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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
26th July 2010 - 30 August 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
Values for relative humidity above the range occasionally occurred, usually following room cleaning, and were considered not to have any influence on the study.
Qualifier:
according to
Guideline:
EU Method B.2 (Acute Toxicity (Inhalation))
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
yes
Remarks:
Values for relative humidity above the range occasionally occurred, usually following room cleaning, and were considered not to have any influence on the study.
GLP compliance:
yes (incl. certificate)
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Identification:
Calcium bis(dihydrogenorthophosphate),
(MONOCALCIUM PHOSPHATE ANHYDROUS (C11-01)

Description: Powder
Batch Number: B02930A

Purity:
95%

Expiry Date (Retest Date):
04-May-2010
Supplier of Test Item: Budenheim KG
Rheinstrasse 27
55257 Budenheim / Germany

Storage conditions:
At room temperature, protected from direct sunlight.

Test animals

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

- Source:
Harlan Laboratories B.V., Kreuzelweg 53, 5961 NM Horst / Netherlands

- Age at study initiation:
Males: 11 weeks, Females: 11 weeks

- Weight at study initiation:
Males: 300.6 to 318.0 g, Females: 189.6 to 217.6 g

- Fasting period before study:
Not applicable

- Housing:
Animals were housed in groups of 5 of the same sex in Makrolon® type-IV cages with wire mesh tops and standard softwood bedding ("Lignocel" J. Rettenmaier & Söhne GmbH & Co KG, 73494 Rosenberg / Germany, imported by Provimi Kliba AG, 4303 Kaiseraugst / Switzerland) including paper enrichment (Enviro-dri from Lillico, Biotechnology, Surrey, UK).

- Diet (e.g. ad libitum):
Animals had ad libitum access to a pelleted standard Harlan Teklad 2914C rat maintenance diet (Provimi Kliba AG, 4303 Kaiseraugst, Switzerland) batch no. 20/10 except during the period when the animals were restrained in exposure tubes. Results of the analyses for contaminants and their limits of acceptability are archived at Harlan Laboratories Ltd.

- Water (e.g. ad libitum):
Community tap water from Füllinsdorf ad libitum in water bottles, except during the period when they were restrained in exposure tubes. Results of representative analyses for contaminants are archived at Harlan Laboratories Ltd.

- Acclimation period:
Performed under Harlan Laboratories Study B68308 for eighteen days under laboratory conditions, after a 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
Optimal Hygienic Conditions (OHC) inside a barrier system. Air-conditioned with 10 - 15 air changes per hour, continuously monitored environment with a temperature range of 22 ± 3 °C, a relative humidity range of 30 - 70% and a 12 hour fluorescent light / 12 hour dark cycle. Values for relative humidity above the range occasionally occurred, usually following room cleaning, and were considered not to have any influence on the study. These data are not reported but retained at Harlan Laboratories Ltd. A radio program was played during most of the light period.

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

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Remarks:
flow-past
Vehicle:
clean air
Mass median aerodynamic diameter (MMAD):
>= 2.95 - <= 3.03 µm
Geometric standard deviation (GSD):
>= 2.97 - <= 3.06
Remark on MMAD/GSD:
Mean Mass Median Aerodynamic Diameter (µm) 3.03, 2.95 and 3.03
Geometric Standard Deviation 3.06, 2.97 and 3.04
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus:
A CR3020 rotating brush aerosol generator connected to a micronizing jet mill. The aerosol generated was then discharged into the exposure chamber through a 63Ni charge neutralizer.

- Exposure chamber volume:
Not applicable (nose-only, flow-past inhalation exposure chamber)

- 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.

- Method of conditioning air:
Respiratory quality filters

- System of generating particulates/aerosols:
A dust aerosol was generated from the test item using a CR3020 rotating brush aerosol generator connected to a micronizing jet mill. The aerosol generated was then discharged into the exposure chamber through a 63Ni charge neutralizer.

- Method of particle size determination:
Mercer Impactor (Model 02-130, In-Tox. Products Inc., Albuquerque, New Mexico, U.S.A.).

