Propyl 3,4,5-trihydroxybenzoate

Carcinogenicity

Description of key information

In two rodent studies conducted similar to OECD TG 451 male and female F344/N rats and male and female B6C3F1 mice received daily doses propyl gallate of 0, 6000 and 12000 ppm in both cases via the diet for 105 -107 weeks. Under the conditions of these studies, there was no evidence of carcinogenic activity. This conclusion was further supported by the EFSA. In the EFSA publication "Scientific Opinion on the re-evaluation of propyl gallate (E310) as a food additive", 2014 several chronic toxicity/carcinogenicity toxicity studies conducted with propyl gallate were presented. It was concluded, that propyl gallate did not induce increased incidence of tumor and is consequently not considered as carcinogenic for mice of either sex. Furthermore, the EFSA Panel concluded that propyl gallate was also not carcinogenic in rats.

Key value for chemical safety assessment

Carcinogenicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Principles of method if other than guideline:

- Principle of test: Chronic toxicity study in B6C3F1 mice
- Short description of test conditions: Groups of 50 rats and 50 mice of each sex were maintained on diets containing 0, 0.6 or 1.2% propyl gallate for 103 weeks
- Parameters analysed / observed: Morbidity, mortality, clinical signs, body weight, feed consumption, gross and histopathological examination

GLP compliance:

not specified

Specific details on test material used for the study:

- Source and lot/batch No.of test material: Tennessee Eastman Co., Kingsport, TN
- Purity: 100%

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: not specified
- Age at study initiation: 4-5 weeks old
- Weight at study initiation: Not specified
- Housing: The animals were housed in groups of five in polycarbonate cages (Lab Products, Inc., Garfield, NJ) with Beta Chips (Northeastern Products Corp., Warrensburg, NY) as bedding. Assignment of animals to cages was made according to tables of random numbers.
- Diet (e.g. ad libitum): Ground Wayne Lab Blox feed (Allied Mills, Inc., Chicago, IL); ad libitum
- Water (e.g. ad libitum): tap water; ad libitum
- Acclimation period: Yes, 13-15 days prior to use in the study.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 °C
- Humidity (%): 30-60%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Experimental diets were prepared by mixing 0, 0.6 or 1.2% propyl gallate (100% pure; Tennessee Eastman Co., Kingsport, TN) into ground Wayne Lab Blox feed.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

103 weeks

Frequency of treatment:

Diet was available ad libitum.

Post exposure period:

no

Dose / conc.:

0 ppm

Dose / conc.:

6 000 ppm

Dose / conc.:

12 000 ppm

No. of animals per sex per dose:

50

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: The doses of propyl gallate used in this study were selected on the basis of mortality, a decrease in body-weight gain, and the necrosis and ulceration of the mucosa and submucosa of the stomach observed at higher doses in 13-week studies.

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: observed daily for morbidity, mortality, and for clinical signs of toxicity

DETAILED CLINICAL OBSERVATIONS: Not specified

BODY WEIGHT: Yes, all animals
- Time schedule for examinations: Body weights were recorded weekly for the first 13 weeks, and monthly thereafter. Mean body weight gain for animals surviving to week 103 was presented in Table 3.

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes
- Food consumption for each animal was measured weekly for the first 13 weeks, and monthly thereafter.
WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes / No / No data
- Time schedule for examinations:

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, necropsies were performed on all animals that survied until the end of the experiment.

HISTOPATHOLOGY: Yes, for each animal that survived until the end of the study, approximately 42 tissues, plus grossly visible lesions, were collected for histopathological examination. Tissues were preserved in 10% neutral buffered formalin, embedded in paraffin, sectioned at 5-6 pm, and stained with haematoxylin and eosin. The following were examined microscopically: tissue masses, abnormal lymph nodes, skin, mandibular lymph nodes, mammary gland, salivary gland, thigh muscle, sciatic nerve, bone, bone marrow, costochondral junction (rib), thymus, larynx, trachea, lungs and bronchi, heart, thyroid, parathyroid, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, mesenteric lymph nodes, liver, external and middle ear, gallbladder (mice), pancreas, spleen, kidneys, adrenals, eyes, urinary bladder, seminal vesicles/ prostate/ testes or ovaries/ uterus/ vagina/ fallopian tubes, nasal cavity, brain, pituitary, and spinal cord.

