Dodecanoic acid, ester with oxybis[propanediol]

Endpoint summary

Description of key information

Based on read-across from a surrogate substance following an analogue approach:
Oral: NOAEL (rat) = 1000 (m,f) mg/kg bw/day (OECD 422)

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP-Guideline study, tested with the source substance 2,3-Dihydroxypropyl 9-cis-octadecenoate ( CAS No. 111-03-5). According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories Japan Inc., Yokohama, Japan
- Age at study initiation: 10 weeks
- Weight at study initiation: 352-426 g (males), 192-249 g (females)
- Housing: animals were housed individually in stainless steel cages
- Diet: ad libtum
- Water: ad libitum
- Acclimation period: 11 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22.1-23.2
- Humidity (%): 48-61
- Air changes (per hr): > 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Aliquots of the dosing solution (prepared in corn oil) corresponding to the amount of daily administration were stored at 2-6 °C in the dard. The stability of the dosing solution was 7 days in a refrigerator and one day at room temperature. Thus, the dosing solutions were used within 7 days.

VEHICLE
- Justification for use and choice of vehicle: the test substance showed low solubility in water.
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required): V4N3566

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

Males: 42 days (14 days before mating and 28 days thereafter)
Females: 42-52 days (from 14 days before mating to Day 4 of lactation)
Satellite males and females: 42 days and 14 days post-exposure observation period

Frequency of treatment:

once daily, 7 days/week

Remarks:

Doses / Concentrations:
100, 300 and 1000 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

12 males and females (including 5 males of the control and high-dose group as recovery group )
5 additional females (in satellite control and high-dose group)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
Prior to the main study, two dose range finding studies were performed. In the first study, 2000 mg/kg bw of test substance were administered for 3 days in male and female rats. No abnormalities were found in general condition and body weight. In the second study, dose levels of 100, 300 and 1000 mg/kg bw/day were administered for 14 days. No abnormalities of general condition, body weight, food consumption, haematological findings, blood biochemical findings, gross pathology and organ wight were found. Therefore, 1000 mg/kg bw/day was selected as the highest dose level for the main study.
- Post-exposure recovery period in satellite groups: 14 days

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: prior to the first administration and weekly thereafter

BODY WEIGHT: Yes
- Time schedule for examinations:
Males: prior to administration on Day 1 and on Day 7, 14, 21, 28, 35 and 42 (before sacrifice)
Females: prior to administration on Day 1 and on Day 7 and 14, during pregnancy on Day 0, 7 14 and 21, during lactation on Days 0 and 4 (before sacrifice)
Satellite males and females: prior to administration on Day 1 and on Day 7, 14, 21, 28, 35, 42, 49 (Day 7 of recovery period) and 56 (Day 14 of recovery period, before sacrifice)

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

HAEMATOLOGY: Yes
- Time schedule for collection of blood: one day after last application
- Anaesthetic used for blood collection: Yes (ether)
- Animals fasted: Yes
- How many animals: 5 per group
- Parameters checked: red blood cell count (RBC), Haemoglobin, Haematocrit, mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), mean cell volume (MCV), Platelets, Reticulocytes, PT, APTT, white blood cell count (WBC), Differential leukocytes: Lymphocytes, Neutrophils, Eosinophils, Basophils, Monocytes

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: one day after last application
- Animals fasted: Yes
- How many animals: 5 per group
- Parameters checked: AST, ALT, ALP, γ-GTP, T-protein, Albumin, A/G, T-bilirubin, BUN, Creatinine, Glucose, T-cholesterol, Triglyceride, Na, K, Cl, Ca, P, LDH, choline esterase

URINALYSIS: Yes (males)
- Time schedule for collection of urine: Day 37 during administration period or Day 9 during recovery period
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes
- Parameters checked: colour, cloudiness, water consumed, volume, specific gravity, Na, K, pH, Protein, Glucose, Ketone body, Bilirubin, Occult blood, Urobilinogen, Epithelial cells, Erythrocytes, Leukocytes, Casts, Crystals, Fat

