2-ethylhexyl 12-(acetoxy)octadecanoate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Reference 1

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 2015 - November 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

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 (incl. QA statement)

Limit test:

no

Specific details on test material used for the study:

Identification : SE7B
Physical State/Appearance : Clear colorless liquid
Chemical Name : Fatty Acids, C8-C18 and C18 unsaturated, reaction product
with isomerized oleic acid homopolymer 2- ethylhexyl ester,
hydrogenated
Chemical Formula : C44H86O4
Purity : >95%
Batch Number : 0000140602
Label : SE7B Lot#0000140602
Date Received : 20 February 2015
Storage Conditions : In the dark, at room temperature
Expiry Date : 18 February 2017

Species:

rat

Strain:

Wistar

Remarks:

Wistar Han™:RccHan™:WIST

Sex:

male/female

Details on test animals or test system and environmental conditions:

A sufficient number of male and female Wistar Han™:RccHan™:WIST strain rats were obtained from Harlan Laboratories U.K. Ltd., Blackthorn, Bicester, Oxon, UK. On receipt the animals were examined for signs of ill-health or injury. The animals were acclimatized for eight days during which time their health status was assessed. A total of one hundred and sixteen animals (fifty eight males and fifty eight females) were accepted into the study. At the start of treatment the males weighed 317 to 360g, the females weighed 188 to 232g, and were approximately twelve weeks old.

Initially, all animals were housed in groups of three or five in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd., Cheshire, UK). During the pairing phase, the non-recovery animals were transferred to polypropylene grid floor cages suspended over trays lined with absorbent paper on a one male: one female basis within each dose group. Following evidence of successful mating, the males were returned to their original cages. Mated females were housed individually during gestation and lactation in solid floor polypropylene cages with stainless steel mesh lids and softwood flakes. Recovery group animals were housed in groups of five in solid floor polypropylene cages with stainless steel mesh lids and furnished with softwood flake bedding.

The animals were allowed free access to food and water. A pelleted diet (Rodent 2018C Teklad Global Certified Diet, Harlan Laboratories U.K. Ltd., Oxon, UK.) was used. Mains drinking water was supplied from polycarbonate bottles attached to the cage. Environmental enrichment was provided in the form of wooden chew blocks and cardboard fun tunnels (Datesand Ltd., Cheshire, UK) except for paired animals and mated females during gestation and lactation. Mated females were also given softwood flakes, as bedding, throughout gestation and lactation. The diet, drinking water, bedding and environmental enrichment was considered not to contain any contaminant at a level that might have affected the purpose or integrity of the study.

The animals were housed in a single air-conditioned room within the Envigo Research Limited, Shardlow, UK Barrier Maintained Rodent Facility. The rate of air exchange was at least fifteen air changes per hour and the low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness. Environmental conditions were continuously monitored by a computerized system, and print-outs of hourly temperatures and humidities are included in the study records. The Study Plan target ranges for temperature and relative humidity were 22 ± 3 °C and 50 ± 20% respectively; there were short term deviations from these targets were considered not to have affected the purpose or integrity of the study; see deviations from Study Plan.

The animals were randomly allocated to treatment groups using a stratified body weight randomization procedure and the group mean body weights were then determined to ensure similarity between the treatment groups. The cage distribution within the holding rack was also randomized. The animals were uniquely identified within the study by an ear punching system routinely used in these laboratories.

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on exposure:

Test Item Preparation
For the purpose of this study the test item was prepared at the appropriate concentrations as a solution in Arachis oil BP. The stability and homogeneity of the test item formulations were determined by Envigo Research Limited, Shardlow, UK, Analytical Services. Results show the formulations to be stable for at least 21 days. Formulations were therefore prepared fortnightly and stored at approximately 4°C in the dark.
Samples of the test item formulation were taken and analyzed for concentration of SE7B at Envigo Research Limited, Shardlow, UK, Analytical Services. The results indicate that the prepared formulations were within ± 10% of the nominal concentration.