- Treatment of exhaust air:
Filtered

- Temperature, humidity, pressure in air chamber:
The oxygen concentration, temperature and relative humidity of the test atmosphere were measured continuously during the exposure on test aerosol samples taken at a representative exposure port using a calibrated device. The results were recorded manually and are reported at 30 minute intervals from the start of exposure.

TEST ATMOSPHERE
- Brief description of analytical method used:
Gravimetric determinations of aerosol concentration were performed four times during exposure. The samples were collected on a Millipore®durapore filter, Type HVLP loaded in a 47 mm in-line stainless steel filter sampling device. The filters were weighed before and immediately after sampling using a calibrated balance. The test aerosol concentration was calculated from the amount of test item present on the filter and the sample volume.

- Samples taken from breathing zone:
yes

VEHICLE
No vehicle used.

Analytical verification of test atmosphere concentrations:
no
Remarks:
Gravimetric only
Duration of exposure:
4 h
Concentrations:
Mean Achieved (mg/L) 2.6
The nominal aerosol concentration was 7.5 mg/L air.
Mean Mass Median Aerodynamic Diameter (µm) 3.03, 2.95 and 3.03
Inhalable Fraction (% <4 µm) 59.8% , 61.8 and 59.9%
Geometric Standard Deviation 3.06, 2.97 and 3.04
No. of animals per sex per dose:
5
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 (day 1) and on Days 2, 4, 8 and 15 or at death.

- Necropsy of survivors performed:
yes

- Other examinations performed:
None
Statistics:
No statistical analysis was performed as only one group was allocated to the study.

Results and discussion

Preliminary study:
Not applicable
Effect levels
Key result
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 2.6 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Mortality:
All animals survived the scheduled observation period.
Clinical signs:
Slight to moderate ruffled fur was noted in all animals on test day 1, one hour after the end of the exposure and persisted slightly until test day 2 in nine animals. From test day 3 onwards, all animals were free from clinical signs until their scheduled necropsy.
Body weight:
From test day 1 to test day 2, marginal to slight body weight loss was noted in all animals. Thereafter all animals gained weight until scheduled necropsy.
Gross pathology:
There were no macroscopic findings.
Other findings:
Not applicable.

Any other information on results incl. tables

The nominal aerosol concentration was 7.5 mg/L air.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The LC50 of Calcium bis(dihydrogenorthophosphate) obtained in this study was estimated to be greater than 2.6 mg/L air (gravimetrically determined mean aerosol concentration). This was the highest technically achievable test concentration. There was no indication of relevant sex-related differences in toxicity of the test item.

In accordance with Regulation (EC) No. 1272/2008 (EU CLP) calcium bis(orthophosphate) is not considered to be classified as acutely toxic via the inhalation route.
Executive summary:

A group of five male and five female albino rats [RccHanTM:WIST(SPF)] was exposed by nose-only, flow-past inhalation for four hours to the test item at agravimetricallydetermined mean concentration of 2.6 mg/L air.All animals were observed for clinical signs and mortality during the inhalation exposure and the subsequent 14-dayobservation period. Body weights were recorded prior to exposure on test day 1, and during the observation period on test days 2, 4, 8 and 15 before necropsy. On test day 15 all animals were sacrificed and necropsied.

The ranges of aerosol concentration, temperature, relative humidity, oxygen content and airflow rate measured during the exposure were considered to be satisfactory for a study of this type. In addition, the test item was considered to be respirable to rats.

 

All animals survived the scheduled observation period.

 

Slight to moderate ruffled fur was noted in all animals after the end of the exposure and was still present in most animals up to test day 2. Thereafter, all animals were free from clinical signs.

 

Transient body weight loss was noted in all animals from test day 1 to test day 2. Normal body weight development was observed thereafter.

 

No macroscopical findings were present at necropsy.

 

In conclusion, the LC50of Calcium bis(dihydrogenorthophosphate) obtained in this study was estimated to be greater than 2.6 mg/L air (gravimetrically determined mean aerosol concentration). There was no indication of relevant sex-related differences in toxicity of the test item.