Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
other information
Study period:
from March 26 to April 12, 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990
Report Date:
1990

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Version / remarks:
1981
GLP compliance:
yes
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 2 -3 months.
- Weight at study initiation: 180 - 210 g.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2 °C.
- Humidity: ca. 50 %.
- Air changes: 10 per hr.
- Photoperiod: 12 h light / 12 h dark.

Administration / exposure

Route of administration:
other: inhalation of aerosol or dust
Type of inhalation exposure:
nose/head only
Vehicle:
other: water (aerosol)
Details on inhalation exposure:
CHAMBER DESCRIPTION
- exposure chamber volume: ca. 20 l
- air: compressed air at 8 - 10 bar
- method of conditioning air: removal of water, dust and oil

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION: aerosol
- exposure apparatus: inhalation chamber with pre-separator.
- aerosol generation: with nozzle and conditioned compressed air (10 l of air per minute, dispersion pressure 500 kPa). 500000 µl/m3 of air of 12 % aqueous dilution were nebulised under dynamic conditions in the pre-separator of the inhalation chamber. Container with the aqueous test sample dilution was continuously stirred using a magnetic stirrer. The solution was transferred using a peristaltic pump into the nozzle.
- control of particle size: pre-separator increases efficiency of aerosol generation and also allows deposition of larger particles.
- air exchange: 30 times per hour.
- equilibrium: reached in 6 minutes.
- treatment of exhaust air: 80 % through cotton-wool filter (aerosol filter).

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION: dust
- exposure apparatus: inhalation chamber without pre-separator.
- system of generating particulates: dust generated by 'Exactomat 4200'.
- air supply: 28 l/min.
- air discharged: 20 l/min.
- air exchange: 84 times per hour.
- equilibrium: reached in 6 minutes.
- treatment of exhaust air: absolute filter.

TEST ATMOSPHERE
- dust temperature and humidity: ca 22 °C and 20 - 30 %.
- aerosol temperature and humidity: ca 23 °C and > 90 %.
- temperature and humidity in air chamber: measured every 10 minutes.
- reference group: exposure 6 h/day for 5 days.
- test group: 4/h exposure.
- brief description of analytical method used: a humidity sensor was used in which a water-attracting polymer serves as a dielectric. As a function of the moisture content of the ambient, air penetrates into water as polymer and causes a large change in the capacitance of the capacitor. The moisture measuring cell is protected by a Teflon membrane against aerosols and dust particles. The calibration of the sensors is wet with saturated salt solutions. The calibration of the temperature sensors was carried out with a standard thermometer.

ANALITICS OF TEST ATMOSPHERE : aerosol
- nominal concentration calculated from the ratio of the sprayed into the pre-separator of the inhalation chamber test sample (mg) and the total air flow rate per inhalation chamber (m3). The analytical lower concentrations - as compared to the nominal concentrations - attributed to the deposition of large particles in the pre-separator. The determination of the actual specimen concentration in the breathing zone of rats was performed with the help of filter analyses dried on gravimetric determination. 10-20 l of air in the test atmosphere breathing region of the rats were removed with a flow of 4 l/min per analysis.
- aerosol distribution: adequate to expose all potential target structures of the respiratory tract.

ANALITICS OF TEST ATMOSPHERE: dust
- indication of a nominal concentration reading is not possible for technical reasons. Determination of the actual sample concentration in the breathing zone of rats was performed with the help of filter analyses evaluated gravimetrically.
- particles features: sampling for analysis of particle distribution was carried out in the immediate breathing zone of rats. The individual impactor stages were evaluated gravimetrically.
- particle size distribution: adequate to expose all potential target structures of the respiratory tract.
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
Analytic concentration of dust: 943 and 5070 mg/m3 air.
Analytic concentration of aerosol: 1075 mg/m3 air.
Nominal concentration of aerosol: 60000 mg/m3 air.
No. of animals per sex per dose:
5 animal/sex/dose.
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days.
- Frequency of observations and weighing: daily.
- Necropsy of survivors performed: yes.
- Other symptoms considered in animal assessment: respiration, circulation, mucous membranes of eyes and respiratory tract, condition of snout skin and ears, coat condition, cleaning activities, somatomotor and behaviour patterns, central nervous system.
Statistics:
Pairwise Fisher's Test and Chi-Square-Test.

