Docosanamide

Endpoint summary

Description of key information

Weight of evidence from RA-S CAS 112-84-5 and RA-S Amides, C16-C18 (even numbered), Skin irritation: not irritating
RA-S CAS 112-84-5, Eye irritation in vivo (EU Method B.5): 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:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Reliability was changed from "1" to "2" according to the ECHA guidance document "Practical guide 6: How to report read-across and categories".

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: The Broekman Institute, Someren, The Netherlands
- Age at study initiation: 10, 13 and 17 weeks
- Weight at study initiation: 2303, 2605 and 2853 g
- Housing: Individually in a plastic cage with a perforated floor
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period: At least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-21
- Humidity (%): 50-60
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

water

Controls:

other: The right flank served as untreated control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 g
- Concentration (if solution): Moistened with 0.5 mL water

VEHICLE
- Amount(s) applied (volume or weight with unit): 0.5 mL

Duration of treatment / exposure:

4h

Observation period:

1, 24, 48 and 72h

Number of animals:

3

Details on study design:

TEST SITE
- Area of exposure: 6 cm²
- Type of wrap if used: The test substance was spread on 6 cm² patch of Metalline (Lobmann, Germany) and mounted on permeable tape (Micropore, 3M, St. Paul, USA). This was applied to the left flank of each animal, the right flank being covered with the same dressing without test substance. Finally, the animals were wrapped in flexible bandage (Coban, 3M, St. Paul, USA)

REMOVAL OF TEST SUBSTANCE
- Washing: The remaining test substance was removed, using a dry tissue and subsequently a tissue moistened with tap-water.
- Time after start of exposure: 4h

SCORING SYSTEM: Draize

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

edema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

edema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritant / corrosive response data:

The test substance caused only very slight erythema in all three animals, 60 minutes after removal of the dressings.

Other effects:

No signs of systemic intoxication were observed in any of the rabbits.

Based on these results the test substance should be considered as not-irritating to the skin. According to the criteria of Regulation (EC) No 1272/2008 the test substance does not have to be classified as irritating to the skin.

Interpretation of results:

other: CLP criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

CLP: not classified

Reference 2

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Reliability was changed from "1" to "2" according to the ECHA guidance document "Practical guide 6: How to report read-across and categories".

Qualifier:

according to guideline

Guideline:

other: EU Method B.46 (In Vitro Skin Irritation: RHE Model Test)

Deviations:

no

Principles of method if other than guideline:

EPISKIN reconstituted human epidermis model: 15 min treatment followed by 42 hours post-exposure incubation period.

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Source species:

human

Cell type:

other: reconstituted human epidermis

Cell source:

other: adult human-derived epidermal keratinocytes

Source strain:

other: not applicable

Vehicle:

unchanged (no vehicle)

Details on test system:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes
- Time after start of exposure: 15 min

SCORING SYSTEM: not applicable, measurement of cytotoxicity by colourimetric MTT reduction assay

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10 ± 2 mg

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

42 hours post-exposure incubation period

Number of replicates:

triplicate tissues

Details on test animals or test system and environmental conditions:

not applicable

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

mean of 3 runs

Value:

117.4

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Irritation / corrosion parameter:

% tissue viability

Remarks:

Negative control

Run / experiment:

mean of 3 runs

Value:

100

Negative controls validity:

not applicable

Positive controls validity:

not applicable

Irritation / corrosion parameter:

% tissue viability

Remarks:

Positive control

Run / experiment:

mean of 3 runs

Value:

7.3

Negative controls validity:

not applicable

Positive controls validity:

not applicable

Other effects / acceptance of results:

The test material was considered to be Non-Irritant (NI).

The test material did not directly reduce MTT.

Mean OD540 values and percentage viabilities for the negative control material, positive control material and test material:

Material	OD540of tissues	Mean OD540of triplicate tissues	± SD of OD540	Relative individual tissue viability (%)	Relative mean viability (%)	± SD of Relative mean viability (%)
Negative control	0.784	0.834	0.045	94.0	100*	5.4
	0.847			101.6
	0.871			104.4
Positive control	0.069	0.061	0.016	8.3	7.3	1.9
	0.071			8.5
	0.043			5.2
Test material	1.079	0.979	0.087	129.4	117.4	10.4
	0.925			110.9
	0.933			111.9

* The mean viability of the negative control tissues is set at 100%

The relative mean viability of the test material treated tissues was 117.4% after a 15 -minute exposure, the test material treated tissues appeared blue which was considered indicative of viable tissue.

