Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27 Nov 2006 - 30 Mar 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
no
Qualifier:
according to
Guideline:
other: Japanese Ministry of Agriculture, Forestry and Fisheries, 12-Nousan-No.8147
Deviations:
no
GLP compliance:
yes
Test type:
standard acute method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Japan, Inc. (Hino Breeding Center, Shiga, Japan)
- Age at study initiation: 8 weeks
- Weight at study initiation: 309 - 352 g (males) and 205 - 225 g (females)
- Fasting period before study: No
- Housing: Two or three animals of same sex were housed in a suspended aluminum cage with a stainless steel wire-meshed front and floor (224W x 419D x 200H mm, Yamato Scientific Co., Ltd., Tokyo, Japan). Cages were arranged in an aluminum cage rack (Yamato Scientific Co., Ltd.) with 25 cages per rack (5 tiers, 5 rows). An aluminum cage tray (Yamato Scientific Co., Ltd.) was placed under each cage. The used cage rack was exchanged for an autoclaved one on the day of group assignment. Used cages were exchanged for autoclaved cages once weekly and used cage trays were exchanged for autoclaved cages twice weekly. The animal room was cleaned daily by mopping the floor with disinfectant.
- Diet: Pelleted diet (CRF-1 sterilized by 60Co at 30kGy, Oriental Yeast Co., Ltd., Tokyo, Japan), ad libitum.
- Water: Filtered tap water, ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 +/- 2 (The actual range of the temperature was 23.7 - 24.3 °C)
- Humidity (%): 40 - 70 (The actual range of the relative humidity was 53.8 -67.4%)
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12 hrs

IN-LIFE DATES: From: 11 Dec 2006 To: 26 Dec 2006

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Animals were placed individually in holding tubes (diameter: 9.4 cm, height: 32 cm, one animal/holding tube, ADG developments Ltd., England). The holding tube, in which each animal was placed, was put in the nasal exposure chamber (ADG Developments Ltd., England).
- Method of holding animals in test chamber: Animals were placed individually in holding tubes.
- Source and rate of air: Compressed air and airflow rate were set at 0.3Mpa and 40 L/min, respectively.
- System of generating particulates/aerosols: The test substance was milled in a mortar and then put in the cup of a Wright Dust Feeder (BGI Incorporated., U.S.A). The dust aerosols generated were then fed into the nasal exposure chamber.
- Method of particle size determination: The particle size distribution of the generated atmosphere in the chamber, except for the air control, was determined twice during the exposure period. A cascade impactor (Marple model 296, Shibata scientific technology Ltd., Tokyo, Japan) was set to the sampling line as shown in Figure 1 and 0.4 L of the dust aerosol was taken from the chamber at a rate of 1 L/min. The weight of the dust aerosol sampled by the cascade impactor was measured to obtain the distribution of aerodynamic diameters of dust particles, and to determine the Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (GSD) by Probit analysis on the basis of the distribution.
- Temperature, humidity, pressure in air chamber: 21.4 - 22.9 °C, 26.6 - 68.3%, and -80 to - 40 Pa, respectively, for the test group. 21.5 - 22.6 °C, 30.7 - 69.7%, and - 90Pa, respectively, for the control group.

TEST ATMOSPHERE
- Brief description of analytical method used: Dust was trapped by a glass filter (GF-75, 47 mm diameter, ADVANTEC TOYO Co., Ltd., Osaka, Japan) in a sampling holder (CR Equipment SA, Swiss). Five litres of atmosphere were taken from the chamber at a rate of 1 L/min through the glass filter using an auto air-sampler (Kitahama Co., Ltd., Osaka, Japan). The aerial concentration was calculated by gravimetric analysis from the amount of test substance that was trapped by the glass filter and the flow rate through the chamber. Chemical analysis of the test substance was conducted at Environmental Science Center (Sumika Technoservice Corporation, 2-1, Takatsukasa 4-Chome, Takarazuka, Hyogo, Japan) to calculate the aerial concentration. The aerial concentration of the exposure group except the air control group was determined gravimetrically 5 times and chemically 3 times during the exposure period.
- Samples taken from breathing zone: Yes

VEHICLE: Air

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: <0.75 to >14.9 µm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The Mass Median Aerodynamic Diameter (MMAD) of dust aerosol particles was 5.26 µm and the Geometric Standard Deviation (GSD) was 2.16 in the 5000 mg/m3 exposure group.
Analytical verification of test atmosphere concentrations:
yes
Remarks:
gravimetric and chemical analysis
Duration of exposure:
4 h
Concentrations:
5000 mg/m3
No. of animals per sex per dose:
5
Control animals:
other: yes, concurrent vehicle
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observation of clinical signs was performed on all animals before exposure, at 30 minutes, 1, 2, 3 and 4 hours after initiation of the exposure, immediately and then hourly for up to 4 hours after termination of the exposure, and once daily from the next day of the exposure. During the exposure, the observation was limited to such signs including mortality and tremor which could be observed. Each animal was weighed on the day of exposure and on days 3, 7 and 14.
- Necropsy of survivors performed: Yes. All animals were necropsied for gross pathological examination on all organs and tissues.
- Other examinations performed: The head (nasal cavity), pharynx, larynx, trachea and lung were removed from all animals and immersed in 10% neutral-buffered formalin solution to fix and preserve. The carcasses were discarded. The histopathological examination was not performed, because there were no abnormal gross findings related to the test substance exposure.
Statistics:
For statistical analysis of body weights and body weight gains, the F test was applied to test for heterogeneity of variance among all groups. And, if no significant heterogeneity of variance was detected, the Student's t-test was applied. If significant heterogeneity of variance was present, the Aspin-Welch test was used to analyze the statistical differences. Incidence of gross pathological findings was analyzed by the Fisher's exact probability test (two-tailed test) between the exposure group and the air control group. Significant difference was evaluated at the 5 and 1% probability level.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5 000 mg/m³ air (nominal)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: Actual aerial concentration chemically was 4750 mg/m³. Actual aerial concentration gravimetrically was 4600 mg/m³ (no mortality).
Mortality:
There was no mortality.
Clinical signs:
2-3 animals in each group had wet patches on their fur (primarily head, thorax region) during the first hr of exposure. This is not considered to be a result of the treatment itself and not the substance, as it occurred in all groups and resolved within 1 hr.
Body weight:
Although there was no significant difference in body weight values, significantly lower body weight gain was observed in the female exposure group of 5000 mg/m3 test substance at the end of the 14-day observation period.
Gross pathology:
There were no treatment-related findings of the gross pathology.

Applicant's summary and conclusion