Other examinations:

no further data

Statistics:

For the statistical analysis of tumor incidence data, two different methods of adjusting for intercurrent mortality were employed. Each used the classical methods for combining contingency tables developed by Mantel and Haenszel (l959). Tests of significance included pairwise comparisons of high-and low-dosed groups with controls and tests for overall dose-response trends.

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Description (incidence):

No significant differences in survival were observed between dosed groups of male mice or groups of female mice. In male mice, 41/50 (82%) of the controls, 37/50 (74%) of the low-dose group, and 44/50 (88%) of the high-dose group lived to the end of the study at 105-107 weeks. In female mice, 37/50 (74%) of the controls, 34/50 (68%) of the low-dose group, and 38/50 (76%) of the high- dose group lived to the end of the study at 105-107 weeks. These incidences include one low- dose female that died during the terminal kill period.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Mean body weights of dosed mice of each sex were lower than those of the controls throughout most of the study. At 104 weeks, mean body weights of low- and high-dose male mice were 5% and 8% lower than those of the controls. Mean body weights of female mice of either dose group were 11% lower than those of the controls.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

The average daily feed consumption per mouse by low- and high-dose mice was 91% and 100% that of the controls for males and 109% and 106% for females.

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not specified

Description (incidence and severity):

Grossly visible lesions were collected for histopathological examination. No results specifically-related to gross pathological findings were reported.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Hematopoietic System: Malignant lymphomas in male mice were observed with a statistically significant positive trend (controls, 1/50, 2%; low-dose, 3/49, 6%; high-dose, 8/50,16%). All tests between the high-dose and control groups were significant. The incidence of male mice with malignant lymphoma, histiocytic type, occurred with a significant positive trend (control, 0/ 50, 0%; low-dose, 0/49, 0%; high-dose, 4/50, 8%); but statistical comparisons between high-dose males and controls were not significant.
Liver: The incidence of male mice with adenomas or carcinomas (combined) occurred with a significant negative trend. Hepatocellular adenomas in female mice occurred with a significant positive trend (control, 0/50, 0%; low-dose, 2/50,4%; high-dose, 5/49,10%). The incidence of high-dose female mice with this tumor is significantly higher than that of the controls. The combined incidence of female mice with either adenomas or carcinomas was not significantly different from that of controls.
Pituitary: Low-dose female mice had fewer adenomas than did animals in the control group, but no statistically significant results were obtained when the incidences of females with adenomas or carcinomas were combined.
Skin or subcutaneous tissue: Fibromas occurred in male mice with a negative trend, and the incidence in the high-dose group was significantly reduced relative to controls (5/50,1/49, 0/50).
Uterus: Endometrial stromal polyps or sarcomas occurred with a significant negative trend in female mice; none of the results of the individual group comparisons were significant.

Other effects:

not examined

Details on results:

In male mice, malignant lymphoma was observed with significantly increased incidence in the high-dose group (16%) relative to concurrent controls (2%) and with a positive trend. However, the high-dose incidence was not statistically significant when compared with the historical rate (60/640, 9.4%) for the laboratory that conducted this study. This tumor was not observed in significant proportions in female mice. The increased incidence of malignant lymphomas in male mice was not clearly related to administration of propyl gallate.

Adenomas of the liver in female mice occurred with a statistically significant positive trend, with the incidence in the high-dose group being significantly higher than that in the controls. To date, the overall historical incidence is 104/3,127 (3.3%), with the group incidence ranging from 0/50 (0%) to 9/49 (18%). In addition, the combined incidence of hepatocellular adenomas or carcinomas was similar in dosed and control groups and hence the increased incidence of hepatocellular adenomas in the high-dose group was not considered to be related to propyl gallate administration.

Relevance of carcinogenic effects / potential:

Tumours commonly occurring in F344 rats were seen in both control and propyl gallate-treated animals, but these were not considered to be compound-related. In those instances where a significant increase in tumour incidence in treated animals was noted, the biological significance was discounted when one of the following conditions was met: (a) a significant increase in tumour incidence was noted in only the low dose group or (b) the incidence was not significantly different from historical control rates. Similarly, the elevated incidences of malignant lymphoma in high dose (12000 ppm propyl gallate) male mice and hepatocellular adenoma in high-dose female mice were not considered to be related to the administration of this compound.

Dose descriptor:

LOAEL

Effect level:

12 000 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: Malignant lymphomas of the haemopoietic system occurred with a positive (P < 0.05) trend in male mice, and the incidence in the 1.2% propyl gallate dose group was higher (8/50; P < 0.05) than in the controls (1/50).

Dose descriptor:

LOAEL

Effect level:

12 000 ppm

Based on:

test mat.

Sex:

female

Basis for effect level:

histopathology: neoplastic

Remarks on result:

other: Hepatocellular adenomas in female mice occurred with a positive (P < 0.05) trend, and the incidence in the 1.2% dose group was higher than that in the controls.

Critical effects observed:

not specified

Conclusions:

In this study, propyl gallate caused a dose-related decrease in the growth rate of rats and mice. In male and female rats given 6000 ppm propyl gallate, tumors at several anatomical sites occurred at a higher (P < 0.05) incidence than in the controls. Undifferentiated leukemia was also observed with a negative (P < 0.05) trend in male rats given propyl gallate. However, study authors concluded propyl gallate was not considered to be carcinogenic to B6C3F1 mice of either sex, because the authors refuted significant results if (1) a significant increase in tumor incidence was noted in only the low dose group or (2) the incidence was not significantly different from historical control rates.

Executive summary:

In a study equivalent to OECD TG 451 (supervised by NTP) male and female B6C3F1 mice received daily by diet 0, 6000 and 12000 ppm propyl gallate mixed with ground feed for 103 weeks ad libitum. In male mice, malignant lymphoma was observed with significantly increased incidence in the high-dose group relative to concurrent controls and with a positive trend. However, the high-dose incidence was not statistically significant when compared with the historical rate for the laboratory that conducted this study. This tumor was not observed in significant proportions in female mice. The increased incidence of malignant lymphomas in male mice was not clearly related to administration of propyl gallate. Furthermore, a statistical significant positive trend of the occurrence of liver adenomas in female mice was observed, with the incidence in the high-dose group being significantly higher than that in the controls. The combined incidence of hepatocellular adenomas or carcinomas was similar in dosed and control groups and hence the increased incidence of hepatocellular adenomas in the high-dose group was not considered to be related to propyl gallate administration. Tumors commonly occurring in B6C3F1 mice were seen in both control and propyl gallate-treated animals, but these were not considered to be compound-related. In those instances where a significant increase in tumor incidence in treated animals was noted, the biological significance was discounted when one of the following conditions was met: (a) a significant increase in tumor incidence was noted in only the low dose group or (b) the incidence was not significantly different from historical control rates. Similarly, the elevated incidences of malignant lymphoma in high dose male mice and hepatocellular adenoma in high-dose female mice were not considered to be related to the administration of this compound.

Reference 2

Endpoint:

carcinogenicity: oral

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 451 (Carcinogenicity Studies)

Principles of method if other than guideline:

- Principle of test: A carcinogenesis bioassay of propyl gallate was conducted by feeding diets containing 6000 or 12000 ppm propyl gallate to groups of 50 F344/N rats of each sex for 103 weeks. Groups of 50 untreated rats of each sex served as controls.

- Parameters analysed / observed: Animals were observed twice daily for signs of morbidity and mortality. Necropsies were performed on all animals and all animals were examined histologically

GLP compliance:

not specified

Specific details on test material used for the study:

- Purity: 100%

SOURCE OF TEST MATERIAL
- Source and lot/batch No. of test material: Harshaw Chemical Co., Philadelphia, PA; Lot No. 2185 (used for the first 22 months) Lot No. 831 was used for the last 2 months from Tennessee Eastman Co. (Kingsport, TN)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored in the dark at 5 °C
- Stability under test conditions: Stability of Propyl gallate mixed in feed and stored in various temperature was 2 weeks at temperatures up to 45 °C

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Test diets were formulated by mixing a small amount of feed and the required amount of Propyl gallate in a plastic bag and then shaking vigorously by hand. This premix and the required amount of animal meal were then mixed for 15 minutes

Species:

rat

Strain:

Fischer 344

Remarks:

F344/N

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Industries Indianapolis, IN
- Females (if applicable) nulliparous and non-pregnant: not specified
- Age at study initiation: 5 weeks
- Weight at study initiation: Males: 102 g (mean); Females: 91 g (mean)
- Housing: Cages: Polycarbonate; Lab Products, Inc. (Garfield, NJ); cages changed twice weekly; Cage filters: Reemay spun-bonded polyester filters, Dupont style #2024, Snow Filtration (Cincinnati, OH); 5 animals per cage
- Diet (e.g. ad libitum): from Wayne Lab Blox Allied Mills, Inc. Chicago, IL; ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: 15 days

DETAILS OF FOOD AND WATER QUALITY: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 – 23 °C
- Humidity (%): 30 – 60%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on exposure:

- DIET PREPARATION
Test diets were formulated by mixing a small amount of feed and the required amount of propyl gallate in a plastic bag and then shaking vigorously by hand. This premix and the required amount of animal meal were then mixed for 15 minutes in a Patterson-Kelly-twin-shell blender equipped with an intensifier bar.
- Storage temperature of food: Test diets were stored in the dark for no longer than 14 days (7 days at 5 °C followed by no more than 7 days at 21 – 23 °C)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentrations of propyl gallate were measured in 55 samples selected at random from test diets administered during the chronic study.

Two-gram-samples of the chemical/feed mixtures were weighed into sample tubes and mixed with 29 mL of methanol. These mixtures were triturated for 2 minutes with the Polytron blender and filtered using a millipore filtering apparatus with a fiberglass filter. The feed residue was then stirred with 20 mL of fresh methanol and filtered. This process was repeated with another 20 mL of methanol. The combined extracts were then diluted to a volume of 100 mL.
These extracts were analysed by ultraviolet absorption spectroscopy. Two-milliliter aliquots of the extracts were diluted to a volume of 50 mL with methanol. The absorbance of the samples was then read at 276 nm and compared to a standard ultraviolet absorption curve for Propyl gallate.
Control feed and spiked control feed were analysed by the same procedure. Correction for absorption of the control feed was applied to the chemical/feed samples and spiked control feed.

Duration of treatment / exposure:

721 days

Frequency of treatment:

Diet was available ad libidum.

Post exposure period:

no

Dose / conc.:

0 ppm

Remarks:

Propyl gallate (100% pure) was mixed with ground feed.

Dose / conc.:

6 000 ppm

Remarks:

Propyl gallate (100% pure) was mixed with ground feed.

Dose / conc.:

12 000 ppm

Remarks:

Propyl gallate (100% pure) was mixed with ground feed.

