Glycerides, mixed C8-10 and succinyl

Endpoint summary

Description of key information

Based on read-across from glycerides and succinic acid (and its sodium salts) and in a weight of evidence approach, no hazard was identified.

Oral: chronic NOAEL (rat, male) = 3930 mg/kg bw/day (based on read-across from sodium hydrogen succinate and after correction for differences in molecular weight and succinic acid content)

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

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 reference substances with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, sharing common functional groups (esters of glycerol with carboxylic acids), common precursors and breakdown products (glycerol, fatty acids and succinic acid) and similarities in toxicological properties (overall low toxicity). Refer to endpoint discussion for further details.
The selected study, in conjunction with the further available data and in a weight of evidence approach, is thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.6, in accordance with Annex XI, 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

Justification for grouping of substances and read-across

There are no data available on the repeated dose toxicity of Glycerides, mixed C8-C10 and succinyl (CAS 91744-56-8). 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 structurally related substances is conducted.

In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, whereby physicochemical, toxicological and ecotoxicological properties may be predicted from data for reference substance(s) by interpolation to other substances on the basis of structural similarity, glycerol trioctanoate (CAS 538-23-8), Glycerides, mixed decanoyl and octanoyl (73398-61-5), Medium-chain triglycerides (no CAS), sodium hydrogen succinate (CAS 2922-54-5) and disodium succinate hexahydrate (CAS 6106-21-4) are selected as reference substances for assessment of the repeated dose toxicity of Glycerides, mixed C8-C10 and succinyl.

The read-across is based on structural similarity between the source and target substances, as the substance Glycerides, mixed C8-C10 and succinyl is composed of esters of glycerol with succinic acid and fatty acids with carbon chain lengths of C8 and C10. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of repeated dose toxicity

CAS#	Chemical name	Molecular weight (range)	Repeated dose toxicity (oral)
91744-56-8 (a)	Glycerides, mixed C8-C10 and succinyl	470.68-1211.64	WoE: RA: CAS 538-23-8 RA: CAS 73398-61-5 RA: Short-, medium- and long-chain triglycerides (SCT, MCT, LCT) RA: CAS 2922-54-5 RA:CAS 6106-24-1
538-23-8 (b)	Glycerol trioctanoate	470.70	Experimental result: NOAEL (rat, m) = 4770 mg/kg bw/day (chronic)
73398-61-5	Glycerides, mixed decanoyl and octanoyl	470.69-554.85	Experimental result: NOAEL (rat, m/f) = 5000 mg/kg bw/day (subchronic)
no CAS	Short-, medium- and long-chain triglycerides (SCT, MCT, LCT)	-	Experimental result: NOAEL (rat, m/f) = 3750 mg/kg bw/day (subchronic)
2922-54-5	Sodium hydrogen succinate	141.08	Experimental result: NOAEL (rat) = 2200 (m) and 2550 (f) mg/kg bw/day (subchronic) NOAEL (rat) = 478 (m) and 608 (f) mg/kg bw/day (chronic)
6106-21-4	Disodium succinate hexahydrate	270.14	Experimental result: NOAEL (rat) = 100 (m) and 300 (f) mg/kg bw/day (subacute)

(a) The substance subject to the REACh Phase-in registration deadline of 31 May 2013 is indicated in bold font. Only for this substance a full set of experimental results and/or read-across is given.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

 

Subacute oral toxicity

CAS No. 6106-24-1

A GLP- compliant combined repeated dose toxicity study with the reproduction/developmental toxicity screening test was conducted with Disodium succinate hexahydrate according to OECD guideline 422 (MHLW, 2001). Groups of male and female rats (12 per dose) were given the test item by oral gavage at 100, 300 and 1000 mg/kg bw/day. Males were treated for 52 days starting 2 weeks prior to mating and females were treated for 42-46 days from 2 weeks before mating up to Day 4 of lactation. A concurrent vehicle (water) control group was included.

No mortality occurred in any group. There were no effects on body weight, food consumption and haematology. Loose stool was observed in one male at 100 mg/kg bw/day and four males and one female at 1000 mg/kg bw/day. Salivation was noted at 1000 mg/kg bw/day in one male and one female. Blood sodium levels were increased in males at 300 and 1000 mg/kg bw/day. Blood urea nitrogen levels were higher in females at 1000 mg/kg bw/day. Higher levels of urinary proteins (≥ 300 mg/dL) were seen in one and two of the five males examined at 300 and 1000 mg/kg bw/day, respectively. These findings suggest that the test item may affect the kidney. Increased absolute weight of the adrenals was noted in males at 1000 mg/kg bw/day. Relative organ weights were not affected. There were no substance-related findings at histopathological examinations.

Based on the higher levels of urinary protein in males and blood urea nitrogen in females, the subacute oral NOAEL was considered to be 100 mg/kg bw/day for male rats and 300 mg/kg bw/day for female rats.

