Registration Dossier

Administrative data

acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
05 Apr 2018 - 25 Sep 2018
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report

Materials and methods

Test guidelineopen allclose all
according to
OECD Guideline 403 (Acute Inhalation Toxicity)
Version / remarks:
September 2009
according to
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Version / remarks:
August 1998
according to
EU Method B.2 (Acute Toxicity (Inhalation))
Version / remarks:
according to
other: Appendix to Director General Notification, No. 12-Nousan-8147. Agricultural Production Bureau, Ministry of Agriculture, Forestry and Fisheries of Japan (JMAFF)
Version / remarks:
November 2000
GLP compliance:
Test type:
traditional method
Limit test:

Test material

Test material form:
solid: particulate/powder
Details on test material:
- Appearance: White powder
Specific details on test material used for the study:
Before use, the test item was grinded with an automatic grinder and passed through a 500 µm steel mesh sieve.

Test animals

other: Crl:WI(Han)
Details on test animals and environmental conditions:
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at the Initiation of dosing: appr. 9-10 weeks
- Weight at the Initiation of dosing: 253 to 287 g. (males); 176 to 201 g. (females)
- Fasting period before study: no
- Housing: Group housing of up to five animals of the same sex and same exposure group per cage containing sterilized sawdust
- Diet: pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany), ad libitum (no access to food during exposure)
- Water: tap water, ad libitum (no access to water during exposure)
- Acclimation period: at least 5 days before the commencement of dosing

- Temperature (°C): 18-24
- Humidity (%): 40-70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 05 Apr 2018 To: 25 Sep 2018

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Remark on MMAD/GSD:
See below for the measurement results.
Details on inhalation exposure:
- Exposure chamber: based on the directed flow nose only inhalation chamber (Am. Ind. Hyg Assoc. J. 44(12): 923-928, 1983). The chamber consists of animal sections with eight animal ports each. Each animal port has its own test atmosphere inlet and exhaust outlet. The number of animal sections and number of open inlets were adapted to the air flow in such a way that at each animal port the theoretical air flow was at least 1 L/min. The main inlet of the test atmosphere was located at the top section and the main outlet was located at the bottom section. The direction of the flow of the test atmosphere guaranteed a freshly generated atmosphere for each individual animal.
- Method of holding animals: polycarbonate restraining tubes, connected to the exposure chamber. Animals were allowed to acclimatize for at least fifteen minutes after the last animal had been placed.
- System of generating particulates/aerosols: Administering the test item to a stream of pressurized air using a combination of a spiral feeder (1.1 mg/L) or dust feeder (2.6 mg/L) and micronizing jet mill generated an aerosol. The aerosol was passed through a series of four (1.1 mg/L) or a single cyclone (2.6 mg/L), allowing larger particles to settle, before it entered the exposure chamber. The mean total airflows were 29 and 15 L/min for the 1.1 and 2.6 mg/L exposure groups, respectively.
- Method of particle size determination: The particle size distribution was characterized twice during each exposure period. The samples were drawn with a flow of 2 L/min. from the test atmosphere through a tube mounted in one of the free animal ports of the exposure chamber. The samples were collected with an 8 stage Marple personal cascade impactor containing fiber glass filters and a fiber glass back-up filter. Amounts of test item collected were measured gravimetrically. Subsequently the Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (gsd) were determined based on OECD guidance document No 39.
Acceptable particle size distribution: target mass median aerodynamic diameter (MMAD) in the range of 1-4 µm with a range of 1.5-3 for the geometric standard deviation (gsd).
- Treatment of exhaust air: filtered and released to the exhaust of the fume hood
- Temperature, humidity during exposure: 21.6-22.9°C; 17-54%

