2-ethylhexyl nitrate

Endpoint summary

Description of key information

Skin irritation / corrosion: not irritating upon one contact, but a repeat-dose DNEL can be set from the data of the 3-week dermal study in rabbits. For this purpose, a repeat-dose local NOAEC was derived as 0.22 mg/cm2/day.

Eye irritation: not irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 10 November 1987 to 14 January 1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: compliant to GLP and testing guideline; adequate coherence between data, comments and conclusions

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: Abbaye de Bellefontaine (France)
- Age at study initiation: not indicated
- Weight at study initiation: mean body weight of 2.5 +/- 0.1 kg
- Housing: polystyrene cages
- Diet (e.g. ad libitum): pelleted diet
- Water (e.g. ad libitum): drinking water filtered by a membrane (0.22 microns)
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20°C +/- 3°C
- Humidity (%): 50% +/- 20%
- Photoperiod (hrs dark / hrs light): 12h/12h

IN-LIFE DATES: From 10 November 1987 to 16 November 1987

Type of coverage:

semiocclusive

Preparation of test site:

other: clipped

Vehicle:

unchanged (no vehicle)

Controls:

other: the left flank was not treated and served as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 mL on the right flank of each animal

VEHICLE
Test substance applied as it.

Duration of treatment / exposure:

4 hours

Observation period:

7 days

Number of animals:

6 animals

Details on study design:

TEST SITE
- Area of exposure: 6 cm2
- Type of wrap if used: gauze pad held in contact with the skin by means of an adhesive hypoallergenic aerated semi-occlusive dressing

SCORING SYSTEM:
Draize scale

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

erythema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

erythema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.33

Max. score:

1

Reversibility:

fully reversible within: 6 days

Irritation parameter:

erythema score

Basis:

animal #4

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

erythema score

Basis:

animal #5

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

erythema score

Basis:

animal #6

Time point:

24/48/72 h

Score:

0.66

Max. score:

1

Reversibility:

fully reversible within: 7 days

Irritation parameter:

edema score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

animal #4

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

animal #5

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritation parameter:

edema score

Basis:

animal #6

Time point:

24/48/72 h

Score:

0

Max. score:

0

Irritant / corrosive response data:

No cutaneous reactions were observed 1 hour and 24 hours after patch removal.
Very slightly erythema was noted in one male (number 6) at 48 hours, and in two animals (number 3 and 6) at 72 and 96 hours.
On days 6, only animal number 6 showed very slightly erythema. No cutaneous reactions were noted in any animals.
No oedema was observed in any animals during the study.

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In the experimental conditions of the study, the test item was considered to be not irritating to the skin.

Executive summary:

In the experimental conditions of the study, the test item was considered to be not irritating to the skin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: compliant to GLP and testing guideline; adequate coherence between data, comments and conclusions

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 437 Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants

Deviations:

not applicable

GLP compliance:

yes (incl. QA statement)

Species:

other: isolated calf cornea

Strain:

other: bovine calf

Details on test animals or tissues and environmental conditions:

Origin: calf eyes were obtained from freshly slaughtered calves at the abattoir SOCAVIA, Cany Barville, France.

Reason for choice: calf corneas are adapted for the evaluation of potential ocular irritants since they are part of the target organ.

Transport from supplier to CIT: the eyes were transported to CIT at ambient temperature, immerged in buffered Hanks medium containing antibiotics (Hank’s Balanced Salts Solution (HBSS) plus penicillin/streptomycin). For the transport, a container with smooth internal surfaces was used to avoid damage to the corneas.

Preparation of the corneas: The corneas were prepared as quickly as possible after receipt. Each step was carried out avoiding to touch the corneas in order to not injure them.

Selection: upon arrival at CIT, all eyes were carefully examined macroscopically for defects (opacity, scratches, pigmentation, etc) and those exhibiting any defect were discarded. The too large eyes were also discarded in order to avoid the formation of folds at the assembly of corneas in the holder. The examination was performed under a lamp and using HBSS in order to maintain the corneas moistened and shiny. Each cornea was observed with attention, while making swivel the eye in order to see any less refringent areas under the light or any scratches.

