2H-Azepin-2-one, hexahydro-, polymer with 1,6-diisocyanatohexane

Endpoint summary

Description of key information

The test item is of low oral and inhalative acute toxicity with an oral LD50 (rat) of > 1800 mg/kg bw (NOTOX, 2002 and Bayer; 2008) and an inhalative LC50 (rat, aerosol, 4 hrs) of > 3069 mg/m3 (BHC, 2012).

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2002-11-12 to 2002-11-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Version / remarks:

(1996)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.1 tris (Acute Oral Toxicity - Acute Toxic Class Method)

Version / remarks:

(1996)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

(1996)

Deviations:

no

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS: 
- Source: WISTAR strain Crl: (EI) BR , Charles River Deutschland, Sulzfeld
- young adult animals
- Fasting period before study: maximum 20 hours
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 5 days
- Temperature (°C): 21 °C +/- 3° C
- Humidity (%): 30 % - 70 %
- Air changes (per hr): 15 times
- Illumination: 12 hours artifical fluorescent light and 12 hours dark

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

ADMINISTRATION: 
- Frequency: single dosage on day 1
- Dose: 2000 mg/kg/bw (1.83 ml/kg), undiluted
- Dose volume was calculated as dose level: density

Doses:

2000 mg/kg, correlating to 1800 mg/kg (based on active ingredient of test substance)

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: periodic intervals on the dayof dosing (day 1) and once daily thereafter, until day 15
- Body weight: days 1 (pre-administration) 8 and 15
- Necropsy: All survived animals were necropsied at the end of the observation period

Statistics:

not required

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 1 800 mg/kg bw

Based on:

act. ingr.

Remarks on result:

other: 90 % substance in solvent

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortalitiy occurred

Clinical signs:

other: Hunched posture, lethargy, rales, red or brown staining of the skin, salivation, chromodacryorrhoea and ptosis were noted among the animals between days 1 and 4. Alopecia was observed in 3 females between days 11 and 15 and in one male between days 5 and

Gross pathology:

No abnormalities were found at macroscopic post mortem examination of the animals.

Other findings:

no other findings

no other information

Interpretation of results:

other: as test item a 90 % solution in solvent naphtha was used; the induced effects might be interpreted as solvent driven

Conclusions:

The oral LD50 value of 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane in female and male Wistar rats was established to exceed 2000 mg/kg bw for the test substance (> 1800 mg/kg based on active ingredient). No mortalities were observed. Therefore, under the conditions of this study the acute toxicity of 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane after oral exposure in rats is low.

Executive summary:

The study for assessment of acute oral toxicity with 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane in rats was carried out according to OECD Guideline 423. The test item was administered by oral gavage to three Wistar rats of each sex at 2000 mg/kg bw (1800 mg/kg based on active ingredient). Animals were subjected to daily observations and weekly determination of body weight. Macroscopic examination was performed after terminal sacrifice (day 15). No mortality occurred. Hunched posture, lethargy, rales, red or brown staining of the skin, salivation, chromodacryorrhoea and ptosis were noted among the animals between days 1 and 4. Alopecia was observed in 3 females between days 11 and 15 and in one male between days 5 and 15. As test item a 90% solution in solvent naphta was used. The induced effects could be interpreted as solvent driven. The body weight gain shown by the animals over the study period was considered to be normal. No abnormalities were found at macroscopic post mortem examination of the animals.

Therefore the oral LD50 value of 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane in Wistar rats was established to exceed 2000 mg/kg bw (> 1800 mg/kg based on active ingredient).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

1 800 mg/kg bw

Quality of whole database:

The study is valid without restriction (Klimisch score 1).

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-06-27 to 2012-07-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

2009

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS: 
- Strain: WISTAR HsdCpd:WU
- Source: Harlan-Nederland
- Age: young adult
- Weight at study initiation: males: 170.0 - 200.0 g, females: 166.0 - 183.0 g
- Number of animals: 13 males and 13 females
- Housing: singly in Makrolon Type III cages
- Diet: ad libitum, ssniff R/M-H
- Water: ad libitum, tap water
- Acclimatisation period: at least 5 days, during this period, rats were also acclimatized to the restraining tubes
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C +/- 3 °C
- Humidity (%): 40 - 60 %
- Photoperiod (hrs dark / hrs light): 12 hours darkness, 12 hours artifical light
- Ventilation: approx. 10 air changes per hour