A total of 18 and 29 representative samples were taken for determination of the actual concentration during exposure at 1.1 and 2.6 mg/L, respectively. Taken equally distributed over the exposure period. Samples were drawn from the test atmosphere through a tube mounted in one of the free animal ports of the exposure chamber. Samples were drawn through a glass fiber filter. Sample volumes were measured by means of a dry gas meter (type G 1.6, Actaris Meterfabriek B.V., The Netherlands). The collected amount of test item in the air sample was measured gravimetrically. Subsequently the time-weighted mean concentrations with the standard deviations were calculated. The results demonstrated that the item was sufficiently stable.
Analytical verification of test atmosphere concentrations:
Duration of exposure:
4 h
Remarks on duration:
For needed interruptions was compensated (to remove test item deposits from the system)
Time-weighted mean actual concentrations:
- 1.1 ± 0.0 mg/L
- Technically maximum attainable concentration (2.6 ± 0.0 mg/L)
No. of animals per sex per dose:
Control animals:
Details on study design:
- A starting target exposure level of 1 mg/L was selected based on the available test item data and was one expected not to cause mortality. Based on the results, one additional group was exposed to a target concentration of 5 mg/L. Since the MMAD obtained during this exposure was extremely large (exceeding 21 µm) resulting in an insufficient lung exposure, the results obtained for this group were declared invalid.
- The performance characteristics of the test atmosphere generation and exposure system to be used was assessed prior to commencement of exposure during trial generations. Trial generation results showed that it was difficult to generate a suitable test atmosphere sufficiently stable at the highest target concentration (5 mg/L). It was attempted to perform the exposure at the maximum concentration of 5 mg/L, but this exposure had to be declared invalid based on particle size. The generation was therefore repeated at the technically maximum attainable concentration (2.6 mg/L).
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Three times during exposure (mortality, signs of distress and effects on respiration); after exposure twice daily for mortality and clinical signs were observed once for the 1 mg/L group (1 hour after exposure) and twice for the 2.6 mg/L group (1 and 3 hours after exposure) on the day of exposure (day 1), and once daily thereafter. Body weight determined on days 1 (pre-administration), 2, 4, 8 and 15.
- Necropsy of survivors performed: yes

Results and discussion

Effect levels
Key result
Remarks on result:
other: LC50 (4h) (male/female): >technically maximum attainable concentration (2.6 mg/L)
No mortality occurred.
Clinical signs:
other: - At 1.1 mg/L, no clinical signs of systemic toxicity were noted. - At 2.6 mg/L, no clinical signs were seen during exposure. After exposure, hunched posture and chromodacryorrhoea (head) was seen for all animals on Day 1 only.
Body weight:
Overall body weight gain in males and females was within the range expected for rats of this strain and age used in this type of study.
Gross pathology:
No abnormalities were found at macroscopic post mortem examination of the animals.

Applicant's summary and conclusion

Interpretation of results:
other: GHS and CLP criteria not met
In an acute inhalation toxicity study with male and female rats, performed according OECD test guideline and GLP principles, an LC50 above the technically maximum attainable concentration was determined for the substance.
Executive summary:

An acute inhalation toxicity study with nose-only exposure was performed according to OECD 403 and GLP principles. A starting target exposure level of 1 mg/L was selected based on the available test item data and was one expected not to cause mortality. Based on the results of trial generations, showing that it was technically not feasible to perform the study at 5 mg/L, the test atmosphere generation was subsequently performed at the technically maximum attainable concentration. Five animals of each sex were exposed for 4 hours at both exposure levels. The MMADs were determined to be in the range of 1 to 4 µm during exposure, while the time-weighted mean concentrations were measured to be 1.1 ± 0 mg/L and 2.6 ± 0 mg/L. No mortality occurred. During exposure, no clinical signs were noted. After exposure, at 2.6 mg/L, hunched posture and chromodacryorrhoea (head) was seen for all animals on Day 1 only. The LC50 was concluded to be above the technically maximum attainable concentration (>2.6 mg/L). Based on the results of this study, the substance is not classified for acute toxicity by the inhalation route according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and Regulation (EC) No 1272/2008 (CLP Regulation).