 

Subchronic oral toxicity

CAS No. 73398-61-5

A 90-day oral feeding study was performed in young rats with Glycerides, mixed decanoyl and octanoyl (Klimmer, 1971). Groups of 20 animals per sex and dose were fed the test substance at 10000 and 50000 ppm in diet. Assuming a mean body weight of 200 g and a mean food intake of 20 g/day for young rats over the study period, approximate mean dose levels of 1000 and 5000 mg/kg bw/day are calculated. Rats fed the plain diet served as control.

No treatment-related abnormalities were observed concerning clinical signs, body weight gain, food consumption, haematology, clinical chemistry, urinalysis and gross pathology. Therefore, the subchronic NOAEL was found to be 5000 mg/kg bw/day (50000 ppm in diet).

Short-, medium- and long-chain triglycerides (SCT, MCT, LCT)

A subchronic oral toxicity study with medium chain triglycerides (MCT) was performed similar to OECD guideline 409 in beagle dogs at concentrations of 5, 10 and 15 % in the diet, corresponding to 1250, 2500 and 3750 mg/kg bw/day, as calculated from an assumed food consumption of 25 g/kg bw/day (Matulka et al., 2009). The MCT in this study comprised mixed esters of glycerol with even-numbered fatty acids in the chain length range of C8-12. Four animals per sex and dose received the test substance once daily during a 3-h feeding regimen for a period of 91 days, whereas a control group was administered the plain diet. No signs of toxic effects and no mortality were observed in any of the animals during the study period. The mean body weight was not altered between control and treated animals. As compared to the control group, all three MCT groups had several consecutive days of reduced food consumption at the beginning and near the end of study. These periods of reduced food intake were not significant to the overall food consumption rates, but were thought to be related to palatability of MCT in feed. No treatment-related effects were found at ophthalmological examination of the animals. In addition, alterations in urinary, serum clinical and haematological parameters were observed in the mid and high dose group. These effects were assumed to be non-adverse and adaptive responses as a result of protein sparing effects due to the high levels of MCT intake at 2500 and 3750 mg/kg bw/day. Based on the overall effects of this study, a NOAEL of ≥ 3750 mg/kg bw/day was derived for male and female beagle dogs.

CAS No. 2922-54-5

A 13-week repeated dose oral toxicity study was conducted with sodium hydrogen succinate similarly to OECD 408 (Maekawa et al., 1990). Groups of rats (10 per sex and dose) were daily exposed to the test substance via drinking water at concentrations of 0.3, 0.6, 1.25, 2.5, 5 and 10%. The corresponding dose levels were approximately 180, 530, 1110, 2200, 7000 and 9290 mg/kg bw/day for males and 360, 600, 1250, 2550, 6040 and 13330 mg/kg bw/day for females, as calculated from the reported body weight and water intake data. A water control group was included in the study.

All animals receiving 10% of the test substance in the drinking water died between Week 3 and 4 of the study and appeared severely emaciated. A slight decrease in body weight started at test substance concentrations of 2.5%. Adverse suppression of body weight (> 10% compared to controls) was observed in animals receiving 5% of the test substance in drinking water. All animals that died (10% concentration group) showed a severe suppression of body weight gain during the first 4 weeks of the experiment. Since no toxic lesions were observed in any organ in rats given 10% of the test substance, the severe suppression in body weight gain at this concentration was not considered to be treatment-related due to the refusal of drinking water because of its salty and specific taste. Animals receiving 10% of the test substance via drinking water only consumed very small amounts of water compared to the control groups. An increase in water consumption (especially in males) was observed in animals treated with 5% of the test substance in the drinking water. Water consumption in the animals administered with 0.3-2.5% of the test substance in the drinking water was comparable to those of the control animals. No effects were observed in haematological and clinical chemistry parameters. In the animals receiving 10% of the test substance in the drinking water, atrophy of the organs (not further specified) was observed. At histopathological examination, No substance-related lesions were observed in the animals that died during Week 4 and in any of the other animals sacrificed at the end of the study.

Based on adverse body weight depression observed at 5% and higher, the subchronic oral NOAEL was considered to be 2.5% in drinking water, corresponding to ca. 2200 and 2550 mg/kg bw/day in male and female rats, respectively.

