Disodium hydrogenorthophosphate

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 14 October 2009 and 10 November 2009.

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 420 (Acute Oral Toxicity - Fixed Dose Method)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.1 bis (Acute Oral Toxicity - Fixed Dose Procedure)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of GLP inspection: 31/03/2010 Date of Signature on GLP certificate: 04/03/2009

Test type:

fixed dose procedure

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Disodium hydrogenorthophosphate

EC Number:

231-448-7

EC Name:

Disodium hydrogenorthophosphate

Cas Number:

7558-79-4

Molecular formula:

H3O4P.2Na

IUPAC Name:

disodium hydrogen phosphate

Test material form:

other: granular solid

Details on test material:

Sponsor's identification : Disodium hydrogenorthophosphate
Description : white granular solid
Batch number : 445/09
Date received : 18 September 2009
Storage conditions : room temperature in the dark over silica gel

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

Female Wistar ( HsdRccHan®™:WIST®™) strain rats were supplied by Harlan Laboratories UK Limited, Bicester, Oxon, UK. On receipt the animals were randomly allocated to cages. The females were nulliparous and non-pregnant. After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink marking on the tail and a number written on a cage card. At the start of the study the animals were eight to twelve weeks of age. The bodyweight variation did not exceed ± 20% of the initial/mean bodyweight of any previously dosed animal(s).
The animals were housed in groups of up to four in suspended solid floor polypropylene cages furnished with woodflakes. With the exception of an overnight fast immediately before dosing and for approximately three to four hours after dosing, free access to mains drinking water and food (2014 Teklad Global Rodent diet supplied by Harlan Teklad, Blackthorn, Bicester, Oxon, UK) was allowed throughout the study. The diet, drinking water and bedding were routinely analysed and were considered not to contain any contaminants that would reasonably be expected to affect the purpose or integrity of the study.
The temperature and relative humidity were set to achieve limits of 19 to 25°C and 30 to 70% respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was at least fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness.
The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

Procedure
Using available information on the toxicity of the test material, 2000 mg/kg was chosen as the starting dose.

Dose Level Concentration Dose Volume Number of Rats
(mg/kg) (mg/ml) (ml/kg) Female
2000 200 10 1


In the absence of toxicity at a dose level of 2000 mg/kg, an additional group of animals was treated as follows:
Dose Level Concentration Dose Volume Number of Rats
(mg/kg) (mg/ml) (ml/kg) Female
2000 200 10 4

A total of five animals were therefore treated at a dose level of 2000 mg/kg in the study.
All animals were dosed once only by gavage using a metal cannula attached to a graduated syringe. The volume administered to each animal was calculated according to its fasted bodyweight at the time of dosing.
Clinical observations were made ½, 1, 2, and 4 hours after dosing and subsequently once daily for fourteen days. Morbidity and mortality checks were made twice daily.
Individual bodyweights were recorded on Day 0 (the day of dosing) and on Days 7 and 14.
At the end of the observation period the animals were killed by cervical dislocation. All animals were subjected to gross necropsy. This consisted of an external examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were retained.

Doses:

Following a sighting test at a dose level of 2000 mg/kg, an additional four fasted female animals were given a single oral dose of test material, as a suspension in arachis oil, at a dose level of 2000 mg/kg bodyweight. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

No. of animals per sex per dose:

1 female at 2000 mg/kg
4 females at 2000 mg/kg

Control animals:

no

Details on study design:

- Duration of observation period following administration:
14 days

- Frequency of observations and weighing:
Clinical observations were made ½, 1, 2, and 4 hours after dosing and then daily for fourteen days. Morbidity and mortality checks were made twice daily. Individual bodyweights were recorded on Day 0 (the day of dosing) and on Days 7 and 14.

- Necropsy of survivors performed:
Yes

- Other examinations performed:
Clinical signs, body weight.