The test item was administered daily by gavage using a stainless steel cannula attached to a disposable plastic syringe. Control animals were treated in an identical manner with 4 mL/kg of Arachis oil BP.
Animals were allocated to treatment groups as follows:
Control
Dose Level(mg/kg bw/day) - 0
Treatment Volume (mL/kg) - 4
Concentration (mg/mL) - 0
Animal Numbers - Male - 12(1-12)
Animal Numbers - Female - 12(13-24)

Recovery Control
Dose Level(mg/kg bw/day) - 0
Treatment Volume (mL/kg) - 4
Concentration (mg/mL) - 0
Animal Numbers - Male - 5(97-101)
Animal Numbers - Female - 5(102-106)

Low
Dose Level(mg/kg bw/day) - 100
Treatment Volume (mL/kg) - 4
Concentration (mg/mL) - 25
Animal Numbers - Male - 12(25-36)
Animal Numbers - Female - 12(37-48)

Intermediate
Dose Level(mg/kg bw/day) - 300
Treatment Volume (mL/kg) - 4
Concentration (mg/mL) - 75
Animal Numbers - Male - 12(49-60)
Animal Numbers - Female - 12(61-72)

High
Dose Level(mg/kg bw/day) - 1000
Treatment Volume (mL/kg) - 4
Concentration (mg/mL) - 250
Animal Numbers - Male - 12(73-84)
Animal Numbers - Female - 12(85-96)

Recovery High
Dose Level(mg/kg bw/day) - 1000
Treatment Volume (mL/kg) - 4
Concentration (mg/mL) - 250
Animal Numbers - Male - 12(107-111)
Animal Numbers - Female - 12(112-116)

Details on mating procedure:

Non-recovery animals were paired on a 1 male: 1 female basis within each dose group, for a period of up to fourteen days. Cage tray-liners were checked each morning for the presence of ejected copulation plugs and each female was examined for the presence of a copulation plug in the vagina. A vaginal smear was prepared for each female and the stage of estrus or the presence of sperm was recorded. The presence of sperm within the vaginal smear and/or vaginal plug in situ was taken as positive evidence of mating (Day 0 of gestation) and the males were subsequently returned to their original holding cages. Mated females were housed individually during the period of gestation and lactation.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentrations determined by GC using an external standard technique.
Formulations investigated comprise test itemin the range o 90% to 109%, thus within acceptable limits of ±10%
Detection system was found to have acceptable linearity, and the proceedure had acceptable recoveries of test item in the vehicle.

Duration of treatment / exposure:

57 days

Frequency of treatment:

Daily

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

Control

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Low

Dose / conc.:

300 mg/kg bw/day (nominal)

Remarks:

Intermediate

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

High

No. of animals per sex per dose:

Control: 12 M, 12 F
Recovery Control: 5 M, 5F
Low: 12 M, 12 F
Intermediate: 12 M, 12 F
High: 12 M, 12 F
Recovery High: 5 M, 5 F

Control animals:

yes, concurrent vehicle

Details on study design:

Chronological Sequence of Study
Non-Recovery Dose Groups
i. Groups of twelve male and twelve female animals were treated daily at the appropriate dose level throughout the study (except for females during parturition where applicable).The first day of dosing was designated as Day 1 of the study.
ii. Prior to the start of treatment and once weekly thereafter, all animals were observed for signs of functional/behavioral toxicity.
iii. On Day 15, animals were paired on a 1 male: 1 female basis within each dose group for a maximum of fourteen days.
iv. Following evidence of mating (designated as Day 0 post coitum) the males were returned to their original cages and females were transferred to individual cages.
v. On completion of the pairing phase (during Week 6), five selected males per dose group were evaluated for functional/sensory responses to various stimuli.
vi. Pregnant females were allowed to give birth and maintain their offspring until Day 5 post partum. Litter size, offspring weight and sex, surface righting and clinical signs were also recorded during this period.
vii. At Day 4 post partum, five selected females per dose group were evaluated for functional/sensory responses to various stimuli.
viii. Blood samples were taken from five males from each dose group for hematological and blood chemical assessments on Day 42. The male dose groups were killed and examined macroscopically on Day 43 or 44.
ix. Blood samples were taken from five randomly selected females from each dose group for hematological and blood chemical assessment on Day 4 post partum. At Day 5 post partum, all females and offspring were killed and examined macroscopically. Any female which did not produce a pregnancy was also killed and examined macroscopically.

