Zinc sulphate

Endpoint summary

Description of key information

In a well-performed primary skin irritation/corrosion study, conducted according to Directive 92/69/EEC B.4 and OECD guideline 404, three male New Zealand White rabbits were exposed to 0.5 g of moistened zinc sulphate (ZnSO₄•7 H₂O), applied onto clipped skin for 4 hours using a semi-occlusive dressing. Observations were made 1, 24, 48 and 72 hours after exposure. No symptoms of systemic toxicity and no skin irritation/corrosion were observed and no mortality occurred (Van Huygevoort, 1999d).

In a well-performed eye irritation/corrosion study, conducted according to Directive 92/69/EEC B.5 and OECD guideline 405, three male New Zealand White rabbits were treated by instillation of approximately 98.1 mg of zinc sulphate (ZnSO₄•7 H₂O) into the conjuctival sac of one eye. The other eye remained untreated and served as control. The eyes (unrinsed) were examined at 1, 24, 48 and 72 hours and 7, 14 and 21 days after instillation. No symptoms of systemic toxicity were observed and no mortality occurred. Corneal injury was seen as slight dulling of the normal lustre (opacity grade 0) and/or epithelial damage (10% of the corneal area) in two animals. This injury had resolved within 24 hours in one animal and within 72 hours in the other animal. Irritation of the conjuctivae was seen as redness (mean scores over 24-72 hours 2, 2.7 and 2.7), chemosis (mean scores 2, 2.7 and 3.7) and discharge. Yellow/white spots were observed in the tissue of the lower eyelid, nictitating membrane and/or sclera in all animals from day 7 until termination. These spots were described as signs of necrosis and consisted of encapsulated material of unknown origin which caused protrusions at termination of the study. Reduced elasticity of the eyelids was noted in one animal, 72 hours and 7 days after instillation (Van Huygevoort, 1999e). Based on the degree and persistence of the corneal injury, zinc sulphate is considered to cause severe ocular irritation.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Deviations:

not specified

Principles of method if other than guideline:

Not applicable

GLP compliance:

not specified

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

No information

Type of coverage:

semiocclusive

Preparation of test site:

other: clipped

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

0.5 g of the moistened test material was applied

Duration of treatment / exposure:

4 h

Observation period:

At 1, 24, 48 and 72 h after the exposure

Number of animals:

Three

Details on study design:

No further details

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

other: 1 h

Score:

ca. 0

Max. score:

8

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

24 h

Score:

ca. 0

Max. score:

8

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

48 h

Score:

ca. 0

Max. score:

8

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

72 h

Score:

ca. 0

Max. score:

8

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

ca. 0

Max. score:

4

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

ca. 0

Max. score:

4

Reversibility:

other: not applicable

Remarks on result:

no indication of irritation

Irritant / corrosive response data:

No skin irritation/corrosion were observed

Other effects:

No symptoms of systemic toxicity and no mortality occurred

None       

Interpretation of results:

GHS criteria not met

Conclusions:

No symptoms of systemic toxicity and no skin irritation/corrosion were observed and no mortality occurred.

Executive summary:

In a well-performed primary skin irritation/corrosion study, conducted according to Directive 92/69/EEC B.4 and OECD guideline 404, three male New Zealand White rabbits were exposed to 0.5 g of moistened zinc sulphate (ZnSO_4.7 H₂O), applied onto clipped skin for 4 h using a semi-occlusive dressing. Observations were made 1, 24, 48 and 72 h after exposure. No symptoms of systemic toxicity and no skin irritation/corrosion were observed and no mortality occurred.

Reference 2

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline followed

Principles of method if other than guideline:

Macroscopic skin reactions, skin histological changes and epidermal keratin binding of the test material were observed after 5 d application to rabbit skin using both open and occlusive patch methods.

