Silver nitrate

Endpoint summary

Description of key information

Reliable studies are available for skin irritation (in-vitro) and eye irritation (in-vivo) for silver nitrate. Based on these studies, silver nitrate is corrosive to the skin and damaging to the eyes. Based on expert judgement on the detailed results of these studies and according to the criteria laid down in Regulation (EC) No 1272/2008 , the following classification is proposed: Skin irritation/corrosion category 1A (H314: Causes severe skin burns) and irreversible effects on the eye (Category 1, H318: Causes serious eye damage). Based on very low inhalation potential (coarse particle size, very low dustiness), no classification for respiratory irritation is proposed.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-06-10 to 2009-06-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline for Testing of Chemicals 431: In vitro Skin Corrosion: Human Skin Model Test (2004)

Deviations:

no

Principles of method if other than guideline:

The In vitro Skin Corrosion (Human Skin Model Test) consists of topical application of the test material to the tissue for 3 minutes and 1 hour, followed by immediate determination of the cytotoxic effect. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the exposure period.

GLP compliance:

yes (incl. QA statement)

Species:

other: in vitro: human skin model

Strain:

other: not applicable

Details on test animals or test system and environmental conditions:

not applicable, in vitro testing

Type of coverage:

other: not applicable

Preparation of test site:

other: not applicable

Vehicle:

other: not applicable

Controls:

other: not applicable, in vitro testing

Amount / concentration applied:

About 25 mg of the test material were applied to the tissues and wetted with 25 µL deionised water. The test item was spread to cover the surface of the tissue.
Prior to the exposure to the test item the pH of a test item solution in deionised water was determined as 6.49, while the weight volume ratio corresponded to the ratio applied to the skin equivalents

Duration of treatment / exposure:

3 minutes and 1 hour, respectively

Number of animals:

not applicable, in vitro testing

Details on study design:

The In vitro Skin Corrosion (Human Skin Model Test) consists of topical application of the test material to the tissue for 3 minutes and 1 hour, followed by immediate determination of the cytotoxic effect. Cytotoxicity is expressed as the reduction of mitochondrial dehydrogenase activity measured by formazan production from MTT at the end of the exposure period.

Cell culture:
EST-1000 kits were purchased from CellSystems Biotechnologievertrieb GmbH. The EST-1000 tissue consisted of normal, human-derived epidermal keratinocytes which have been cultured to form a multilayered, highly differentiated model of the human epidermis. It consisted of organised basal, spinous and granular layers, and a multi-layered stratum corneum containing intercellular lamellar lipid layers arranged in patterns analogous to those found in vivo. The EST-1000 tissues (surface 0.6cm²) were cultured on specially prepared cell culture inserts.

Controls:
- Deionised water was used a the negative control. Volumes of 50 µL (>30 µL/cm²) were applied to each set of duplicate tissues for the exposure periods.
- Potassium Hydroxide as an 8.0 N ready-made solution was used as a positive control material. Volumes of 50 µL (> 30 µL/cm²) were applied to each set of duplicate tissues for the exposure periods.

Experimental performance:
At least 2 hours before dosing the EST-1000 tissues were removed from the refrigerator where they were stored. Under sterile conditions, the inserts were transferred into 6-well plates containing the pre-warmed assay medium. Two 24-well plates were prepared as holding plates, each well containing 300 µL assay medium per well. The holding plates were pre-warmed in an incubator (37 ± 1.5 °C, 5 ± 0.5% CO2) until use.
Duplicate EST-1000 tissues were exposed to the test item, positive control or negative control for each of two different exposure periods.
At the end of the exposure period the tissues were removed from the 6-well plate and gently rinsed using a wash bottle containing PBS to remove any residual test material.

MTT assay:
After the exposure procedure was completed for all tissues of each time point, the cell culture inserts were transferred from the holding plates to the MTT-plates. After a 3 hour incubation period the MTT solution was aspirated from the wells. The inserts were transferred into new 24 -well plates. The inserts were immersed in extractant solution. The 24 -well plate was sealed to minimise isopropanol evaporation. The formazan salt was extracted for 2 hours while shaking at room temperature.
After the extraction period the inserts were pierced with an injection needle to allow the extract to run into the well from which the insert was taken, and the insert was discarded. 24-well plates were then placed on a shaker for approx. 15 minutes until the solution was homogeneous in colour.
The optical density (OD) was read in a microplate reader at 570 nm (OD570) without reference filter. The mean values were calculated for each set of 3 wells per tissue insert.

