Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
18 March 1980 and 28 April 1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Meets generally accepted scientific standards, well documented and acceptable for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1980
Report Date:
1980

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: WTP-8
Deviations:
yes
Remarks:
Please see below for details.
Principles of method if other than guideline:
Species: Fischer 344
Exposure: Single, four hour exposures to 32899 dust at concentrations of 1.6 and 5.8 mg/L in groups of twelve (6 male and 6 female) per dose.
Examinations: Mortalities, sublethal effects and necropsy

1. Protocol specified twice daily observation of animals post exposure; animals actually observed once daily.
2. Study terminated 28 April 1980; protocol specified 18 April 1980.
3. The initial body weight range described in the Methods section of the report corresponds to the 0 day weights as required by the protocol.
4. Tissues indicated on gross necropsy forms as having been saved for microscopic exam (animals 8-040002, 8-040004, 8-040008, and 8-040009)
were not examined as this was not specified by the protocol.
5. In contrast to the protocol, the high dose exposure (5.8 mg/L) was performed after the low dose exposure (1.6 mg/L). This occurred due to difficulties in generating the higher concentration.

The above protocol deviations do not compromise the validity of the study.
GLP compliance:
no
Test type:
other:
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Portage, Michigan facility of Charles River Breeding Laboratories, Inc.
- Age at study initiation:
- Weight at study initiation: Initial body weight range: 150-260 grams (male and female).
- Fasting period before study:
- Housing: Housed individually in stainless steel, wire mesh suspended cages except during the exposure period.
- Diet: ad libitum(except during exposures): Purina Rat Chow
- Water: ad libitum (except during exposures): Water was provided to the rats through an automatic watering system (Edstrom Industries, Inc.)
- Acclimation period: Seven days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): Mean ambient temperature of 23°C.
- Humidity (%): Mean ambient humidity of 45%.
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
head only
Vehicle:
air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Head only exposure chamber.
- Exposure chamber volume: 220 Litre
- Method of holding animals in test chamber: Plastic restrainers mounted on the exposure chamber.
- Source and rate of air: No data
- Method of conditioning air: No data
- System of generating particulates/aerosols: The test material was passed through a plate mill grinder twice in order to achieve the particle size distribution required by the protocol. Dust was generated using an NBS dust generator for the 5.8 mg/L exposure and a Wright Dust Feeder for the 1.6 mg/L exposure. Especially at the higher dust concentration, technical difficulties were encountered with the dust generation equipment, e.g., clogging of nozzles and occasional mechanical adjustments. which necessitated interruptions of dust generation for as much as 30 minutes of each exposure period.
- Method of particle size determination: Particle size distribution was analyzed using dust samples from the chamber concentration measurements and was performed using a Coulter counter Model TA II equipped with Model TZ II population accessory, Data Convertor and Model M3 data interface unit. In addition. particle sizes were determined with a Sierra cascade impactor.
- Treatment of exhaust air: No data
- Temperature, humidity, pressure in air chamber: Chamber air flow. temperature and humidity were monitored continuously throughout the exposure period.

TEST ATMOSPHERE
- Brief description of analytical method used: Chamber dust concentrations were sampled through an unused exposure port by pulling a known volume of air through a preweighed filter. In addition, nominal concentrations were determined by difference by weighing the amount of 32899 in the dust generators before and after exposures.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated): Please see table 2 and table 3 below.
Analytical verification of test atmosphere concentrations:
no
Duration of exposure:
4 h
Concentrations:
1.6 and 5.8 mg/L
No. of animals per sex per dose:
Six animals per sex per dose (24 animals in total).
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Examined once daily for signs of general toxicity and mortality. Body weights were determined on post-exposure days 1, 7, and 14 or at the time of discovery after death.
- Necropsy of survivors performed: yes
- Other examinations performed: Gross pathologic examination was performed and organ weights were taken for all animals as soon as possible after death or upon sacrifice.
Each rat was subjected to a complete necropsy, which included gross examination of skin and external orifices, viscera, brain, and nasal turbinates.
Abnormalities were recorded by a qualified observer. Rats which died during the course of the study were necropsied as soon as practical after discovery.
Rats surviving to the end of the experiment were killed just prior to necropsy by exposure to an atmosphere of carbon dioxide. The terminal body weight was
obtained and the following organs were weighed: lungs (with trachea/larynx), liver, left kidney, and right kidney.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
3 mg/L air (nominal)
Based on:
test mat.
Exp. duration:
4 h
Mortality:
Male rats
1.6 mg/L - All rats survived the 14-day observation period.