No. of animals per sex per dose:

50

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: Doses of 6000 and 12000 ppm propyl gallate were selected because in the previous 13-week study in rats, gastrointestinal effects were observed in rats administered 25000 ppm (see IUCLID entry in chapter 7.5.1 Repeated dose toxicity: oral "NTP 1982_sup_rats 13w")

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations: Observed for signs of morbidity and mortality

DETAILED CLINICAL OBSERVATIONS: Not specified

BODY WEIGHT: Yes
- Time schedule for examinations: every week for the first 13 weeks and monthly thereafter

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- The average feed consumption per animal was calculated by dividing the total feed consumption measured for all cages by the number of surviving animals in the group
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Not specified
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Not specified

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Not specified

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, on major tissues and organs

HISTOPATHOLOGY: Yes
The following were examined microscopically: tissue masses, abnormal lymph nodes, skin, mandibular lymph nodes, mammary gland, salivary gland, thigh muscle, sciatic nerve, bone, bone marrow, costochondral junction (rib), thymus, larynx, trachea, lungs and bronchi, heart, thyroid, parathyroid, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, mesenteric lymph nodes, liver, external and middle ear, gallbladder (mice), pancreas, spleen, kidneys, adrenals, eyes, urinary bladder, seminal vesicles/ prostate/ testes or ovaries/ uterus/ vagina/ fallopian tubes, nasal cavity, brain, pituitary, and spinal cord.

Statistics:

For the statistical analysis of tumor incidence data, two different methods of adjusting for intercurrent mortality were employed. Each used the classical methods for combining contingency tables developed by Mantel and Haenszel (1959). Tests of significance included pairwise comparisons of high-and low-dosed groups with controls and tests for overall dose-response trends.

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, non-treatment-related

Description (incidence):

No significant differences in survival were observed between groups of male rats or between groups of female rats. Survival during the last 10 months of the study was slightly better for high-dose in rats than for low-dose or control rats of each sex. In male rats, 39/50 (78%) of the controls, 38/50 (76%) of the low-dose group, and 44/50 (88%) of the high-dose group lived to the end of the study at 105-107 weeks. In female rats, 39/50 (78%) of the controls, 38/50 (76%) of the low-dose group, and 42/50 (84%) of the high-dose group lived to the end of the study at 105-107 weeks. These incidences include one control male that died during the terminal kill period.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Throughout the study, mean body weights of dosed rats of each sex were lower than those of the controls. At 104 weeks, mean body weights of low- and high-dose rats were 4% and 8% lower than those of the controls for males and 11% and 19% lower than those of the controls for females. The depression in mean body weight gain was dose related. The average daily feed consumption per rat by low- and high-dose rats was 94% and 98% that of the controls for males and 95% and 115% of that of the controls for females.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

The average daily feed consumption per rat by low- and high-dose rats was 94% and 98% that of the controls for males and 95% and 115% of that of the controls for females.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not specified

Description (incidence and severity):

Grossly visible lesions were collected for histopathological examination. No results specifically-related to gross pathological findings were reported.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Liver: The incidences of dosed male rats with cytoplasmic vacuolization were higher than was the incidence in the controls (control, 4/50, 8%; low-dose, 22/50, 44%; high-dose, 22/50, 44%). The severity of this lesion ranged from mild/minimal to moderate. The vacuoles appeared to be composed primarily of glycogen, but fat was also present.

Eye: An increased incidence of non-neoplastic lesions, consisting of retinopathy and cataract formation, was observed in high-dose male rats and low-dose female rats. Retinopathy was seen in 12/50 (24%) control males, 8/50 (16%) low-dose males, 35/50 (70%) high-dose males, 10/50 (20%) control females, 40/50 (80%) low-dose females, and 14/50 (28%) high-dose females. Cataract formation occurred in 12/50 (24%) control males, 4/50 (8%) low-dose males, 35/50 (70%) high-dose males, 8/ 50 (16%) control females, 39/ 50 (78%) low-dose females, and 13/ 50 (26%) high-dose females.

Prostate: Suppurative inflammation was observed at an increased incidence in high-dose male rats (controls, 17/50, 34%; low-dose, 18/46, 39%; high-dose, 30/50, 60%).

Kidney: Nephrosis was observed at an increased incidence in low-dose female rats (control, 8/50,16%; low-dose, 28/50, 56%; high-dose, 4/54, 8%).

