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Acute Toxicity: dermal

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Administrative data

Endpoint:
acute toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Study period:
The study was performed between 12 May 2010 and 26 May 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 402 (Acute Dermal Toxicity)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.3 (Acute Toxicity (Dermal))
Deviations:
no
Principles of method if other than guideline:
The sequence of dosing may not always follow the Test Guideline as shown in the schematic diagram in attachment 1. It is Company Policy to minimisethe number of animals used on each study in accordance with UK Government Home Office guidelines.
GLP compliance:
yes (incl. certificate)
Remarks:
Date of Inspection: 15 September 2009 Date of signature: 26 November 2009
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Sponsor's identification: Disodium dihydrogenpyrophosphate
Description : white solid
Batch number : 447/09
Date received : 18 September 2009
Expiry date : 31 August 2011
Storage conditions: room temperature in the dark over silica gel

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
Test Animals:
Animals: Rat, HsdRccHan: WIST

Rationale: Recognized by international guidelines as a recommended test system.

Breeder: Harlan Laboratories UK Limited, Oxon, UK.

Number of Animals per Group: 5 males and 5 females

Total number of Animals: 5 males and 5 females

Age when treated: At the start of the study the animals weighed at least 200g, and were eight to twelve weeks of age. The weight variation did not exceed ± 20% of the mean weight for each sex.

Identification: 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.

Acclimatization: At least 5 days under laboratory conditions, after health examination. Only animals without any visible signs of illness were used for the study.

Environmental Conditions:
Conditions:
The temperature and relative humidity were within the range of 19 to 21 cC and 45 to 56% respectively. 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.

Accommodation:
The animals were housed in suspended solid-floor polypropylene cages furnished with woodflakes. The animals were housed individually during the 24-hour exposure period and in groups of five, by sex, for the remainder of the study.

Diet:
Free access food (2014 Teklad Global Rodent diet supplied by Harlan Laboratories UK, Oxon, UK) was allowed throughout the study. The diet was routinely analysed and were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Water:
Free access to mains drinking water was allowed throughout the study. The drinking
water was routinely analysed and were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Administration / exposure

Type of coverage:
semiocclusive
Vehicle:
arachis oil
Details on dermal exposure:
On the day before treatment the back and flanks of each animal were clipped free of hair.

Using available information on the toxicity of the test material, a group of five male and five female rats was treated with the test material at a dose level of 2000 mg/kg.

The appropriate amount of test material, moistened with arachis oil, was applied as evenly as possible to an area of shorn skin (approximately 10% of the total body surface area). A piece of surgical gauze was placed over the treatment area and semi-occluded with a piece of self adhesive bandage. The animals were caged individually for the 24-Hour exposure period. Shortly after dosing the dressings were examined to ensure that they were securely in place.
Duration of exposure:
24 hours
Doses:
2000 mg /kg body weight
No. of animals per sex per dose:
5
Control animals:
not required
Details on study design:
After the 24-Hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with distilled water to remove any residual test material. The animals were returned to group housing for the remainder of the study period.

The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for fourteen days.

After removal of the dressings and subsequently once daily for fourteen days, the test sites were examined for evidence of primary irritation and scored according to the following scale from Draize J H (1977) "Dermal and Eye Toxicity Tests" In: Principles and Procedures for Evaluating the Toxicity of Household Substances, National Academy of Sciences, Washington DC p.31:

EVALUATION OF SKIN REACTIONS
Erythema and Eschar Formation Value
No erythema 0
Very slight erythema (barely perceptible) 1
Well-defined erythema 2
Moderate to severe erythema 3
Severe erythema (beef redness) to slight eschar formation (injuries in depth) 4
Oedema Formation
No oedema 0
Very slight oedema (barely perceptible) 1
Slight oedema (edges of area well-defined by definite raising) 2
Moderate oedema (raised approximately 1 millimetre) 3
Severe oedema (raised more than 1 millimetre and extending beyond the area of exposure) 4

Any other skin reactions, if present were also recorded.

Individual bodyweights were recorded prior to application of the test material on Day 0 and on Days 7 and 14.

At the end of the study 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.



Statistics:
No statistical analysis was performed.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LD50
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
Remarks on result:
other: 95% confidence limits not reported.
Mortality:
No deaths occurred during the study.
Clinical signs:
No clinical signs were observed during the course of the study.

There were no signs of dermal irritation.
Body weight:
All animals showed expected gains in bodyweight over the study period.
Gross pathology:
No macroscopic findings were recorded at necropsy.
Other findings:
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 Initiation of Exposure (Hours)

Effects Noted After Initiation of Exposure (Days)

½

1

2

4

1

2

3

4

5

6

7

8

9

10

11

12

13

14

2000

1-0

Male

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1-1

Male

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1-2

Male

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1-3

Male

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1-4

Male

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

2-4

Female

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0



0= No signs of systemic toxicity

See attachment for Tables 2 - 4

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
The acute dermal median lethal dose (LD50) of the test material in the Wistar strain rat was found to be greater than 2000 mg/kg bodyweight.
Disodium dihydrogenpyrophosphate is not considered to be classified according to Regulation (EC) No. 1272/2008 (EU CLP).

This study is considered to be reliable and acceptable for use as a key study.
Executive summary:
Introduction. The study was performed to assess the acute dermal toxicity of the test material in the Wistar strain rat. The method was designed to meet the requirements of the following

OECD Guidelines for the Testing of Chemicals No. 402 “Acute Dermal Toxicity” (adopted24 February 1987)

Method B3 Acute Toxicity (Dermal) of Commission Regulation (EC) No. 440/2008

Method. A group of ten animals (five males and five females) was given a single, 24-hour, semi‑occluded dermal application of the test material to intact skin 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.

Dermal Irritation. There were no signs of dermal irritation.

Bodyweight. All animals showed expected gains in bodyweight over the study period.

Necropsy. No abnormalities were noted at necropsy.

Conclusion. The acute dermal median lethal dose (LD50) of the test material in the Wistar strain rat was found to be greater than 2000 mg/kg bodyweight.