 

Chronic oral toxicity

CAS No. 538-23-8

Oral chronic toxicity of Glycerol trioctanoate was investigated in a GLP-conform study in male Fischer 344/N rats (NTP, 1994). Sixty animals per test group received the undiluted test substance via gavage at dose volumes of 2.5, 5, 10 mL/kg bw/day, corresponding to doses of 2390, 4770, 9540 mg/kg bw/day, as calculated from a density of 0.954 g/mL. A group of 60 animals remained untreated and served as control group. The animals were treated for a period of 104 weeks, except for 10 animals of each group which were already sacrificed after 15 months for interim examinations. A total of 30 animals died or were humanely killed in extremis after treatment with 9540 mg/kg bw/day. Based on these data, the two-year survival rate was significantly lower in animals of the highest dose compared to controls (31/50 survivors in controls vs. 23/53 survivors in the 9540 mg/kg bw/day dose group). Clinical findings of dyspnoea, ataxia and lethargy were observed in 50/60 animals of the high-dose group. 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. However, 8 of 30 rats died between weeks 45 to 49 when the incidence of clinical findings (dyspnoea, 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) after 11 months (44 weeks) of treatment. Mean body weights of high dose group animals were decreased when compared to controls throughout the study, although the difference was less than 5% after week 61. A dose-dependent decrease in food consumption was determined, which was most probably due to the fact that rats received more than 10% of their caloric intake from the test item. Thus, the effects on food consumption were considered to be non-adverse. No changes in clinical chemistry parameters were observed in treated animals compared to controls. Significant changes in haematological parameters (increase in the haematocrit, haemoglobin and erythrocyte levels) were only observed in the high dose group when compared to controls. Statistically significant lower absolute kidney weights were only noted in animals of the mid dose (4770 mg/kg bw/day). Since no dose-dependency occurred, these effects were considered to be incidental and not treatment-related. No adverse effects were reported at gross pathology. Histopathological examination revealed a significant decrease in the incidence of nephropathy between animals of the high dose group and controls, which was due to the lower protein intake as a result of lower food consumption A dose-related increase in the incidences of pancreatic exocrine hyperplasia and adenoma as well as proliferative lesions of the forestomach was observed in the treated animals. Based on the results of this study, the NOAEL for male Fischer 344/N rats was set at 4770 mg/kg bw/day.

CAS No. 2922-54-5

Maekawa et al.(1990) reported the results of a long-term oral toxicity study with focus on carcinogenicity and thus similar to OECD guideline 453. In this study, 50 male and 50 female rats per dose group were given sodium hydrogen succinate via drinking water for 104 weeks followed by a 9-week recovery period. The concentrations in water were 1 and 2%, corresponding to approximately 478 and 1092 mg/kg bw/day in males and 608 and 1373 mg/kg bw/day in females (based on reported body weight and water consumption data). A concurrent water control group was included.

At the end of the study, the mortality rate in males was slightly higher in control groups (ca. 50%) compared to treatment groups (ca. 40%). In females, the mortality rate was lower compared to males and nearly similar between treatment and control groups (ca. 20%). In animals receiving 2% concentration of the test substance in the drinking water, a 10% decrease in body weight was observed compared to controls. The decrease in body weight was found to be treatment-related. No effects on water consumption were observed between control and treated animals. No data on clinical sings, haematology and clinical chemistry were reported.

In animals of both the control and treatment groups, myocardial fibrosis, bile duct proliferation and chronic nephropathy were observed. These lesions were not considered to be treatment-related, since they were found in animals of all test groups. No other specific lesions were observed in the treatment groups.

Tumours were found in many organs and tissues in all groups including controls. The incidence of tumours in males was almost 100% in control and treatment groups. In females, tumour incidences were 82% in control and 77-81% in treatment groups. In males, tumours of the testes were the most frequent, followed by those of the haematopoietic organs, thyroid, adrenals, prostate, pancreas and pituitary. The most common tumours in females were those of the uterus, pituitary, haematopoietic organs, mammary gland, thyroid and adrenals. In the thyroid of females, the incidence of C-cell adenoma/carcinoma was higher in the treatment groups compared to the control groups, but marginally not significant by the chi square test. In the age-adjusted statistical test, a positive trend for the incidence of this tumour was observed in the treatment groups. However, C-cell tumours have been commonly observed to develop spontaneously in the rat strain used (F344). In addition, the incidence of C-cell tumours in the female control group (2%) was noticeably lower than in the historical controls (7-19%), whereas the incidence of C-cell tumours in the male control group (13%) was within the range of historical control data. Since no increase or positive trend in the incidence of C-cell tumours was observed in males, the increase in these thyroid tumours in females receiving 2% of the test substance in the drinking water was considered to a result of experimental variability, and thus not related to treatment. This was further supported by the fact that no difference in the incidence of preneoplastic lesions (C-cell hyperplasia) of the thyroid gland was found between the female treatment groups and the controls. Tumours were also detected in other organs or tissues, but the incidences were very low. In both sexes, there were no statistically significant changes in overall tumour incidences between control and treated groups. Histologically, all tumours, except for the prostate tumours, were similar to those known to occur spontaneously in the F344 rat strain.