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Thyroid: Two follicular-cell carcinomas and one follicular-cell adenoma were found in high- dose male rats; none were observed in male controls, male low-dose rats, or female rats. The combined incidence of male rats with either follicular-cell adenomas or carcinomas was statistically significant (P<0.05) by the trend tests, but the incidence in the high-dose group was not statistically different from that in the control group in a direct comparison.

Mammary Gland: Three of 50 high-dose female rats had adenomas; none were observed in the control and low-dose groups. The tests for trend were all statistically significant (P<0.05), but the comparisons between the high-dose and control groups were not significant. The incidence of control females with fibroadenomas (11/50, 22%) was significantly higher (P<0.011) than that in the low-dose group (2/50, 4%) and somewhat higher than that observed in the high-dose group (5/50, 10%).

Preputial Gland: Adenomas, adenocarcinomas, or carcinomas (combined) were observed in 1/ 50 control males, 8/50 low-dose males, and 0/50 high-dose males. The tests between the low-dose and control groups were all significant, but there was no evidence of a positive dose response.

Pancreas: The combined incidence of islet-cell adenomas and carcinomas was higher in low- dose males than in control and high-dose males (control, 2/50, 4%; low-dose, 9/50, 18%; high- dose 4/50, 8%). The tests between the low-dose and control groups were all statistically significant (P<0.05), but neither the dose-response trend nor the high-dose effect was statistically significant.

Uterus: A statistically significant (P=0.049, incidental tumor test) positive trend was observed in the incidence of female rats with endometrial stromal polyps (6/50, 12%; 8/50, 16%; 13/50, 26%). However, none of the pairwise comparisons of incidence in either dose group with the control group were statistically significant.

Adrenal: Pheochromocytomas were observed in 4/50 control males, 13/48 low-dose males, and 8/50 high-dose males. The tests between the low-dose and control groups were all statistically significant, but no trend tests or comparisons between the high-dose and control groups were significant.

Brain: One low-dose female rat had an astrocytoma and another rat in the same group had a glioma

Hematopoietic System: A negative trend was observed in the incidences of male rats with leukemia of the hematopoietic system (controls, 16/50, 32%; low-dose, 7/50, 14%; high-dose, 6/50, 12%). All tests for trend were significant, and the incidence in the high-dose group differed significantly from that in the controls. Hematopoietic tumors did not occur in significant proportions in female rats.

Liver: The incidences of liver tumors were similar among groups (male: 2/50, 1/50, 1/50; female: 0/50, 1/50; 0/50).

Other effects:

not specified

Details on results:

The growth rates of dosed female rats were more than 10% lower than those of controls. No significant differences in survival were observed between dosed or control rats.
The incidences of dosed male rats with cytoplasmic vacuolization of the liver and of high-dose male rats with suppurative inflammation of the prostate were related to administration of propyl gallate. The presence of fat in vacuoles may be an indication of a disorder in fat metabolism. It is likely that propyl gallate administration to rats may result in methyl donors (e.g., choline) deficiency.
Rare tumors (an astrocytoma or a glioma) were found in the brain of two low-dose female rats. However, the presence of this tumor in the brain of low-dose female rats was not considered to be related to propyl gallate administration, since none of the high-dose female rats had this tumor.

Thyroid follicular-cell adenomas or carcinomas (combined) occurred in male rats with a statistically significant (P<0.05) positive trend, but the incidences in the dosed groups were not statistically significant in direct comparisons with the controls. Moreover, the incidence of high-dose male rats with follicular cell tumors was quite low (3/50, 6%) and was not statistically significant relative to the historical control rate (14/584, 2.4%) in the laboratory that conducted this bioassay.

