5-ethyl-1,3-dioxane-5-methanol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Effects on developmental toxicity

Description of key information

A developmental toxicity study performed in the rat with CTF reports maternal and developmental NOAELs of 300 mg/kg bw/d.   

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 January 2016 to 09 Nov 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

22nd January 2001

Deviations:

no

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

Identity: CTF
Alternative name: Cyclic Trimethylolpropane Formal
Batch no.: 150803652
EC number: 225-967-8
EC name: 5-ethyl-1,3-dioxane-5-methanol
CAS number: 5187-23-5
IUPAC name: (5-ethyl-1,3-dioxan-5-yl)methanol
Expiry date: 12 August 2016
Appearance: Colourless undefined liquid
Purity: 99.8%
Storage conditions: Room temperature, under nitrogen

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Hsd: SpragueDawley SD

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Envigo RMS srl, San Pietro al Natisone (UD), Italy
- Age at study initiation: at least 11 weeks
- Weight at study initiation: 213-221 g
- Fasting period before study: None
- Housing: group
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 18 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 40-70
- Air changes (per hr): 15-20
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 18th January 2016 To: 16th February 2016

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

CTF was administered orally by gavage (in water) at a dose volume of 10mL/kg bw; control animals received the vehicle alone at the same dose volume. The dose was administered to each animal on the basis of the most recently recorded body weight and the volume administered was recorded for each animal. All animals were dosed once a day on Gestation Days 6-19.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

28-hour stability at room temperature and 8-day stability at +4°C were verified for CTF in water at 100 mg/mL; 28- hour stability at room temperature and 8-day were also verified at 10 mg/mL. Concentrations following storage were within acceptable limits (90-110%). The proposed formulation procedure was checked in the range from 10-100 mg/mL by chemical analysis (concentration) during the pre-treatment period to confirm that the method was suitable. Final results for all levels were within acceptable limits (90-110%). Samples of the formulations prepared during the first and final weeks of the were analysed to check the concentration. Results of the analyses were within acceptable limits (90-110%). The analytical method was previously validated (RTC Study A1846) in the range 5-100 mg/mL. Linearity, accuracy and precision were within acceptable limits (r > 0.98; accuracy 90-110%; precision CV < 5%).

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: not reported
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: presence of sperm in the vaginal smear or by the presence of a copulation plug, was considered as Day 0 of gestation

Duration of treatment / exposure:

All animals were dosed once a day on Gestation Days (GD) 6-19.

Frequency of treatment:

Daily

Duration of test:

All animals were dosed once a day on Gestation Days (GD) 6-19 and terminated on GD20.

Dose / conc.:

0 mg/kg bw/day

Remarks:

Control group

Dose / conc.:

100 mg/kg bw/day

Remarks:

Low dose group

Dose / conc.:

300 mg/kg bw/day

Remarks:

Intermediate dose group

Dose / conc.:

1 000 mg/kg bw/day

Remarks:

High dose group

No. of animals per sex per dose:

24 mated females per group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: dose levels were based on range-finding data
- Rationale for animal assignment: random

Maternal examinations:

Mortality
All animals were checked twice daily.

Clinical signs
Each animal was observed daily from allocation to termination and clinical signs recorded.

Body weight
All animals were weighed on Gestation Days 0, 6, 9, 12, 15 and 20.

Food consumption
Food consumption was measured on Gestation Days 0, 6, 9, 12, 15 and 20. Values were recorded per cage and the amount was divided for
the animals in the cage and for the days of the interval of measurement, in order to obtain the value of food consumed by animal per day.

Animals were euthanised with carbon dioxide on Gestation Day 20 and subjected to gross necropsy.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: gross evaluation of placentae

Fetal examinations:

All live foetuses were examined externally. Approximately one-half of the foetuses in each litter was preserved in Bouin’s solution for subsequent fixed-visceral examination. The remaining foetuses were eviscerated after which the carcasses were fixed in 95% (v/v) ethanol for subsequent skeletal examination. Skeletal and fixed-visceral examinations were performed in all groups.

Statistics:

For continuous variables the significance of the differences amongst group means was assessed by Dunnett’s test or a modified t test, depending on the homogeneity of data. Statistical analysis of non-continuous variables was carried out by means of the Kruskal-Wallis test and intergroup differences between the control and treated groups assessed by a non-parametric version of the Williams test.

Indices:

Pre-implantation loss, pos-implantation loss and total implantation loss were calculated.

Historical control data:

Not referenced.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

A slight (but statistically significant) decrease in bodyweight was seen in mid-dose females on GD15 (approximately -3%) and in high dose females from GD9-20 (up to approximately -5%), compared to controls. These changes were minimal and not considered to be of toxicological relevance.

Weight gain was significantly reduced in the high dose group on GD 9 and 12, compared to controls. The values became comparable at the end of the study.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Statistically significant decreases were detected in food consumption of mid-dose (up to approximately -12%) and high dose females (up to approximately -25%) from GD9-15, compared to controls. The values became comparable at the end of the study.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Endocrine findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

A statistically significant decrease in uterus weight (-12%) was observed in females of the high dose group, compared to controls.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Details on results:

No deaths occurred and there were no clinical signs noted. Marginal (but statistically significant) and transient effects on mean bodyweight were observed at 300 and 1000 mg/kg bw/d, and decreases in absolute weight gain were noted at these doses. Food consumption was also reduced at 300 and 1000 mg/kg bw/d. Statistically significant decreases in uterus weights at 1000mg/kg bw/d were noted (associated with lower mean fetal weight).

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

effects observed, non-treatment-related

Description (incidence and severity):

In the high dose group one female showed unilateral implantation with total resorption. This single incidence is not considered to be related to treatment.

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

effects observed, non-treatment-related

Description (incidence and severity):

A total of two females were found not pregnant at necropsy: one in the low dose group and one in the mid-dose group. FIndings are not related to treatment.

Other effects:

no effects observed

Details on maternal toxic effects:

A total of two females were found not pregnant at necropsy: one in the low dose group and one in the mid-dose group. FIndings are not related to treatment. In the high dose group one female showed unilateral implantation with total resorption. This single incidence is not considered to be related to treatment. A statistically significant decrease in terminal body weight (-6%), uterus weight (-12%), and absolute weight gain (-19%) was observed in females of the high dose group, compared to controls. A slight statistically significant decrease was also observed in the absolute weight gain of the mid-dose group (-10%), with respect to controls. The decrease in absolute weight gain in mid- and high dose females was an indication of a slight treatment and dose-related maternal toxicity; the slight decrease in uterus weight in high dose females was also associated with the lower mean foetal weight.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

body weight and weight gain

food consumption and compound intake

Key result

Abnormalities:

no effects observed

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

A slight (but statistically significant) decrease was seen for mean foetal weight (approximately -6%) at the high dose level.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

effects observed, treatment-related

Description (incidence and severity):

A slight (but statistically significant) decrease was seen for mean foetal weight (approximately -6%) and mean litter weight (approximately -13%) at the high dose level.

Anogenital distance of all rodent fetuses:

not examined

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

Incomplete ossification or no ossification of sternal elements (5th and 6th), as well as incomplete ossification of the centrum of the thoracic vertebrae, unossified metacarpals (4th), were seen in all groups with a higher incidence in the high dose group. This higher incidence could be associated with the decreases in mean foetal weight and litter weight observed in the high dose group.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The following malformations were detected:

- hepatic lobe agenesis seen in 3 foetuses in the control group and 1 foetus in the low dose group
- extreme renal pelvic dilatation in 3 foetuses in the control group and 1 foetus in the high dose group
- extreme enlargement of the ureters in 1 foetus in the control group and 1 foetus in the high dose group
- kinked ureters in 1 foetus in high dose group

Since these findings were seen only in few foetuses, both in the control and high dose groups with similar incidence, they were to be considered incidental.
No toxicological significance was attributed to the other findings observed, since they were seen in treated as well as in control groups with similar incidence.

Details on embryotoxic / teratogenic effects:

No evidence for embryotoxicity or teratogenicity.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

other: Reduced foetal skeletal ossification

Remarks on result:

other: Findings are likely to be secondary to maternal toxicity.

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

1 000 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:

yes

Summary of maternal and litter findings:

Dose level (mg/kg bw/d)		0	100	300	1000
Mated (#)		24	24	24	24
Not pregnant (#)		-	1	1	-
Total resorption (#)		-	-	-	1
Litters (#)		24	23	23	23
Weight (g)	Day 9	273.97	271.92	269.03	265.58*
	Day 12	289.07	286.59	282.57	277.45**
	Day 15	308.98	306.41	300.15*	296.33**
	Day 20	382.17	379.90	375.64	361.97**
Weight gain (g/d)	Day 6-9	3.903	3.006	2.777	1.483**
	Day 9-12	5.035	4.992	4.514	3.958*
Weight gain (g)	Day 6-9	11.71	9.02	8.33	4.45
	Day 0-20	145.77	143.69	140.94	127.31
	Day 6-20	119.91	117.00	114.94	100.84
Food consumption (g/d)	Day 9	21.24	20.92	18.74*	15.98**
	Day 12	22.54	22.08	20.29**	17.91**
	Day 15	22.96	21.97	20.49**	19.53**
Terminal bodyweight (g)		378.88	375.16	370.35	356.08*
Absolute weight gain (g)		64.01	59.95	57.87*	52.12*
Gravid uterus weight (g)		78.45	79.00	77.77	69.30*
Corpora lutea (#)		14.79	14.39	14.26	13.43
Pre-implantation loss (%)		1.90	1.72	1.71	0.64
Implantations (#)		14.50	14.13	14.00	13.35
Post-implantation loss (%)		5.74	2.67	3.30	7.02
Foetuses (#)		13.67	13.74	13.52	12.52
Foetal weight (g)		3.83	3.79	3.75	3.60*
Litter weight (g)		52.24	52.07	50.68	45.19*

*significantly different to control (p<0.05); **p<0.01)

Summary of foetal findings:

Dose level (mg/kg bw/d)	0	100	300	1000
Hepatic lobe agenesis	3(3)	1(1)	-	-
Renal pelvis dilation (extreme)	1(1)	-	-	1(1)
Ureter enlarged (extreme)	1(1)	-	-	1(1)
Kinked ureter (extreme)	-	-	-	1(1)
5^thsternebra: no ossification	1(1)	2(2)	3(3)	4(4)
5^thsternebra: incomplete ossification	21(9)	15(11)	11(10)	21(12)
6^thsternebra: no ossification	-	1(1)	1(1)	1(1)
6^thsternebra: incomplete ossification	15(8)	11(7)	15(10)	26(13)
Centrum: no ossification	2(2)	1(1)	-	-
Centrum: incomplete ossification	10(5)	11(8)	9(6)	23(14)

Conclusions:

No evidence of teratogenicity was seen in this study. Findings were limited to slight maternal toxicity (reduced weight gain and food consumption) and slight foetal effects (reduced foetal weight, reduced skeletal ossification at the high dose level). On the basis of the results obtained in this study, the dose level of 1000 mg/kg bw/day could be considered the NOAEL (No Observed Adverse Effect Level) for maternal and developmental toxicity.

Executive summary:

Groups of 24 mated female SD rats were gavaged with CTF (in water) at dose levels of 0 (vehicle control), 100, 300 or 1000 mg/kg bw/d on Gestation Days 6-19. No deaths occurred and no signs of toxicity were observed during the study period. Mean bodyweights of high dose females were slightly (but statistically significantly) lower than controls at Day 9 (-3.1%), Day 12 (-4.0%), Day 15 (-4.1%) and Day 20 (-5.3%); the mean bodyweight of mid-dose females was significantly lower (-2.9%) at Day 15 only. Maternal weight gain at the high dose level was lower over the treatment period (-16%) and over the study period (-13%); weight gain over the initial part of the treatment period was also lower in this group. Reduced food consumption was seen at the high dose level and, to a lesser extent, at the mid-dose level. Gravid uterus weight was significantly lower at the high dose level (-12%); however this may be due, in part, to the slightly smaller litter size in this group. Single females in the low- and mid-dose groups were found not to be pregnant. Total resorption of implantations was seen in one female at the high dose level; this finding is not considered to be treatment-related due to the low incidence. Mean litter size at the high dose level was slightly lower than the other groups; however this was a consequence of the lower numbers of corpora lutea and is not related to treatment. Mean foetal weight was slightly (-6%) but significantly lower than controls; mean litter weight in this group was significantly lower (-13.5%) due to a combination of the smaller litter size and lower foetal weight. There was no effect of treatment on the incidence or pattern of foetal malformations. A slight increase in the incidence of foetal skeletal variations (reduced or absent ossification of sternebra(e), vertebral centra and/or metacarpals) was seen in the high dose group. Findings are likely to be secondary to reduced foetal weight and represent a slight developmental delay, secondary to maternal toxicity. On the basis of the results obtained in this study, the dose level of 1000 mg/kg bw/day could be considered the NOAEL (No Observed Adverse Effect Level) for maternal and developmental toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

A high quality modern GLP- and guideline-compliant study is available for CTF in the rat.

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

No evidence of teratogenicity was seen in an oral developmental toxicity study with CTF. Findings were limited to slight maternal toxicity (reduced weight gain and food consumption) and slight foetal effects (reduced foetal weight, reduced skeletal ossification at the high dose level). Maternal and developmental NOAELs of 1000 mg/kg bw/d are therefore determined for this study.

Justification for classification or non-classification

Evidence for the developmental toxicity of CTF was seen in the rat study, but is limited to slightly reduced foetal skeletal ossification in the presence of maternal toxicity. Findings are not sufficient to classify CTF for reproductive (pre-natal developmental) toxicity according to the CLP Regulation.