The relative mean tissue viability for the positive control treated tissues was ≤ 40% relativ to the negative control, and the standard deviation value of the percentage viability was ≤ 20%. The positive control acceptance criterion was therefore satisfied.

The mean OD540 for the negative control treated tissues was ≥0.6 and the SD value of the percentage viability was ≤ 20%. The negative control acceptance criterion was therefore satisfied.

Conclusion:

The test material was considered to be Non-Irritant (NI).

Interpretation of results:

other: CLP criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

CLP: not classified

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:

migrated 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:

other: GLP guideline study. Reliability was changed from "1" to "2" according to the ECHA guidance document "Practical guide 6: How to report read-across and categories".

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: The Broekman Institute, Someren, The Netherlands
- Age at study initiation: approx. 10 weeks
- Weight at study initiation: 2.07 - 2.51 kg
- Housing: Individually in plastic cages with perforated floors.
- Diet: Standard laboratory animal diet (LK-01 and LK-04, diameter 4mm; Hope Farms, Woerden, The Netherlands), 100 g/d
- Water: tap water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-20
- Humidity (%): 50-65
- Air changes (per hr): air conditioned, not further specified
- Photoperiod (hrs dark / hrs light): 12/12

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated contralateral eye served as control

Amount / concentration applied:

60 ± 2 mg (approx. equivalent to 0.1 mL)

Duration of treatment / exposure:

Once, not washed out

Observation period (in vivo):

1, 24, 48, 72 hours and 7 days

Number of animals or in vitro replicates:

3

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): no

SCORING SYSTEM: Draize

TOOL USED TO ASSESS SCORE: pocket flash-light, 2% fluorescein in (adjusted to pH 7.0; 24 hours after instillation)

Each portion of the dispensed amount of test substance was instilled into the conjunctival sac of the left eye of each animal using a spatula. The lids were then held gently together for two seconds and released. The right eye, remaining untreated, served as a control.

Immediately after instillation of the test substance, the animals were observed and abnormalities were recorded. In addition, the eyes were examined approximately 60 minutes, 24, 48 and 72 hours and 7 days after instillation of the test substance. The examinations were performed using a pocket flash-light. Observed local (or systemic) effects other than those covered by the scoring system, were also recorded.

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritation parameter:

iris score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

other: no effects

Irritation parameter:

iris score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

other: no effects

Irritation parameter:

iris score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

other: no effects

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 7 days

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1

Max. score:

3

Reversibility:

fully reversible within: 7 days

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.67

Max. score:

3

Reversibility:

fully reversible within: 72 hours

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0.67

Max. score:

4

Reversibility:

fully reversible within: 72 hours

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 48 hours

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: no effects

Irritant / corrosive response data:

Approximately 60 minutes after exposure two animals showed diffuse conjunctival redness and slight chemosis; the other animal showed slight conjunctival redness and slight chemosis. The conjuctival redness had resolved in one animal by day 3 and in the other two animals between days 3 and 7. The chemosis resolved within 24, 48 or 72 hours for each rabbit separately. Treatment of the eyes with fluorescein 24 hours after exposure revealed no epithelial damage in any of the animals.

Other effects:

No signs of systemic intoxication were observed in any of the rabbits.

Interpretation of results:

other: CLP criteria not met, no classification required according to Regulation (EC) No 1272/2008

Conclusions:

CLP: not classified
Based on the estimated Draize score of 6 (60 minutes) the test substance should be classified as mildly irritating according to the scheme of kay and Calandra. According to the EEC criteria for classification and labelling of dangerous substances, the test substance need not be labelled as an eye irritant.

Executive summary:

Instillation of approximately 60 mg of the test substance in one of the eyes of each of three albino rabbits resulted in slight to diffuse redness of the conjuctivae and slight chemosis. The conjuctival redness had resolved in one animal by day 3 and in the other two animals between days 3 and 7. The chemosis resolved within 24, 48 or 72 hours for each rabbit separately. Based on the estimated Draize score of 6 (60 minutes) the test substance should be classified as mildly irritating according to the scheme of Kay and Calandra. According to the criteria laid down in Annex I of the Regulation (EC) No 1272/2008, the test substance need not be labelled as an eye irritant.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There is no data available on the skin and eye irritation potential of docosanamide (CAS 3061-75-4). In order to fulfil the standard information requirements set out in Annex VIII, 8.1 and 8.2, and in accordance with Annex XI, 1.5 of Regulation (EC) No 1907/2006, read-across from structurally very closely related substances is conducted.