Recovery Dose Groups
i. Groups of five male and five female rats were dosed according to dose group continuously up to the point of sacrifice of non-recovery males at which time treatment was discontinued.
ii. The males and females were maintained without treatment for a further fourteen days.
iii. Urinalysis was performed for all males during the final week of recovery.
iv. Blood samples were taken for hematological and blood chemical assessment on Day 56.
v. After fourteen days of recovery, males and females were killed and examined macroscopically.

Clinical signs:

no effects observed

Description (incidence and severity):

There were no clinical signs of toxicity related to the test item.

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths during the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no detrimental effects detected for overall body weight development in treated animals of either sex.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No adverse effects were detected in food consumption or food efficiency for treated males throughout the treatment period or in treated females during maturation, gestation or lactation.

Food efficiency:

no effects observed

Description (incidence and severity):

No adverse effects were detected in food consumption or food efficiency for treated males throughout the treatment period or in treated females during maturation, gestation or lactation.

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

no effects observed

Description (incidence and severity):

Daily gravimetric assessment of the water bottles throughout the pre-pairing phase showed no effect on water intake when compared to controls. Water bottles were assessed by visual inspection for the remainder of the study.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

There were no toxicologically significant changes in the haematological parameters measured.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No toxicologically significant changes were detected in blood chemical parameters.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no treatment-related urinalytical effects detected for any treated male dose groups.

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

There were no treatment-related effects detected in animals of either sex treated with 1000, 300 or 100 mg/kg bw/day.
There were no treatment-related changes in functional performance for animals of either sex treated with 1000, 300 or 100 mg/kg bw/day
There were no treatment-related changes in sensory reactivity for animals of either sex treated with 1000, 300 or 100 mg/kg bw/day.

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There was no evidence of test item-related histopathological findings.

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

There was no evidence of test item-related histopathological findings.

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Description (incidence and severity):

No treatment-related effects were detected in mating performance.

Reproductive function: sperm measures:

no effects observed

Description (incidence and severity):

No treatment-related effects were detected in mating performance.

Reproductive performance:

no effects observed

Description (incidence and severity):

There were no treatment-related differences in fertility. One control female and one female treated with 100 mg/kg bw/day were non-pregnant following positive evidence of mating. No histopathological abnormalities were detected in either the male or females to explain the failure of the animals to breed successfully. Two females treated with 100 mg/kg bw/day showed positive evidence of mating however failed to give birth to any live offspring.
There were no differences in gestation lengths. Gestation lengths were between 22 and 23½ days.

Key result

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

food consumption and compound intake

food efficiency

water consumption and compound intake

haematology

clinical biochemistry

urinalysis

organ weights and organ / body weight ratios

gross pathology

histopathology: non-neoplastic

histopathology: neoplastic

reproductive function (oestrous cycle)

reproductive function (sperm measures)

reproductive performance

Clinical signs:

no effects observed

Description (incidence and severity):

There were no clinical signs of toxicity observed in offspring, or any macroscopic abnormalities detected at terminal kill, litter response is based on all litters reared to termination on Day 5 of lactation/age. The incidental clinical signs detected throughout the control and treatment groups consisting of small, no milk in stomach, ear damage, hind limb malformation, missing and found dead were considered to be low incidence findings observed in offspring in studies of this type and were considered unrelated to test item toxicity.

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Description (incidence and severity):

There was no effect of treatment on the mean number of corpora lutea, implantation sites, and pre- or post implantation losses. Of the litters born, litter size at birth and subsequently on Day 1 and 4 post partum was comparable to controls. Sex ratio (percentage male offspring) for the offspring was similar in all groups.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Offspring body weights and litter weights on Days 1 and 4 post partum were comparable to controls. Body weight changes for the pups across all treatment groups were similar to controls.
Statistical analysis of surface righting reflex did not reveal any significant intergroup differences.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

There were no toxicologically significant changes in the haematological parameters measured

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No toxicologically significant changes were detected in blood chemical parameters

Urinalysis findings:

no effects observed

Description (incidence and severity):

No treatment related effects were detected for any treated male dose groups.