Results and discussion

Effect levelsopen allclose all
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5 070 mg/m³ air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: dust
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 3 245 mg/m³ air (analytical)
Based on:
act. ingr.
Exp. duration:
4 h
Remarks on result:
other: dust
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 1 075 mg/m³ air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: aerosol
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 688 mg/m³ air (analytical)
Based on:
act. ingr.
Exp. duration:
4 h
Remarks on result:
other: aerosol
Mortality:
Dust and aerosol exposure: no mortality up to the highest doses.
Body weight:
Dust exposure: significant difference only in group 3 (5070 mg/m3 air).
Aerosol exposure: significant difference only in group 2 (1075 mg/m3 air).
Gross pathology:
Dust and aerosol exposure: no evidence of specific organ changes.

Any other information on results incl. tables

Dust exposure

The analysis of the particle size distribution of the dust in the breathing zone of the rats did not produce adequate respirable mass fraction .

Group 1 (control): all rats tolerated the treatment clinically asymptomatic.
Group 2 and 3 (943 and 5070 mg/m3air): dyspnea, respiratory sounds, slow and difficult breathing, decreased motility, laxity, serous nasal discharge and unkempt fur.

Qualitative differences between group 2 and 3 were not evident. With regard to the duration of symptoms, however, a concentration dependency was seen. Group 3 rats showed strong respiratory tract irritation.

The relatively rapid reversibility of respiratory tract irritation, the overall low inhalability of dust and the only slightly pronounced concentration dependence lead to the conclusion that the irritation is induced by a particle deposition in the upper respiratory tract or in the nose and throat.

group sex no. animals conc. mg/m3 air dead animals animals with symptoms symptom duration % particles ≤ 3 µm
1 M 5 0 0 0 - -
2 M 5 943 0 5 4h - 1d 4
3 M 5 5070 0 5 4h - 2d 1
1 F 5 0 0 0 - -
2 F 5 943 0 5 4h - 2d 4
3 F 5 5070 0 5 4h - 2d 1

Aerosol exposure

The analysis of the particle size distribution of the aerosol in the breathing zone of the rats revealed a high inhalable mass fraction.

Group 1 (control): all rats tolerated the treatment clinically asymtomatic.

Group 2 (1075 mg/m3air): slow and difficult breathing, reduced motility, unkempt and ruffled fur.

group sex no. animals conc. mg/m3 air dead animals animals with symptoms symptom duration % particles ≤ 3 µm
1 M 5 0 0 0 - -
2 M 5 1075 0 5 4h - 5d 61
1 F 5 0 0 0 - -
2 F 5 1075 0 5 4h - 3d 61

Applicant's summary and conclusion

Interpretation of results:
study cannot be used for classification
Remarks:
no mortality up to the highest tested doses, which are below the threshold fof classification within the CLP Regulation (EC 1272/2008)
Conclusions:
Overall, dust and aerosol exposure showed that, via the respiratory tract, particles had no particular acute inhalation toxicity. Indeed, no mortalities were recorded up to the highest tested doses. Thus, LD50 > 1075 and 5070 mg/m3 air for aerosol and dust respectively.
However, high concentrations of particulate material, as dust, may cause respiratory tract irritation due to physical properties of the dust, which dries the mucous membranes of the upper respiratory tract.
Executive summary:

Method

Acute toxicity by inhalation of dust particles or aerosol in male and female rats with a 14 -day observation period.

Results

No mortalilty was recorded up to the highest tested concentrations, namely 5070 mg/m3 air as dust and 1075 mg/m3 air as aerosol, i.e. 3245 and 688 mg active ingredient/m3 air . Accordingly, no LC50 could be identified.

A large fraction of aerosol particles is respirable, while upon dust exposure, irritation of the respiratory tract was seen.

Symptoms, as slow/difficult breathing and reduced motility, were reversible under test conditions, with duration depending on physical form (dust or aerosol) of the substance, concentration of the substance and sex of animals.