdR incorporation was determined by liquid scintillation counting. A stimulation index (SI), the increase in 3HTdR incorporation relative to vehicle-treated controls, was derived for each experimental group. With the same method, skin sensitization potential of potassium dichromate and cobalt chloride was tested.

Results and discussion

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Value:

1.28

Test group / Remarks:

c(FeSO4) = 0.5%

Results 2

Parameter:

SI

Value:

0.61

Test group / Remarks:

c(FeSO4) = 1.0%

Results 3

Parameter:

SI

Value:

1.64

Test group / Remarks:

c(FeSO4) = 2.5%

Results 4

Parameter:

SI

Value:

1.12

Test group / Remarks:

c(FeSO4) = 5.0%

Cellular proliferation data / Observations:

Exposure to FeSO4 failed to induce significant lymph node responses at all concentrations (see table 1). In comparable tests, exposure to potassium dichromate (K2Cr2O7) and cobalt chloride (CoCl2) induced strong proliferative responses.

Any other information on results incl. tables

Table 1: The draining LNC proliferative activity in the rat following exposure to iron sulfate.

LNC: lymph node cells; mean cpm: mean counts/minute ,values from five culture wells.

c(FeSO4) / (w/v%)	LNC proliferation 3HTdR incorporation / mean cpm x 10 ^-3	standard deviation / cpm x 10 ^-3	stimulation index
0.0	2.35	0.18	-
0.5	3.02	0.32	1.28
1.0	1.42	0.16	0.61
2.5	3.87	0.23	1.64
5.0	2.63	0.17	1.12

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Exposure to FeSO4 failed to induce significant lymph node responses at all concentrations investigated. In comparable tests, exposure to potassium dichromate (K2Cr2O7) and cobalt chloride (CoCl2) induced strong proliferative response. Since GHS criteria for skin sensitization are not met, iron(II) sulfate is not classified.

Executive summary:

The skin sensitizing potential of Iron(II) Sulfate was tested by local lymph node assay (LLNA) in female rats. Following exposure to solutions of the metal salt (concentration: 0% to 5%), the lymph node cell proliferative response was assessed by measuring the incorporation of [methyl-3H]thymidine. According to this article by Ikarashi et al. (published in 1992), exposure to FeSO4 failed to induce significant lymph node responses at all concentrations investigated.  In comparable tests, exposure to potassium dichromate (K2Cr2O7) and cobalt chloride (CoCl2) induced strong proliferative responses. Since GHS criteria for skin sensitization are not met, iron(II) sulfate is not classified.