2-hydroxy-N-1H-1,2,4-triazol-3-ylbenzamide

Endpoint summary

Description of key information

Determination of Skin Irritation Potential using the EPISKIN™ Reconstructed Human Epidermis Model has been carried out (JQ20JV, Envigo Research Limited, 2018). The test item was classified as non-irritant.

In the in vitro EPIDERM™ Skin Corrosion Test ( YF40MX, Envigo Research Limited, 2018) the corrosivity potential of the test item using the EpiDerm™ Human Skin Model after treatment periods of 3 and 60 minutes was assessed. Based on the conditions of this test the test item was considered to be non-corrosive to the skin.

Eye irritation has been assesed in The Bovine Corneal Opacity and Permeability (BCOP) Assay ( RV52SQ, Envigo Research Limited, 2018). It was concluded that the test item is not requiring classification under EU CLP Regulation.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 August 2017 - 21 August 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Qualifier:

according to guideline

Guideline:

EU Method B.46 (In Vitro Skin Irritation: Reconstructed Human Epidermis Model Test)

GLP compliance:

yes (incl. QA statement)

Test system:

human skin model

Source species:

human

Cell type:

non-transformed keratinocytes

Cell source:

foreskin from a single donor

Source strain:

not specified

Details on animal used as source of test system:

Not specified

Justification for test system used:

The EPISKINTM model is a three-dimensional reconstructed human epidermis model consisting of adult human-derived epidermal keratinocytes seeded on a dermal substitute consisting of a collagen type I matrix coated with type IV collagen. A highly differentiated and stratified epidermis model is obtained after a 13-Day culture period comprising of the main basal, supra basal, spinous and granular layers and a functional stratum corneum.
Following a full validation study the EpiSkinTM reconstructed human epidermis model showed evidence of being a reliable and relevant stand-alone test for predicting rabbit skin irritation when the endpoint is measured by MTT reduction and for being used as a replacement for the Draize Skin Irritation Test for the purpose of distinguishing between Irritating and Non-Irritating test items.

Vehicle:

unchanged (no vehicle)

Details on test system:

SKIN DISC PREPARATION
- Procedure used: 2 mL of maintenance medium, warmed to approximately 37 °C, was pipetted into the first column of 3 wells of a pre-labeled 12-well plate. Each epidermis unit was transferred into the maintenance medium filled wells (3 units per plate). A different 12-well plate was used for the test item and each control item.
TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37 °C
REMOVAL OF TEST MATERIAL AND CONTROLS
At the end of the exposure period, each tissue was removed from the well using forceps and rinsed using a wash bottle containing DPBS with Ca++ and Mg++. Rinsing was achieved by filling and emptying each tissue insert for approximately 40 seconds using a constant soft stream of DPBS to gently remove any residual test item. The rinsed tissues were transferred to the second column of 3 wells containing 2 mL of maintenance medium in each well. The rinsed tissues were incubated at 37 °C, 5% CO2 in air for 42 hours.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

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

NEGATIVE CONTROL
- Amount(s) applied (volume or weight): DPBS used as supplied

POSITIVE CONTROL
- Concentration (if solution): 5% w/v aqueous solution

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

37 °C, 5% CO2 in air for 42 hours

Number of replicates:

Three

Irritation / corrosion parameter:

% tissue viability

Value:

ca. 102.5

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

- OTHER EFFECTS:
- Visible damage on test system: no
- Direct-MTT reduction:no
- Colour interference with MTT: no

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes
- Acceptance criteria met for variability between replicate measurements: yes

Interpretation of results:

GHS criteria not met

Conclusions:

The test item was classified as non-irritant. The following classification criteria apply:
EU CLP Not classified for Irritation.
UN GHS Not classified for Irritation (category 3 can not be determined).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

21 September 2017 - 21 September 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

Qualifier:

according to guideline

Guideline:

EU method B.47 (Bovine corneal opacity and permeability test method for identifying ocular corrosives and severe irritants)

GLP compliance:

yes (incl. QA statement)

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
Eyes from adult cattle (typically 12 to 60 months old) were obtained from a local abattoir as a by-product from freshly slaughtered animals. The eyes were excised by an abattoir employee after slaughter, and were placed in Hanks’ Balanced Salt Solution (HBSS) supplemented with antibiotics (penicillin at 100 IU/mL and streptomycin at 100 μg/mL). They were transported to the test facility over ice packs on the same day of slaughter. The corneas were prepared immediately on arrival.

