Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
The study was performed between 01 May 2012 and 23 May 2012.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Study conducted to GLP and in compliance with agreed protocols, with no deviations from standard test guidelines (OECD 436) and no methodological deficiencies. This study has been selected as the key study because the results are sufficient in order to derive a reliable conclusion on classification and labelling in accordance with Regulation (EC) No. 1272/2008 (EU CLP).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
Deviations:
yes
Remarks:
Deviations are discussed under 'results'. Any deviations are not considered to affect the validity of the results.
GLP compliance:
yes (incl. certificate)
Remarks:
Date of Inspection: 19-12 July 2011 Date of signature: 31 August 2011
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Sponsor's identification: Tetrairon tris (pyrophosphate)
Description: Off white powder
CAS number: 10058-44-3
EC number: 233-190-0
Batch number: 2-47501-56
Total iron: 21.0 %
Date received: 12 April 2012
Expiry Date: 28 February 2015
Storage conditions: Room temperature, in the dark
In order to facilitate aerosolisation and reduce particle size, the test item was ground in a Lloytron electric mini grinder prior to use. The absorption of the test item was not determined.

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS

- Source: Harlan Laboratories UK Ltd, Oxon, UK
- Age at study initiation: 8-12 weeks old
- Weight at study initiation: weight range of 200g to 350g
- Fasting period before study: Not applicable
- Housing: Animals were housed in groups of 3 of the same sexin solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes (Datesand Ltd., Cheshire, UK) and provided with environmental enrichment items: wooden chew blocks and cardboard “fun tunnels” (Datesand Ltd., Cheshire, UK).
- Diet (e.g. ad libitum): Animals had ad libitum access to standard Harlan Teklad 2914C rat maintenance diet (Harlan 2014C Rodent Diet, Harlan Laboratories UK Ltd, Oxon, UK). Results of the analyses for contaminants and their limits of acceptability are archived at Harlan Laboratories Ltd.
- Water (e.g. ad libitum): Ad libitum. Results of representative analyses for contaminants are archived at Harlan Laboratories Ltd.
- Acclimation period: For at least 5 days under laboratory conditions, after clinical health examination. Only animals without any visible signs of illness were used for the study. A further observation of clinical signs was performed on the day of exposure, before exposure start.


ENVIRONMENTAL CONDITIONS
Temperature: 19-25°C
Humidity: 30-70%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): the lighting was controlled to give twelve hours continuous light and twelve hours darkness.

The animals were retained in this accommodation at all times except during the exposure period.


IN-LIFE DATES: From: Day 1 To: Day 14

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
clean air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION

- Exposure apparatus: A dust atmosphere was produced from the test item using a SAG 410 Solid Aerosol Generator (TOPAS GmbH, Dresden, Germany) located adjacent to the exposure chamber. The SAG 410 was connected to a metered compressed air supply.
Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the SAG 410.

- Exposure chamber volume: The cylindrical exposure chamber had a volume of approximately 30 litres (dimensions: 28 cm diameter x 50 cm high). The concentration within the chamber was controlled by adjusting the test item feed rate from the SAG 410. The extract from the exposure chamber passed through a ‘scrubber’ trap and was connected with a high efficiency filter to a metered exhaust system. The chamber was maintained under negative pressure.


- Method of holding animals in test chamber: The animals were confined separately in restraint tubes which were positioned radially around the flow-past, nose-only exposure chamber. Only the nose of each animal was exposed to the test atmosphere.
- Source of air: Compressed air was supplied by means of an oil free compressor and passed respiratory quality filters before it was introduced into the exposure system.
- Exposure Chamber Atmosphere Concentration: The actual chamber concentration was measured at regular intervals during the exposure period. The gravimetric method used glass fibre filters placed in a filter holder. The holder was temporarily sealed in a vacant port in the exposure chamber in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through the filter using a vacuum pump.
Each filter was weighed before and after sampling in order to calculate the weight of collected test item. The difference in the two weights, divided by the volume of atmosphere sampled, gave the actual chamber concentration.
The nominal chamber concentration was calculated by dividing the mass of test item used by the total volume of air passed through the chamber.
The nominal concentration is 817% of the actual mean achieved atmosphere concentration and shows that keeping the aerosol airborne was difficult.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter (Hanna Instruments Ltd, Beds., UK) located in a vacant port in the animals’ breathing zone of the chamber and recorded every thirty minutes throughout the four-hour exposure period.

TEST ATMOSPHERE

- Brief description of analytical method used: Homogeneity of the test atmosphere within the chamber was not specifically determined during this study. Chambers of the same design (ADG Developments Ltd, Hitchin, Herts, UK) have been fully validated and shown to produce evenly distributed atmospheres in the animals’ breathing zone with a wide variety of test items (Green J D et al, 1984).
Prior to the start of the study, test item atmospheres were generated within the exposure chamber. During this characterisation period test item input rates were varied in order to achieve the required atmospheric conditions.

