Hydrogen (glycinato-N,O)[sulphato(2-)-O,O']ferrate(1-)

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
The target substance, ferrous monoglycinate sulfate, is a chelate-complex which consists of the divalent iron ion as center-ion and glycine as ligand. The remaining sulfate group stabilizes the center-ion within the complex. In aqueous solutions the complex may dissociate, although it is known to be more stable than iron salts also containing the divalent ion. However, once absorbed into a cell (organism) ferrous monoglycinate sulfate is expected to be enzymatically hydrolyzed and delivers Fe2+ to the respective transport protein. Thus, at least due to hydrolysis, Fe2+ is released from the complex as also sulfate and glycine. Therefore, the read-across hypothesis is based on the generation of common breakdown products, namely, glycine and Fe2+.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across hypothesis is based on transformation of the target and source substances to common compounds (scenario1 of the RAAF).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the justification for read-across analogue approach in Chapter 13 for more detailed information.

3. ANALOGUE APPROACH JUSTIFICATION
Please refer to the justification for read-across analogue approach in Chapter 13 for more detailed information.

4. DATA MATRIX
Please refer to the justification for read-across analogue approach in Chapter 13 for more detailed information.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

The test was performed in 3 animals instead of 4 and the test was performed in rats.

GLP compliance:

no

Type of study:

mouse local lymph node assay (LLNA)

Species:

other: rat

Strain:

other: F344

Sex:

not specified

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Japan Charles River Breeding Laboratories, Inc.
- Females (if applicable) nulliparous and non-pregnant: not specified
- Microbiological status of animals, when known:
- Age at study initiation: 6-8 weeks
- Housing: 3 per cage

Vehicle:

other: Iron sulfate was dissolved in DMSO:water (4:1)

Concentration:

Iron sulphate was applied at concentrations of 0 (vehicle alone), 0.5, 1.0, 2.5, and 5.0% (w/v)

No. of animals per dose:

3 animals were used per group

Details on study design:

MAIN STUDY
Rats received 100µL and guinea pigs received 200 µL of chemicals or vehicle. 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 LNC was prepared by mechanical disaggregation through sterile 200-mesh stainless steel gauze. Cell suspensions were washed once in phosphate-buffered saline (pH 7.2) and resuspended in RPMI-1640 culture medium supplemented with 10% FCS, 25 mM N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid (HEPES), 100 µg/mL penicillin, 100 units/ml streptomycin (FCS-RPMI). Total LNC number was determined using an automated cell counter. Cell suspensions (1E+06 cells/200µL) 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.

Positive control substance(s):

other: nickel sulfate, potassium dichromate and cobalt chloride were also tested in this publication and are well known metall allergens.

Positive control results:

K2Cr2O7, CoCl2 and NiSO4 are known metal allergens. K2Cr2O7 and CoCl2 revealed a SI of > 3 in at least two concentrations. For K2Cr2O7 the SI was 6.64 at 1%, 10.94 at 2.5% and 5.44 at 5%. For CoCl2 the SI was 3.82 at 2.5% and 3.57 at 5%. Both Substances were tested in rats.

Key result

Parameter:

SI

Value:

1.28

Test group / Remarks:

0.5%

Key result

Parameter:

SI

Value:

0.61

Test group / Remarks:

1.0%

Key result

Parameter:

SI

Value:

1.64

Test group / Remarks:

2.5%

Key result

Parameter:

SI

Value:

1.12

Test group / Remarks:

5.0%

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA
Exposure to 2.5% K2Cr20 7 induced a strong proliferative response (10.9-fold increase in 3HTdR incorporation) compared with the vehicle-treated control group. However, LNC proliferation was decreased in the 5% K2Cr2O7 group compared with the 2.5% K2Cr2O7 group. In the case of CoCI 2, SI of 3.82 was maximum in the 2.5% group. Lymph node weight and total LNC number increased following exposure to K2Cr2O7 and CoCI 2 but, compared with in vitro LNC proliferation, were less sensitively correlated to lymph node activation. Exposure to NiSO4 and FeSO4 failed to induce significant lymph node responses at all concentrations.

