Potassium propionate

Endpoint summary

Description of key information

- published data (Smyth et al., 1962), male Wistar rats were administered orally several doses of propionic acid. The LD50 value was determined according to the method of Thompson using the Tables of Weil. The LD50 was reported to be 4.29 g/kg bw, not classified

- published data (Rodrigues et al. 1986), male Fischer 344 rats were administered 4% propionic acid in feed for 9 - 27 days. The parameters observed were cell proliferation by measurement of incorporation of [methyl-3H]thymidine and histopathology of the forestomach in order to detect neoplatic lesions. These changes were only observed after 21 and 27 days respectively, thus propionic acid is expected to be of low toxicity.

- published data (Harshbarger et al. 1942), Wistar rats were orally administered calcium and sodium propionate at 1% and 3% in feed, There were no changes in body weight gain in the treatment groups compared to the control group, thus, the highest applied dose which caused no effect was 2200 mg/kg bw (3% dose group), not classified

- published data (Bueld and Netter 1992), Male wistar rats were exposed to feed containing either powdered diet with 4% propionic acid or pelleted feed containing 8% propionic acid, In the group treated with the pelleted feed no hyperplasias were observed whereas in the group fed with powdered diet hyperplasias occurred. No other signs of toxicity were reported, thus, the dose at which the first adverse effect was observed (i.e. changes in the forestomach tissues) was 3600 mg/kg bw. after 12 weeks repeated exposure, not classified

- QSAR calculation with ACD/Percepta: Rat Oral Acute Toxicity (2012). ACD/Labs Tox Suite version 2.95.1.. The alogrithm used by ACDLabs is based on baseline toxicity of structural fragments and a comparison of the experimental data and the baseline LD50 predictions for the five most similar compounds in the training set. The GALAS modelling methodology was used to build this model. The GALAS model is described in details in Sazonovas et al. (2010). The GALAS model is a combination of the following two systems: 1) A global baseline QSAR model: a fragment-based QSAR model to predict LD50 values was constructed and constitutes the baseline model. 2) Local corrections: any baseline LD50 prediction is subjected to the local similarity correction procedure, in order to capture the deviations from linear trend of the responses that may occur in specific chemical spaces. The LD50 for potassium propionate was estimated to be 2700 mg/kg bw with a RI of 0.88 (robust prediction)

- Trendanalysis with OECD QSAR Toolbox 4.4.1. The LD50 was estimated with a linear approximation from LD50 values of strucutral similar substances. Th LD50 was estimated to be 7570 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD guideline 408 (90 day repaeted dose toxicity study)

Deviations:

yes

Remarks:

rats were exposed to propionic acid via food either as powedered or pelleted feed for 12 or 20 weeks. The occurrence of hyperplasias in the forestomach and the accumulation of propionic acid were evaluated.

Principles of method if other than guideline:

- Principle of test: Exposure of male Wistar rats to 0, 4%, and 8% propionic acid in feed over 12 and 20 weeks respectively, to investigate the occurrence of hyperplasias and the accumulation of propionic acid in the forestomach.
- Short description of test conditions: Groups of six male Wistar rats (approx. 130g) were fed for 24wk a pelleted diet containing 0 or 8% PA . In a second experiment, four groups of male Wistar rats (24 in total; 120-140 g)
were fed either control powdered diet or powdered diet supplemented with 4% PA, 1% L-carnitine or 4%PA and 1% L-carnitine for 12wk. Body weights were taken at the start of the study and weekly thereafter. Food onsumption was determined daily by weighing the containers (after filling and before spilling on the next day at 9 am).
Food spillage was minimized by a special construction of the food containers; therefore it was not considered further. At the end of the study, rats were killed by CO2 inhalation. Parts of the food bolus within the forestomach and glandular stomach were collected and stored at - 20°C to prevent evaporation of PA. The remaining bolus was then removed with icecold saline, and the stomach was flattened and fixed while attached to a piece of cardboard and examined macroscopically. Sections taken parallel to the lesser curvature, including the forestomach, limiting ridge and glandular stomach, were pinned flat in Bouin's solution (saturated picric acid-37% formalin-glacial acetic acid; 15:4:1, by vol.) and prepared for haematoxylin and eosin staining.
- Parameters analysed / observed: macroscopically determination of hyperplasias, accumulation of propionic acid in the forestomach tissues.

GLP compliance:

no

Test type:

other: repeated dose oral toxicity study over at least 84 days

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: approx. 130 g in the first experiment and 120-140 g in the second experiment
- Fasting period before study: no
- Housing: In each experiment rats were housed two in Macrolon cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 55-60
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

water

Details on oral exposure:

For the preparation of food pellets, the appropriate amount of PA was diluted with water before being mixed with the powder. Pellets of about 10 g were pressed and air-dried for at least 3 days but stored not longer than 10 days.

Doses:

0, 4, and 8% in feed

No. of animals per sex per dose:

6

Control animals:

yes

Details on study design:

- Duration of observation period following administration: n/a; repeated dose study over 12 or 20 wk
- Frequency of observations and weighing: Body weights were taken at the start of the
study and weekly thereafter. Food consumption was determined daily by weighing the containers (after filling and before filling on the next day at 9 am).
- Necropsy of survivors performed: not specified
- Other examinations performed: body weight, macroscopically observation of the forestomach

Key result

Sex:

male

Dose descriptor:

other: macroscopical observation of changes in tissues of the forestomach; effects observed

Effect level:

3 600 mg/kg bw

Based on:

test mat.

Remarks:

dose calculated according to EFSA Scientific Commitee (2012), concentration as stated in the publication 4% propionic acid in the diet

Mortality:

not observed

Clinical signs:

other: other: not observed

Gross pathology:

When pelleted diet was used, no
hyperplasias were observed. Macroscopical and
histopathological examinations showed no changes in various parts of the gastric mucosa; this could be attributed to the administration of PA in pelleted food for 24 wk. After 12wk of administration, powdered PA produced severe changes in the forestomach but not in the glandular stomach.
Grossly, crater-like growths with marginal hyperplasias and central ulceration were found in the forestomachs of all animals, particularly in the prefundic region (area proximate to the glandular stomach). The limiting ridge was substantially thickened. No histological examinations were made.

Interpretation of results:

study cannot be used for classification

Conclusions:

The present study was conducted to examine the effects of 0, 4, and 8% propionic acid in the diet of the rats forestomach. Male wistar rats were exposed to feed containing either powdered diet with 4% propionic acid or pelleted feed containing 8% propionic acid. In the group treated with the pelleted feed no hyperplasias were observed whereas in the group fed with powdered diet hyperplasias occurred. No other signs of toxicity were reported, thus, the dose at which the first adverse effect was observed (i.e. changes in the forestomach tissues) was 3600 mg/kg bw. after 12 weeks repeated exposure.

Executive summary:

The study of Bueld and Netter (1992) was conducted to examine the effects of 0, 4, and 8% propionic acid in the diet to the rats forestomach. Groups of 6 male Wistar rats weighing approximately 130g were exposed to feed containing pelleted diet with 0 or 8% propionic acid for 24 weeks. In a second experiment six male Wistar rats each group were fed powdered diet containing 4% propionic acid for 12 weeks. In the group treated with the pelleted feed no hyperplasias were observed whereas in the group fed with powdered diet hyperplasias occurred. No other signs of toxicity were reported, thus, the dose at which the first adverse effect was observed (i.e. changes in the forestomach tissues) was 3600 mg/kg bw after 12 weeks repeated exposure. Based on the determined value propionic acid does not need to be classified with regard to acute oral toxicity according to Regulation (EU) No. 1272/2008 (CLP) under the conditions of the test.

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: Male Fischer 344 rats were administered 4% propionic acid in feed for 9 - 27 days. Animals were weighed daily on a top loading balance. Food consumption was determined daily by weighing the diet immediately after filling
the c!ontainer and again immediately preceding the next day's filling. One hour before death with Fluothane each rat was injected i.p. with 0.25 ~Ci/g [methyl-3H]thymidine. Each rat was dissected, the stomachs removed and 0.5 mL 10% buffered formalin (pH 7.2) instilled into the lumen.
The tissues were fixed in the same medium for at least 24 h. The forestomach was dissected sagitally, cleaned of its contents and slides prepared
for histopathology (H and E staining) or for radioautography using Kodak NTB-2 emulsion (1 : 1 dilution) on 5-µm sections with a 3-day development time. Labelled squamous epithelial cells were counted in both the prefundic region of the forestomach (1000 cells immediately adjacent to the fundic mucosa) and the mid-region of the forestomach (2000--4000 cells from the tissue immediately opposite to the opening between the forestomach and glandular stomach).
- Parameters analysed / observed: radioautography from forestomach cells, histopathology of the forestomach

GLP compliance:

no

Test type:

other: 9 - 27 days treatment

Limit test:

no

Species:

rat

Strain:

Fischer 344

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, Kingston, Ontario, Canada
- Age at study initiation: Weanling rats
- Weight at study initiation: 75g
- Housing: individually in stainless steel cages with hardwood chip bedding (C.I.P. Paper Products Div., Montreal, Quebec, Canada)
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 7 days

Route of administration:

oral: feed

Vehicle:

water

Doses:

