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Toxicological information

Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
short-term repeated dose toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
From 27 NOV 1978 to 9 JAN 1978
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions (no GLP)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1979
Report Date:
1979

Materials and methods

Principles of method if other than guideline:
21-days repeated dose inhalation toxicity study
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
other: RAI f SPF (RA25)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: approximately 7 weeks
- Weight at study initiation: mean body weights males: 174-177g; mean body weights females: 166-168g
- Housing: groups of 5; Macrolon cages type 3
- Diet: pelleted standard diet, Nafag No. 890 (NAFAG, Gossau SG, Switzerland)
- Water: tap water, ad libitum
- Acclimatisation to exposure conditions: 2 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 55 +/- 10
- Air changes (per hr): 15

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
other: unchanged (no vehicle)
Remarks on MMAD:
MMAD / GSD: > 80% < 7µm in diameter
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Method of holding animals in test chamber: in PVC-tubes which were positioned radially around the exposure chamber
- System of generating particulates/aerosols: by injecting three different amounts of the solid test material with the help of a Grafix Exaktomat Injector (Cerutti AG, Bern, Switzerland) into an airstream which was discharged into the exposure chamber
- Temperature, humidity, pressure in air chamber (group means): 22.5-22.9 °C, 41.7-44.9%, 2 atm
- Air flow rate: 20 l/min
- Method of particle size determination: gravimetrically with a 4 stage cascade impactor on selectron filters, pore size 0.2 µm and 25 mm diameter



TEST ATMOSPHERE
- Brief description of analytical method used: gravimetrically on selectron filters, pore size 0.2 µm and 50 mm in diameter
- Samples taken from breathing zone: yes
- Frequency: 5 times a day
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
gravimetrically on selectron filters, pore size 0.2 µm and 50 mm in diameter
Duration of treatment / exposure:
15 exposure days, 6 hours/day
Frequency of treatment:
5 days per week
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 54, 157, 410 mg/m3
Basis:
analytical conc.
No. of animals per sex per dose:
10
Control animals:
yes, sham-exposed
Positive control:
none

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations were included.

DETAILED CLINICAL OBSERVATIONS: Yes


BODY WEIGHT: Yes
- Time schedule for examinations: daily, except weekends, during exposure; weekly during recovery


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Time schedule for examinations: twice weekly during exposure; weekly during recovery


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes


WATER CONSUMPTION: No


OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: weekly
- Dose groups that were examined: all dose groups


HAEMATOLOGY: Yes
- Time schedule for collection of blood: once at the end of the exposure
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: all
- Parameters examined: haemoglobin, methaemoglobin, erythrocytes, packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, reticulocytes, inclusion bodies, thrombocytes, prothrombin time, activated partial thromboplastin time, leucocytes (total count and differential count)


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: once at the end of the exposure
- Animals fasted: Yes
- How many animals: all
- Parameters examined: glucose, urea, total protein, protein electrophoresis, electrolytes, glutamate oxalacetate transaminase, glutamate pyruvate transaminase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyl-transpeptidase


URINALYSIS: No


NEUROBEHAVIOURAL EXAMINATION: No


OTHER:
- organ weights: yes (at the end of the exposure and recovery period; brain, heart, liver, kidney, adrenals, thymus, gonades, lung)


Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY
No death occurred during the exposure and recovery period. No toxic symptoms were observe in the animals of the control and test groups.

BODY WEIGHT AND WEIGHT GAIN
There was a slight but significant (p>/= 0.01) decrease in the body weigth gain of the male rats of the highest concentration group during the exposure period, when compared with that of the recovery period of these animals and the other treated and control group.

FOOD CONSUMPTION
No significant differences between treated animals and controls.

FOOD EFFICIENCY
No significant differences between treated animals and controls.

WATER CONSUMPTION
No data.

OPHTHALMOSCOPIC EXAMINATION
No occular changes were observed.

HAEMATOLOGY
The observed haematological findings between treated rats and controls were generally unremarkable.


CLINICAL CHEMISTRY
No significant differences between treated animals and controls.


ORGAN WEIGHTS
With the exception of the absolute and relative lung weigths, which were significantly increased in male and female rats of the highest dose group after the exposure as well as the recovery period, the organ weights, organ to bodyweight and organ to brainweight ratios were generally comparabel between the control and treated rats.