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: ethyl acetate and dry compressed air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Type of exposure: nose-only, using a dynamic inhalation apparatus, comparable with a directed-flow exposure
- Method of holding animals in test chamber: separately in Plexiglas exposure restrainers
- Source of air: dry compressed filtered air
- Method of conditioning air: manometer and air-flow meter (TSI Mass Flow-meter 4040), flow rates were monitored continuously by flow meters
and if necessary readjusted
- Type or preparation of particles: Portions of the solid test article were scrapped-off from the resin and were dissolved in ethyl acetate at a targeted concentration of 20 %(w/v). Stability was verified over 7 days. Nebulization of the resin was attempted up to 80°C (decomposition temperature
100°C). Despite these effects, the test article remained in a physical state of high viscosity with glue-like properties. The last resource was to
aerosolize the test article in ethyl acetate at relative low concentration (20%) and low nozzle accordingly.
Under dynamic conditions the test substance is atomized into the baffle (pre-separator) of the inhalation chamber. For atomization a binary
Schlick-type nozzle and conditioned compressed air (15 Llmin) was used. The representative dispersion pressure was in the range of 600 kPa. The nozzle was maintained at 10°C by a water jacket connected to a digitally controlled water bath. The test article was injected into the nozzle system
using a digitally controlled pump (Harvard PHD 2000 infusion pump). In the control group conditioned dry air only was used. The same
aerosolization principles were used in the vehicle and test article groups. The atomization temperature and concentration of the test article in the
vehicle was optimized to attain stable and highly respirable aerosol concentrations at the expense of a high concentration of vehicle.
- Analysis of the aerosol concentration: The actual aerosol concentration in the inhalation chamber was measured gravimetrically with an air sample
filter (Minisart SM 17598 0.45 µm) and pump (Vacuubrand, MZ 2C ) controlled by a rotameter. Dust samples were taken once every hour during the exposure
- Method of particle size distribution: The particle-size distribution was analyzed using a BERNER critical orifice cascade impactor. Each impactor
stage was covered by an aluminum foil and an additional glass fiber filter to prevent liquid run-off from the filter. Gravimetric analyses of filters
used a digital balance. Prior to gravimetric analysis the filter was dried for 30 min @70°C. Due to the glue-like properties, no additional coating
agent was used to minimize bouncing and re-entrainment of aerosol. The samples for the analysis of the particle-size distribution were taken in the
vicinity of the breathing zone. During each exposure two samples were taken, which was the maximum feasible due to the analytical samples taken.
- Temperature, humidity: T: 21.8 - 22.5 °C, H:
TEST ATMOSPHERE
- Concentrations: 3069 mg/m³ 
Air flow entrance (L/min): 15
Air flow exit (L/min): 12.8
Air change (changes per hour): 237
- Analytical method used: The nominal concentration was calculated from the ratio of the quantity of the atomized liquid and the total throughput of air through the inhalation chamber.The test-substance concentration was determined by gravimetric analysis (filter: glass-fiber filter, Sartorius,
Gottingen, Germany; digital balance). This method was used to define the actual concentration.
- Samples taken from breathing zone: Chamber samples were taken in the vicinity of the breathing zone
- MMAD (Mass median aerodynamic diameter): 2.7 µm
- GSD (Geometric st. dev.): 2.6

VEHICLE
- Composition of vehicle: etyl acetate purum, an atomization without the carrier ethyl acetate at an already mildly toxic concentration
(3069 mg/m3 ) was technically not feasible

CONTROL ANIMALS
- 5m/5f: conditioned air
- 5m/5f: vehicle ethyl acetate

Analytical verification of test atmosphere concentrations:

yes

Remarks:

The nominal concentration was calculated from the ratio of the quantity of the atomized liquid and the total throughput of air through the inhalation chamber.

Duration of exposure:

4 h

Concentrations:

Gravimetric concentration of 3069 mg test item/m3
The respirability of the aerosol was adequate to achieve the objective of study, i.e. the average mass median aerodynamic diameter (MMAD) was
2.7 µm, the average geometric standard deviation (GSD) was 2.6.

No. of animals per sex per dose:

3

Control animals:

yes

Details on study design:

EXAMINATIONS: 
- Post dose observation period: 14 days
- body weights: before exposure, on days 1, 3,  7 and 14 after treatment   
- mortality: time of death is recorded as precisely as possible
- clinical signs: several times on the day of exposure and at least once daily thereafter, no specific assessment was performed during exposure while animals were restrained, only if unequivocal signs occurred e.g. spasms, abnormal movements, and severe respiratory signs.
Following exposure, observations are made and recorded systematically; individual records are maintained for each animal. Cage-side
observations included, but were not limited to, changes in the skin and fur, eyes, mucus membranes, respiratory, circulatory, autonomic and
central nervous system, and somatomotor activity and behavior pattern. Particular attention was directed to observation of tremors, convulsions,
salivation, diarrhea, lethargy, somnolence and prostration.
The following reflexes were tested: visual placing response and grip strength on wire mesh, abdominal muscle tone, corneal and pupillary reflexes, pinnal reflex, righting reflex, tail-pinch response, startle reflex with respect to behavioral changes stimulated by sounds (finger snapping) and
touch (back).
- rectal temperatures: were measured shortly after cessation of exposure (approximately within 1/2 hour after the end of exposure) using a digital thermometer with a rectal probe for rats.
- Necropsy: All rats, irrespective of the day of death, were given a gross-pathological examination, with particular reference to changes related to
the respiratory tract.

Statistics:

Data of body weights and rectal temperature measurements are statistically evaluated using the ANOVA procedure.

Preliminary study:

The maximum technically attainable concentration is 3069 mg test item/m3.

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 3 069 mg/m³ air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: maximum technically achievable concentration

Mortality:

No animal died prematurely.

