Potassium hydrogencarbonate

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993-01-21 to 1993-06-10

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EPA OPP 81-2 (Acute Dermal Toxicity)

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Potassium hydrogencarbonate

EC Number:

206-059-0

EC Name:

Potassium hydrogencarbonate

Cas Number:

298-14-6

Molecular formula:

CH2O3.K

IUPAC Name:

potassium hydrogen carbonate

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Albino rabbits strain Hra:(NZW)SPF
- Source: Hazleton Research Products, Inc., Hazleton Wisconsin facility at 3802 Packers Avenue, Madison, Wisconsin, USA
- Age at study initiation: young adults
- Weight at study initiation: males 2431 to 2829 g (mean 2602 g), females 2432 to 2699 g (mean 2596 g)
- Fasting period before study: no data in study summary
- Housing: individually housed in screenbottom cages in temperature- and humidity-controlled quarters
- Diet: ad libitum, High Fiber Rabbit ChoW® #5326, Purina Mills, Inc., USA
- Water: ad libitum
- Acclimation period: 21 days


ENVIRONMENTAL CONDITIONS
- Temperature: 20 to 24 °C
- Humidit:y: 54 to 67% relative humidity
- Air changes (per hr): no data in study summary
- Photoperiod (hrs dark / hrs light): no data in study summary

Administration / exposure

Type of coverage:

occlusive

Vehicle:

water

Details on dermal exposure:

TEST SITE
- Area of exposure: back, clipped free of hair with an electric clipper. The clipped area made up not less than10% of the total body surface.
- % coverage: 10 x 10 cm patch
- Type of wrap if used: occlusive

REMOVAL OF TEST SUBSTANCE
- Washing (if done): test sites were washed using tap water and disposable paper towels
- Time after start of exposure: 24 hours

Preparation of Test Material
An individual dose of test material was calculated and weighed out based on each animal's body weight on the day of test material administration. Each dose was thoroughly moistened with 0.9% saline before application.

Treatment
The test material was applied to the intact skin on each animal's back at a dose level of 2000 mg/kg of body weight. The area of application was covered with a 10-cm x 10-cm gauze patch secured with paper tape and overwrapped with Saran Wrap® and Elastoplast® tape. The test material was applied to the test site at a rate of approximately 0.05 g/cm2 in a thin and uniform layer. Collars were used to restrain the test animals during the 24-hour exposure period. At the end of the 24-hour exposure period, the restraining collars and bandages were removed and the test sites were washed using tap water and disposable paper towels.

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
-- Clinical observations and mortality checks were conducted at approximately 1, 2.5, and 4 hours after test material administration. Additional clinical observations and twice a day mortality checks (morning and afternoon) were conducted daily thereafter for 14 days.
--Body weights were determined before test material application (Day 0), at Day 7, and at termination of the experimental phase (Day 14).
-- The initial dermal irritation reading was made approximately 30 minutes after removal of the test material according to the Draize technique (recorded as the Day 1 score). Subsequent readings of dermal irritation were made on Days 3, 7, 10, and 14.
- Necropsy of survivors performed: yes, At termination of the experimental phase, all animals were euthanized, subjected to an abbreviated gross necropsy examination, and any abnormalities were recorded.
- Other examinations performed: no

Statistics:

No

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Remarks on result:

other: no animal died

Mortality:

All animals survived.

Clinical signs:

All animals appeared clinically normal throughout the study.

Body weight:

All animals gained weight.

Gross pathology:

The gross necropsy at termination revealed no visible lesions with the exception of an incidental dermal finding in one animal.

Other findings:

Dermal reactions:
Dermal irritation (based on the most severe score for each animal at any time point) consisted of slight to moderate erythema and slight edema, atonia, and desquamation (no individual scores reported in available study summary). No other dermal irritation was observed. The slight to moderate dermal irritation cleared in all animals by Day 10.

At necropsy, the skin of the mid-dorsal region of one male had multiple red, dry crusted areas of variable size. Although possibly caused by the test material, in the absence of similar changes in the skin of all other animals, these changes were probably incidental. There were no visible lesions in the remaining animals.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

On the basis of the results obtained after a single dermal administration, the oral LD50 of the test article "Potassium Biarbonate"
was determined to be > 2000 mg/kg bw. All animals survived. No significant clinical signs, effects on body weight or gross pathological findings were observed apart from slight to moderate dermal irritation at the dose site of all animals.

Executive summary:

In an acute dermal toxicity study performed according to the guideline US EPA OPP 81-2 (Acute Dermal Toxicity) which is similar to OECD Guideline 402 (Acute Dermal Toxicity), 5 male and 5 female young adult albino rabbits strain Hra:(NZW)SPF were dermally exposed to the test article "Potassium Bicarbonate" moistened with 0.9% saline for 24 hours at a dose of  2000 mg/kg bw (limit test). Animals then were observed for 14 days.

 

Dermal LD₅₀ Combined:  > 2000 mg/kg bw

 

No animal died in this limit test.       

 

No significant clinical signs or effects on body weight were observed, apart from dermal irritation at the dose site of all animals. There were no treatment related gross necropsy findings at terminal sacrifice.

 

Dermal irritation (based on the most severe score for each animal at any time point) consisted of slight to moderate erythema and slight edema, atonia, and desquamation (no individual scores reported in available study summary). No other dermal irritation was observed. The slight to moderate dermal irritation cleared in all animals by Day 10. At necropsy, the skin of the mid-dorsal region of one male had multiple red, dry crusted areas of variable size. Although possibly caused by the test material, in the absence of similar changes in the skin of all other animals, these changes were probably incidental. There were no visible lesions in the remaining animals.