Propane-1,2,3-triyl trisheptanoate

Repeated dose toxicity: oral

Administrative data

Endpoint:

chronic toxicity: oral

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented study report which meets basic scientific principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Materials and methods

Principles of method if other than guideline:

Male rats were exposed to corn oil, safflower oil and tricaprylin via gavage. After 15 months (interim evaluation) and 2 years, animals were sacrificed for gross and histopathological examinations to evaluate the treatment-related effects on neoplasm incidence.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Glycerol trioctanoate

EC Number:

208-686-5

EC Name:

Glycerol trioctanoate

Cas Number:

538-23-8

IUPAC Name:

propane-1,2,3-triyl trioctanoate

Details on test material:

- Name of test material (as cited in study report): tricaprylin
- Molecular formula (if other than submission substance): C27H50O6
- Molecular weight: 470.69
- Analytical purity: 94% (A15), 97% (A11), 91% (8812-806876)
- Lot/batch No.: A15, A11, 8812-806876
- Physical state: clear, colorless to amber liquid
- Stability under test conditions: in amber glass containers at 4°C under an argon headspace

Test animals

Species:

rat

Strain:

other: Fischer 344/N

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Simonsen Laboratories (Gilroy, CA)
- Age at study initiation: 7 weeks
- Weight at study initiation: 126 - 159 g
- Housing: groups of 5 animals in polycarbonate cages with hardwood chips
- Diet: NIH-07 open-stock mash diet (Zeigler Bros., Inc., Gardners, PA), ad libitum
- Water: Worcester public water, ad libitum
- Acclimation period: 14 to 22 days; prior to study start, five rats from each study were randomly selected and killed for parasite evaluation and gross observation of disease.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 - 22
- Humidity (%): 47.1 ± 4.9
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Tricaprylin was dispensed into vials for gavage dosing on a weekly basis. After dispensing, the test item was stored at 4°C for no more than 3 weeks.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Accelerated bulk chemical stability studies were performed using gas chromatography. The test substance was found to be stable as a bulk chemical for 2 weeks when stored protected from light at temperatures up to 60°C. The stability of tricaprylin was monitored periodically by ultraviolet spectroscopy and gas chromatography. In addition, the peroxide concentration was determined prior to use. The acceptable peroxide concentration was set at 2 mEq/L. A bottle was discareded if it exceeded this specification. No significant degradation of the bulk chemical was observed throughout the study.

Duration of treatment / exposure:

104 weeks

Frequency of treatment:

daily, 5 days/week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
2.5, 5, 10 mL/kg bw/day
Basis:
actual ingested

Doses / concentrations 2

Remarks:

Doses / Concentrations:
2390, 4770, 9540 mg/kg bw/day
Basis:
other: actual ingested; based on a density of 0.9540 g/cm3 (Final Report on the Safety Assessment of Trilaurin, Triarachidin, Tribehenin, Tricaprin, Tricaprylin; International Journal of Toxicology, 2011)

No. of animals per sex per dose:

60 males/group; 10 from each group were sacrificed after 15 months

Control animals:

yes, concurrent no treatment

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily, findings were recorded at least monthly

BODY WEIGHT: Yes
- Time schedule for examinations: at study initiation, than weekly for 13 weeks, and monthly thereafter

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at 15 months. Blood was collected from the posterior vena cava.
- How many animals: 10
- Parameters checked: haematocrit, haemoglobin, erythrocyte count, mean erythrocyte haemoglobin, mean erythrocyte haemoglobin concentration, mean erythrocyte haemoglobin volume, reticulocyte count, total and differential leukocyte count

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at 15 months from the posterior vena cava
- How many animals: 10
- Parameters checked: potassium, total protein, albumin, cholesterol, alanine aminotransferase, creatine kinase, sorbitol dehydrogenase, bile acids

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, on all animals. Animals found in a moribund state, selected for the 15-month interim evaluations, or surviving to the end of the 2-year study were killed by the use of "Biotol", an ultra fast-acting barbiturate. All organs and tissues were examined for gross lesions.

HISTOPATHOLOGY: Yes, on all animals. All of the following tissues were preserved in 10% neutral puffered formalin, embedded in paraffin, sectioned, and stained with hematoxylin and eosin for microscopic examination: adrenal gland, bone and marrow, brain, esophagus, gross lesions, heart, kidney, large intestine (cecum, colon, rectum), liver, lung, mammary gland, lymph nodes (mandibular and mesenteric), pancreas, parathyroid gland, pituitary gland, preputial gland, salivary gland, skin, small intestine (duodenum, jejunum, ileum), spleen, stomach, testis with epididymis and seminal vesicle, thymus, thyroid gland, tissue masses, trachea, and urinary bladder.

Other examinations:

Brain, kidney (right) and liver of each animal were weighed at the 15 month interim evaluation.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

9540 mg/kg bw/day: 30 animals died

Mortality:

mortality observed, treatment-related

Description (incidence):

9540 mg/kg bw/day: 30 animals died

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

9540 mg/kg bw/day: decreased body weights

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

9540 mg/kg bw/day: decreased food consumption (non-adverse)

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

9540 mg/kg bw/day: increase in the haematocrit, haemoglobin and erythrocyte levels

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

4770 mg/kg bw/day: significant decrease in the absolute kidney weight (non-adverse)

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

9540 mg/kg bw/day: decreased incidence in nephropathy and severity

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

dose-related increase in the incidences of pancreatic exocrine hyperplasia and adenoma; proliferative lesions of the forestomach

Details on results:

CLINICAL SIGNS AND MORTALITY
Clinical findings including dyspnea, ataxia and lethargy were observed in 50 out of 60 animals in the high-dose group. However, most of the animals generally recovered prior to the next daily dosing and the incidence of clinical findings declined during the second half of the study.
The two-year survival rate was lower in test animals compared to the respective controls with statistical significance for the high-dose group (31/50, 30/50, 31/50, 23/53 for control, 2390, 4770, 9540 mg/kg bw/day, respectively (Table 1)). 23 rats of the high-dose group died or were killed between weeks 33 - 85 including 10 animals found dead and 13 animals killed moribund. In 20 of these animals, the cause of death or moribund condition could not be determined. 8 rats died between weeks 45 - 49 when the incidence of clinical findings (dyspnea, ataxia and lethargy) was highest. In addition, these animals revealed a significantly lower body weight than the mean group body weight (316 g vs 360 g) at 11 months. Only one of the moribund animals had a pulmonary mass that may explain the dyspnea. Up to 4 animals died or were killed in each subsequent month.

BODY WEIGHT AND WEIGHT GAIN
9540 mg/kg bw/day: Mean body weights were decreased in test animals compared to controls throughout the study. However, the difference was less than 5% after week 61.
No effects were observed in the low- and mid-dose group (Table 2).

FOOD CONSUMPTION
A dose-dependent decrease in food consumption was determined in test animals (Table 3) which resulted in a decreased protein consumption per day (protein consumption (g/rat/day): 3.88, 3.45, 3.09 and 2.70, for control, low-, mid- and high-dose animals, respectively). This effect is most probably due to the fact that rats exposed to tricaprylin received more than 10% of their caloric intake from the test item (10.4%, 19.8% and 35.4% for the low-, mid- and high-dose animals, respectively). Thus, the effect on food consumption is considered as non-adverse.

HAEMATOLOGY
Significant increases in the haematocrit, haemoglobin and erythocyte counts were determined for the high-dose group. No effects were observed in the low- and mid-dose group (Table 4).

ORGAN WEIGHTS
Test animals of the mid-dose group revealed a statistically significant lower absolute kidney weight. As the relative organ weight is not different from the control and the effect is not observed in the low- and high-dose group (Table 5), the effect is considered as incidental and not treatment-related.

HISTOPATHOLOGY: NON-NEOPLASTIC
A significant decrease in the incidence of nephropathy was determined in the high-dose group (control: 46/50, 2390 mg/kg bw/day: 42/50, 4770 mg/kg bw/day: 45/50, 9540 mg/kg bw/day: 27/49) with a dose-related decrease in severity (control: 2.0, 2390 mg/kg bw/day: 1.5, 4770 mg/kg bw/day: 1.7, 9540 mg/kg bw/day: 0.9, Table 6)). As the severity of nephropathy is normally related to the amount of protein in the diet, the decrease in severity induced by tricaprylin might be due to the lower food consumption in test animals (Table 3).
No further findings have been determined in control vs test animals.

HISTOPATHOLOGY: NEOPLASTIC
Tricaprylin induced dose-related increases in the tumor incidences of pancreatic exocrine hyperplasia reaching statistically significance for the mid-and high-dose group (control: 8/49, 2390 mg/kg bw/day: 9/49, 4770 mg/kg bw/day: 18/49, 9540 mg/kg bw day: 28/50), adenoma (control: 2/49, 2390 mg/kg bw/day: 6/49, 4770 mg/kg bw/day: 13/49, 9540 mg/kg bw/day: 18/50) and proliferative lesions in the forestomach (basal cell hyperplasia: control: 4/50, 2390 mg/kg bw/day: 7/50, 4770 mg/kg bw/day: 12/49, 9540 mg/kg bw/day: 21/52; squamous cell papilloma: control: 0/50, 2390 mg/kg bw/day: 0/50, 4770 mg/kg bw/day: 3/50, 9540 mg/kg bw/day: 10/53) reaching statistically significance for squamous cell papilloma in the high-dose group. In contrast, a decrease in the incidence of mononuclear cell leukemia was observed in high-dose animals (control: 23/50, 2390 mg/kg bw/day: 28/50, 4770 mg/kg bw/day: 22/50, 9540 mg/kg bw/day: 9/53). The incidence of pancreatic islet hyperplasia and adenoma or carcinoma decreased in a dose-dependent, but not significant manner (hyperplasia: control: 6/49, 2390 mg/kg bw/day: 5/48, 4770 mg/kg bw/day: 3/49, 9540 mg/kg bw/day: 1/49; adenoma/carcinoma: control: 5/49, 2390 mg/kg bw/day: 2/48, 4770 mg/kg bw/day: 3/49, 9540 mg/kg bw/day: 1/49) (Table 6).

Effect levels

1

Dose descriptor:

LOAEL

Effect level:

9 540 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: systemic toxicity (clinical signs, mortality, body weight ); corresponding to 10 mL/kg bw /day (calculation based on a density of 0.9540 g/cm³)

2

Dose descriptor:

NOAEL

Effect level:

4 770 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: systemic toxicity (clinical signs, mortality, body weight ); corresponding to 5 mL/kg bw /day (calculation based on a density of 0.9540 g/cm³)

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table 1: Mortality data after tricaprylin exposure

	control	2390 mg/kg bw/day	4770 mg/kg bw/day	9540 mg/kg bw/day
number of animals included in the study	60	60	60	60
sacrificed for 15-month interim evaluation^a	10	10	10	7
natural deaths	4	7	4	13
moribund kills	15	13	15	17
animals surviving until study termination	31^d	30	31^d	23^d
mean survival (days)^b	651	639	642	553
survival analysis^c	P = 0.004	P = 0.944	P = 0.969	P = 0.014

a: censored from survival analyses

b: mean of all death including uncensored, censored and terminal sacrifice

c: The result of the life table trend test is shown in the control column whereas the results of life table pairwise comparisons with the controls are listed in the dosage columns.

d: Includes 2 rats for the control and 1 rat for the mid- and high-dose groups that died during the last week of the study.

 

Table 2: Effects on body weight after tricaprylin exposure

	body weight (g)
weeks on study	control	2390 mg/kg bw/day	4770 mg/kg bw/day	9540 mg/kg bw/day
1	146	144	145	145
2	172	171	169	168
3	199	198	193	190
4	219	215	215	207
5	243	241	239	231
7	263	259	255	247
8	266	265	257	254
9	283	282	277	266
10	300	295	285	278
12	306	301	294	283
13	306	301	296	284
14	317	311	303	289
17	332	329	319	303
21	351	350	339	319
25	363	367	354	330
29	376	372	357	335
33	381	379	371	345
37	386	387	376	353
41	388	389	377	347
45	389	389	382	358
49	388	395	388	368
53	401	408	396	380
57	404	411	394	380
61	403	416	400	390
65	408	419	399	392
69^a	406	421	400	392
73	408	422	403	395
77	414	423	406	403
81	413	419	405	404
85	405	412	396	399
89	402	412	390	395
93	400	413	393	397
97	393	406	386	391
101	387	404	379	379
104	386	391	371	366
mean (week 1–13)	246	243	239	232
mean (week 14–52)	367	367	357	335
mean (week 53–104)	402	413	394	390

a: interim evaluation occurred during week 67

 

Table 3: Effects on food consumption after tricaprylin exposure

	food consumption per animal per day (g)
weeks on study	control	2390 mg/kg bw/day	4770 mg/kg bw/day	9540 mg/kg bw/day
2	14.2	13.7	12.5	11.4
5	16.9	15.9	16.0	14.4
9	17.1	16.5	16.4	13.6
13	13.0	12.1	9.9	8.9
17	20.2	16.9	16.0	13.5
21	15.8	14.9	12.5	10.0
25	18.3	18.3	16.5	13.5
29	17.8	16.2	14.0	12.2
33	17.8	16.3	16.0	13.7
37	18.3	15.6	14.2	12.1
41	15.2	12.8	11.5	8.8
45	16.7	14.9	12.5	10.8
49	20.3	17.7	15.8	13.3
53	18.2	16.2	14.2	12.1
57	20.4	17.5	14.1	12.7
61	17.9	16.5	14.2	12.5
65	16.8	13.7	11.9	10.6
69	18.6	17.3	16.5	15.6
73	16.8	14.1	12.9	10.2
77	17.7	14.3	12.9	11.2
81	17.7	14.5	13.2	10.7
85	15.9	14.3	12.2	10.3
89	13.9	12.6	10.6	9.5
93	16.6	14.4	15.9	15.1
97	16.5	12.3	12.3	12.9
101	13.7	12.3	9.4	8.7
104	13.5	10.6	9.2	7.6
mean	17.0	15.1	13.6	11.8

 

Table 4: Haematology data after tricaprylin exposure at the 15-month interim evaluation

	control	2390 mg/kg bw/day	4770 mg/kg bw/day	9540 mg/kg bw/day
number of animals	9	10	8	7
haematocrit (%)	45.6 ± 1.1	50.7 ± 2.7	49.2 ± 2.3	51.7 ± 2.0*
haemoglobin (g/dL)	15.6 ± 0.4	17.3 ± 0.8	16.7 ± 0.6	17.5 ± 0.6*
erythrocytes (10^6/ µL)	8.77 ± 0.31	9.72 ± 0.41	9.30 ± 0.34	9.91 ± 0.32*

*: significantly different from control by Dunn´s or Shirley´s test (P ≤ 0.05)

 

Table 5: Organ weights of the kidney (right) after tricaprylin exposure at the 15-month interim evaluation

	control	2390 mg/kg bw/day	4770 mg/kg bw/day	9540 mg/kg bw/day
number of animals	10	10	10	7
body weight at necropsy	430 ± 15	419 ± 11	402 ± 15	406 ± 12
absolute	1.349 ± 0.04	1.23 ± 0.036	1.194 ± 0.041*	1.328 ± 0.053
relative	3.15 ± 0.07	2.95 ± 0.07	2.98 ± 0.07	3.27 ± 0.08

*: significantly different from the control by William´s or Dunnett´s test (P ≤ 0.05)

Organ weights are given in grams; organ-weight-to body-weight ratios are given as mg organ/g bw

 

Table 6: Histopathological findings after tricaprylin exposure

		control	2390 mg/kg bw/day	4770 mg/kg bw/day	9540 mg/kg bw/day
non-neoplastic	nephropathy incidence	46/50	42/50	45/50	27/49
	nephropathy severity	2.0 ± 0.12	1.5 ± 0.13	1.7 ± 0.11	0.9 ± 0.13
neoplastic	exocrine pancreas hyperplasia	8/49	9/49	18/49	28/50
	exocrine pancreas adenoma	2/49	6/49	13/49	18/50
	forestomach: basal cell hyperplasia	4/50	7/50	12/49	21/52
	forestomach: squamous cell papilloma	0/50	0/50	3/50	10/53
	mononuclear cell leukemia	23/50	28/50	22/50	9/53
	pancreatic islet hyperplasia	6/49	5/48	3/49	1/49
	pancreatic islet adenoma/carcinoma	5/49	2/48	3/49	1/49

For the interpretation of carcinogenic effects, please see Section 7.7, study entry "NTP, 1994, 2y, rat, gavage, RL2".