Disulfiram

Endpoint summary

Description of key information

Skin irritation (comparable to OECD 404): not irritating.

Eye irritation (Draize method): not irritating.

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:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

adopted in 2002

Deviations:

not specified

GLP compliance:

not specified

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Roucher SA, Couhé
- Weight at study initiation: 2.5 kg

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied: 0.5 g moistened with 0.5 ml water

Duration of treatment / exposure:

4 hours

Observation period:

at 1, 24, 48, 72 hours and at day 7 and day 14.

Number of animals:

6 animals

Details on study design:

TEST SITE
- Area of exposure: dorsal region of the trunk

SCORING SYSTEM: Draize score

Irritation parameter:

erythema score

Basis:

mean

Remarks:

for all 6 animals

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility not applicable

Remarks on result:

other: reassessed based on the provided PCI (OECD protocol) score of 0 (refer to attached publication)

Irritation parameter:

edema score

Basis:

mean

Remarks:

for all 6 animals

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility not applicable

Remarks on result:

other: reassessed based on the provided PCI (OECD protocol) score of 0 (refer to attached publication)

Irritant / corrosive response data:

Each treated area was scored for erythema and edema according to Draize (0-4). The scores obtained for erythema and edema at both of the treated sites in all animals were totalled, summed up for all animals and then divided by the total number of readings. The readings were performed according to OECD 404 after 1, 24, 48 and 72 h and the mean of all readings was calculated to provide a mean score termed the primary cutaneous irritation index (PCII). For further details, please refer to the attached publication. Since the PCII for the test substance was 0 according to the OECD protocol, erythema and edema scores were reassessed.

Interpretation of results:

GHS criteria not met

Conclusions:

The study was conducted similar to OECD guidelines. Under the conditions of the test, the test substance was a not skin irritating.

Reference 2

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

22 Jun - 29 Jun 1982

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 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

adopted in 2002

Deviations:

yes

Remarks:

observation after 48 h is missing

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Isaac’s Farm, Litchfield, Illinois
- Age at study initiation: young adult
- Weight at study initiation: 2.26-2.70 kilograms
- Housing: individually housed
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at 5 five days

Type of coverage:

occlusive

Preparation of test site:

clipped

Vehicle:

physiological saline

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 ± .003 grams
- moistened witzh physiological saline

Duration of treatment / exposure:

24 hours

Observation period:

After one hour, 24 hours, 72 hours and 7 days of exposure

Number of animals:

6 animals (3 males and 3 females)

Details on study design:

TEST SITE
- Area of exposure: dorsal surface
- Type of wrap if used: an occlusive wrap of latex rubber
- Abrasion: per animal, 4 test sides were exposed to the test substance, 2 with intact skin, 2 with abraded skin. For evaluation, only the intact skin sides were assessed.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): the excess material was wiped from the treated sites of the animals
- Time after start of exposure: 24 hours

SCORING SYSTEM: Dermal irritation was scored by the method of Draize (1944)

Irritation parameter:

edema score

Basis:

mean

Remarks:

of all 6 animnals

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility not applicable

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 3 days

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility not applicable

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 3 days

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Irritation parameter:

erythema score

Basis:

animal #4

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility: not applicable

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Irritation parameter:

erythema score

Basis:

animal #5

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility not applicable

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Irritation parameter:

erythema score

Basis:

animal #6

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 3 days

Remarks on result:

other: no 48 h data are available; for calculation of mean scores, the 48 h values were assumed to be the same as those at 24 h (worst case assumption: persistence of effects seen at 24 h over 48 h)

Interpretation of results:

GHS criteria not met

Conclusions:

The study was conducted similar to OECD guidelines and under GLP conditions. Under the conditions of the test, the test substance was not skin irritating.

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:

18 May - 25 May 1982

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 405 (Acute Eye Irritation / Corrosion)

Version / remarks:

adopted 2021

Deviations:

yes

Remarks:

Limited information on the scoring system.

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Isaac’s Farm, Litchfield, Illinois
- Age at study initiation: young adult
- Weight at study initiation: 2.16 - 2.37 kg
- Housing: one per cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days

Vehicle:

unchanged (no vehicle)

Controls:

yes, concurrent no treatment

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): A mass of 32 ± 1 mg, determined to occupy a volume of 0.1 mL of test material

Duration of treatment / exposure:

single eye instillation

Observation period (in vivo):

24, 48, 72 hours and 7 day

Number of animals or in vitro replicates:

6 animals (3 males and 3 females)

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing: No washing

SCORING SYSTEM: The method of Draize (1944)

TOOL USED TO ASSESS SCORE: fluorescein

Irritation parameter:

overall irritation score

Basis:

mean

Remarks:

of 6 animals

Time point:

24/48/72 h

Score:

4.2

Max. score:

110

Reversibility:

fully reversible within: 7 days

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

of 6 tested animals and mean of readings at

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: reversibility not applicable

Irritation parameter:

iris score

Basis:

animal #1

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

0.33

Max. score:

2

Reversibility:

fully reversible within: 48 h

Remarks on result:

other: Iris values according to current EU classification criteria

Irritation parameter:

iris score

Basis:

animal #3

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

0.33

Max. score:

2

Reversibility:

fully reversible within: 48 h

Remarks on result:

other: Iris values according to current EU classification criteria

Irritation parameter:

iris score

Basis:

mean

Remarks:

of the remaining 4 tested animals and mean of readings at

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

other: reversibility not applicable

Irritation parameter:

conjunctivae score

Basis:

animal #1

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

6.67

Max. score:

20

Reversibility:

fully reversible within: 7 days

Remarks:

the scores were 16 after 24 h, and 2 after 48 and 72 h

Remarks on result:

other: max. score as a sum of redness, chemosis and discharge

Irritation parameter:

conjunctivae score

Basis:

animal #2

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

2.66

Max. score:

20

Reversibility:

fully reversible within: 48 h

Remarks on result:

other: max. score as a sum of redness, chemosis and discharge

Irritation parameter:

conjunctivae score

Basis:

animal #3

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

4

Max. score:

20

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: max. score as a sum of redness, chemosis and discharge

Irritation parameter:

conjunctivae score

Basis:

animal #4

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

3.33

Max. score:

20

Reversibility:

fully reversible within: 72 h

Remarks on result:

other: max. score as a sum of redness, chemosis and discharge

Irritation parameter:

conjunctivae score

Basis:

animal #5

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

2.66

Max. score:

20

Reversibility:

fully reversible within: 72 h

Remarks on result:

other: max. score as a sum of redness, chemosis and discharge

Irritation parameter:

conjunctivae score

Basis:

animal #6

Remarks:

mean of readings at

Time point:

24/48/72 h

Score:

2.66

Max. score:

20

Reversibility:

fully reversible within: 72 h

Remarks on result:

other: max. score as a sum of redness, chemosis and discharge

Irritant / corrosive response data:

Only one out of 6 tested animals showed stronger irritation of conjunctivae. No data on chemosis was available as it was used for the calculation of the conjunctivae score:

Iris Values were given as total scores x 5

Conjunctivae values were given as total results from (A+B+C) x 2 with a total maximum of 20 (A = Redness, B = Chemosis and C = Discharge)

As can be seen in the table entered in "Any other information on results incl. tables", the iris score was 5 for 2 animals on observation Day 1 (corresponding to total scores of 1 for each animal). For conjunctivae, no single scores can be calculated. However, according to the scoring system of Draize in combination with the scoring system of Kay and Calandra (1962), information on classification can be gained by calculating the overall irritation score. Therefore, the scores for conjunctivae, iris and cornea for each animal at each time point are added together and the mean calculated. An overall irritation score of 4.2 on a scale of 0 to 110 is considered a mild irritant, if the overall irritation scoe is >0 at the 48 h time point.

Reference: Kay JH, Calandra JC. 1962. Interpretation of eye irritation tests. J Soc Cosmet Chem 13:281–289

Table 1: Ethyl Thiurad: Primary Eye Irritation to Rabbits - Individual Irritation Scores*

Animal #	Obs. Day	Cornea	Iris	Conjunctivae	Total	Average of 24, 48 and 72 h
1	1	0	5	16	21	8.33
	2	0	0	2	2
	3	0	0	2	2
	7	0	0	0	0
2	1	0	0	8	8	2.66
	2	0	0	0	0
	3	0	0	0	0
3	1	0	5	8	13	5.66
	2	0	0	2	2
	3	0	0	2	2
	7	0	0	0	0
4	1	0	0	8	8	3.33
	2	0	0	2	2
	3	0	0	0	0
5	1	0	0	6	6	2.66
	2	0	0	2	2
	3	0	0	0	0
6	1	0	0	6	6	2.66
	2	0	0	2	2
	3	0	0	0	0

* Scores according to Draize, J.H. et al., 1944, J. Pharmacol. Exp. Therap. 82: 377-390.

Iris Values were given as total scores x 5

Conjunctivae values were given as total results from (A+B+C) x 2 with a total maximum of 20 (A = Redness, B = Chemosis and C = Discharge)

Interpretation of results:

other: CLP/EU criteria not met

Conclusions:

The study was conducted similar to OECD guidelines and under GLP conditions. Under the conditions of the test, the test substance was a mild eye irritant.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There are reliable studies on skin irritation with the test substance disulfiram. However, since the available data have restrictions, all available information is used in a weight of evidence to assess the irritation potential of disulfiram. In a study addressing skin irritation, rabbits were exposed to undiluted disulfiram for 4 hours under occlusive conditions (Guillot et al., 1982). According to the OECD protocol, primary cutaneous irritation index of 0 was derived, thereby indicating that no local skin reactions in form of erythema and edema were observed. When disulfiram was tested similar to OECD guideline 404 and under GLP conditions on intact skin, the substance was not irritating (Report number: 82056). Data on abraded skin are not considered for hazard assessment and are therefore not further discussed here. For sake of completeness, a study record for those data is included in the technical dossier.

A primary eye irritation study was performed similar to OECD Guideline 405 to assess the irritation potential of disulfiram (Report number: 82056). The eyes of six New Zealand White rabbits were treated with the unchanged test material by single instillation. The eye reactions were recorded according to Draize scores (Draize 1944). Only one out of 6 animals showed remarkable conjunctival reactions at the 24 hour reading. All findings were fully reversible within 7 days. Thus, the test substance was found to be not irritating to the rabbit eye in vivo.

This result is further supported by a study conducted similar to FDA regulation guideline that predates GLP (Report number R5037). Under the conditions of the test, only mild irritations were found, mainly in one rabbit. The other animals showed signs of irritation (redness and chemosis), but only to a low degree. Most irritations were reversible within 48 hours and no irritations were found after 7 days. Therefore, the substance was not considered irritating.

Justification for classification or non-classification

The available data on skin and eye irritation are conclusive but not sufficient for classification according to Regulation (EC) No 1272/2008.

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