Sexual maturation:

not examined

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No toxicologically significant changes were evident in the organ weights measured

Gross pathological findings:

no effects observed

Description (incidence and severity):

No treatment-related macroscopic abnormalities were detected in interim death or terminal kill offspring. The incidental findings observed were those occasionally observed in reproductive studies of this type and were considered to be unrelated to toxicity of the test item.

Histopathological findings:

no effects observed

Description (incidence and severity):

There was no evidence of test item-related histopathological findings. All of the histopathological findings encountered were considered to have occurred spontaneously or post mortem.

Other effects:

not specified

Behaviour (functional findings):

no effects observed

Developmental immunotoxicity:

no effects observed

JUSTIFICATION OF NO OBSERVED EFFECT LEVEL
Oral administration of the test item SE7B to rats for a period of up to eight weeks at dose levels of up to 1000 mg/kg bw/day did not result in any treatment-related changes. The ‘No Observed Adverse Effect Level’ (NOAEL) was, therefore considered to be 1000 mg/kg bw/day.
The following differences between treated and control animals were considered not to be indicative of test item toxicity:

Clinical Observations
- There were isolated incidents of one male and one female treated with 1000 mg/kg bw/day showing signs of generalised fur loss. Two control males and two males treated with 1000 mg/kg bw/day had scab formation. This was considered likely to be due to a physical injury. Both of these observations were considered to be of no toxicological importance.

Funtional Observations
Functional Performance Tests
- Males treated with 1000 and 300 mg/kg bw/day attained a statistically significant reduction in the forelimb Test 1 and all treated female groups attained a statistically significant increase in the fore limb Test 3. All individual values were within the background control ranges and without the presence of dose-related response. Therefore, these findings were considered to be incidental and to be of no toxicological importance.
- Overall activity for non recovery males treated with 1000 mg/kg bw/day was lower when compared to controls, subsequently attaining statistical significance but without any dose relationship. The corresponding value in high non-recovery females was comparable with control and as there were no apparent signs of neurotoxicity for any of these animals. The intergroup difference was considered to be incidental.

Body Weight
- Intergroup differences were observed, in particular for the recovery male achieving statistical significance in some instances, however, overall body weight gain was comparable to controls. Overall weight gains for all non-recovery male dose groups were slightly higher than controls and there was no effect of treatment on female body weight development during pre-pairing, gestation or lactation.

Haematology
- Non-recovery males treated with 1000 mg/kg bw/day showed a statistically significant increase (p<0.05) in hematocrit levels when compared to controls. Individual values were all within the normal background ranges for animals of the age, sex and strain and in the absence of any supporting histopathological correlates the intergroup difference was considered to be incidental and of no toxicological importance.

Blood Chemistry
- Non-recovery males treated with 1000 mg/kg bw/day showed a statistically increase in chloride concentration. Non-recovery females from all treatment groups showed a statistically significant reduction in alkaline phosphates; which there were no dose relationships. Recovery high dose males showed a statistical significant reduction in Albumin/globulin ratio values and an increase in bile acid when compared to controls. All individual values were all within the normal background ranges for animals of the age, sex and strain and in the absence of any supporting histopathological correlates the intergroup differences were considered to be incidental and of no toxicological importance.

Organ Weights
- Incidental findings were confined to all treated non-recovery males showing a statistically significant increase (p<0.05) in absolute and relative brain weights when compared to controls. Recovery high dose males revealed a statistically significant reduction (p<0.05) in absolute and relative thyroid/parathyroid weights. The majority of the individual values were within the anticipated background ranges and in the absence of any histopathological correlates these changes were considered to be of no toxicological importance.