-Exposure chamber oxygen concentration: Oxygen levels within the exposure chamber were measured by an electronic oxygen analyser (Servomex (UK) Ltd, Crowborough, East Sussex) located in a port in the animals breathing zone during the characterisation phase of the study, the test atmosphere was generated to contain at least 19% oxygen. Due to a malfunction it was not possible to determine oxygen concentrations during the four hour exposure period.


- Samples taken from breathing zone: Yes

.
Analytical verification of test atmosphere concentrations:
no
Remarks:
Gravimetric only
Duration of exposure:
4 h
Concentrations:
Mean Achieved (mg/L) 5.19
The nominal aerosol concentration was 42.4 mg/L air.
The chamber flow rate was maintained at 60 L/min providing 120 air changes per hour.

Mean Mass Median Aerodynamic Diameter (µm): 4.22
Inhalable Fraction (% <4 µm): 48.3%
Geometric Standard Deviation: 3.63
No. of animals per sex per dose:
3
Control animals:
no
Details on study design:
- Duration of observation period following administration:
14 days

- Frequency of observations and weighing:
All animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for fourteen days. Individual bodyweights were recorded prior to treatment on the day of exposure and on Days 1, 3, 7 and 14.

- Necropsy of survivors performed:
yes
At the end of the fourteen day observation period the animals were killed by intravenous overdose of sodium pentobarbitone. All animals were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded. The respiratory tract was subjected to a detailed macroscopic examination for signs of irritancy or local toxicity.

- Other examinations performed:
None
Data evaluations included the relationship, if any, between the animals’ exposure to the test item and the incidence and severity of all abnormalities including behavioural and clinical observations, necropsy findings, bodyweight changes, mortality and any other toxicological effects. Using the mortality data obtained, an estimate of the acute inhalation median lethal concentration (LC50) of the test item was made.
Statistics:
No statistical analysis was performed as only one group was allocated to the study.

Results and discussion

Preliminary study:
Not applicable
Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.19 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: CL not given
Mortality:
All animals survived the scheduled observation period.
Clinical signs:
Signs of hunched posture, pilo-erection and red/brown staining around the eyes and/or snout are commonly seen in animals for short periods on removal from the chamber following 4-Hour inhalation studies. Wet fur is commonly recorded both during and for a short period after exposure. These observations are considered to be associated with the restraint procedure and, in isolation, are not indicative of toxicity.
In addition to the observations considered to be due to the restraint procedure, increased respiratory rate was noted in all animals during exposure, on removal from the chamber and one hour post-exposure.
One day after exposure, all animals exhibited increased respiratory rate, hunched posture and pilo-erection. Signs of recovery were noted on Day 2, however, on Day 3 one female animal showed a deterioration in condition; decreased respiratory rate, laboured respiration and hunched posture were now apparent and persisted until Day 4. Subsequently, animals recovered to appear normal from Days 5 to 8 post-exposure.
Body weight:
All animals exhibited bodyweight losses or showed no bodyweight gains on the first day post-exposure. All animals exhibited bodyweight gains during the remainder of the recovery period, with the exception of one female animal which a slight bodyweight loss from Days 1 to 3 post-exposure.
Gross pathology:
With the exception of one instance of dark patches on the lungs, no macroscopic abnormalities were detected amongst animals at necropsy.
Other findings:
Not applicable.

Any other information on results incl. tables

It is noted that the MMAD and GSD exceed the ranges given in the test guidelines (1-4 μm and 1.5 – 3.0 respectively). These deviations are considered to be due to the physical characteristics of the test item, even after significant grinding these values could not be improved further. These results show that the aerosol concentration achieved was at the technical limit with a respirable particle size.

At a mean achieved concentration of 5.19 mg/L the animals were exposed to approximately 2.51 mg/L particles <4 μm. It must be noted that if a MMAD of 4 μm had been achieved at a concentration of 5 mg/L then the approximate concentration of particle that the animals would have been exposed to that were <4 μm would have been 2.50 mg/L. Therefore, it can be considered that the slight increase in the MMAD achieved during this study is considered not to be significant.

It was not possible to determine oxygen concentrations for the formal exposure due to a malfunction of the oxygen analyser, however, as the oxygen concentration was taken during the characterisation phase of the study it can be concluded that this test item does not deplete oxygen. It can therefore be considered that the oxygen concentration would have been maintained above 19 % as per the characterisation phase of the study.

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
No deaths occurred in a group of six rats exposed to a mean achieved atmosphere concentration of 5.19 mg/L for four hours. It was therefore considered that the acute inhalation median lethal concentration (4 hr LC50) of Tetrairon tris (pyrophosphate), in the RccHanTM : WIST strain rat, was greater than 5.19 mg/L (Globally Harmonised Classification System – unclassified).
This study is conducted according to an appropriate guideline and under the conditions of GLP, the study is therefore considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint.