Hexanoic acid, 2-ethyl-, C16-18-alkyl esters

Endpoint summary

Description of key information

A 28 -day study (BASF, 1993) with the structural analogue Fatty acids, C8 -10, C12 -18 -alkyl esters is available, where no adverse effects were found revealing a NOAEL of 1000 mg/kg bw (highest dose tested).

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

Type of information:

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

Adequacy of study:

key study

Study period:

09 Mar - 12 May 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP-guideline study with acceptable restrictions. No neurological examinations were performed, no clinical observations outside the home cage, the test substance was administered 5 days/week, the analytical purity of the test substance was not specified.

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.7 (Repeated Dose (28 Days) Toxicity (Oral))

Deviations:

yes

Remarks:

no neurological examinations performed, no clinical observations outside the home cage

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

no neurological examinations performed, no clinical observations outside the home cage

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Wistar Bor:WISW (SPF) Cpb

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Winkelmann, Borchen, Germany
- Age at study initiation: approximately 4 weeks
- Weight at study initiation: 44-61 g (males), 46-60 g (females)
- Housing: 2-3 animals of the same sex in macrolon cages, type III with wood shavings (ARWI-Center, Essen, Germany)
- Diet: nitrosamine-poor pellets, Altromin 1324 DK (Fa. Altromin GmbH, Lage, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-24
- Humidity (%): 41-55
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 25 Feb 1992 To: 9-10 Mar 1992 (main groups), 12 May 1992 (satellite groups)

Route of administration:

oral: gavage

Vehicle:

other: 0.5% carboxymethylcellulose and 0.25% cremophor in aqua dest. (CMCC)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: dosing solutions were prepared daily prior to administration. The application volumes were adopted weekly to the current body weights.

VEHICLE
- Concentration in vehicle: 1, 2 and 10% for the 100, 300 and 1000 mg/kg bw/day groups, respectively.
- Amount of vehicle (if gavage): 10 mL/kg bw

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

28 days (control and treatment group)
28 days and 33 days post-exposure observation period (satellite control and treatment group)

Frequency of treatment:

once daily, 5 days/week (23-24 doses in total)

Remarks:

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

No. of animals per sex per dose:

10 (main groups)
5 (satellite groups)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: the dose levels were selected in order to find the highest possible safety margin for the determination of the non-cumulative toxic dose level and the determination of toxic dose ranges.
- Rationale for selecting satellite groups: satellite control and high-dose groups were selected to determine the reversibility of potentially cumulative toxic effects
- Post-exposure recovery period in satellite groups: 33 days

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: the animals were observed for mortality and clinical signs twice daily (once daily during weekends and public holidays)

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No, the intake per cage per week was recorded and calculated as g/rat/week
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

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: No

WATER CONSUMPTION: Yes
- Time schedule for examinations: once weekly, per cage

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: one day prior to the sacrifice of the animals. Mydriaticum Roche R (Hoffmann-La Roche, Grenzach-Wyhlen) was instilled into the right eye, which was then examined using a Topcon-SL-5D slit lamp (Bon, D-Wahlstedt).
- Dose groups that were examined: control and 1000 mg/kg bw/day group

HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to necropsy
- Anaesthetic used for blood collection: Yes (ether)
- Animals fasted: No
- How many animals: all animals in the main groups
- Parameters examined: haematocrit, haemoglobin content, red blood cell count, white blood cell count, mean cell volume, thrombocyte cell count, differential blood count

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to necropsy
- Animals fasted: No
- How many animals: all animals in the main groups
- Parameters examined: gamma-glutamyl transferase, aspartate-aminotransferase, alanine-aminotransferase, alkaline phosphatase, sodium, potassium, glucose, urea, total protein, calcium, creatinine, cholesterol, chloride, bilirubin

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes. The animals in the main groups and satellite groups were sacrificed using an overdose of ether and gross pathology was conducted with all animals. The eyeballs and the inner organs were removed and fixed in 10% neutral formalin solution (Formol-Fixx-Concentrate, Shandon). The weight of the brain, testes, heart, liver, spleen, adrenals, kidneys and thymus of all main and satellite groups was recorded.