Key result

Dose descriptor:

NOEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

viability

clinical signs

mortality

body weight and weight gain

gross pathology

histopathology: non-neoplastic

histopathology: neoplastic

Key result

Reproductive effects observed:

no

Results tables attached ( Results Tables - OECD 422 - SE7B.pdf)

Conclusions:

The oral administration of SE7B to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, was tolerated well. Based on these results the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day. The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day.

Reference 2

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Read-Across Justification is attached below.

Reason / purpose for cross-reference:

read-across source

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Key result

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

food consumption and compound intake

food efficiency

water consumption and compound intake

haematology

clinical biochemistry

urinalysis

organ weights and organ / body weight ratios

gross pathology

histopathology: non-neoplastic

histopathology: neoplastic

reproductive function (oestrous cycle)

reproductive function (sperm measures)

reproductive performance

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Sexual maturation:

not examined

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Other effects:

not specified

Behaviour (functional findings):

no effects observed

Developmental immunotoxicity:

no effects observed

Key result

Dose descriptor:

NOEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

viability

clinical signs

mortality

body weight and weight gain

gross pathology

histopathology: non-neoplastic

histopathology: neoplastic

Key result

Reproductive effects observed:

no

Conclusions:

Read-Across is claimed between BT4 (target) and SE7B (Source), according to the justification attached to the target record, and based on structural and physical/chemical similarities.

Analogue diesters (SE7B, SE6B) and BT4 contain the same functional groups, i.e the ester group adjacent to the ethylhexane side chain, and the ester group at the opposite end of the molecules. The carbon range in the main backbone of the molecules is all the same (C18) though the acetate moiety is attached at slightly different positions (C12 for BT4, C9/10 for the analogue diesters). The analogue diesters have the additional alkane chain attached to the acetate cap. The alkane chains themselves are not typically considered to be functional groups, per se, as they are relatively inactive biologically. Thus the parent molecules BT4 and the analogue diesters are similar enough to allow for read across in that there are no differences with respect to functional groups, and their only real difference is number of, and length of, saturated hydrocarbon chains.

Mammalian carboxylesterases are enzymes that are capable of metabolizing a wide variety of estercontaining substances, hydrolyzing them to their corresponding carboxylic acids and alcohols (S. Casey Laizure, 2013) (Jihong Lian, 2018). In general, carboxylesterases hydrolyze substrates to more polar molecules that are more readily excreted. The two predominant carboxylesterases in humans are most abundant in liver and gut where their function is believed to be related to first pass clearance of xenobiotics (Jihong Lian, 2018). Hydrolysis of the analogue diesters or BT4 would yield 2-ethylhexanol.

In addition, hydrolysis of BT4 would yield acetic acid plus 12-hydroxystearic acid (C18), versus either lauric acid (C12) or the coconut oil fatty acid mixture (C8-18) for SE6B and SE7B, respectively. The difference in these fatty acid chain lengths is not expected to impact toxicity of breakdown products, particularly since none of these fatty acids have been shown to be toxic, and they are in fact, commonly found in foods and used in personal care products. While fatty acids that would occur following the breakdown of the analogue diesters are known to be severe eye irritants, exposure of the eyes to the analogue diesters or BT4 would be to the parent chemicals themselves and not to
hydrolysis products. Similarly, fatty acids from the breakdown of the analogue diesters may be irritants to the skin, though expression of carboxylesterase in human skin is not expected to be significant, and exposure through skin contact would again be to the parent compounds. Breakdown of BT4 also results in acetic acid; acetic acid is of very low toxicity in humans, and is in fact a natural component in body fluids. Thus, the possibility of it occurring as a potential breakdown product from exposure to BT4 is not expected to be of toxicological concern.

Thus, toxicological data generated on any of these materials, SE6B, SE7B, and BT4, is appropriate for read-across to the other, as the variable length of the saturated hydrocarbon chain from the initial fatty acids, the slight difference in position of the acetate moiety on the fatty acid backbone, and the additional saturated hydrocarbon chain on SE6B and SE7B versus BT4 is not expected to contribute significantly to the overall toxicity profiles of the finished chemicals. Further, the difference in breakdown products, i.e. variable chain length fatty acids and additional breakdown product of acetic acid in the case of BT4, is not expected to contribute significantly to the toxicological profiles
of these chemicals. In conclusion, it is considered that toxicological data generated for either SE6B or SE7B is appropriate for read-across to BT4.