Statistics:

The test material will be classified according to Annex 3 of the OECD Guidelines for Testing of Chemicals No. 420 "Acute Oral Toxicity - Fixed Dose Method" (adopted 17 December 2001).

Evaluation of data included identification of the number of animals that died during the study (or that were killed for humane reasons), and determination of the nature, severity, onset and duration of the toxic effects. If possible, the signs of evident toxicity were described. Evident toxicity refers to the toxic effects of sufficient severity that administration of the next higher dose level could result in development of severe signs of toxicity and probable mortality. Effects on bodyweights and abnormalities noted at necropsy were also identified.
Using the mortality data obtained, an estimate of the acute oral median lethal dose (LD50) of the test material was made.

Results and discussion

Preliminary study:

A sighting test at a dose level of 2000 mg/kg was performed.

Effect levels

Sex:

female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 95% confidence limits not given in study report.

Mortality:

There were no deaths.

Clinical signs:

other: There were no signs of systemic toxicity.

Gross pathology:

Individual necropsy findings are given in Table 3.
No abnormalities were noted at necropsy.

Other findings:

- Organ weights:
Not recorded

- Histopathology:
Not recorded

- Potential target organs:
Not recorded

- Other observations:
None

Any other information on results incl. tables

Table1              Individual Clinical Observations and Mortality Data

Dose Level mg/kg	Animal Number and Sex	Effects Noted After Dosing (Hours)				Effects Noted During Period After Dosing (Days)
		½	1	2	4	1	2	3	4	5	6	7	8	9	10	11	12	13	14
2000	1-0 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	2-0 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	2-1 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	2-2 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
	2-3 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

 

Table2              Individual Bodyweights and Bodyweight Changes

Dose Level mg/kg	Animal Number and Sex	Bodyweight (g) at Day			Bodyweight Gain (g) During Week
		0	7	14	1	2
2000	1-0 Female	170	182	191	12	9
	2-0 Female	190	202	212	12	10
	2-1 Female	183	196	211	13	15
	2-2 Female	184	195	209	11	14
	2-3 Female	182	190	207	8	17

 

Table3              Individual Necropsy Findings

Dose Level mg/kg	Animal Number and Sex	Time of Death	Macroscopic Observations
2000	1-0 Female	Killed Day 14	No abnormalities detected
	2-0 Female	Killed Day 14	No abnormalities detected
	2-1 Female	Killed Day 14	No abnormalities detected
	2-2 Female	Killed Day 14	No abnormalities detected
	2-3 Female	Killed Day 14	No abnormalities detected

0= No signs of systemic toxicity

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The acute oral median lethal dose (LD50) of the test material in the female Wistar strain rat was estimated to be greater than 2000 mg/kg bodyweight (EU CLP - Unclassified).

This study is conducted according to an appropriate guideline and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint. In addition, the study is considered to be acceptable and reliable for the classification and labelling of disodium hydrogenorthophosphate in accordance with Regulation (EC) No. 1272/2008 (EU CLP).

Executive summary:

Introduction. 

The study was performed to assess the acute oral toxicity of the test material in the Wistar strain rat. The method was designed to meet the requirements of the following:

OECD Guidelines for Testing of Chemicals No 420 “Acute Oral Toxicity - Fixed Dose Method” (adopted 17 December 2001)

Method B1 bis Acute Toxicity (Oral) of Commission Regulation (EC) No. 440/2008

Method. 

Following a sighting test at a dose level of 2000 mg/kg, an additional four fasted female animals were given a single oral dose of test material, as a suspension in arachis oil BP, at a dose level of 2000 mg/kg bodyweight. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Mortality. 

There were no deaths.

Clinical Observations. 

There were no signs of systemic toxicity.

Bodyweight. 

All animals showed expected gains in bodyweight.

Necropsy. 

No abnormalities were noted at necropsy.

Conclusion. 

The acute oral median lethal dose (LD₅₀) of the test material in the female Wistar strain rat was estimated to be greater than 2000 mg/kg bodyweight (EU CLP -Unclassified).