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations:
Males: on Week 6 (administration period)
Females: on Week 6 (administration period)
Males and females of satellite groups: on Week 6 of the administration period and on Week 2 of the recovery period
- Dose groups that were examined: all
- Battery of functions tested: hearing reaction, eye sight reaction, sense of touch reaction, pain reaction, pupil reflex, pinna reflex, ipsilateral flexor reaction, eyelid reflex, righting reflex

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, body surface, mucous membranes and internal organs

HISTOPATHOLOGY: Yes, brain, pituitary, thyroid, thymus, lung trachea (after liquid immersion fixation), stomach, intestines, heart, liver, spleen, kidney, adrenal gland, bladder, testis, epididymis, prostate, seminal vesicles, ovaries, uterus, spinal cord (cervical, thoracic, lumbar), sciatic nerve, bone marrow (femur), lymph nodes (cervical lymph node, mesenteric lymph nodes), mammary gland, and other gross abnormalities
Spermatogenic cycle (Stage II, III, V, VII, and XII) was also investigated.

SACRIFICE
- Males: Day 43
- Females: Day 5 of lactation
- Females (unsuccessful mating): Day 53
- Females (mated but non-pregnant): Day 5 after scheduled delivery
- Satellite males and females: Day 15 of the recovery period

Other examinations:

ORGAN WEIGHT: brain, liver, kidney, spleen, heart, thymus, thyroid, pituitary, adrenal, testis, seminal vesicle, epididymis

Statistics:

ANOVA, Barlettm Kruskal-Willis, Dunnett test, F-test, Studen t-test, Aspin-Welch t-test, Mann-Whitney U-test, Fisher's exact test

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw/day males (satellite group): significant increase, non-adverse

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw/day females (satellite group): significant increase on Day 14, 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):

100 and 300 mg/kg bw/day (males): decrease in APTT, non-adverse

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

300 and 1000 mg/kg bw/day (females): significant increase inorganic P, non-adverse; 1000 mg/kg bw/day females (satellite group): significant increase in choline esterase, non-adverse

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

100 mg/kg bw/day: significant decrease in absolute weight of seminal vesicles in male and significant decrease in relative weight of spleen in females, non-adverse

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

300 mg/kg bw/day females: mass in subcutis in one animal, not treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

300 mg/kg bw/day females: benign fibroadenoma of the mammary gland in one animal, not treatment-related

Details on results:

CLINICAL SIGNS AND MORTALITY
No mortalities and no clinical signs of toxicity were observed.

BODY WEIGHT AND WEIGHT GAIN
No changes in body weight and weight gain were observed during the treatment period.
During the recovery period, in males of the high-dose group a significant increase in body weight was noted, probably due to a tendency of the control group animals to lose body weight. One male in the control group showed a significant decrease in body weight during the recovery period. However, no other abnormalities were observed in this male.

FOOD CONSUMPTION
No differences in food consumption were observed during the administration period in the test groups.
In satellite females of the high-dose, a significant increase in food consumption was found on Day 14 of administration. However, the finding was regarded as incidental and not substance-related, since the food consumption of the corresponding control group was relatively low on the respective day.

HAEMATOLOGY
No changes in the observed parameters were noted. However, a significant decrease in APTT ( Activated Partial Thromboplastin Time) was observed in males of the low and mid-dose groups in comparison to the control group. The finding was considered not to be of toxicological relevance; no dose-relationship was observed and the value was still within the reference range.

CLINICAL CHEMISTRY
A significant decrease in inorganic phosphate was observed in females of the low and high-dose group. However, this change was not regarded as test substance-related, since no dose-relationship was observed and most of the individual data were within the reference ranges. Furthermore, choline esterase was increased in females of the high dose group after the recovery period but was still was within the reference range. Since the difference was only slight and no change was observed after the administration period, the effect was considered not to be substance-related.

URINALYSIS
No significant changes in urine parameters were found during the administration and recovery periods.

NEUROBEHAVIOUR
No abnormalities were observed for the sensory/reflex function, landing foot, grip strength and motor activity during the administration period. During the recovery period, motor activity increased from 0 to 60 min, but not from 0 to 30 min in high dose females. This effect was not considered to be substance-related since the observed difference was slight and no change was observed during and after the administration period.