In an OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test), the oral administration of SE7B to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, was tolerated well. No mortalities occured during the study. There was no evidence of systemic toxicity, nor any adverse effects on reproductive function. Based on these results the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day. The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Justification for classification or non-classification

Read-Across is claimed between BT4 (target) and SE7B (Source), according to the justification attached to the target record, and based on structural and physical/chemical similarities.

Analogue diesters (SE7B, SE6B) and BT4 contain the same functional groups, i.e the ester group adjacent to the ethylhexane side chain, and the ester group at the opposite end of the molecules. The carbon range in the main backbone of the molecules is all the same (C18) though the acetate moiety is attached at slightly different positions (C12 for BT4, C9/10 for the analogue diesters). The analogue diesters have the additional alkane chain attached to the acetate cap. The alkane chains themselves are not typically considered to be functional groups, per se, as they are relatively inactive biologically. Thus the parent molecules BT4 and the analogue diesters are similar enough to allow for read across in that there are no differences with respect to functional groups, and their only real difference is number of, and length of, saturated hydrocarbon chains.

Mammalian carboxylesterases are enzymes that are capable of metabolizing a wide variety of estercontaining substances, hydrolyzing them to their corresponding carboxylic acids and alcohols (S. Casey Laizure, 2013) (Jihong Lian, 2018). In general, carboxylesterases hydrolyze substrates to more polar molecules that are more readily excreted. The two predominant carboxylesterases in humans are most abundant in liver and gut where their function is believed to be related to first pass clearance of xenobiotics (Jihong Lian, 2018). Hydrolysis of the analogue diesters or BT4 would yield 2-ethylhexanol.

In addition, hydrolysis of BT4 would yield acetic acid plus 12-hydroxystearic acid (C18), versus either lauric acid (C12) or the coconut oil fatty acid mixture (C8-18) for SE6B and SE7B, respectively. The difference in these fatty acid chain lengths is not expected to impact toxicity of breakdown products, particularly since none of these fatty acids have been shown to be toxic, and they are in fact, commonly found in foods and used in personal care products. While fatty acids that would occur following the breakdown of the analogue diesters are known to be severe eye irritants, exposure of the eyes to the analogue diesters or BT4 would be to the parent chemicals themselves and not to

hydrolysis products. Similarly, fatty acids from the breakdown of the analogue diesters may be irritants to the skin, though expression of carboxylesterase in human skin is not expected to be significant, and exposure through skin contact would again be to the parent compounds. Breakdown of BT4 also results in acetic acid; acetic acid is of very low toxicity in humans, and is in fact a natural component in body fluids. Thus, the possibility of it occurring as a potential breakdown product from exposure to BT4 is not expected to be of toxicological concern.

Thus, toxicological data generated on any of these materials, SE6B, SE7B, and BT4, is appropriate for read-across to the other, as the variable length of the saturated hydrocarbon chain from the initial fatty acids, the slight difference in position of the acetate moiety on the fatty acid backbone, and the additional saturated hydrocarbon chain on SE6B and SE7B versus BT4 is not expected to contribute significantly to the overall toxicity profiles of the finished chemicals. Further, the difference in breakdown products, i.e. variable chain length fatty acids and additional breakdown product of acetic acid in the case of BT4, is not expected to contribute significantly to the toxicological profiles

of these chemicals. In conclusion, it is considered that toxicological data generated for either SE6B or SE7B is appropriate for read-across to BT4.

In an OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test), the oral administration of SE7B to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, was tolerated well. No mortalities occured during the study. There was no evidence of systemic toxicity, nor any adverse effects on reproductive function. Based on these results the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day. The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day.

Considering the discussion above, and in view of structural similarity and low soubility of BT4, this result is also considered relevant for the read-across target BT4.