Propane-1,2,3-triyl 3,5,5-trimethylhexanoate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Screening study (OECD 422): fertility NOAEL (rat) = 1000 mg/kg bw/day (based on read-across from glycerides, C8-18 and C18-unsatd. mono- and di-, acetates [CAS 91052-13-0]). Supported by a two-generation fertility/post-natal development toxicity study with glycerol (CAS 56-81-5) and other information (secondary literature only) obtained with 3,5,5-trimethylhexanoic acid (CAS 3302-10-1) accounted for in a Weight-of-Evidence approach.

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

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

Remarks:

Summary of available data used for the endpoint assessment of the target substance

Adequacy of study:

weight of evidence

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Key result

Dose descriptor:

NOAEL

Remarks:

parental fertility

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Remarks on result:

other: Source: CAS 91052-13-0, Notox, 2010c

Key result

Dose descriptor:

NOAEL

Remarks:

development

Generation:

F1

Effect level:

>= 1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no toxicologically relevant effects observed on viability, clinical signs, body weight and during macroscopic examination

Remarks on result:

other: Source: CAS 91052-13-0, Notox, 2010c

Reproductive effects observed:

not specified

Further supporting studies:

NOAEL (fertility): ca. 2000 mg/kg bw/day (Source: CAS 56-81-5, Wegener, 1953)

NOAEL (development): ca. 2000 mg/kg bw/day (Source: CAS 56-81-5, Wegener, 1953)

NOAEL (fertility): 147 - 167 mg/kg bw/day (Source: CAS 3302-10-1, BG Chemie, 2005)

NOAEL (development): 0.12 % in diet (Source: CAS 3302-10-1, BG Chemie, 2005)

Executive summary:

The reproductive toxicity of the target substance is estimated based on adequate and reliable studies of the analogue substance glycerides, C8-18 and C18-unsatd. mono- and di-, acetates (CAS 91052-13-0) and of the hydrolysis products glycerol (CAS 56-81-5) and 3,5,5-trimethylhexanoic acid (CAS 3302-10-1). While no toxicologically relevant effects have been observed in the studies with glycerides, C8-18 and C18-unsatd. mono- and di-, acetates and glycerol (NOAEL values determined correspond to the highest doses tested), the live birth index was reduced in the study with 3,5,5-trimethylhexanoic acid. However, since only a short abstract (secondary source) of the study is available, the reliability of the study cannot be evaluated and no NOAEL is derived for the target substance. As explained in the analogue justification, the differences in molecular structure between the target and the source substances are unlikely to lead to differences in the toxicological properties. Hence, data from the source substances can be used for the hazard assessment of the target substance.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate and reliable studies (Klimisch score 1 and 2) from analogue substances with similar structure and intrinsic properties. Read-across is justified based on common precursors and breakdown products of hydrolysis and consistent trends in environmental fate, ecotoxicological and toxicological profile. The selected studies are thus sufficient to fulfil the standard information requirements set out in Annex VIII, Item 8.7, in accordance with Annex XI, Item 1.5, of Regulation (EC) No. 1907/2006 (REACH).

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Justification for grouping of substances and read-across

There are no data available on the reproductive toxicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate (CAS 56554-53-1). In order to fulfil the standard information requirements set out in Annex VIII, Item 8.7, in accordance with Annex XI, Item 1.5, of Regulation (EC) No. 1907/2006, read-across from structurally related substances and common hydrolysis products 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 and/or hydrolysis/biodegradation products (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, glycerides, C8-18 and C18-unsatd. mono- and di-, acetates (CAS 91052-13-0) was selected as glyceride source substance for assessment of the reproductive toxicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate. In addition, the hydrolysis products 3,5,5-trimethylhexanoic acid (CAS 3302-10-1) and glycerol (CAS 56-81-5) were chosen as source substances. The read-across is based on the metabolism of propane-1,2,3-triyl 3,5,5-trimethylhexanoate, in particular on the fact that the substance undergoes enzymatic hydrolysis resulting in the formation of 3,5,5-trimethylhexanoic acid and glycerol. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of toxicity to reproduction

CAS#	56554-53-1	3302-10-1	56-81-5	91052-13-0
Chemical name	Propane-1,2,3-triyl 3,5,5-trimethylhexanoate	3,5,5-Trimethylhexanoic acid	Glycerol	Glycerides, C8-18 and C18-unsatd. mono- and di-, acetates
Molecular weight	512.78	158.24	92.10	442.64-500.67
Screening study	RA: CAS 3302-10-1 RA: CAS 91052-13-0	Secondary source data:   P generation NOAEL (rat, m) = 145 mg/kg bw/day   NOAEL (rat, f) = 167 mg/kg bw/day   F1 generation NOAEL (rat, m/f) = 81 mg/kg bw/day (at maternal toxic doses)	--	Experimental result: P generation NOAEL (rat, f/m) =1000 mg/kg bw/day   F1 generation NOAEL (rat, m/f) = 1000 mg/kg bw/day
Two-generation study	RA: CAS 56-81-5	--	Experimental result: P and F1 generations NOAEL (rat, m/f) = 2000 mg/kg bw/day	--

--: Data lacking

 

Study with glyceride source substance

CAS No. 91052-13-0

An oral gavage screening toxicity study was performed with glycerides, C8-18 and C18-unsatd. mono- and di-, acetates according to OECD guideline 422 and under conditions of GLP in rats at doses of 0, 100, 300 and 1000 mg/kg bw/day (Notox, 2010c). Dilutions of the test substance in polyethylene glycol were administered once daily to groups of 10 male and 5 female rats (main animals) via gavage. A similar constituted group received the vehicle and served as a control. In addition, satellite groups of 5 males and 5 females (recovery animals) each for the control and high dose group were used to investigate reversibility of effects during a 14-day post-exposure recovery period. Furthermore, 10 females (repro animals) were added to each group for the assessment of reproduction and developmental toxicity. Main and recovery animals were exposed for at least 28 days from start of treatment up to termination or start of recovery. Females used for the assessment of reproduction/developmental toxicity were exposed for 41-49 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation. In parental animals, no effects on reproductive function (spermatogenetic and oestrus cycle) and performance (mating, fertility and conception indices, precoital time, and number of corpora lutea and implantation sites) were observed after treatment compared to controls. Testis weight, epididymis weight, and histology of testes in males as well as histology of uterus epithelium in female did not reveal any substance-related effects in the parental animals. No toxicologically relevant alterations in offspring viability indices were observed. Therefore, a NOAEL for parental fertility of 1000 mg/kg bw/day was derived for male and female rats.

Studies with hydrolysis products

CAS No. 56-81-5

In a two-generation reproduction toxicity study, glycerol was administered to 10 male and 10 female Albino rats at a dose level of 2000 mg/kg bw/day via oral gavage (Wegener, 1953). Parental females received the test substance diluted in water for at least 8 weeks (before and during mating), whereas parental males were treated with the diluted test substance for at least 12 weeks (8 weeks before mating, during mating and gestation (5/10 animals), through weaning of their F1 offspring (5/10 animals). A further group of 10 animals per sex received the vehicle only and served as controls. Half of the males and female of the F1 generation were exposed to the test substance during and via lactation (5/10 litters). The selection of parental animals from the F1 generation was performed when animals were 100 days of age. All other animals not selected as parental animals were sacrificed at this time point. No effects on the reproductive performance compared to controls were observed in any animal of the P and F1 generation. In the offspring of the F1 generation, post-natal mortality was increased in the test group compared with the control. Within the first 50 days post-partum, 12/90 (13.3%) animals in the test group and 3/73 (4.1%) animals in the control group died. However, it was unclear whether this increase in post-natal mortality was related to treatment of the P generation, as no other effects in the examined parameters were observed. No information on viability of pups of the F2 generation was available. Body weight development in animals of both the F1 and F2 generation were not altered compared to controls. Furthermore, no effects were observed in the onset of oestrous cycle in either generation. In the F1 generation, no remarkable differences between control and test group offspring were noted in the relative weights of pituitary, thyroid, adrenals and testes. The mean relative ovaries weight was increased by ca. 17% in the offspring of the test group compared with the control offspring. It was unclear whether this effect was related to treatment of the P generation, as microscopic examination of the endocrine organs did not reveal any adverse findings compared to control. Histopathological examination of pituitary gland, thyroid, adrenals, ovaries and testes in both the F1 and F2 generation did not show any adverse findings. Based on the study, the NOAEL was set at 2000 mg/kg bw/day for parental fertility and post-natal development and effects via lactation of the F1 generation in male and female rats, respectively.

CAS 3302-10-1

The available data on the reproductive toxicity of 3,5,5-trimethylhexanoic acid is limited to summarised published data reviewed by BG Chemie (2005). The attempt to gain a letter of access for the original study report in order to use the data for registration of the substance was not successful. The data owner did not agree to provide a letter of access for the study report after negotiations with the lead registrant. Therefore, only the publically available data can be used for the registration of the target substancepropane-1,2,3-triyl 3,5,5-trimethylhexanoate. In the published data the following information is reported. A one generation reproduction toxicity range finding study was conducted in rats following a method similar to OECD guideline 421 (Exxon 1998, as cited in BG Chemie, 2005). Animals (10 per sex and dose) were fed the test substance at 0.06, 0.12, 0.25 and 0.5% in diet (corresponding to ca. 32, 66, 145 and 290 mg/kg bw/day in males and ca. 40, 81, 167 and 347 mg/kg bw/day in females). Control animals received the plain diet. Males and females were treated over 10 weeks prior to mating to the end of the 2-week mating period. Females were treated further through gestation and lactation until weaning on Day 28 post-partum. F1 offspring animals were treated from Day 28 to 42 (males) or 49 (females) post-partum.

Parental animals showed no clinical symptoms. In females of the mid- and high-dose groups, food consumption and body weight gain were transiently decreased. In these animals, absolute and relative liver weights were increased. Absolute and relative liver weights were also increased in high-dose males. Macroscopical examination of reproductive organs revealed no substance-related adverse effects. Sperm parameters were likewise not affected. At the parental toxic dose of 290/347 (m/f) mg/kg bw/day, live births were decreased by about 6%. No effects were observed on mating behaviour, mating efficiency, gestation or parturition. The NOAEL for systemic toxicity was 0.12% (81 mg/kg bw/day) in females and 0.25% (145 mg/kg bw/day) in males. The NOAEL for fertility was 0.25%, corresponding to 145 (males) and 167 (females) mg/kg bw/day, due to the decrease in live births.

In the F1 generation, body weight gain up to Day 42 (males) or 49 (females) was dose-dependently decreased starting at 0.25%. At the parental toxic concentration of 0.5% survival indices on Days 1 and 4 post-partum were decreased by 14 and 21%, respectively. A slight retardation in the onset of developmental landmarks (eye opening, pinna detachment and preputial separation) was observed. Based on reduced body weight in the 0.25% group, the NOAEL for post-natal development was 0.12% (corresponding to 66 and 81 mg/kg bw/day in the male and female parental animals).

Conclusion on toxicity to reproduction

Due to the fact that there are no data on the reproductive toxicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate, studies performed with a glyceride source substance and with the expected hydrolysis products are considered.

Although it would be the most robust approach to base the hazard assessment of propane-1,2,3-triyl 3,5,5-trimethylhexanoate on experimental results obtained with 3,5,5-trimethylhexanoic acid in a worst-case approach (as is done for other endpoints), the results of a screening study with 3,5,5-trimethylhexanoic acid could not be taken into consideration since there is no access to the original data and there is only a short study summary publically available. Instead, the hazard assessment is based on studies conducted with glycerol and the glyceride source substance glycerides, C8-18 and C18-unsatd. mono- and di-, acetates.

In a two-generation study with glycerol, no adverse effects were observed in any generation up to the highest dose of ca. 2000 mg/kg bw/day. Furthermore, no effects on reproductive parameters and post-natal offspring development were observed with glycerides, C8-18 and C18-unsatd. mono- and di-, acetates up to and including the highest dose tested of 1000 mg/kg bw/day. A NOAEL of 1000 mg/kg bw/day is thus also considered for propane-1,2,3-triyl 3,5,5-trimethylhexanoate.

Effects on developmental toxicity

Description of key information

Prenatal developmental toxicity study (OECD 414, rat): NOAEL (maternal toxicity) = 60 mg/kg bw/day, NOAEL (development) = 60 mg/kg bw/day, secondary effects on offspring observed only at dose levels causing distinct maternal systemic toxicity, no teratogenic potential identified (worst-case assumption based on read-across from 3,5,5-trimethylhexanoic acid [CAS 3302-10-1]). Supported by additional teratogenicity, prenatal developmental toxicity and two-generation reproductive toxicity studies with 3,5,5-trimethylhexanoic acid (CAS 3302-10-1), glycerol trioctanoate (CAS 538-23-8), propane-1,2,3-triyl 2-ethylhexanoate (CAS 7360-38-5), and glycerol (CAS 56-81-5) accounted for in a Weight-of-Evidence approach.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

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

Remarks:

Summary of available data used for the endpoint assessment of the target substance

Adequacy of study:

weight of evidence

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Species:

other: mouse, rabbit, rat

Key result

Dose descriptor:

NOAEL

Remarks:

maternal toxicity

Effect level:

60 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Remarks on result:

other: Source: CAS 3302-10-1, BASF, 2013b

Key result

Dose descriptor:

NOAEL

Remarks:

development

Effect level:

60 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Remarks on result:

other: Source: CAS 3302-10-1, BASF, 2013b

Abnormalities:

effects observed, treatment-related

Localisation:

skeletal: skull

skeletal: rib

Developmental effects observed:

yes

Lowest effective dose / conc.:

200 mg/kg bw/day

Treatment related:

yes

Relation to maternal toxicity:

developmental effects as a secondary non-specific consequence of maternal toxicity effects

Dose response relationship:

yes

Relevant for humans:

no

Executive summary:

The developmental toxicity of the target substance is estimated based on an adequate and reliable prenatal developmental toxicity study of the hydrolysis product 3,5,5 -trimethylhexanoic acid (CAS 3302-10-1) in a worst-case approach. Under the conditions of this prenatal developmental toxicity study, the oral administration of the test substance to pregnant rats caused distinct maternal toxicity, incl. mortality, at a dose of 200 mg/kg bw/day. Morphological changes in offspring were only observed at the dose level which caused maternal toxicity. Effects in offspring are, therefore, considered to occur only as secondary effect to maternal toxicity. No toxicologically relevant effects have been observed in further supporting studies with the read-across source substances glycerol (56-81-5) and glycerol trioctanoate (CAS 538-23-8). The target substance propane-1,2,3-triyl 3,5,5-trimethylhexanoate is, therefore, considered to be not mutagenic in a Weight-of-Evidence approach taking all available data into account. As explained in the analogue justification, the differences in molecular structure between the target and the source substances are unlikely to lead to differences in repeated dose toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

60 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The available information comprises an adequate and reliable (Klimisch score 1) prenatal developmental toxicity study from the source substance (hydrolysis product) 3,5,5-trimethylhexanoic acid. Read-across is justified based on the fact that (i) propane-1,2,3-triyl 3,5,5-trimethylhexanoate undergoes enzymatic hydrolysis resulting in the formation of 3,5,5-trimethylhexanoic acid and that (ii) 3,5,5-trimethylhexanoic acid is a known hazardous substance. Hence, the read-across is based on a worst-case assumption. The study providing the NOAEL value used for the hazard assessment of the registered substance is supported by several studies with additional source substances. The selected studies are thus sufficient to fulfil the standard information requirements set out in Annexes VIII - X, Item 8.7, in accordance with Annex XI, Item 1.5, of Regulation (EC) No. 1907/2006.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Justification for grouping of substances and read-across

There are no data available on the developmental toxicity and teratogenicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate (CAS 56554-53-1). In order to fulfil the standard information requirements set out in Annex VIII - X, Item 8.7, in accordance with Annex XI, Item 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 and/or hydrolysis/biodegradation products (grouping or read-across).

Having regard to the general rules for grouping of substances and read-across approaches 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) and propane-1,2,3-triyl 2-ethylhexanoate (CAS 7360-38-5) were selected as glyceride source substances for the assessment of the developmental toxicity and teratogenicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate. In addition, the hydrolysis products 3,5,5-trimethylhexanoic acid (CAS 3302-10-1) and glycerol (CAS 56-81-5) were chosen as source substances. The read-across is based on the metabolism of propane-1,2,3-triyl 3,5,5-trimethylhexanoate, in particular on the fact that the substance undergoes enzymatic hydrolysis resulting in the formation of 3,5,5-trimethylhexanoic acid and glycerol. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of developmental toxicity

CAS#	56554-53-1	3302-10-1	56-81-5	538-23-8	7360-38-5
Chemical name	Propane-1,2,3-triyl 3,5,5-trimethyl-hexanoate	3,5,5-Trimethylhexanoic acid	Glycerol	Glycerol trioctanoate	Propane-1,2,3-triyl 2-ethylhexanoate
Molecular weight	512.78	158.24	92.10	470.69	470.69
Two-generation study (developmental effects)	RA: CAS 56-81-5	--	Experimental result: F1/F2 generations NOAEL (rat, m/f) = 2000 mg/kg bw/day	--	--
Developmental toxicity	RA: CAS 3302-10-1 RA: CAS 538-23-8 RA: CAS 7360-38-5	NOAEL (development) = 60 mg/kg bw/day, secondary effects on offspring observed only at dose levels causing distinct maternal toxicity	--	Experimental result: NOAEL (mouse) = 9540 mg/kg bw/day NOAEL (rabbit) = 2862 mg/kg bw/day	No maternal and no teratogenic effects

--: Data lacking

Studies with glyceride source substances

CAS 7360-38-5

Propane-1,2,3-triyl 2-ethylhexanoate was investigated for adverse effects on prenatal development in a study conducted according to OECD guideline 414 and under GLP conditions (Envigo, 2019b). The test substance was administered during the organogenesis and fetal growth phases of pregnancy (Days 6 to 19 of gestation) in the Han Wistar Rat. Three groups of 20 females received the test substance at doses of 100, 300 or 1000 mg/kg bw/day by oral gavage. A control group received the vehicle (corn oil) only. Animals were killed on Day 20 after mating for reproductive assessment and fetal examination. Clinical observations (Days 0, 5, 12, 18 and 20 after mating), body weight (Days 0, 3 and 6-20 after mating) and food consumption (Days 0-3, 3-6, 6-10, 10-14, 14-18 and 18-20 after mating) were recorded. Adult females were examined macroscopically at necropsy on Day 20 after mating and the gravid uterus weight and thyroid weight were recorded. Microscopic pathology investigations of the maternal thyroid glands were also performed. Ano-genital distance was measured in the fetuses. All fetuses were examined externally at necropsy and subsequently by detailed internal visceral examination or skeletal examination. Treatment of pregnant female rats with the test item was well tolerated and there were no unscheduled deaths or test item-related signs. Group mean body weight gain, gravid uterine weight, adjusted body weight gain, food consumption and thyroid/parathyroid weights were unaffected at all dose levels investigated, and there were no test item-related maternal macroscopic abnormalities detected at scheduled termination. Histopathological examination of the thyroids did not reveal any test item-related lesions. There was no effect of the test substance on T3/T4 or TSH concentrations at any dose level investigated. There was also no effect of maternal exposure to the test substance on developmental parameters, as assessed by the mean numbers of implantations, resorptions, live young, sex ratio and pre- and post-implantation losses. Placental weight, litter weight and fetal weights and ano-gential distance were similar between treatment groups and control. The incidence of major and minor fetal abnormalities, skeletal variants and macroscopic abnormalities showed no relation to maternal treatment with the test substance. Based on the results, it was concluded that the high dose level of 1000 mg/kg bw/day (the limit dose) represented the No Observed Adverse Effect Level (NOAEL) for maternal toxicity and for embryo-fetal survival, growth and development.