Irritation / corrosion parameter:

other: Relative absorbance value (%) at 570 nm

Run / experiment:

After 3 min exposure

Value:

8.4

Irritation / corrosion parameter:

other: Relative absorbance value (%) at 570 nm

Run / experiment:

After 1 hour

Value:

25.1

After exposure to the test item Silver nitrate the relative absorbance values were decreased to 8.4% after 3 minutes. This value is well below the threshold for corrosivity of 50% for the 3 minutes treatment. After the 1 hour exposure relative absorbance values were reduced to 25.1%. Although this value was not below the threshold of 15% for the 1 hour exposure, the test item was nevertheless considered to be corrosive, firstly, since the value for the 3 minutes exposure was very convincing, and secondly, since the test item precipitated and the precipitate could not be washed of the tissues completely after the 1 hour exposure. This fact distorted the measurement of the absorbance values. Probably, the poorly soluble precipitate was silver chloride, which was formed during the washing step with PBS (which contains 0.8% / 8 g/L NaCl). In addition, the cells of the 1 hour treatment tissues were not able to reduce the MTT at all (no blue coloration at all) indicating complete death of the cells due to exposure to the test item.

Interpretation of results:

Category 1A (corrosive) based on GHS criteria

Conclusions:

In conclusion, it can be stated that in this study and under the reported experimental conditions, the test item Silver nitrate was corrosive to skin.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

The study was conducted according to state of the art methodology at that time; methods are well described and results are presented reasonable in the text and in tabular format.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Study on effects of some silver salts on the eye. The following irritation parameters were scored in this old study (1941): hyperemia, swelling, scar tissue formation, mucopurulent exudation, coagulation and corneal injury. These parameters are different from current standardised test protocols. Unfortunately, they cannot be entered in the technical dossier in a way that the CSR plugin provides a meaningful output in the CSR. Thus we merely state that based on this study silver nitrate can classified as highly irritating to eyes. The full study report is attached to the corresponding endpoint record in the technical dossier.

GLP compliance:

no

Species:

rabbit

Strain:

other: pure albino

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: several different sources
- Age at study initiation: young adults (exact ages were not known)
- Weight at study initiation: 1.5 - 3 kg
- Housing: in air-conditioned quarters, individually housing
- Diet: standard diet
No further details are given.

Vehicle:

not specified

Controls:

other: the right eye served as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): The material was administered by instilling 0.2 - 1.0 drop of the solution into the lower cul-de-sac of the left eye.
- Concentration (if solution): The concentrations of the solutions varied in strength from 1 to 12%, calculated on the basis of silver nitrate.
- Positive controls: One group of animals received distilled water, another 3% boric acid and another an 0.85% saline solution.

Duration of treatment / exposure:

2 to 5 minutes

Observation period (in vivo):

at least once every 24 hours

Number of animals or in vitro replicates:

up to 10 animals

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): 2 to 5 minutes after application a lavage of 1% boric acid was used in the eye.

SCORING SYSTEM:
Conditions evaluated as follows
0 = no observed changes
1 = mild changes or small amount
2 = moderate changes or a moderate amount
3 = severe changes or a large amount
4 = intense changes or an enormous amount

Irritation parameter:

chemosis score

Remarks:

hyperemia, swelling, scar tissue formation, mucopurulent exudation, coagulation and corneal injury

Basis:

mean

Time point:

other: several days

Reversibility:

not specified

Remarks on result:

not determinable because of methodological limitations

Irritant / corrosive response data:

Study on effects of some silver salts on the eye. The following irritation parameters were scored in this old study (1941): hyperemia, swelling, scar tissue formation, mucopurulent exudation, coagulation and corneal injury. These parameters are different from current standardised test protocols. Unfortunately, they cannot be entered in the technical dossier in a way that the CSR plugin provides a meaningful output in the CSR. Thus we merely state that based on this study silver nitrate can classified as highly irritating to eyes. The full study report is attached to the corresponding endpoint record in the technical dossier.

Other effects:

Positive controls: In all of these animals the results were negative or there was mild hyperemia, the distilled water being th greatest offender, indicating that osmotic properties may play some part.

Study on effects of some silver salts on the eye. The following irritation parameters were scored in this old study (1941): hyperemia, swelling, scar tissue formation, mucopurulent exudation, coagulation and corneal injury. These parameters are different from current standardised test protocols. Unfortunately, they cannot be entered in the technical dossier in a way that the CSR plugin provides a meaningful output in the CSR. Thus we merely state that based on this study silver nitrate can classified as highly irritating to eyes. The full study report is attached to the corresponding endpoint record in the technical dossier.

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Effects on skin irritation/corrosion: corrosive 1A

Effects on eye irritation: highly irritating (Eye Damage 1)

Justification for classification or non-classification

Reliable studies are available for skin irritation (in-vitro) and eye irritation (in-vivo) for silver nitrate. Based on these studies, silver nitrate is corrosive to the skin and irritating to the eyes. Based on expert judgement on the detailed results of these studies and according to the criteria laid down in Regulation (EC) No 1272/2008 , the following classification is proposed: Skin irritation/corrosion category 1A (H314: Causes severe skin burns) and irreversible effects on the eye (Category 1, H318: Causes serious eye damage). Based on very low inhalation potential (coarse particle size, very low dustiness), no classification for respiratory irritation is proposed.