CLINICAL OBSERVATIONS:
Not reported
BODY WEIGHTS
Not reported

Chemical	Concentration (w/v%)	LNC proliferation 3HTdR incorporation (mean cpm±SD x E-03)	SI	Total LNC number (E+06/group)	Lymph node weight (mg/group)
FeSO4	0	2.35±0.18	-	25.68	61.8
	0.5	3.02± 0.32	1.28	23.71	65.0
	1.0	1.42± 0.16	0.61	26.20	59.5
	2.5	3.87± 0.23	1.64	20.52	48.4
	5.0	2.63± 0.17	1.12	26.86	54.3
K2Cr2O7	0	1.71± 0.06	-	27.86	59.3
	0.5	3.43± 0.11	2.00	28.74	67.0
	1.0	11.39± 0.33	6.64	58.72	85.6
	2.5	18.76± 0.36	10.94	92.28	114.3
	5.0	9.33± 0.26	5.44	60.86	114.4
CoCl2	0	1.95± 0.17	-	23.26	54.7
	0.5	1.71± 0.21	0.88	21.35	51.1
	1	1.95± 0.10	1.00	29.72	52.0
	2.5	7.45± 0.65	3.82	70.70	71.5
	5	6.95± 0.69	3.57	38.81	59.2

Interpretation of results:

GHS criteria not met

Conclusions:

In a dermal sensitization study conducted similar to OECD guideline 429 with FeSO4 in DMSO:water; 4:1, young adult F344 rats (4/group) were tested using the method of Kimber et al., 1989. As positive control substances in this case can be regarded K2Cr2O7 and CoCl2 which are known metal allergens. No clinical signs were observed for in the rats treated with FeSO4 at any concentration, no mortality occurred nor any pathological change was detected at necropsy. Furthermore, there was no indication for skin sensitisation after treatement with FeSO4.                                                 
 
The test was conducted for 24h after initial treatment for three consecutive days. In this study, FeSO4 is not a dermal sensitizer and thus does not need to be classified according to Regulation (EC) No 1272/2008 (CLP) and the Globally Harmonized System for Classification and Labelling of Chemicals (GHS).

Executive summary:

In a dermal sensitization study conducted similar to OECD guideline 429 with FeSO4 in DMSO:water; 4:1, young adult F344 rats (4/group) were tested using the method of Kimber et al., 1989. As positive control substances in this case can be regarded K2Cr2O7 and CoCl2 which are known metal allergens No clinical signs were observed for in the rats treated with FeSO4 at any concentration, no mortality occurred nor any pathological change was detected at necropsy. Furthermore, there was no indication for skin sensitisation after treatement with FeSO4.                                                 

 

The test was conducted for 24h after initial treatment for three consecutive days. In this study, FeSO4 is not a dermal sensitizer and thus does not need to be classified according to Regulation (EC) No 1272/2008 (CLP) and the Globally Harmonized System for Classification and Labelling of Chemicals (GHS).

Cross-reference 2

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
VEGA-QSAR:AI inside a platform for predictive toxicology
2. MODEL (incl. version number)
1.1.5
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
O=C(O)CN
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
For more detailed information please refer to the 'attached justification' section

5. APPLICABILITY DOMAIN
For more detailed information please refer to the 'attached justification' section

6. ADEQUACY OF THE RESULT
For more detailed information please refer to the 'attached justification' section

Qualifier:

no guideline followed

Principles of method if other than guideline:

Result of a QSAR prediction using VEGA-QSAR platform Skin Sensitization model (CAESAR) 2.1.6.

GLP compliance:

no

Species:

other: not applicable for an in silico system

Strain:

other: not applicable for an in silico system

Details on test animals and environmental conditions:

not applicalbe for an in silico system

Vehicle:

other: not applicable for an in silico system

Concentration:

not applicable for an in silico system

No. of animals per dose:

not applicable for an in silico system

Details on study design:

not applicable for an in silico system

Key result

Parameter:

other: not applicable for an in silico system

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

Interpretation of results:

study cannot be used for classification

Conclusions:

In the present QSAR calculation using VEGA-QSAR platform and its Skin Sensitization model (CAESAR) 2.1.6. the skin sensitizing potential of Glycine was estimated. There are no indications for skin sensitisation by appliying this QSAR prediction method. The results are considered to be reliable because the substance falls in the applicability domain of the used model. Glycine is not a sensitizier according to this prediction.

Executive summary:

There are no experimental data available regarding the skin sensitizing potential of glycine. Therefore, a QSAR estimation was performed using the VEGA_QSAR platform. There are no indications for skin sensitisation by appliying this QSAR prediction method. The results are considered to be reliable because the substance falls in the applicability domain of the used model. Glycine is not a sensitizier according to this prediction.

Cross-reference 3

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020-02-04

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
EPISUITE v4.11
2. MODEL (incl. version number)
MPBPWIN v1.43 (September 2010)
3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES: O=C(O)CN
CAS: 56-40-6
4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Please refer to the document in 'attached justification'
5. APPLICABILITY DOMAIN
Please refer to the document in 'attached justification'
6. ADEQUACY OF THE RESULT
Please refer to the document in 'attached justification'

Qualifier:

no guideline followed

Principles of method if other than guideline:

Vapour pressure was determined by QSAR calculation using EpiSuite Software and the MPBPWIN v1.43 (September 2010) model.

