Registration Dossier

Administrative data

acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-07-11 to 2016-11-21
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
Version / remarks:
individual chamber conc. samples deviated from mean chamber conc. by more than ±20 %; time to chamber equilibrium was not determined; GSD on particle size determinations were > 3 µm; rel. humidity was < 30% during exposure
GLP compliance:
yes (incl. QA statement)
signed 2016-09-23
Test type:
acute toxic class method
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
Triiron bis(orthophosphate)
EC Number:
EC Name:
Triiron bis(orthophosphate)
Cas Number:
Molecular formula:
Fe.2/3H3O4P or Fe3(PO4)2
tris(lambda2-iron(2+)) diphosphate
Test material form:
solid: particulate/powder
Details on test material:
- State of aggregation: solid (light grey powder)
- Average particle size: 6.3 µm
- Bulk density: 490 g/L
Specific details on test material used for the study:
- Storage condition of test material: room temperature and protected from light

- Treatment of test material prior to testing: test material was desiccated for about 72 hours and subjected to three 60 minute-sieving rounds

Test animals

Details on test animals or test system and environmental conditions:
- Source: Charles River, C/Argenters 7, Local AB, 08290 Cerdanyola del Valles, Barcelona, Spain
- Females nulliparous and non-pregnant: yes
- Age at study initiation: about 9 weeks
- Weight at study initiation: mean weights 309.1 g/ 256.0 g (males/ females)
- Housing: housed in groups of three; bedding material: Capsumlab Lecho_10 (autoclavable)
- Diet (ad libitum): Teklad certified irradiated Global 14 % protein rodent maintenance diet (2914C) (Harlan Teklad, Oxon, UK)
- Water (ad libitum): tap water
- Acclimation period: 12 days

- Temperature: 14.8 - 22.1 °C
- Relative humidity: 21 % - 59 %
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
clean air
Mass median aerodynamic diameter (MMAD):
1.26 µm
Remark on MMAD/GSD:
Mean mass median aerodynamic diameter of particle size distribution (PSD) (1.26 µm) was calculated from two gravimetric measurements PSD#1 and PSD#2. PSD#1 resulted in a MMAD of 0.43 µm with a geometrical standard deviation (GSD) of 5.92 and PSD#2 resulted in a MMAD of 2.08 µm with a GSD of 3.1. The GSD on PSD#1 abd Psd#2 was above the upper limit of 3 but considered acceptable as more than 73 % of particles were below the upepr limit of 4 µm in both cases (74.0 % for PSD#1 and 73.5 % for PSD#2).
Details on inhalation exposure:
- Exposure apparatus: flow-past, nose-only exposure chamber type EC-FPC-232 (anodised aluminium), equipped with glass exposure tubes were used. Before treatment start, the homogeneity for the different levels of the exposure chamber was confirmed. The exposure system ensured a uniform distribution and provided a constant flow of test material to each exposure tube. The flow of air at each tube was approximately 1 L/min, which was sufficient to minimize rebreathing of the test aerosol as it is more than twice the respiratory minute volume of rats.
- Exposure chamber volume: approx. 3 L
- Method of holding animals in test chamber: animals were confined separately in restraint tubes which were positioned radially around the exposure chamber.
Acclimatisation to the nose-only restraining tubes was performed for about 90 minutes on the day of exposure

- System of generating particulates/aerosols: a dust aerosol was generated from the desiccated and sieved test item using a Dust Generator SAG 410 (TOPAS GmbH, Germany). The dust was diluted with filtered air from a compressor and conveyed via glass tubing, from the generator to the exposure chamber. The flow rate through the exposure chamber was adjusted as necessary.

- Method of particle size determination: particle size distribution was determined gravimetrically twice during exposure. Cumulative particle size distribution of the dust was determined using a PIXE cascade impactor. Particle size distribution of the test material in the generated dust was measured bygravimetry analyzing the test item deposited on each stage of the cascade impactor. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) were calculated on the basis of the results from the impactor.

- Temperature, humidity,and air flow: temperature and relative humidity in the chamber were measured continuously during exposure using a thermohygrometer (Kimoth110, Kimo) and reported approx. hourly:
Temperature: 21.7 °C to 22.5 °C (mean value: 22.2 °C ± 0.4 °C)
Relative humidity: 17.1 % to 20.0 % (mean value: 18.6 % ± 1.2)
Exposure airflow rate was adjusted as appropriate before the start of the exposure using the pressure difference over a Venturi tube. Actual airflow rate was monitored hourly in each group during exposure. Target range was 0.5 - 1 L/min through each inhalation tube.
Mean oxygen and carbon dioxide concentrations were 20.9 % and 0.04 % respectivley.

- Brief description of analytical method used: gravimetric determination of the dust concentration was performed once during each hour of exposure. Samples were collected onto a Whatman filter (grade F319-04) using a filter sampling device. Sampling flow was similar to the air flow rate per exposure port. Duration of sampling was 2 minutes. Filters were weighed before and immediately after sampling using a calibrated balance. Gravimetric dust concentration was calculated from the amount of test material present on the filter and the sample volume.
- Samples taken from breathing zone: yes

- Rationale for the selection of the starting concentration: the target starting dose was 2 mg/L air. According to the results from the technical trials, this concentration was found to be the highest technically achievable that could be maintained for at least 4 hours. However, during the study a mean dose of 2.76 mg/L air could be achieved. In a technical trial, an initially dust concentration of 5 mg/L air was aimed to achieve, but saturation and blockade of the system was observed shortly after starting.
Analytical verification of test atmosphere concentrations:
see above "Details on inhalation exposure"
Duration of exposure:
4 h
2.76 mg/L ± 1.06 (actual concentration)
2.0 mg/L (target concentration)
No. of animals per sex per dose:
3 males / 3 females
Control animals:
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: animals were examined daily for mortality and moribidity. Clinical observation were performed hourly during exposure (only grossly abnormal signs), immediately and 1 hour after exposure, and once daily thereafter until the end of the observation period. All animals were weighed on the day of treatment just before starting exposure (study day 1), on study days 2, 4, 8 and immediately before sacrifice on study day 15.
- Necropsy of survivors performed: yes, consisting of the examination of the abdominal and thoracic cavities and contents. Special attentian was paid to any change in the respiratory tract.
No statistical analysis was required.

Results and discussion

Effect levels
Key result
Dose descriptor:
Effect level:
> 2.76 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: maximum attainable dose
No animal died prematurely.
Clinical signs:
other: No grossly abnormal signs were observed during the 4 hour exposure period. Main clinical signs after exposure were transient piloerection, loud breathing, dirty fur and prostration. Piloerection was observed in all three males and one female immediately
Body weight:
A decrease in mean body weight of approx. 7 % in males and 5 % in females was observed between study day 1 (exposure) and study day 2. From study day 2 to the end of the observation period, body weight increased gradually in all three males and in two females. In one female, a body weight decrease of ~ 1.4 % was observed between study days 8 and 15.
Mean body weight gains of approx. 13 % and 2.5 % were recorded for males and females, respectively, during the 14 days observation period.
Gross pathology:
No necropsy macroscopic findings were present in any of the animals

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
LC50 (male and female rats) > 2.76 mg/L (maximum attainable dose)
According to the Regulation (EC) No 1272/2008 and subsequent adaptations, the substance is not acutely toxic via the inhalative route.