Preparation of the selected corneas: the tissue surrounding the eyeball was carefully pulled away and the cornea was dissected such that approximately 2 to 3 mm of sclera was present around the cornea. The isolated corneas were stored in HBSS until all corneas were dissected.
As the corneas were not used extemporaneously for a treatment, they were washed three times of 15 minutes each in HBSS plus penicillin/streptomycin (100 units/100 µg/mL final) at room temperature, then stored individually in 12 mL of M199 medium containing 5% dextran, plus penicillin/streptomycin, at +4°C for 24 hours maximum before use.

Vehicle:

unchanged (no vehicle)

Controls:

other: not applicable

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): a volume of 750 µL ± 8 µL was gently applied to the cornea, as uniformly as possible

Duration of treatment / exposure:

30 minutes and 4 hours

Observation period (in vivo):

Not applicable

Number of animals or in vitro replicates:

Three corneas were used for each treated series (test item, positive control and negative control).

Details on study design:

REMOVAL OF TEST SUBSTANCE
- Washing (if done): At the completion of the treatment period, the test item (or positive control or negative control) was removed from the front opening of the anterior part of the holder and the epithelium was washed. As the dosage form was liquid, the anterior compartment of the holder was emptied using a metal gavage tube attached to a vacuum pump, then the compartment was filled with heated cMEM (32°C). The rinsing was repeated three times.

TOOL USED TO ASSESS SCORE: opacitometer, fluorescein and spectrophotomter.

Irritation parameter:

in vitro irritation score

Value:

3

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Other effects:

No notable opaque spots or irregularities were observed on negative control corneas, either following the 30-minute treatment or following the 4 hour treatment.
No notable opaque spots or irregularities were observed on test item-treated corneas, following the 30-minute treatment while fluoresceine fixation was noted on corneas, following the 4 hour treatment.

For each experiment, the acceptancecriteria were fulfilled:

.           the individual corneal opacity values of negative controls were < 10 in both experiments,

.           the individual OD_{490 nm}values of negative control corneas were < 0.100 in both experiments,

.           the solution of fluoresceine (at 5 mg/mL in DPBS) diluted 1:1000 in cMEM had OD_{490 nm} values between 0.850 and 0.940 inb oth experiments,

.           following the 30-minute treatment, the positive control mean in vitro scores was 124.1, thus demonstrating the sensitivity of the test system under the experimental conditions of this study.

Interpretation of results:

slightly irritating

Remarks:

Migrated information Criteria used for interpretation of results: other: scoring table showed above (see section "any other information on materials and methods")

Conclusions:

Under the experimental conditions of this study, according to both mean in vitro scores of the 30 minute and 4-hour treatments, the test item 2-Ethylhexyl nitrate tested in its original form is classified as slightly irritant for the isolated calf cornea.

Executive summary:

Method

The corneas were obtained from the eyes of freshly slaughtered calves at the abattoir. They were mounted in the corneal holders with the endothelial side against the O-ring of the posterior half of the holder. Both compartments of the corneal holder were filled in excess with Minimal Essential Medium Eagle completed with 1% fetal calf serum plus penicillin/streptomycin (cMEM), then the holders were preincubated for 1 hour at 32°C.

 

Three corneas were used for each treated series (test item, positive control and negative control).

Before the treatment, a first opacity measurement was performed using an opacitometer (determining the light transmission through the center of each mounted cornea).

For the treatment, the test item was used undiluted.

The test item was tested sequentially in two consecutive experiments.

As the mean in vitro score at the 30-minute treatment was ≤ 10, the second experiment was undertaken using a 4-hour treatment.

 

At the completion of the treatment period, the test item was removed from the front opening of the anterior part of the holder and the epithelium was washed.

Following the 30-minute treatment, the corneas were incubated for 2 hours at 32°C. At the completion of the 2-hour incubation period, the second opacity measurement was performed.