GROSS PATHOLOGY
In the treated rats from all concentration level groups yellowish or yellow discoloration of the lungs was seen at autopsy. No other compound related anatomical changes were noted.

HISTOPATHOLOGY: NON-NEOPLASTIC
In the lungs of the animals from the highest concentration group (410 mg/m3) histological signs of a slight pneumoconiosis were seen. There were small brown-yellow birefringent particles in the lumen of numerous alveoli, small bronchi, in the numerous histiocytes in the interstitium and in the peribronchial lymphatic tissue. The size of these particles varied between 2-4 µm in diameter. In numerous alveoli focal accumulation of foamy cells containing usually birefringent particles in their cytoplasm was observed. There was slight focal lymphohistiocytic infiltration in the vicinity of the foreign particles. After a recovery period of 21 days only minimal or questionable regression of the pneumoconiosis was seen in the animals from the highest concentration group.
In the lungs of the animals from the intermediate concentration group (157 mg/m3) focal accumulation of small brown-yellow birefringent particles in the cytoplasm of histiocytic elements in the interstitium, in occasional alveoli, in the lumen of a few bronchi and occasionally in the peribronchial lymphatic tissue was found.
Similar only slightly less pronounced finding in the lung was observed in the rats from the lowest concentration group (54 mg/m3).
Neither accumulation of the foamy cells in the lungs nor lymphohistiocytic inflammatory infiltration in the interstitium were noted in rats from the lowest and intermediate concentration groups.
All other minor changes seen in some control and treated rats were only incidental in nature and not related to the inhalation of the test item.



Effect levels

Dose descriptor:
NOAEC
Effect level:
157 mg/m³ air (analytical)
Sex:
male/female
Basis for effect level:
other: histopathologic investigation revealed minimal deposition of test material in the lung, but this was not accompanied by an inflammatory or any other adverse response

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Analysed test item concentrations were:

0 mg/m3

54 +/- 6 mg/m3

157 +/- 9 mg/m3

410 +/- 12 mg/m3

Applicant's summary and conclusion

Conclusions:
The test item did not elicit relevant toxicological effects after subacute inhalation exposure except for some local effects in the lungs of the treated animals probably due to the particulate matter of the test item and not due to inherent toxicity. Therefore, no NOEL can be derived from this study. Whereas inflammatory effects up to pneumoconiosis occurred in the high concententration group, the effects observed at the mid and lowest test concentration groups were mainly due to the deposition of the test material, but not adverse. Therefore the 157 mg/m3 can be regarded as NOAEC.
Executive summary:

Subacute toxicity of the test item was investigated in an 21 days aerosol inhalation study in rats, which were exposed to 0, 54, 157, 410 mg/m3 test item (6 h/d, 5 d/w).

The bodyweights of the male and female rats of the highest treatment group were slightly decreased during the exposure period when compared with those of the control and other treated groups. In the treated rats from all concentration level groups yellowish or yellow discoloration of the lungs was seen at autopsy. Slight but significant increase of both absolute and relative weights of the lungs was noted in rats from the top concentration group. Histopathology revealed in the lungs of these rats pneumoconiosis showing numerous brown-yellow, birefringent particles about 2 - 4 um in diameter in the lumen of numerous alveoli, in small bronchi, in numerous histiocytes in the interstitium and in peribronchial lymphatic tissue, associated with focal accumulation of foamy pneumocytes in the alveoli and focal lymphohistiocytic infiltration.

After a recovery period of 21 days, to which a further group of rats exposed to the 410 mg/m3concentration of the tested compound was subjected, practically no regression of the pulmonal changes was observed.

In treated rats from the 157 mg/m3and 54 mg/m3concentration groups focal accumulation of minute brown-yellow, birefringent particles was observed in the cytoplasm of histiocytic elements in the interstitium, in occasional alveoli, in the lumen of a few small bronchi and very occasionally also in the peribronchial lymphatic tissue, however without obvious accumulation of foamy cells in the alveoli and without inflammatory infiltration.

Other minor microscopical findings obtained in some treated and control animals were only incidental in nature and not related to the inhalation of the test item.

It can be inferred from the observations made during the above study that the "no observable effect level" for rats is below 54 mg/m3air.

The effects observed at the mid and low test concentration were only due to the deposition of the test material but did not cause adverse effects like inflammation etc. Therefore, the mid test concentration of 157 mg/m3 can be regarded as "no observable adverse effect level".