GLP compliance:

not specified

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Sex: Male
- Source: Charing Cross and Westminster Medical School, London, UK
- Weight at study initiation: 2.5-4.0 kg
- Housing: Housed singly
- Diet: R14 pellets (Biosure) (zinc content 74 mg/kg, w/w)
- Water: Tap water
- Acclimation: Acclimatized to conventional restraining boxes before open patch test


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18±2
- Humidity (%): 45
- Photoperiod (h dark/h light): 12/12

Type of coverage:

other: Both open and occlusive in two different tests

Preparation of test site:

other: Clipped

Vehicle:

water

Controls:

yes, concurrent vehicle

Amount / concentration applied:

TEST SOLUTION
- Amount(s) applied (volume): 0.5 mL
- Concentration (if solution): 1 % w/v zinc sulphate solution in deionized water
- pH: 5.7

Duration of treatment / exposure:

5 d

Observation period:

Open patch test: Observed during and after 5 d exposure period
Occlusive patch test: On Day 3 and Day 5

Number of animals:

Four animals each for control and test groups in both open and occlusive patch tests

Details on study design:

Open patch test: Eight test sites (5 cm2) were designated, four on each side of the mid-dorsal line. Test solution or vehicle was applied daily for 5 successive days. The animals were restrained for 30 min to allow test sites to dry. Skin sites were observed during and after 5 d exposure period. Rabbits were killed 24 h after the fifth daily treatment.

Occlusive patch test: Animals were prepared similar to open patch test. Test solution or vehicle was applied to the skin on a sterile gauze pad that was secured by a hypoallergenic adhesive tape. The trunks of these animals were wrapped in rubberized fabric and impermeable dressing for 3 d. At this stage, dressings were removed and skin sites were evaluated for irritancy. Two rabbits were sacrificed at this stage. The remaining animals were re-dressed with freshly impregnated gauze pads and then re-examined and sacrificed after a further 2 d.

In both tests, representative samples of each test and control skin sites of sacrificed animals were preserved in 10 % phosphate buffered formalin for histology. Thin sections cut along the anterior-posterior axis were stained with haematoxylin and eosin, or with morin dye, which fluoresces blue-green in the presence of zinc ions and ultraviolet light (to demonstrate zinc binding to epidermal keratin).

SCORING SYSTEM: Not reported

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

other: 5 d

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

other: 5 d

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

other: 5 d

Reversibility:

not specified

Remarks on result:

no indication of irritation

Irritation parameter:

erythema score

Basis:

animal #4

Time point:

other: 5 d

Reversibility:

not specified

Remarks on result:

probability of weak irritation

Irritation parameter:

erythema score

Time point:

24 h

Remarks on result:

not measured/tested

Irritation parameter:

erythema score

Time point:

48 h

Remarks on result:

not measured/tested

Irritation parameter:

erythema score

Time point:

72 h

Remarks on result:

not measured/tested

Irritation parameter:

edema score

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritant / corrosive response data:

Slight irritation (lower level of erythema) was observed in one out of four animals of test group in both open and occlusive patch tests after 5 d exposure. Macroscopic observations of animals exposed for 3 d resembled those seen after 5 d in occlusive patch test. No reactions were observed in control group.

Other effects:

Histological changes: Marginal epidermal thickening with no inflammatory change in open patch test. Similar but more severe changes were observed in occlusive patch test.

Morin fluorescence for zinc on skin: No obvious reaction was observed.

None

Interpretation of results:

study cannot be used for classification

Conclusions:

Based on the above results, 1 % w/v zinc sulphate was found to be slightly irritating to rabbit skin.

Executive summary:

A study was conducted to evaluate the skin irritation potential of zinc sulphate in New Zealand White rabbits both by open and occlusive patch methods.

In open patch test, 0.5 mL of 1 % w/v zinc sulphate solution or vehicle was applied to clipped sites (5 cm2) of groups of four animals for 5 d. Skin sites were observed during and after 5 d exposure period. Animals were sacrificed 24 h after the fifth daily treatment.

In occlusive patch test, groups of four animals were treated similarly to open patch test, but the test solution or vehicle was applied to the skin using occlusive dressing for 3 d. After 3 d, dressings were removed and skin sites evaluated for irritancy. Two rabbits were sacrificed at this stage. The remaining animals were re-dressed with freshly impregnated gauzes and then re-examined and sacrificed after a further 2 d.

In both tests, representative samples of each test and control skin site of sacrificed animals were analysed histologically and stained with morin dye to study epidermal keratin binding of zinc.

Slight irritation (lower level of erythema) was observed in one out of four test animals in both open and occlusive patch test after 5 d exposure. Macroscopic observations of animals exposed for 3 d resembled those seen after 5 d in occlusive patch test. Marginal epidermal thickening with no inflammatory change was observed in open patch test upon histological examination. Similar changes were observed in occlusive patch test but tended to be more severe. No reactions were observed in control group. No morin fluorescence was observed in skin sections.