Following the 4-hour treatment, the second opacity measurement was performed immediately without any further incubation after the rinsing of the dosage form.

After the second opacity measurement, the medium was removed from both compartments of each holder. The posterior compartment was refilled with cMEM at, while the anterior compartment received 1 mL of a 5 mg/mL fluoresceine solution in Dulbecco's Phosphate-Buffered Saline (DPBS). Then, the holders were incubated vertically for 90 minutes at 32°C.

 

At the end of the 90-minute incubation, the optical density of the solution from the posterior compartment of the holder was measured at 490 nm in order to determine the permeability of the cornea. Then the cornea was removed from the holder and observed for opaque spots and other irregularities.

Results

For each experiment, the acceptance criteria were fulfilled and the study was therefore considered to be valid.

 

No notable opaque spots or irregularities were observed on negative control corneas, either following the 30-minute treatment or following the 4‑hour treatment. 

No notable opaque spots or irregularities were observed on test item-treated corneas, following the 30-minute treatment while fluoresceine fixation was noted on corneas, following the 4‑hour treatment.

 

Following the 30-minute treatment, the mean in vitro score was 3.0. Then following the 4‑hour treatment, the mean in vitro score was 6.2.

 

Conclusion

Under the experimental conditions of this study, according to both mean in vitro scores of the 30‑minute and 4-hour treatments, the test item 2-Ethylhexyl nitrate tested in its original form is classified as slightly irritant for the isolated calf cornea.

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 11 March 2010 to 16 Sept 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: compliant to GLP and testing guideline; adequate coherence between data, comments and conclusions

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Grimaud Frères Sélection S.A.S., La Corbière, Roussay, France.
- Age at study initiation: about 4 months old
- Weight at study initiation: mean body weight ± standard deviation of 3.321 ± 0.313 kg
- Housing: Pajon cages
- Diet (e.g. ad libitum): free access to 110 pelleted diet
- Water (e.g. ad libitum): water filtered by a FG Millipore membrane (0.22 micron)
- Acclimation period: at least 5 days before the beginning of the study

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 ± 3°C
- Humidity (%): 50 ± 20%,
- Air changes (per hr): 12 cycles/hour
- Photoperiod (hrs dark / hrs light): 12h/12h

IN-LIFE DATES: From 27 April 2010 To 03 May 2010

Vehicle:

unchanged (no vehicle)

Controls:

other: right eye, which remained untreated, served as control

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.1 mL on left eye

Duration of treatment / exposure:

For about one second by helding the lower and upper eyelids together

Observation period (in vivo):

4 days

Number of animals or in vitro replicates:

3 males

Details on study design:

SCORING SYSTEM: see the following scale (any other information on materials and methods incl. tables)

TOOL USED TO ASSESS SCORE: UV lamp, 0.5% sodium fluorescein

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

iris score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

iris score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

iris score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

0

Reversibility:

other: not applicable

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

1

Reversibility:

fully reversible within: 1 day

Remarks on result:

other: max score a 1 h

Irritation parameter:

chemosis score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

1

Reversibility:

fully reversible within: 1 day

Remarks on result:

other: max score a 1 h

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

1

Reversibility:

fully reversible within: 1 day

Remarks on result:

other: max score a 1 h

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

1

Reversibility:

fully reversible within: 1 day

Remarks on result:

other: max score a 1 h

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.3

Max. score:

2

Reversibility:

fully reversible within: 2 days

Remarks on result:

other: max score a 1 h

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.3

Max. score:

1

Reversibility:

fully reversible within: 2 days

Irritant / corrosive response data:

A slight chemosis (grade 1) was noted in all animals on day 1. A slight or moderate redness of the conjunctiva (grade 1 or 2) was observed in all animals on day 1; persisting until day 2 in two of them. A clear discharge was recorded on day 2 in 1/3 animals.

Interpretation of results:

slightly irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the experimental conditions of the study, the test item 2-Ethylhexyl nitrate was slightly irritant when administered by ocular route to rabbits.