GLP compliance:

no

Type of method:

other: QSAR prediction

Key result

Test no.:

#1

Temp.:

25 °C

Vapour pressure:

0 Pa

Conclusions:

The vapour pressure of glycine was determined by QSAR calculation using EPiSuite software and the MPBPWIN v1.43 (September 2010)model. The vapour pressure of glycine is 1.09E-005 Pa at 25 °C.

Executive summary:

The vapour pressure of glycine was determined by QSAR calculation using EPiSuite software and the MPBPWIN v1.43 (September 2010)model. The vapour pressure of glycine is 1.09E-005 Pa at 25 °C. Based on the ionic structure the vapour pressure of Ferroglycine sulfate is considered to be lower as the respective value for glycine. The calculated value cannot be determined experimentally for glycine either due to residual content of solvent (water) which results in a higher solvent vapour pressure than test substance vapour pressure. The residual content of solvent cannot be reduced below the limit of measurement with reasonable effort. As this is also the case for Ferroglycine sulfate the vapour pressure of glycine is used for further assessment of the substance as the closest approximation.

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Manganate(1-), glycinato-N,O)[sulfato(2-)-O]-, hydrogen

EC Number:

838-538-0

Cas Number:

52139-31-8

Molecular formula:

C2H5MnNO6S

IUPAC Name:

Manganate(1-), glycinato-N,O)[sulfato(2-)-O]-, hydrogen

Results and discussion

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

1.28

Test group / Remarks:

0.5% FeSO4 in water

Remarks on result:

other: Results obtained from Ikarashi 1992

Results 2

Key result

Parameter:

SI

Value:

0.61

Test group / Remarks:

1.0% FeSO4 in water

Remarks on result:

other: Results obtained from Ikarashi 1992

Results 3

Key result

Parameter:

SI

Value:

1.64

Test group / Remarks:

2.5% FeSO4 in water

Remarks on result:

other: Results obtained from Ikarashi 1992

Results 4

Key result

Parameter:

SI

Value:

1.12

Test group / Remarks:

5.0% FeSO4 in water

Remarks on result:

other: Results obtained from Ikarashi 1992

Results 5

Key result

Parameter:

other: not applicalbe for an in silico system

Test group / Remarks:

test substance glycine

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

Remarks:

QSAR prediction was performed using VEGA

Results 6

Key result

Parameter:

EC3

Test group / Remarks:

test substance glycine

Remarks on result:

no indication of skin sensitisation based on QSAR/QSPR prediction

Remarks:

Value not reported in QSAR Toolbox

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

based on a Weight of Evidence approach. For detailed information please refer to the attached justification

Conclusions:

There are no data about the skin sensitisation potential of ferrous monoglycinate sulfate. Based on the read-across hypothesis that the test item dissociates/is hydrolyzed into common break down products, data from the main constituents, namely ferrous sulfate and glycine were used to determine the skin sensitizing properties of ferrous monoglycinate sulfate. The available data, publicly available studies and QSAR estimations, revealed no indications for for skin sensitizing potential of either constituent, thus ferrous monoglycinate sulfate is not considered a sensitizer.

Executive summary:

There are no data about the skin sensitization potential of ferrous monoglycinate sulfate. Based on the read-across hypothesis that the test item dissociates/is hydrolyzed into common break down products, data from the main constituents, namely ferrous sulfate and glycine were used to determine the skin sensitizing properties of ferrous monoglycinate sulfate.

In the study of Ikarashi (1992) the skin sensitizing potential of FeSO₄was determined according to OECD guideline 429 (LLNA). FeSO₄dissolved in water was applied to the dorsum of the ear of three animals per group for four groups with the concentrations 0.5, 1.0, 2.5 and 5.0% (w/v). The test item was applied for three consecutive days, animals were sacrificed after 24h after the last application and the draining lymph nodes were isolated and cultured for 18h with³HTdR. Adjacently, the incorporation of³HTdR was measured and FeSO₄did not result in an SI of ≥ 3, thus FeSO₄is not a skin sensitizer under the conditions of the test.

Testing of glycine, the smallest amino acid, was omitted because in vitro test systems are not considered to be suitable for the determination of a skin sensitizing potential of glycine. For registrations according to Annex VII in vivo testing is not foreseen. However, also in vivo tests are not considered to be the appropriate test method for the determination of skin sensitization as described in the justification for waiving testing of skin sensitization attached in 7.4.1. These considerations are also supported by QSAR estimations performed with the VEGA module and with the information that can be gathered from the OECD QSAR Toolbox, revealing that glycine is not a skin sensitizer.

 

Based on the available information the target substance ferrous monoglycinate sulfate is not classified as skin sensitizer according to Regulation (EU) No. 1272/2008 (CLP) and the Globally Harmonized System for Classification and Labelling of Chemicals (GHS).