Based on the above results, 1 % w/v zinc sulphate was found to be slightly irritating to rabbit skin.

 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion)

Deviations:

not specified

Principles of method if other than guideline:

Not applicable

GLP compliance:

not specified

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

No information

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

Approximately 98.1 mg of the test material

Duration of treatment / exposure:

Single instillation into the conjuctival sac of the eye, no eye wash

Observation period (in vivo):

At 1, 24, 48 and 72 hours, 7, 14 and 21 days after exposure.

Number of animals or in vitro replicates:

Three male animals

Details on study design:

No further details

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Time point:

24 h

Score:

ca. 2

Max. score:

3

Reversibility:

not specified

Remarks on result:

probability of severe irritation

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Time point:

48 h

Score:

2.7

Max. score:

3

Reversibility:

not specified

Remarks on result:

probability of severe irritation

Irritation parameter:

conjunctivae score

Remarks:

redness

Basis:

mean

Time point:

72 h

Score:

ca. 2.7

Max. score:

3

Reversibility:

not specified

Remarks on result:

probability of severe irritation

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24 h

Score:

ca. 2

Max. score:

4

Reversibility:

not specified

Remarks on result:

probability of moderate irritation

Irritation parameter:

chemosis score

Basis:

mean

Time point:

48 h

Score:

ca. 2.7

Max. score:

4

Reversibility:

not specified

Remarks on result:

probability of severe irritation

Irritation parameter:

chemosis score

Basis:

mean

Time point:

72 h

Score:

ca. 3.7

Max. score:

4

Reversibility:

not specified

Remarks on result:

probability of severe irritation

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritant / corrosive response data:

Corneal injury was seen as slight dulling of the normal lustre (opacity grade 0) and/or epithelial damage (10% of the corneal area) in two animals. This injury had resolved within 24 hours in one animal and within 72 hours in the other animal.
Irritation of the conjuctivae was seen as redness (mean scores over 24-72 hours 2, 2.7 and 2.7), chemosis (mean scores 2, 2.7 and 3.7) and discharge.
Yellow/white spots were observed in the tissue of the lower eyelid, nictitating membrane and/or sclera in all animals from day 7 until termination. These spots were described as signs of necrosis and consisted of encapsulated material of unknown origin which caused protrusions at termination of the study.

Other effects:

Reduced elasticity of the eyelids was noted in one animal, 72 hours and 7 days after instillation.

None       

Interpretation of results:

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

Conclusions:

Based on the degree and persistence of the corneal injury, zinc sulphate is considered to cause severe ocular irritation

Executive summary:

In a well-performed eye irritation/corrosion study, conducted according to Directive 92/69/EEC B.5 and OECD guideline 405, three male New Zealand White rabbits were treated by instillation of approximately 98.1 mg of zinc sulphate (ZnSO_4.7H₂O) into the conjuctival sac of one eye. The other eye remained untreated and served as control. The eyes (unrinsed) were examined at 1, 24, 48 and 72 hours and 7, 14 and 21 days after instillation.

No symptoms of systemic toxicity were observed and no mortality occurred.

Corneal injury was seen as slight dulling of the normal lustre (opacity grade 0) and/or epithelial damage (10% of the corneal area) in two animals. This injury had resolved within 24 hours in one animal and within 72 hours in the other animal.

Irritation of the conjuctivae was seen as redness (mean scores over 24-72 hours 2, 2.7 and 2.7), chemosis (mean scores 2, 2.7 and 3.7) and discharge.

Yellow/white spots were observed in the tissue of the lower eyelid, nictitating membrane and/or sclera in all animals from day 7 until termination. These spots were described as signs of necrosis and consisted of encapsulated material of unknown origin which caused protrusions at termination of the study. Reduced elasticity of the eyelids was noted in one animal, 72 hours and 7 days after instillation.

Based on the degree and persistence of the corneal injury, zinc sulphate is considered to cause severe ocular irritation.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on animal studies, zinc sulphate is not irritating to skin but is a severe eye irritant and has been classified as a severe eye irritant, Eye Damage 1; H318 according to EC criteria.