Based on the study results, it was concluded that the test substance had no carcinogenic activity in rats continuously exposed via drinking water for 2 years. Based solely on adverse body weight depression at the higher dose, a chronic NOAEL for systemic toxicity of 1% in water (478 and 608 mg/kg bw/day for males and females, respectively) can be identified.

 

For the purpose of hazard assessment of Glycerides, mixed C8-C10 and succinyl, the lowest dose descriptor from the longest available study for the reference substances is selected as starting point. The chronic oral toxicity study with sodium hydrogen succinate (CAS 2922-54-5) provides the lowest long-term NOAEL value of 478 mg/kg bw/day for systemic toxicity in male rats. In order to correct the dose descriptor for differences in molecular weight between the source and reference substance, the following is taken into account:

- In a worst case approach, the substance Glycerides, mixed C8-C10 and succinyl is assumed to be fully hydrolysed by esterases activity in the gastrointestinal tract and/or the liver, thus leading to the formation and 100% bioavailability of glycerol, octanoic, decanoic and succinic acid. The substance Glycerides, mixed C8-C10 and succinyl is a UVCB and according to the substance specifications, full hydrolysis would result in a mixture containing about 5 to 10% succinic acid.

- The NOAEL of 478 mg/kg bw/day is related to the monosodium salt of succinic acid, and must therefore be corrected for differences in molecular weight between the sodium salt (141.08 g/mol) and salt-free succinic acid (116.07 g/mol). The corrected NOAEL value for succinic acid is hence ca. 393 mg/kg bw/day ([478 mg/kg bw/day] x [116.07/141.08]).

In order to achieve a succinic acid dose of 393 mg/kg bw/day, and assuming a maximum content of 10% succinic acid, an external dose of 3930 mg/kg bw/day of Glycerides, mixed C8-C10 and succinyl would be required ([393 mg/kg bw/day]/0.1) .

Thus, for Glycerides, mixed C8-C10 and succinyl a chronic NOAEL of 3930 mg/kg bw/day is assumed for the purpose of hazard assessment, and is consistent with the likewise high values determined for glycerides.

Repeated dose toxicity: inhalation and dermal routes

This information is not available

Conclusions for repeated dose oral toxicity

There are no data available on the repeated dose oral toxicity of Glycerides, mixed C8-C10 and succinyl. The substance is composed of mixed esters of glycerol with octanoic (C8), decanoic (C10) and succinic acid. Therefore, hazard assessment is conducted by means of read-across and in a weight of evidence approach with available data for esters of glycerol with C8 and/or C10 acids as well as for succinic acid (and its sodium salts).

Subchronic and chronic studies with glycerides containing esters of C8 and C10 acids consistently show that the substances are not toxic after repeated oral exposure, as all identified NOAEL values were above the currently applicable limit dose value of 1000 mg/kg bw/day. Thus, for Glycerides, mixed decanoyl and octanoyl (CAS 73398-61-5) the subchronic NOAEL value in rats was 5000 mg/kg bw/day. For Medium-chain triglycerides (mixed esters of glycerol with even-numbered C8-C12 fatty acids) the subchronic NOAEL in dogs was 3750 mg/kg bw/day. In a chronic study with glycerol trioctanoate (CAS 538-23-8), a NOAEL of 4770 mg/kg bw/day was identified in male rats.

Studies with succinic acid ant its sodium salts indicate that the substance is of low toxicity after long-term oral exposure. In a subacute oral gavage study with disodium succinate hexahydrate (CAS 6106-21-4) in rats, NOAEL values of 100 (male) and 300 mg/kg bw/day (female) were identified, based only on higher levels of urinary protein (males) and blood urea nitrogen (females). In contrast, subchronic and chronic studies in rats exposed to sodium hydrogen succinate (CAS 2922-54-5) via drinking water resulted in subchronic and chronic (male/female) NOAEL values of 2200/2550 and 478/608 mg/kg bw/day, respectively, solely based on adverse body weight depression at the next higher dose level.

The lowest long-term NOAEL of 478 mg/kg bw/day for sodium hydrogen succinate (molecular weight = 141.08 g/mol) is selected for hazard assessment of Glycerides, mixed C8-C10 and succinyl. In order to account for differences in molecular weight, full enzymatic hydrolysis of Glycerides, mixed C8-C10 and succinyl and a maximum content of 10% succinic acid (molecular weight = 116.07 g/mol) are assumed. The resulting estimated long-term NOAEL is thus 3930 mg/kg bw/day.

Overall, the available data provide sufficient weight of evidence leading to the conclusion that the substance Glycerides, mixed C8-C10 and succinyl is not toxic after long-term oral exposure.

There are no data available on repeated dose toxicity by the inhalation and dermal routes.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:

Hazard assessment is conducted by means of read-across from structural analogues and surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure 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 structural analogues/surrogates, the available data on the repeated dose toxicity of Glycerides, mixed C8-C10 and succinyl do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.