HISTOPATHOLOGY: Yes. For the control and 1000 mg/kg bw/day groups, the following organs were histologically examined: aorta thoracia, eyes, colon, stomach, small intestine, cerebrum, urinary bladder, skin, heart, testes, hypophysis, cerebellum, liver, trachea, lung, axilliary lymph nodes, mesenteric lymph nodes, spleen, epididymides, adrenals, periphery nerve, kidneys, ovaries, pancreas, prostate, seminal vesicle, thyroid, salivary gland, oesophagus, sceletal muscle, thymus, uterus, forestomach, tongue.
In the satellite groups and the 500 mg/kg bw/day main group, the forestomach was examined as a target organ.

Statistics:

The inter-groups variations for body weight, clinical chemistry and hematology were determined using a t-test. The differences in organ weight were evaulated using a Steel-test.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

100 mg/kg bw/day: 1/10 females died at the end of the study during the collection of blood (not test substance-related)

Mortality:

mortality observed, treatment-related

Description (incidence):

100 mg/kg bw/day: 1/10 females died at the end of the study during the collection of blood (not test substance-related)

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw/day: increased level leucoytes with segmented nuclei, males (non-adverse)

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw/day: increased ALT level, males (non-adverse)

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):

300 mg/kg bw/d: increased relative heart weight, males; 100 mg/kg bw/day: increased relative/absolute heart weight, males (non-adverse)

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

1000 mg/kg bw/day: effects on the mucosa of the forestomach

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
One female administered 100 mg/kg bw/day died when a blood sample was drawn during anesthesia. There was no substance-related mortality. No clinical signs were observed during the study period.

BODY WEIGHT AND WEIGHT GAIN
There was no difference in body weight gain between the control and treatment groups.

FOOD CONSUMPTION
There was no statistically significant difference in food consumption between the control and treatment groups.

WATER CONSUMPTION
There was no statistically significant difference in water consumption between the control and treatment groups. The females in the 1000 mg/kg bw/day group showed an increase in water consumption in week 2, however, as this was due to a mechanical failure this is not considered to be a relevant finding (see Table 1).

OPHTHALMOSCOPIC EXAMINATION
There were no substance-related changes to the eyes of the examined animals.

HAEMATOLOGY
The males administered 1000 mg/kg bw/day had a significant increase in the level of leucocytes with segmented nuclei (see Table 2). As this effect was only observed in one sex and there were no other haematologic or histopathologic effects, this is not considered to be a treatment-related effect.

CLINICAL CHEMISTRY
In males administered 1000 mg/kg bw/day, the ALT-level was statistically significantly increased (see Table 3). This increase in a liver enzyme may be caused by an increase in the liver metabolism due to the test substance. However, no other effects were seen on clinical chemistry parameters or in the histopathological results and the effects are considered not to be of toxicological relevance. An increase in the protein- and calcium levels of males in the 100 mg/kg bw/day group is not considered to be substance-related as these increases were not observed at any other dose level and in one sex only.

ORGAN WEIGHTS
A slight decrease was observed in the relative and absolute heart weight of males in the 100 mg/kg bw/day group and in the relative heart weight in males in the 300 mg/kg bw/day group (see Table 4). As no effect was observed in the highest dose group, this is not deemed to be a treatment-related effect.

GROSS PATHOLOGY
1/10 females administered 1000 mg/kg bw/day had severe oedema in the forestomach and 1/10 had thickening of the forestomach mucosa. These findings were probably compound-related, however, humans do not have a forestomach and this effect is therefore not relevant to human exposure. No other effects were noted during necropsy.

HISTOPATHOLOGY: NON-NEOPLASTIC
4/10 males and 2/10 females in the 1000 mg/kg bw/day group had oedema in the mucosa of the forestomach, and the 2 females also had ulcerations (see Table 5). These findings were probably compound-related, however, as humans do not have a forestomach this effect is not relevant to human exposure. As none of the animals in the satellite group had effects on the forestomach, this is considered to be a reversible effect.

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: No treatment-related effects were observed up to and including the highest dose level

Critical effects observed:

not specified

Table 1: Water consumption as group mean value (mL/animal/day)

	Group (mg/kg bw/day)
	Males				Females
Week	Control	100	300	1000	Control	100	300	1000
1	209	196	205	197	156	154	159	155
2	209	215	217	192	145	152	158	195
3	229	215	209	207	138	141	147	149
4	217	208	203	211	141	143	145	149

 

 

Table 2: Haematological results

	Group (mg/kg bw/day)
	Males				Females
	Control	100	300	1000	Control	100	300	1000
leucocytes with segmented nuclei (%)	0.3	0.1	0.4	1.1*	0.7	0.7	0.7	0.7

*Statistically significant (p < 0.01)

 

Table 3: Clinical chemistry

	Group (mg/kg bw/day)
	Males				Females
	Control	100	300	1000	Control	100	300	1000
ALT (U/L)	30	30	30	40*	23	23	21	27
Protein (g/L)	60	62**	61	60	63	63	63	63
Calcium (mmol/L)	2.3	2.4**	2.4	2.4	2.4	2.4	2.4	2.4

*Statistically significant (p < 0.01)

**Statistically significant (p < 0.05)

 

Table 4: Organ weights

	Group (mg/kg bw/day)
	Males				Females
	Control	100	300	1000	Control	100	300	1000
Heart, absolute (g)	0.84	0.75**	0.77	0.82	0.58	0.61	0.59	0.60
Heart, relative (%)	0.34	0.32**	0.31*	0.33	0.36	0.36	0.36	0.37

*Statistically significant (p < 0.01)

**Statistically significant (p < 0.05)

 

 

 

Table 5: Histopathological effects

	Group (mg/kg bw/day)
	Males				Females
	Control	100	300	1000	Control	100	300	1000
Edema in forestomach	0/10	-	-	4/10	0/10	-	-	2/10
Ulcer(s) in forestomach	0/10	-	-	0/10	0/10	-	-	2/10

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate and reliable subacute toxicity study (Klimisch score 2), and is thus sufficient to fulfil the standard information requirements set out in Annex VIII, 8.6, 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 for repeated dose toxicity of Hexanoic acid, 2-ethyl, C16-18 alkyl esters (CAS No. 90411-68-0). 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 was 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, 1.5, of Regulation (EC) No 1907/2006, whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

Repeated dose toxicity

CAS	90411-68-0	95912-86-0
Chemical name	Hexanoic acid, 2-ethyl, C16-18 alkyl esters	Fatty acids, C8-10, C12-18-alkyl esters
MW	368.6-396.7 g/mol	312.53-424.74 g/mol
Repeated dose toxicity, oral	RA: CAS 95912-86-0	NOAEL: 1000 mg/kg bw
Repeated dose toxicity, inhalation	-	-
Repeated dose toxicity, dermal	-	-

 

The above mentioned substances are considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information is used to predict the same endpoints for Hexanoic acid, 2-ethyl, C16-18 alkyl esters (CAS No. 90411-68-0).

A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Discussion

Toxicity after long-term exposure is assessed by use of a subacute oral toxicity study with Fatty acids, C8-10, C12-18-alkyl esters, which was performed in male and female Wistar rats similar to OECD guideline 407 and in compliance with GLP (Pittermann, 1993). No neurological examinations and no clinical observations outside the home cage were performed. Rats were allocated to main control and treatment (10 rats per group) and satellite control and treatment (5 rats per group) groups. The rats were dosed with 100, 300, and 1000 mg/kg bw of the test substance by oral gavage. They were dosed once daily, 5 days/week for 28 days, resulting in 23-24 doses in total. There was no substance-related mortality and no clinical signs were observed during the study period. No effect on body weight gain was observed. Food and water consumption were similar in the control and treatment groups. Ophthalmoscopic examination revealed no effects. The males administered 1000 mg/kg bw/day had a significant increase in the level of leucocytes with segmented nuclei. As this effect was only observed in one sex and there were no other haematologic or histopathologic effects, this was not considered to be a treatment-related effect. No treatment-related effects on organ weights and clinical chemistry were observed. 1/10 females administered 1000 mg/kg bw/day had severe oedema in the forestomach and 1/10 had thickening of the forestomach mucosa. No other effects were noted during necropsy. Histopathology revealed that 4/10 males and 2/10 females in the 1000 mg/kg bw/day group had oedema in the mucosa of the forestomach, and the 2 females also had ulcerations. The findings in the forestomach were probably compound-related, however, humans do not have a forestomach and this effect is therefore not relevant to human exposure. As none of the animals in the satellite group had effects on the forestomach, this is considered to be a reversible effect. In conclusion, no adverse effects were observed after treatment of Wistar rats with up to 1000 mg/kg bw Fatty acids, C8-10, C12-18-alkyl esters. Thus, a NOAEL of 1000 mg/kg bw was deduced. 

 

 

 

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
There is only one study available.