4% in feed

No. of animals per sex per dose:

7 for treatment and 14 for controls

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 27 days
- Frequency of observations and weighing: daily body weighing and weighing of feed
- Necropsy of survivors performed: yes
- Other examinations performed: histopathology, radioautography

Statistics:

Separate statistical analyses of the radioautography results were carried
out for each experiment and forestomach region. As with previous data of
this nature, all analyses were carried out on the logarithmic scale.
Averages and differences on the logarithmic scale were transformed back to
the original scale where they represent geometric means and ratios of geo-
metric means respectively. Standard deviations on the logarithmic scale were
multiplied by 100 to yield approximate coefficients of variation on the
original scale. For each 'experiment-forestomach region' pairwise compari-
sons of each diet vs. the control diet were based on either a one-sided
Dunnett's t-test or a Student's t-test with the pooled variance estimate
from the corresponding analysis of variance. Analyses of variance were based
on either a one-way or a two-way classification and for the two-way classifi-
cations a preliminary F-test for diet X duration interaction was carried out.
Analysis of variance residuals were also screened to identify extreme observa-
tions or outliers .

Key result

Sex:

male

Dose descriptor:

other: Observed effect level

Effect level:

4 other: % in feed

Based on:

test mat.

Remarks on result:

other: effect were observable after 21 and 27 days only

Mortality:

not reported

Clinical signs:

other: other: not reported

Gross pathology:

Animals given 4% propionic acid for 27 days showed mucosal thickening along the lesser curvature and also nodular thickening on the anterior wall of the forestomach .

Other findings:

Four percent dietary propionic acid had no significant effect by 9 days in the prefundic region but induced a 5.6-fold increase in the labelling index of the midregion of the tissue by 27 days. To confirm this observation groups of 6 rats receiving 4% dietary propionic acid were killed 9, 15, 21 and 27 days after the start of treatment. The only change in the [methyl-3H] thymidine labelling index occurred at 21 and 27 days and was a 2.0-fold increase in the main body of the forestomach epithelium.

Interpretation of results:

study cannot be used for classification

Conclusions:

In the present study of Rodrigues et al. (1986) male Fischer 344 rats were administered 4% propionic acid in feed for 9 - 27 days. The parameters observed were cell proliferation by measurement of incorporation of [methyl-3H]thymidine and histopathology of the forestomach in order to detect neoplatic lesions. Changes in histopathology were only detected after 21 and 27 days of treatment, respectively, and compared to other susbtances used as preservatives the side of action was the midregion of the forstomach instead of the prefundic region. It is unlikely that propionic acid undergoes metabolic activation akin to that suggested for the phenolic chemicals that have been tested. The delayed proliferative effect observed in both studies may reflect the response of the forestomach epithelium to changed pH, thus, the effect is rather based on site of contact irritation than of systemic toxicity. The results substantiate the other available data providing evidence that propionic acid is of rather low acute oral toxicity.

Executive summary:

In the published study of Rodrigues et al. (1986) weanling male Fischer 344 rats weighing approximately 75g were acclimatized for at least 7 days and were then transferred to a propionic acid containing diet. The diet contained 4% propionic acid either in pelleted or powdered diet and was fed for 9-27 days. Afterwards the rats were injected i.p. with 0.25 µCi/g [methyl-3H]thymidine and subsequently dissected, the stomach was removed and stined for histopathology or radioautgraphy. Labelled squamous cells were counted in the prefundic and mid-region of the stomach. Changes in histopathology were only detected after 21 and 27 days of treatment, respectively, and compared to other susbtances used as preservatives the side of action was the midregion of the forstomach instead of the prefundic region. Thus, repeated exposure to 4% propionic acid in the diet revealed no signs of toxicity. Propionic acid is hence considered of low acute oral toxicity.

Reference 3

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

no guideline followed

Principles of method if other than guideline:

- Principle of test: White rats were fed diets containing calcium propionate, sodium propionate. Feeding of the experimental diets started when the rats were about four weeks of age and continued for four to five weeks. The toxicity of the substances was determined by chenges of body weight changes.
- Short description of test conditions: The paired-feeding technique was used, with a modification so that one control animal was compared with two experimental animals. Eight triplicates (24 rats) were fed during each part of the experiment. In each triplicate, litter mates of the same sex were used. Rats were fed with a basal diet containing calcium lactate, a second group was fed diets containing 1 per cent and 3 per cent calcium propionate, and a third group was fed diets containing 1 per cent and 3 per cent sodium propionate. Body weight gain was observed and recorded for four weeks.
- Parameters analysed / observed: Body weight gain

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

not specified

Route of administration:

oral: feed

Vehicle:

water

Doses:

no exact values reported

No. of animals per sex per dose:

8

Control animals:

yes

Remarks:

The paired-feeding technique was used, with a modification so that one control animal was compared with two experimental animals.