Executive summary:

Methods

The test item was first administered to a single male New Zealand White rabbit. Since the test item was not severely irritant on this first animal, it was then evaluated simultaneously in two other animals.

A single dose of 0.1 mL of the undiluted test item was instilled into the left conjunctival sac. The right eye was not treated and served as control.

The eyes were not rinsed after administration of the test item.

 

Ocular reactions were observed approximately 1 hour, 24, 48 and 72 hours after the administration.

The mean values of the scores for chemosis, redness of the conjunctiva, iris lesions and corneal opacity were calculated for each animal.

The interpretation of results was carried out according to the classification criteria laid down in Council Directive 67/548/EEC (and subsequent adaptations).

 

Results

A slight chemosis was noted in all animals on day 1. Slight or moderate redness of the conjunctiva was observed in all animals on day 1; persisting until day 2 in two of them. A clear discharge was recorded on day 2 in 1/3 animals.

Mean scores calculated for each animal over 24, 48 and 72 hours were 0.0, 0.0 and 0.0 for chemosis, 0.0, 0.3 and 0.3 for redness of the conjunctiva, 0.0, 0.0 and 0.0 for iris lesions and 0.0, 0.0 and 0.0 for corneal opacity.

 

Conclusion

Under the experimental conditions of the study, the test item 2-Ethylhexyl nitrate was slightly irritant when administered by ocular route to rabbits.

However, according to the classification criteria laid down in Council Directive 67/548/EEC (and subsequent adaptations), the test item should not be classified as irritating to the eyes.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

SKIN

The following concentration-response data are available for single application in rabbits:

- study N° EB3413: highly irritant at an excessive concentration (vs recommendation) of 0.5 mL over 2.5 cm2 skin (too small surface) over 4h = 192 mg/cm2;

- study N° 3552 TAL: non irritant at the recommended level of 0.5 mL over 6 cm2 skin over 4h = 0.962 * 0.5 / 6 g/cm2 = 80 mg/cm2; a minimal erythema started at 48 or 72h and lasted for <1 week;

- study N° 80-2189A, on day 1: non-irritant (at most: one grade 2 edema out of 3 animals, no other reaction) at 7.7 mg/cm2 (high-dose), applied over 6h to non-abraded animals.

These data show that single application leads to concentration-dependent results. The relevant conclusion is that of the test performed at the recommended concentration. The importance and persistence of reactions in the first (excessive concentration) study may also suggest an impact of impurities.

The substance induced delayed atypical skin reactions (there is no classification for such properties) as suggested by the standard assay above, and largely confirmed by marked irritation and skin cracking after repeated applications to rabbits (the same animals showed no relevant effect within the first three applications). As indicated in the sensitisation section (7.4), this was not attributable to sensitisation in the absence of histological signs of immunological reaction in Magnusson and Kligman assays. It seems possible that this effect partly corresponds to vasodilation (2-ethylhexyl nitrate being an organic nitrate so possibly a nitric oxide donor). However, skin cracking was also observed in the repeated application study in rabbits, and could also suggest interaction with skin lipids due to the very high log Kow value. Last, an impact of impurities could be suspected: the IUCLID4 file (see attached file) of the synthesis precursor 2EH, which may be present as an impurity in some studies (no data), is attached and shows that this substance is clearly a skin irritant.

EYES

Minimally irritant (this is the minimal possible conclusion grade) in vitro (BCOP). Non irritant in vivo in rabbits.

It is noteworthy that the IUCLID4 file of the synthesis precursor 2EH (see attached file), which may be present as an impurity in some studies (no data), shows that this substance induces some eye irritation but apparently not of a level requiring classification.

RESPIRATORY TRACT

No data. Based on absence of irritation for skin and eyes, no irritation to respiratory tract is expected.

Justification for classification or non-classification

Non irritant to skin and eyes based on standard single-application studies in rabbits.

NB: for the skin, this conclusion is only valid for a sufficiently pure substance due to a possible impact of impurities (e.g. 2EH).

EUH 066 and R66 are applicable due to skin cracking and dryness after repeated dermal exposure.

No conclusion for respiratory tract.