[No public or meaningful name is available]

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

10 May - 6 Sept 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

adopted 2009

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Bayer Heatlh Care - Bayer Pharma AG, Experimental Toxicology - Inhalation, Wuppertal, Germany

Test type:

standard acute method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

28182-81-2

Molecular formula:

Unspecified (UVCB substance)

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan-Nederland, Netherlands (Hsd Cpb:WU (SPF) wistar strain)
- Age at study initiation: 2 months
- Weight at study initiation: males: 178 - 187 g; females: 168 - 183 g
- Housing: singly in conventional Makrolon Type IIIH cages
- Diet: standard fixed-formula diet (KLIBA 3883), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 40 - 60
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Plexiglas exposure restrainers (TSE, Bad Homburg)
- Method of holding animals in test chamber: 20 rats in each inhalation chamber segment
- Source and rate of air: Dry conditioned air, 15 L/min
- Method of conditioning air: Compressed air was supplied by Boge compressors and was conditioned (free from water dust and oil) automatically by a VIA compressed air dryer.
- System of generating particulates/aerosols: Under dynamic conditions the targeted concentrations were achieved by atomization using the nozzle-baffle system and inhalation chamber. For atomization a binary nozzle and conditioned compressed air was used (15 L/min). The representative dispersion pressure was approximately 600 kPa. The test article was fed into the nozzle system using a digitally controlled pump.
- Method of particle size determination: Cascade impactor
- Treatment of exhaust air: The exhaust air was purified via filter systems.
- Temperature, humidity: mean temperatures from 20.7 to 22°C, 5% relative humidity

TEST ATMOSPHERE
- Brief description of analytical method used: Measurements were carried out using a RAS-2 real-time aerosol photometer.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: The particle size distribution was analyzed using a BERNER critical orifice cascade impactor.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 1.8 µm/~1.6

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

0.235, 0.284, 0.314 mg/L

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observations were made several times on the day of exposure and daily thereafter, body weights were determined before exposure and on days 1, 3 and 7 and weekly thereafter.
- Necropsy of survivors performed: yes
- Other examinations performed: Reflexes were tested (visual placing response, grip strength on wire mesh, abdominal muscle tone, corneal and pupillary reflex, 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 determined shortly after cessation of exposure.

Statistics:

Analysis of variance (ANOVA) was used for statistical evaluation.
Calculation of LC50 was performed according to Rosiello et al. (1977; Rosiello, Essigmann and Wogan, Tox and Environ. Health, 3, pp797) as modified by Pauluhn (1983). It is based on the maximum likelihood method of Bliss (1983; Q.J.Pharm.Pharmacol., 11, pp192).

Results and discussion

Preliminary study:

Based on previous experience with this class of isocyanates the likely LC50 could be anticipated and a preliminary study was relinquished.

Effect levels

Effect levels 1

Sex:

male

Dose descriptor:

LC50

Effect level:

0.264 mg/L air

Based on:

test mat.

95% CL:

>= 0.241 - <= 0.291

Exp. duration:

4 h

Effect levels 2

Sex:

female

Dose descriptor:

LC50

Effect level:

> 0.314 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No animal died in the lowest dose group of 0.235 mg/L. 4 male animals and 2 female animals of the middle dose group (0.284 mg/L) died during the first day following application. In the highest dose group (0.314 mg/L) all male ainmals died within one day, but only 1 female animal died.

Clinical signs:

other: Almost all treated animals showed bradypnoea, labored and irregular breathing patterns, reduced motility, atony, high-legged and uncoordinated gait, tremor, ungroomed hair-coat, piloerection, cyanosis, serous nasal discharge and encrustations of nose and

Body weight:

Treated animals showed reduced body weights as compared to control animals.

Gross pathology:

Necropsy of animals that died during the study revealed nasal/muzzle with red encrustations, nostrils with foamy content/discharge, lung less collapsed with foamy whitish content in trachea, hydrothorax, abdomen bloated and discoloration/bloodless appearance of parenchymatous organs.
Necropsy of surviving animals at the end of the study period did not reveal any abnormal finding compared to control.

Other findings:

- Other observations: All treated animals showed significantly reduced rectal temperatures (hypothermia). A battery of reflex measurements was made on the first post-exposure day. ln comparison to the rats of the control group, rats of groups 2-4 exhibited impaired reflexes. Male animals of the low dose group showed a reduced tonus, impaired righting reflex and one animal each landed on side or back during drop method. Each one male animal from the mid dose group showed reduced grip strength (vertical and horizontal) and reduced tonus. One male animal was slightly uncoordinated.
Female animals from low dose showed reduced tonus (3/5), impaired righting reflex (2/5) and one female was slightly uncoordinated. Female animals from the mid dose group showed reduced vertical (1/5) and horizontal (3/5) grip strength, reduced tonus (1/5) and 2/5 animals were slightly uncoordinated. 4/5 female animals from the high dose group showed reduced tonus and one animal impaired righting reflex and another one was slightly uncoordinated.

Any other information on results incl. tables

Table 1. Table for acute inhalation toxicity. 

Target concentration [mg/L air]	Toxicological results*	Duration of clinical signs	Time of death	Mortality (%)	Rectal Temperature (°C)
Males
0	0/0/5	---	---	0	38.0
0.235	0/5/5	Day 0-3	---	0	29.7**
0.284	4/5/5	Day 0-5	Day 0-1	80	29.6**
0.314	5/5/5	Day 0-1	Day 1	100	28.3**
Females
0	0/0/5	---	---	0	38.5
0.235	0/5/5	Day 0-10	---	0	29.5**
0.284	2/5/5	Day 0-9	Day 1	40	30.1**
0.314	1/5/5	Day 0-5	Day 1	20	29.2**
LC50 = 0.264 mg/L air

**significant different from control value, p<0.01

* first number = number of dead animals, second number = number of animals with clinical sings,third number = number of animals used