CAS 538-23-8

The teratogenic potential of glycerol trioctanoate was investigated in ICR-JCL mice at dose volumes of 2 and 10 mL/kg bw/day, corresponding to doses of 1908 and 9540 mg/kg bw/day, as calculated from a density of 0.954 g/mL (Ohta et al., 1970). The test substance was diluted in a mixture of 1.2% Tween 80/0.8% Span 80 in water and administered once daily to groups of 20 females via gavage between day 7 and 12 of pregnancy. Two similar constituted control groups received saline or soybean oil as vehicle, respectively. At Day 18 of pregnancy, dams were sacrificed and maternal and foetal examinations were performed. In dams, no substance-related effects on the number of implantations and early resorptions were observed compared to controls. Litter size and weights, the number of viable foetuses (number alive and number dead) and the sex ratio were comparable between treated and control animals. External, soft tissue and skeletal examination of exposed foetuses did not reveal any treatment-related effects compared to controls. Most findings in treated foetuses (curled tail, cleft palate and club foot) also occurred in controls or were of incidental nature (assimilation of ribs and cervical vertebra). Based on these results, a NOAEL of ≥ 9540 mg/kg bw/day was derived for teratogenicity in male and female ICR-JCL mice.

In a further teratogenicity study, the undiluted test substance was administered once daily at a dose volume of 3 mL/kg bw/day (approximately 2862 mg/kg bw/day based on a density of 0.954 g/mL) via gavage to 8 female rabbits during Day 7 and 16 of pregnancy (Ohta et al., 1970). Two control groups of 8 females each were gavaged with physiological saline or soybean oil, respectively. On Day 29 of gestation, animals were sacrificed and ovaries and uterine content as well as foetuses were examined. In dams, no substance-related effects on the number of implantations or total litter losses by resorption were observed when compared to controls. No external or skeletal malformations were observed in the foetuses of exposed mothers. Litter size and weights, number of viable foetuses (number alive and number dead) and the sex ratio were comparable between control and treated animals. Based on the results of the study, a NOAEL of ≥ 2862 mg/kg bw/day was derived for teratogenicity in male and female rabbits.

Studies with hydrolysis products

CAS 56-81-5

In a two-generation reproduction toxicity study, glycerol was administered to 10 male and 10 female Albino rats at a dose level of 2000 mg/kg bw/day via oral gavage (Wegener, 1953). Parental females received the test substance diluted in water for at least 8 weeks (before and during mating), whereas parental males were treated with the diluted test substance for at least 12 weeks (8 weeks before mating, during mating and gestation (5/10 animals), through weaning of their F1 offspring (5/10 animals). A further group of 10 animals per sex received the vehicle only and served as controls. Half of the males and females of the F1 generation were exposed to the test substance during and via lactation (5/10 litters). The selection of parental animals from the F1 generation was performed when animals were 100 days of age. All other animals not selected as parental animals were sacrificed at this time point. In the offspring of the F1 generation, post-natal mortality was increased in the test group compared with the control. Within the first 50 days post-partum, 12/90 (13.3%) animals in the test group and 3/73 (4.1%) animals in the control group died. However, it was unclear whether this increase in post-natal mortality was related to treatment of the P generation, as no other effects in the examined parameters were observed. No information on viability of pups of the F2 generation was available. Body weight development in animals of both the F1 and F2 generation were not altered compared to controls. Furthermore, no effects were observed in the onset of oestrous cycle in either generation. In the F1 generation, no remarkable differences between control and test group offspring were noted in the relative weights of pituitary, thyroid, adrenals and testes. The mean relative ovaries weight was increased by ca. 17% in the offspring of the test group compared with the control offspring. It was unclear whether this effect was related to treatment of the P generation, as microscopic examination of the endocrine organs did not reveal any adverse findings compared to control. Histopathological examination of pituitary gland, thyroid, adrenals, ovaries and testes in both the F1 and F2 generation did not show any adverse findings. Based on the study, the NOAEL was set at 2000 mg/kg bw/day for post-natal development and effects via lactation of the F1 generation in male and female rats, respectively.

CAS 3302-10-1

A prenatal developmental toxicity study was conducted with 3,5,5-trimethylhexanoic acid according to OECD guideline 414 and observing GLP provisions (BASF, 2013b). The test substance was administered daily by oral gavage to pregnant Wistar rats from implantation to one day prior to the expected day of parturition (GD 6-19). The dose levels employed were 20, 60 and 200 mg/kg bw/day. The animals of the control group received the pure vehicle (corn oil). In the high-dose group, the following test substance-related adverse effects were noted:

- Mortality in 2 dams shortly before term.