The following tumors occurred in low-dose male rats at incidences significantly higher (P<0.05) than those in the controls but showed little evidence of an increase in high-dose males: adenomas (alone) and adenomas, adenocarcinomas, or carcinomas (combined) of the preputial gland, and adenomas (alone) and adenomas or carcinomas (combined) of the pancreatic islet cells, and pheochromocytomas of the adrenal gland. Because there is no significant effect in the high-dose group, these increases are not considered to be clearly related to propyl gallate administration.

Adenomas in the mammary gland occurred in female rats with a statistically significant positive trend, but the incidence in the high-dose group was not significantly higher than that in the controls. Fibroadenomas in the mammary gland in female rats occurred with a statistically significant negative trend. Endometrial stromal polyps of the uterus occurred in female rats with a marginally significant positive trend, but the incidence in the high-dose group (13/50, 26%) was not significant relative to controls (6/50, 12%). The high-dose incidence falls within the overall historical control range (2/50,4% to 18/49,36%) and this increase is not believed to be related to administration of propyl gallate.

Relevance of carcinogenic effects / potential:

Tumors commonly occurring in F344 rats were seen in both control and propyl gallate-treated animals, but these were not considered to be compound-related. In those instances where a significant increase in tumor incidence in treated animals was noted, the biological significance was discounted when one of the following conditions was met: (a) a significant increase in tumor incidence was noted in only the low dose group or (b) the incidence was not significantly different from historical control rates. Accordingly, the increased incidences of thyroid follicular cell adenoma or carcinoma (combined) in treated male rats and the increased incidences of preputial gland tumors, pancreatic islet-cell tumors, and phaeochromocytoma of the adrenal gland in low-dose male rats were not considered to be related to propyl gallate administration.

Dose descriptor:

LOAEL

Effect level:

6 000 ppm

Based on:

not specified

Sex:

male/female

Basis for effect level:

histopathology: neoplastic

Critical effects observed:

not specified

Conclusions:

In this study, male and female rats given 6000 ppm propyl gallate, tumours at several anatomical sites occurred at a higher (p< 0.05) incidence than in the controls. Undifferentiated leukaemia was also observed with a negative (p < 0.05) trend in male rats given propyl gallate. However, study authors concluded propyl gallate was not considered to be carcinogenic to F344 rats or B6C3F1 mice of either sex, because the authors refuted significant results if (1) a significant increase in tumour incidence was noted in only the low dose group or (2) the incidence was not significantly different from historical control rates.

Executive summary:

In a study equivalent to OECD TG 451 (supervised by NTP) male and female F344 rats received daily by diet 0, 6000 and 12000 propyl gallate mixed with ground feed for 103 weeks ad libitum. In male and female rats given 6000 ppm propyl gallate, tumors at several anatomical sites occurred at a higher (p< 0.05) incidence than in the controls. Undifferentiated leukemia was also observed with a negative (p< 0.05) trend in male rats given propyl gallate. However, study authors concluded propyl gallate was not considered to be carcinogenic to F344 rats of either sex, because the authors refuted significant results if (1) a significant increase in tumor incidence was noted in only the low dose group or (2) the incidence was not significantly different from historical control rates.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Study duration:

chronic

Species:

rat

Carcinogenicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Carcinogenicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available data and according to criteria of Regulation (EC) No. 1272/2008 classification for carcinogenicity is not warranted.

Additional information

In two rodent studies conducted similar to OECD TG 451 male and female F344/N rats and male and female B6C3F1 mice received daily doses propyl gallate of 0, 6000 and 12000 ppm in both cases via the diet for 105 -107 weeks. Under the conditions of these studies, there was no evidence of carcinogenic activity. This conclusion was further supported by the EFSA. In the EFSA publication "Scientific Opinion on the re-evaluation of propyl gallate (E310) as a food additive", 2014 several chronic toxicity/carcinogenicity toxicity studies conducted with propyl gallate were presented. It was concluded, that propyl gallate did not induce increased incidence of tumor and is consequently not considered as carcinogenic for mice of either sex. Furthermore, the EFSA Panel concluded that propyl gallate was also not carcinogenic in rats.