ORGAN WEIGHTS
In males of the low dose group, after the administration period a significant decrease in the absolute weight of seminal vesicles was observed. Furthermore, a significant decrease in the relative spleen weight of females in the low dose group was apparent. These changes were considered not to be compound-related as no corresponding findings were apparent in the histopathological examination and no dose-relationship was observed.
After the recovery period, the relative weight of pituitary in males of the high dose group was significantly decreased. In addition, high dose females showed a decrease in the relative thyroid weight. These effects were also not considered to be substance-related because no abnormalities were reported regarding these organs after the administration period.

GROSS PATHOLOGY
Gross pathology showed no substance-related changes. No differences were found in breeding pairs which were not successful at mating and in those which were successful at mating but not pregnant.
After the administration period, in one male of the control reddish thymus was noted and in one female of the mid-dose group subcutis mass was found. After the recovery period, larger spleen and capsular thickening in spleen was found in one male and reddish area in thymus was observed in one female of the high-dose group.

HISTOPATHOLOGY: NON-NEOPLASTIC
No test substance-related changes were observed in histopathological examinations.
Furthermore, no differences were found regarding spermatogenic cycle.
In male control animals, accumulation of foam cell, microgranuloma in the liver, solitary cyst in the kidnes and haemorrhage of the thymus were observed with low incidence. In female animals of the control group, artery mineralization of the lung, hyaline cast and cortex fibrosis of the kidney were apparent with low incidence in control animals only. Both in the high-dose group and in the control group, myocardial degeneration/fibrosis, extramedullary haematopoiesis of the spleen, foam cell accumulation of the lung, and focal liver necrosis, were found with low incidence in control and test groups. In all males of the high-dose and control group, hyaline droplet of proximal tubular epithelium in the kidney was found. Furthermore, in all males and females of the control and high dose group, brown deposit pigment and extramedullary haematopoiesis in spleen were found without differences between control and test group.
Incidental not substance-related findings of lymphocyte interstitium infiltration in prostate were found in one male of the high-dose group and interstitial focal inflammation in the lung and focal necrosis in the liver of one female of the high dose group were observed.
No abnormalities were found in the uterus and ovaries in the non-pregnant females and the unsuccessful copulation females of the control and high-dose groups, respectively. Degeneration of seminiferous tubules of testis, decrease in sperm and atrophy in prostate was observed in one control male only.

HISTOPATHOLOGY: NEOPLASTIC
In the mid-dose group, mass on abdomen was found in one female after 40 days of administration. This subcutaneous tumour of the mammary gland was a benign fibroadenoma and generated naturally and was therefore not considered to be substance related.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: overall effects

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from a reference substance with similar structure (intact surrogate ester) and intrinsic properties. Read-across is justified based oncommon functional group(s) and common precursors/breakdown products properties (refer to endpoint discussion for further details).
The selected study is thus sufficient to fulfil thestandard information requirements set
out in Annex VIII-IX, 8.6, in accordance with AnnexXI, 1.5, of Regulation (EC) No
1907/2006.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Repeated dose toxicity: oral

No data are available on the repeated dose toxicity of Reaction product of lauric acid and oxybis(propanediol) (List No. 700-672-1) via the oral route.

In order to fulfil the standard information requirements set out in Annex IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006 read-across from the structurally related surrogate substance, glycerol oleate (CAS No. 111-03-5), a mixture of mono-,di-,and triglycerides of lauric acid and data on medium- and long-chain triacylgycerols as well as from the predicted metabolite lauric acid (CAS No. 143-07-7) was considered. In addition, data of the polyol dipropylenglycol (CAS No. 25265-71-8) a structurally related substance to the predicted metabolite diglycerol are available. The data on the structural surrogates were considered for read-across and assessment was conducted based on an analogue and weight of evidence approach.

Glycerol oleate (CAS No. 111-03-5) was tested for subacute oral toxicity in a 28-day screening study according to OECD guideline 422 under GLP conditions (Yamaguchi).

Prior to the main study, two dose range finding studies were performed. Based on the results of the preliminary studies, 1000 mg/kg bw/day was selected as the highest dose level for the main study. Groups of 12 Sprague-Dawley rats per sex were given the test substance by gavage at dose levels of 100, 300 and 1000 mg/kg bw/day including 5 males of the control and high-dose groups which were allowed 14 days of recovery. Additionally, 5 females were added to a satellite control and high-dose group (recovery group). A concurrent negative control group receiving the vehicle corn oil only was included in the testing as well.

No clinical signs or mortality occurred in relation to the test substance. No changes in body weight and weight gain were observed during the treatment period. In recovery males of the high-dose group, a significant increase in body weight was noted during recovery. This increase was considered to be of no toxicological relevance since a tendency of the control animals to lose body weight was observed. No toxicological relevant differences in food consumption were observed during the administration period in the test groups. No changes in the haematological parameters were noted which were considered to be of toxicological relevance. Observations of clinical chemistry showed a significant decrease in inorganic phosphate in females of the low- and high-dose group. However, this change was not regarded as test substance-related, since no dose-relationship was observed and most of the individual data were within the reference ranges. No significant changes in urine parameters were found during the administration and recovery period. No abnormalities were observed for the tested neurobehavioural parameters during the administration period. In low-dose males, a significant decrease in absolute weight of seminal vesicles and in the low-dose female group a significant decrease in the relative weight of spleen was observed. These changes were considered not to be compound-related as no corresponding findings were apparent in the histopathological examination and no dose-relationship was observed. Moreover, gross pathology and histopathology showed no substance-related changes in any animal. Furthermore, no differences were found regarding spermatogenic cycle and no abnormalities were found in the uterus and ovaries in the non-pregnant females and the unsuccessful copulation females of the control and high-dose groups, respectively.

Based on the lack of toxicological relevant effects, a NOAEL of 1000 mg/kg bw/day (males/females) was identified in this study.

A subchronic 18-weeks feeding study with the predicted metabolite lauric acid (CAS No. 143-07-7) was conducted in five male Osborne-Mendel rats (Fitzhugh, 1960). The animals were given 10% lauric acid in the diet (corresponding to 4000 mg/kg bw/day).

No clinical signs of toxicity, no adverse effects on body weight (gain) and no mortality were observed during the study period in any animal. Moreover, gross organ pathology and comparison of individual organ weights showed no significant differences between the controls and the test animals.

Thus, a dose level of 10% in diet, corresponding to 4000 mg/kg bw/day in male rats was investigated and no toxicological relevant effects were observed.

Additionally, in a 2 year feeding study with rats, the chronic oral toxicity of a mixture of mono-, di-, and triglycerides of lauric acid was assessed (Fitzhugh, 1960).

24 Osborne-Mendel rats per sex were fed 25% of the test compound in the diet (corresponding to 12500 mg/kg bw/day (females) and 10,000 mg/kg bw/day (males)). Concurrent control animals were fed the plain diet or diet with hydrogenated cottonseed oil (25% in the diet).

No significant differences in mortality were observed during the study period.

Body weight and weight gain of rats fed the test compound or the control animals fed the hydrogenated vegetable oil in the diet were not significantly different. However, lower body weight gains were apparent in rats fed the basal diet alone which reflected the higher caloric intake in the other groups. The autopsy revealed no gross pathology findings (no further details given). Histological examination revealed a slight excess of hepatic cell fatty change in the treatment groups and the control group on vegetable oil as compared to a small amount in the controls fed basal diet alone. The same difference occurred to a lesser degree for intrahepatic bile duct proliferation (no further details given).

A dose level of 25% of the test compound in the diet, corresponding to 12,500 mg/kg bw/day in female and 10,000 mg/kg bw/day in male rats, was investigated and no toxicological relevant effects were observed.

In addition, studies with the polyol dipropylenglycol a structurally related substance to the predicted metabolite diglycerol are available. In a 14-day subacute, a 90-day subchronic and a 2-year chronic drinking water study in rats, the repeated dose toxicity of dipropylenglycol (CAS No. 25265-71-8) was assessed (NTP, 2004).

In the 14-day subacute study, groups of 5 Fischer 344 rats per sex were dosed with 5000, 10000, 20000, 40000 and 80000 ppm (corresponding to 635, 1450, 2650, 5850 and 13000 mg/kg bw/day in males and 850, 1670, 2860, 5420 and 11100 mg/kg bw/day in females) dipropylenglycol in the drinking water.

During the study period no mortality occurred and clinical signs were only apparent in high-dose males including hypoactivity, piloerection and perinasal staining. The final mean body weights and body weight gains of animals of the mid- and high-dose group were significantly less when compared with control. No treatment-related differences in water consumption were observed. Kidney weights of males were significantly increased from the 5850 mg/kg bw/day group and higher and liver weights were increased from the 2650 mg/kg bw/day group and higher. Similarly, females exposed to dose levels of 5420 mg/kg bw/day showed increased relative kidney weights and increased absolute and relative higher liver weights. Microscopically minimal focal fatty change was observed in livers of single males exposed from 2650 mg/kg bw/day and above.

Based on the effects on organ weights of liver and kidney in females and males and on histopathology results of liver and kidney in males, a NOAEL of 2860 mg/kg bw/day (females) and a NOAEL of 1450 mg/kg bw/day (males) was identified in this study.

In the subchronic study, groups of 10 animals per sex were dosed with 5000, 10000, 20000, 40000 and 80000 ppm (corresponding to 425, 890, 1840, 3890 and 12800 mg/kg bw/day in males and 460, 920, 1690, 3340 and 8950 mg/kg bw/day females) dipropylenglycol in the drinking water.

No mortality occurred during the study period. In the male high-dose group, clinical sings were hypoactivity and poor hair coats. The final body weights in all male groups and in females from 1690 mg/kg bw/day were significantly less when compared with controls. Water consumption in the high-dose groups increased during the second week of the study and was greater than that of the controls for the remainder of the study. In males dosed with 890 mg/kg bw/day and higher, treatment induced a minimal erythron decrease at Week 14. Furthermore, an increase in serum alanine aminotransferase and sorbitol dehydrogenase activities and/or total bile acid concentrations were observed in males (1840 mg/kg bw/day) and females (from 1690 mg/kg bw/day) that were suggested to be a hepatic effect in males and females.

Liver weights of rats receiving 890 and 920 mg/kg bw/day and kidney weights of rats receiving 3890 and 3340 mg/kg bw/day and higher were greater when compared to controls. Histopathological examinations showed that the incidences of liver and kidney lesions were significantly increased in males dosed with 1840 mg/kg bw/day group and higher and in high-dose females. Focal olfactory epithelial degeneration was present in all high-dose rats. Male rats in the high-dose group had small testes, preputial glands, seminal vesicles, and prostate glands. The left testis, cauda epididymis, and epididymis weights of the high-dose males were significantly decreased. The incidences of testicular atrophy, epididymal hypospermia, preputial gland atrophy, and seminal vesicle depletion were generally increased in the high-dose group. However, the effects in the genital system of males occurred only in the high-dose group (dosed with 12800 mg/kg bw/day). For these animals a final mean body weight of 53% when compared to controls was observed.

Based on the effects on organ weights of liver and kidney in females and males, a NOAEL of 460 mg/kg bw/day (females) and a NOAEL of 425 mg/kg bw/day (males) was identified in this study.

In the chronic study, groups of 50 animals per sex were dosed with 2500, 10000 and 40000 ppm (corresponding to 115, 470 and 3040 mg/kg bw/day in males and 140, 530 and 2330 mg/kg bw/day in females) dipropylenglycol in the drinking water for 105 weeks.

Survival of the high-dose males was significantly less when compared to controls. Mortality was largely due to chronic progressive nephropathy and subsequent renal insufficiency. Mean body weights of the high-dose groups were reduced in comparison to the respective control groups throughout the study period. Water consumption in high-dose males was increased from Week 53. The higher average water consumption in comparison to the control group suggested renal insufficiency, as well. This was confirmed in histopathological examination showing significantly increased incidences of nephropathy in all mid- and high-dose males. Furthermore, increased incidences of focal histiocytic (46/49 and 48/48) and focal granulomatous inflammation in the liver in mid- and high-dose males (42/49, 27/48), bile duct hyperplasia of the liver in males of the mid- and high-dose group and females of the mid-dose (7/50) and high-dose groups (18/49). Olfactory epithelium atrophy in males and olfactory epithelium degeneration in female rats was observed. According to the author, these effects may have been related to enzymatic metabolism of the test material in the olfactory epithelium. The incidence of minimal to mild suppurative inflammation of the salivary gland was significantly increased in high-dose males. There was no evidence of carcinogenic activity of dipropylene glycol in male and female rats.

Based on the overall effects, a NOAEL of 530 mg/kg bw/day for female rats and a NOAEL of 115 mg/kg bw/day for male rats was identified in this study.

The structurally-related surrogate substances, medium- and long-chain triacylglycerols (MLCT) were tested in comparison with long-chain triacylglycerols (LCT) for subacute oral toxicity in a 56-day feeding study in rats (Matsuo und Takeuchi, 2004).

Groups of 6 male Wistar rats were given 5, 10, 15 and 20% of the respective test substance in the diet, corresponding to 4090, 8170, 12260 and 16340 mg/kg bw/day, calculated from the reported mean body weight and mean food intake values.

No clinical signs or mortality were observed during the study period. Body weight (gain) was higher in groups with higher fat/kg in the diet amount. Furthermore, in dose groups receiving 150 and 200 g fat/kg diet fed MLCT, body weight (gain) was significantly lower than in the LCT groups. The observed changes in body weight were considered to be of no toxicological relevance.

No toxicological relevant changes in clinical chemistry were observed. However, serum triacylglycerol concentration was significantly higher in MLCT-fed rats, when compared to LCT-fed rats. Serum glucose and insulin concentrations were significantly lower in the lowest dose group. Hepatic capacities of the citrate synthase and cytochrome oxidase were significantly higher in rats fed MLCT, when compared to LCT-fed rats. Liver triacylglycerol content was significantly increased in rats fed the MLCT diet, when compared to rats fed LCT. Perirenal adipose tissue weight and intra-abdominal adipose tissue weight was significantly lower in the high-dose MLCT groups, when compared to the respective LCT groups.

Based on the lack of toxicological relevant effects, a NOAEL of 16340 mg/kg bw/day for male rats was identified in this study.

Furthermore, a 90-day subchronic feeding study with medium chain triglycerides was conducted following a protocol similar to OECD guideline 409 (Matulka, 2009). Four Beagle dogs per dose (5, 10 and 15% in the diet corresponding to 1250, 2500 and 3750 mg/kg bw/day) received the test substance daily in the diet.

There were no signs of toxic effects, mortality or body weight changes observed in any of the animals during the study period. Periods with reduced food intake were not significant to the overall food consumption rates and were probably due to the palatability of the test compound in the feed. Findings from ophthalmic examinations were unremarkable and of no toxicological relevance.

Elevated nitrogen and reductions in total blood protein and urine volumes were observed in the mid- and high-dose group. Furthermore, a non-significant increase in cholesterol in this groups compared to vehicle fed animals was apparent. An increase in serum potassium and a decrease in globulin protein levels were also observed in the high-dose group, but did not follow a dose-dependent manner. These changes may be the result of protein sparing effects due to the high levels of medium chain triglyceride intake, and were not deemed to be adverse effects.

Based on the lack of toxicological relevant effects, a NOAEL of 3750 mg/kg bw/day (m, f) was identified in this study.

 

In conclusion, the overall weight of evidence from the available data on repeated dose toxicity via the oral route of the surrogate esters and the predicted metabolite lauric acid showed no adverse effects in animals fed doses from 100 up to 16340 mg/kg bw/day. The surrogate substance dipropylene glycol which is a structurally related substance of the predicted metabolite diglycerol, a NOAEL of 115 mg/kg bw/day (males) in a chronic study was observed.

The results of the intact fatty acid esters which are structurally closely related to the source substance indicate a very low evidence of toxicity after repeated oral exposure. Thus, for hazard assessment, read-across was based on data from the intact surrogate ester glycerol oleate following an analogue approach. Therefore, an oral NOAEL of 1000 mg/kg bw/day is considered for Reaction product of lauric acid and oxybis(propanediol) (List No. 700-672-1).

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Hazard assessment is conducted by means of read-across from a structural surrogate. The selected study is the most adequate and reliable study based on the identified similarities of the intact surrogate ester and intrinsic properties between source and target substance and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Justification for classification or non-classification

Based on read-across from an analogue substance following an analogue approach, the available data on repeated dose toxicity of Reaction product of lauric acid and oxybis(propanediol) (List No. 700-672-1) do not meet the criteria for classification according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and the data are therefore conclusive but not sufficient for classification.