- Decreased food consumption towards the end of gestation (13 - 23% below control).

- Decreased net body weights (8% below control) at the end of gestation, distinctly reduced net body weight gain during treatment (47% below control)

- Increased red blood cell (RBC) counts, hemoglobin and hematocrit values.

- Decreased relative reticulocyte counts.

- Increased absolute and relative monocyte and large unstained cell (LUC) counts.

- Increased urea levels.

- Decreased total protein, albumin, globulin, cholesterol, triglyceride and calcium levels.

- Increased absolute (+30%) and relative (+25%) weights of the livers.

Therefore, maternal toxicity indicated by mortality, reduced body weights/weight gain, hematological alterations, dysregulated liver cell metabolism and dose-related increased liver and adrenal weights was evident in animals of the high-dose group. An increase in liver weight in the mid-dose group had no histopathological correlation and was not considered adverse. In conclusion, the no observed adverse effect level (NOAEL) for maternal toxicity was established to be 60 mg/kg bw/day.

The pups of the high-dose group showed signs of developmental defects as shown by reduced body weights, severely altered rib cages (leading to an increased malformation rate), wavy ribs, decreased ossification of skulls, sternebrae, sacral arch, metacarpal, pubis and ischium. Considering strong systemic toxicity observed in dams, these effects are most likely due to maternal toxicity and not a direct effect of the substance on development. In the mid dose-group, fetal body weights were statistically significantly reduced (5%). Since there were no effects on the degree of fetal maturity at 60 mg/kg bw/day, the slight weight reduction in this group was not considered to be an adverse effect of the test substance. Moreover, the decrease in fetal body weight was within the historical control range. Skull ossification was decreased in mid-dose animals. However, these decreases were still within historical control data, indicating that this effect is not considered adverse. A yellow discoloration of fetal livers was noted in almost all high-dose litters and approximately half of the mid-dose litters. The rate of affected fetuses per litter was about 60% and 20%, respectively. The dose-relationship suggests an association to the treatment, but the cause of this discoloration is not known. The shape and size of affected livers were completely unchanged. As there was no morphological change observable, the level of concern for this finding is considered low and it is not considered to be adverse.

Since no effects were noted in low-dose animals and effects observed in mid-dose rats were not considered to be adverse and of toxicological relevance, the NOAEL for developmental toxicity is set at the mid dose level of 60 mg/kg/day. Since morphological changes in offspring were only observed at 200 mg/kg bw/day, a dose level which caused distinct maternal toxicity, including mortality, 3,5,5-trimethylhexanoic acid is not considered to exhibit a teratogenic potential.

Conclusion on developmental toxicity

As there are no data on the developmental toxicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate, studies performed with glyceride source substances and with the expected hydrolysis products are considered. As described in detail in the analogue approach justification (refer to the document attached to section 13 of the technical dossier), only the data obtained with 3,5,5-trimethylhexanoic acid are considered for the hazard assessment of propane-1,2,3-triyl 3,5,5-trimethylhexanoate in a worst-case approach.

The prenatal developmental toxicity study showed maternal systemic toxicity in the high-dose group (200 mg/kg bw/day), incl. two dead dams which died shortly before term. NOAEL values of 60 mg/kg bw/day for maternal toxicity as well as fetal developmental toxicity, were established. The fetal abnormalities were observed only at doses inducing distinct maternal systemic toxicity (200 mg/kg bw/day). Based on these finding, fetal effects are considered to be secondary and a result of maternal toxicity. No teratogenic potential has been identified for 3,5,5-trimethylhexanoic acid. In conclusion, also no teratogenic potential is expected for propane-1,2,3-triyl 3,5,5-trimethylhexanoate.

Justification for classification or non-classification

Based on read-across following an analogue approach, the available data on reproductive and developmental toxicity of propane-1,2,3-triyl 3,5,5-trimethylhexanoate do not meet the classification criteria according to Regulation (EC) No. 1272/2008 and are therefore conclusive but not sufficient for classification.