Details on study design:

- Duration of observation period following administration: 4 weeks

Key result

Sex:

not specified

Dose descriptor:

LD0

Effect level:

2 200 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 3% sodium or calcium propionate was administered corresponding to 0.75 g/kg bw and 2.2 g/kg bw respectively

Mortality:

not reported

Clinical signs:

other: other: not reported

Interpretation of results:

study cannot be used for classification

Conclusions:

In the present study of Harshbarger (1942) Wistar rats were orally administered calcium and sodium propionate at 1% and 3% in feed. The toxicity parameter which was observed was body weight gain. There were no changes in body weight gain in the treatment groups compared to the control group, thus, the highest applied dose which caused no effect was 2200 mg/kg bw (3% dose group). Hence the neither calcium nor sodium propionate are callsified with respect to acute oral toxicity.

Executive summary:

In the study of Harshbarger (1942) Wistar rats were orally administered calcium and sodium propionate at 1% and 3% in feed for 3 and 4 weeks, respectively. The toxicity parameter which was observed was body weight gain. There were no changes in body weight gain in the treatment groups compared to the control group, thus, the highest applied dose which caused no effect was 2200 mg/kg bw (3% dose group). Hence, neither calcium nor sodium propionate need to be classified with respect to acute oral toxicity according to Regulation (EU) No. 1272/2008 (CLP).

Reference 4

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

exact doses and number of doses were not reported, dosages were arranged in a logarithmic series differing by a factor of two.

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

Carworth-Wistar male rats

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Rationale for alternative/additional species to rat (if applicable)
- Source: reared in own colony
- Age at study initiation: 4 to 5 weeks
- Weight at study initiation: 90 to 120 g
- Diet (e.g. ad libitum): during maintenance Rockland rat diet

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

When a lesser concentration is necessary, solution in water

Doses:

not reported

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days

Statistics:

Based upon mortalities during a 14-day observation period, the most probable LD50 value and its fiducial range are estimated by the method of Thompson
using the Tables of Weil.

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

4.29 other: g/kg bw

Based on:

test mat.

Mortality:

not reported

Clinical signs:

other: other: not reported

Gross pathology:

not reported

Interpretation of results:

GHS criteria not met

Conclusions:

In the present study of Smyth et al., 1962, male Wistar rats were administered orally several doses of propionic acid. The LD50 value was determined according to the method of Thompson using the Tables of Weil. The LD50 was reported to be 4.29 g/kg bw, thus the substance is not classified according to Regulation (EU) No. 1272/2008 (CLP) and the Globally Harmonized System for Classification and Labelling of Chemicals (GHS).

Executive summary:

In the published study of Smyth et al. (1962), male Wistar rats, four to five weeks of age and 90 to 120 g in weight were orally exposed to several doses of propionic acid. The  dosages  are  arranged  in  a  logarithmic series differing by  a factor of  two. The animals were observed for Mortalities for 14 days. The LD50 value was estimated by the method of Thomson  using the tables of Weil.

 

Propionic acid LD50= 4.29 g/kg bw (3.07-5.98)

 

The results are considered acceptable based on the brief described method which is in general identical to OECD TG 401.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 2 200 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

No acute oral toxicity data are available for potassium propionate, however, based on its pKa (4.85), potassium propionate the predominantly form in the stomach is the ionized form, propionate.

Similarly, sodium or calcium propionate are expected to dissociate in aqueous solutions, thus, the toxicity determining species is propionate.

Published data are available for propionic acid, sodium and calcium propionate. All of the substances showed a low acute oral toxicity. Smyth et al (1962) reported a LD50 of 4290 mg/kg bw, in the publication of Rodrigues et al. (1986) Effects in a feeding study (4% propionic acid) were only observed in a subchronic test design. Harshbarger et al. (1942) reported no effects up to 2200 mg/kg bw and Bueld and Netter (1992) only observed effects in rats at a dose of approximately 3600 mg/kg bw again in a subchronic test design. Based on structural similarity a value of 7570 mg/kg bw as LD50 was estimated with the QSAR Toolbox. The QSAR Toolbox was used to substantiate the similarity in toxicity based on structural similarity. At least a QSAR prediction was performed using the ACDLabs model, revealing a LD50 value of 2700 mg/kg bw. The evaluation of the Weight of Evidence approach are described in more detail under “Attached background material”.

 In sum the presented results substantiate the potassium propionate does not need to be classified according to Regulation (EU) No. 1272/2008 (CLP). All determined values were above 2000 mg/kg bw.