Clinical signs:

other: Group 1-males & females: No specific signs observed. Group 2-males: Bradypnea, labored breathing patterns, piloerection. Group 2-females: Bradypnea labored breathing patterns, piloerection, motility reduced, atony Group 3-males: Bradypnea, labored breathi

Body weight:

Comparisons between the vehicle control and the test article exposure group did not reveal significant differences of body weight gains.

Gross pathology:

There were no observable findings at the end of the study. The macroscopic findings of extrapulmonary organs were essentially indistinguishable
amongst the groups.

Other findings:

A battery of reflex measurements was made on the first post-exposure day, differences between groups 1 to 3 were not observed.

Conclusions:

In summary, the aerosolized test substance 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane proved to have a low acute inhalation toxicity to rats. Due to the similarity of the vehicle and test article group, it seems that the glue-like resin aerosol may have acted as carrier for the liquid vehicle which aggravated the response observed. An atomization without the carrier ethyl acetate at an already mildly toxic concentration (3069 mg/m3) was
technically not feasible.
LC50inhalation (liquid aerosol, 4 h): LC50 males & females: >3069 mg/m3
NO(A)EL: males & females: <3069 mg/m3 air 

Executive summary:

The aim of the present experiment was to obtain information on the acute toxicity and LC50, following a single 4-hour inhalation exposure in an acute inhalation study in WISTAR rats.

A study on the acute inhalation toxicity of 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane on rats has been conducted in accordance with OECD TG 403 (2009). Test procedures were adapted so as to comply also with the EU Directive 92/69/EEC, and especially OECD GD 39 (2009). One group of rats was nose-only exposed to a concentration of 3069 mg/m3 (maximum technically achievable concentration). The aerosol was generated using the vehicle ethyl acetate. Test article exposed rats were compared to a historical air control group and a concurrent vehicle control group. The results can be summarized as follows:

LC50inhalation (liquid aerosol, 4 h): LC50 males & females: >3069 mg/m3 air

NO(A)EL: males & females: < 3069 mg/m3 air 

Mortality did not occur up to the maximum technically attainable concentration of 3069 mg/m3.  The clinical signs observed in the vehicle control (bradypnea, labored breathing patterns, piloerection, motility reduced, atony) and in the test article group (bradypnea, labored breathing patterns, piloerection, motility reduced, atony, gait high-legged, muzzle area: red encrustations, hair-coat: clotted and depilated areas) were somewhat similar but differed markedly in their duration (up to the first postexposure day in the vehicle group and first postexposure week in the test article group. The changes in body weights and rectal temperature (hypothermia) were essentially indistinguishable between these groups. The hair-coat with clotted and depilated areas was clearly related to the glue-like physical properties of the test article.

The respirability of the aerosol was adequate to achieve the objective of study, i.e. the average mass median aerodynamic diameter (MMAD) was 2.7 µm, the average geometric standard deviation (GSD) was 2.6.

 

In summary, the aerosolized test substance proved to have a low acute inhalation toxicity to rats. Due to the similarity of the vehicle and test article group, it seems that the glue-like resin aerosol may have acted as carrier for the liquid vehicle which aggravated the response observed. An atomization without the carrier ethyl acetate at an already mildly toxic concentration (3069 mg/m3) was technically not feasible.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

3 069 mg/m³ air

Quality of whole database:

The study is valid without restriction (Klimisch score 1).

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

other justification

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane was of low oral acute toxicity when tested up to the limit dose of 2000 mg/kg bw. Since commercial products with 90% and 72% active ingredient in solvent were tested the oral LD50 (rat) was actually > 1800 mg/kg bw and 1440 mg/kg bw, respectively (NOTOX, 2002 and Bayer, 2008). For acute inhalation toxicity a LC50 (rat, aerosol, 4 hrs) of > 3069 mg/m3 (maximum technically achievable concentration; BHC, 2012) was found.

Justification for selection of acute toxicity – oral endpoint
The study with the highest test concentration (90% test item in solvent) is selected.

Justification for selection of acute toxicity – inhalation endpoint
Only one study available.

Justification for selection of acute toxicity – dermal endpoint
According to REACH Annex VIII (Column 2 of section 8.5.3) acute dermal study is not needed, because inhalation is considered to be the relevant route of exposure during production / use of the substance.

Justification for classification or non-classification

Based on the available studies no classification on acute oral toxicity according to Regulation (EC) No 1272/2008, Annex I is concluded. Although the maximum oral dose of the substance tested was 1800 mg/kg (commercial product with 90 % content of the active ingredient) and thus below the limit for non-classification of 2000 mg/kg, it can be assumed that the LD50 for 2H-Azepin-2-one, hexahydro-, polymer with 1,6 diisocyanatohexane is higher than 2000 mg/kg bw, as only slightly effects were observed which could be interpreted as solvent driven. Furthermore, based on the available study also no classification on acute inhalatin toxicity according to Regulation (EC) No 1272/2008, Annex I is concluded as the maximum technically achievable concentration of 3069 mg/m3 was tested and no test substance related effects were observed.