5.8 mg/L - With the exception of one rat which died during exposure all deaths occured during the first or second day post exposure.

Female rats
1.6 mg/L - No other abnormalities were observed. All rats survived the 14-day observation period.

5.8 mg/L - One rat died during exposure, one each died during the second and third day post exposure.
Clinical signs:
other: Male rats 1.6 mg/L - No abnormalities were observed. 5.8 mg/L - Two male rats survived the 14-day observation period. Both showed corneal opacities; no scarring was observed. No other abnormalities were observed. Female rats 1.6 mg/L - The spleen of o
Body weight:
No noteworthy differences between 32899-exposed and untreated control rats oocurred.
Gross pathology:
Male rats
The lungs of two male rats which died were discolored. No other pulmonary changes were seen. Congestion of the nasal turbinates was seen in the four rats which died. Some free blood was present in the nasal passages of one of these rats; particulates were observed in another. Gross changes were not observed in the larynx or trachea of any of the six male rats exposed at this dose level.
Other changes observed in rats which died were discoloration of body surfaces, crusting around the nares and eyes, gaseous distention of the stomach and intestines, and hemorrhage around the hind limbs/knees.

Female rats
For the female rats which died, the lungs of one were not grossly abnormal, the lungs of another were mottled dark red but collapsed as expected, and the lungs of the third were disoolored. Two of these rats had nasal turbinates which were congested. No gross changes were observed in the larynx or trachea of these three rats.
Other gross abnormalities observed in the three female rats which died included white powder on the surfaces of the oral cavity, eyes, ears and nares, dirty matted hair, gas filled intestines, and hemorrhage in the limb of one rat.

Any other information on results incl. tables

The greater air flow rate used for the 5.8 mg/L exposure was due to the requirements of the NBS dust generator. The particle size analysis of the delivered 32899 dust determined by two methods is shown in Table 2 (Coulter counter) and Table 3 (Sierra cascade impactor).

The four-hour LC50 of catalyst 32899 was estimated in this study to be 3 mg/L by the use of a probit graph.

Exposure of male and female rats to 1.6 mg/L 32899 for four hours did not induce grossly observable pathology when the rats were necropsied 14 days after exposure. Rats which died following exposure to 5.8 mg/L 32899 for four hours showed variable signs of nasal turbinate and pulmonary pathology. Lesions were not observed in the larynx or trachea of these rats. The severity of the pulmonary lesions was insufficient to explain the death of the rats, death was not ascribable to any of the other lesions observed. Of note, was the presence of corneal opacity in three rats which survived the 14-day observation period following exposure to 5.8 mg/L 32899.

Applicant's summary and conclusion

Interpretation of results:
harmful
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The four-hour inhalation LC50 of catalyst 32899 was estimated to be 3 mg/L.
Executive summary:

In order to determine the inhalation LC50 groups of male and female Fischer 344 rats underwent single, four hour exposures to 32899 dust at concentrations of 1.6 and 5.8 mg/L. Exposures were performed in a 220 L head only chamber. Paticle size distribution and both nominal and actual concentrations of 32899 dust were determined. After exposure the animals were observed for fourteen days and underwent gross necropsy soon after death or upon sacrifice at the end of the observation period. Gross pathology findings which were observed only in the 5.8 mg/L exposure groups were insufficient to explain the observed deaths. As a result of this study the four-hour inhalation LC50 of catalyst 32899 was estimated to be 3 mg/L.