Vehicle:

other: sodium chloride 0.9% w/v

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Concentration (if solution): 20% w/v in sodium chloride 0.9% w/v
VEHICLE
- Concentration (if solution): sodium chloride 0.9% w/v

Duration of treatment / exposure:

240 minutes

Duration of post- treatment incubation (in vitro):

not specified

Number of animals or in vitro replicates:

Three corneas were randomly allocated to the negative control. Three corneas were also allocated to the test item and three corneas to the positive control item.

Details on study design:

All eyes were macroscopically examined before and after dissection. Only corneas free of damage were used.
The cornea from each selected eye was removed leaving a 2 to 3 mm rim of sclera to facilitate handling. The iris and lens were peeled away from the cornea. The isolated corneas were immersed in a dish containing HBSS until they were mounted in Bovine Corneal Opacity and Permeability (BCOP) holders. The anterior and posterior chambers of each BCOP holder were filled with complete Eagle’s Minimum Essential Medium (EMEM) without phenol red and plugged. The holders were incubated at 32 ± 1 ºC for 95 minutes. At the end of the incubation period each cornea was examined for defects. Only corneas free of damage were used.
The medium from both chambers of each holder was replaced with fresh complete EMEM. A pre-treatment opacity reading was taken for each cornea using a calibrated opacitometer. The average opacity for all corneas was calculated. Three corneas were randomly allocated to the negative control. Three corneas were also allocated to the test item and three corneas to the positive control item.
The EMEM was removed from the anterior chamber of the BCOP holder and 0.75 mL of the test item preparation or control items were applied to the appropriate corneas. The holders were gently tilted back and forth to ensure a uniform application of the item over the entire cornea. Each holder was incubated, anterior chamber uppermost, at 32 ± 1 ºC for 240 minutes.
At the end of the exposure period the test item and control items were removed from the anterior chamber and the cornea was rinsed three times with fresh complete EMEM containing phenol red before a final rinse with complete EMEM without phenol red. The anterior chamber was refilled with fresh complete EMEM without phenol red. A post-treatment opacity reading was taken and each cornea was visually observed.
Following the opacity measurement the permeability of the corneas to sodium fluorescein was evaluated. The medium from the anterior chamber was removed and replaced with 1 mL of sodium fluorescein solution (5 mg/mL). The dosing holes were plugged and the holders incubated, anterior chamber uppermost, at 32 ± 1 ºC for 90 minutes.
After incubation the medium in the posterior chamber of each holder was decanted and retained.
360 μL of media representing each cornea was dispensed into the appropriate wells of a pre-labeled 96-well plate. The optical density was measured (quantitative viability analysis) at 492 nm (without a reference filter) using the Labtech LT-4500 microplate reader.
The change in opacity for each cornea (including the negative control) was calculated by subtracting the initial opacity reading from the final opacity reading. These values were then corrected by subtracting the average change in opacity observed for the negative control corneas. The mean opacity value of each treatment group was then calculated by averaging the corrected opacity values of each cornea for that treatment group.
The corrected OD492 was calculated by subtracting the mean OD492 of the negative control corneas from the OD492 value of each treated cornea. The OD492 value of each treatment group was calculated by averaging the corrected OD492 values of the treated corneas for the treatment group.
The following formula was used to determine the In Vitro Irritancy Score: In Vitro Irritancy Score = mean opacity value + (15 x mean permeability OD492 value)
Additionally, the opacity and permeability values were evaluated independently to determine whether the test item induced a response through only one of the two endpoints.

Irritation parameter:

in vitro irritation score

Value:

ca. 0.6

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

OTHER EFFECTS:
- Visible damage on test system: none observed

DEMONSTRATION OF TECHNICAL PROFICIENCY: The positive control In Vitro Irritancy Score was within the range of 65.1 to 123.3. The positive control acceptance criterion was therefore satisfied.
The negative control gave opacity of ≤2.4 and permeability ≤0.072. The negative control acceptance criteria were therefore satisfied.

ACCEPTANCE OF RESULTS:
- Acceptance criteria met for negative control: yes
- Acceptance criteria met for positive control: yes

Interpretation of results:

GHS criteria not met

Conclusions:

No category. Not requiring classification to UN GHS or EU CLP.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available