A detailed justification for the analogue approach is provided in the technical dossier (see IUCLID sections 7.1 and 13).

Skin irritation

Reliable and GLP conform studies investigating the skin irritation potential are available for the structurally related substances (Z)-Docos-13-enamide (CAS 112-84-5, erucamide) and Amides, C16-C18 (even numbered), which are used for read-across based on the analogue approach.

The skin irritating potential of Amides, C16-C18 (even numbered) was investigated in an in vitro skin irritation test using a human skin model according to EU Method B.46 (Warren, 2010). This is a validated method that has been accepted by the authorities in the light of animal welfare for the assessment of skin irritating potential. Three replicates of intact reconstructed human epidermis (EPISKIN Model) were topically treated with the test substance for 15 minutes, followed by a 42-hour post-exposure incubation period. After exposure to the test substance, cell viability was determined compared to the control by means of the colourimetric MTT reduction assay. No adverse effects on cell viability in the human epidermal culture compared to the negative control were observed after 15 min exposure to the test substance. The positive (5% SDS) and negative (PBS) controls included showed the expected results, and thus confirmed the validity of the assay. Therefore, the structurally related substance was considered to be non-irritating to the skin in vitro under the conditions of the test.

In addition to the in vitro data, there also exists a study on the skin irritation potential of the structurally related substance (Z)-Docos-13-enamide (CAS 112-84-5) in rabbits according to OECD guideline 404 (Daamen, 1988). In this study, the undiluted test substance (0.5 g) was moistened with water and applied for 4 h to the shaved skin of 3 New Zealand White rabbits under semiocclusive conditions. The opposite flank of the animals remained untreated and served as control. The scoring of skin reactions (erythema and edema) was performed 1, 24, 48 and 72 h after removal of the dressing. The test substance caused only very slight erythema in all three animals 1 h after removal of the dressings, which were fully reversible thereafter. No further skin reactions and no signs of systemic toxicity were noted at any other reading time point in any of the treated animals. The mean erythema and edema scores after 24, 48 and 72 h were 0 for all 3 animals. Therefore, the results demonstrate that the structurally related substance (Z)-Docos-13-enamide (CAS 112 -84 -5) was not irritating to skin.

Based on the weight of evidence from all available data on skin irritation of the structural analogues, it may be concluded that docosanamide (CAS 3061-75-4) is not irritating to skin, either.

 

Eye irritation

An eye irritation study performed in compliance with Eu method B.5 and GLP is available for the structurally very closely related substance (Z)-Docos-13-enamide (CAS 112-84-5, erucamide), which is used for read-across based on the analogue approach (Bradshaw, 2010). The undiluted test material (ca. 0.1 mL) was placed into the conjunctival sac of one eye of 3 New Zealand White rabbits each. The other eye remained untreated and served as control. The eyes were examined and scored 1, 24, 48 and 72 h as well as 7 days after application. After one hour, administration of the test substance resulted in diffuse conjunctival redness and slight chemosis in two of the animals, whereas the other animal showed slight conjunctival redness and chemosis, respectively. Conjunctival redness had resolved in one animal by day 3 and in the other two animals between days 3 and 7 of the study. In all animals, chemosis was fully reversible within 3 days after test substance instillation. No iridial and corneal effects and no signs of systemic toxicity were observed in the animals at any observation time point. The mean conjunctivae and chemosis scores over all relevant observation time points ( 24, 48, and 72 h) were 1/1/0.67 and 0.67/0.33/0, respectively, for the 3 individual animals. For iris and cornea, mean scores of 0 after 24, 48 and 72 h were obtained for all 3 animals. Considering the mild character and the complete reversibility of the observed effects within 7 days, the structurally related substance erucamide was considered to be not irritating to the eyes.

Therefore, it is anticipated that docosanamide (CAS 3061-75-4) does not exert an eye irritation potential, either.

Justification for classification or non-classification

The available data on the skin and eye irritation of substances structurally related to docosanamide (CAS 3061-75-4) according to the criteria of Regulation (EC) No 1907/2006, Annex XI, 1.5, do not meet the criteria for classification according to Regulation (EC) No 1272/2008; therefore, docosanamide (CAS 3061-75-4) is not expected to exert a skin and eye irritation potential, either, and the data are conclusive but not sufficient for classification.