2,2-di(tetrahydrofuryl)propane

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 September - 28 November 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: OECD Guidelines for Testing of Chemicals, Guideline 421, Reproduction/Developmental Toxicity Screening Test, July 1995.

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: The United States EPA Health Effects Test Guidelines, OPPTS 870.3550, Reproduction/Developmental Toxicity Screening Test, July 2000.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-[2-(oxolan-2-yl)propan-2-yl]oxolane

EC Number:

700-263-8

Cas Number:

89686-69-1

Molecular formula:

C11 H20 O2

IUPAC Name:

2-[2-(oxolan-2-yl)propan-2-yl]oxolane

Test material form:

liquid

Details on test material:

- Name of test material (as cited in study report): Ditetrahydrofurylpropane
- Lot/batch No.: 6-OH13S
- Analytical purity: 98.8%
- Substance type: Clear colourless liquid
- Physical state: liquid
- Expiration date of the lot/batch: 19 August 2014
- Storage condition of test material: At room temperature in the dark
- Stability under storage conditions: Stable
- Specific Gravity: 1.0
- pH: Not indicated
- Stability in vehicle (water): At least 96 hours
- Solubility in vehicle (water): ~0.1%

Test animals

Species:

rat

Strain:

other: Crl:WI(Han)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories France, L'Arbresle Cedex, France.
Nulliparous and nonpregnant females and untreated animals were used at initiation of the study.
- Age at study initiation: Approximately 11 weeks.
- Weight at study initiation: mean weight range at start of treatment was 316 - 323 gr (males) or 201 - 204 gr (females).
- Fasting period before study: All males were deprived of food before necropsy. Fasting does not adversely affect interpretation of the examined parameters. Females were not fasted before necropsy.
- Housing:
Pre-mating: Animals were housed in groups of 5 animals/sex/cage in Macrolon cages (MIV type, height 18 cm).
Mating: Females were caged together with males on a one-to-one-basis in Macrolon cages (MIII type, height 18 cm).
Post-mating: Males were housed in their home cage (Macrolon cages, MIV type, height 18 cm) with a maximum of 5 animals/cage. Females were individually housed in Macrolon cages (MIII type, height 18 cm).
Lactation: Pups were kept with the dam until termination in Macrolon cages (MIII type, height 18 cm).
General: Sterilised sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France) and paper as cage-enrichment (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) were supplied. Certificates of analysis were examined and then retained in the NOTOX archives. During activity monitoring, animals were housed individually in Macrolon cages (MIII type; height 15 cm) with sterilised sawdust as bedding material. No cage-enrichment was provided during activity monitoring.
- Diet (e.g. ad libitum): Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany). Results of analyses for nutrients and contaminants were examined and archived.
- Water (e.g. ad libitum): Free access to tap-water. Certificates of analysis (performed quarterly) were examined and archived.
- Acclimation period: At least 5 days prior to start of treatment.
- Randomization: Prior to commencement of treatment, by computer-generated random algorithm according to body weight, with all animals within ± 20% of the sex mean.

A health inspection was performed prior to commencement of treatment to ensure that the animals were in a good state of health.

Analysis of bedding, paper, diet and water did not reveal any findings that were considered to have affected the study integrity.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.3 – 22.2°C
- Humidity (%): 43 - 81%
Temporary deviations from the maximum level of relative humidity occurred in the animal room. Evaluation: Laboratory historical data do not indicate an effect of the deviations.
- Air changes (per hr): 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial light and 12 hours darkness per day.

IN-LIFE DATES: From: 28 September - 28 November 2010

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

Method of formulation: Formulations (w/w) were prepared daily within 6 hours prior to dosing and were homogenized to a visually acceptable level.

Storage conditions of formulations: At ambient temperature.

Dose volume: 5 mL/kg body weight. Actual dose volumes were calculated according to the latest body weight.

Method of gavage: using a plastic feeding tube. Formulations were placed on a magnetic stirrer during dosing.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were conducted on a single occasion during the treatment phase, according to a validated method (NOTOX Project 484749). Samples of formulations were analyzed for homogeneity (highest and lowest concentration) and accuracy of preparation (all concentrations).


The accuracy of preparation was considered acceptable if the mean measured concentrations were 85-115% of the target concentration. Homogeneity was demonstrated if the coefficient of variation was ≤ 10%.

The concentrations analysed in the formulations of Group 2, Group 3 and Group 4 were in agreement with target concentrations (i.e. mean accuracies between 85% and 115%). No test substance was detected in the Group 1 formulation.
The formulations of Group 2 and Group 4 were homogeneous (i.e. coefficient of variation ≤ 10%).

Details on mating procedure:

- M/F ratio per cage:1/1 (one female was cohabitated with one male of the same treatment group, avoiding sibling mating (Charles River supplied non-litter mates).
- Length of cohabitation: A maximum of 14 days was allowed for mating.
- Proof of pregnancy: Detection of mating was confirmed by evidence of sperm in the vaginal lavage, by staging of the estrous cycle and/or or by the appearance of an intravaginal copulatory plug. This day was designated Day 0 post-coitum. Once mating had occurred, the males and females were separated.
- After successful mating each pregnant female was caged individually in Macrolon cages (MIII type, height 18 cm).

Duration of treatment / exposure:

Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to termination. Females were exposed for 41-55 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation. Some females (1, 2, 1,1 in Group 1,2,3,4 respectively) were not dosed during littering.

Pups were not treated directly, but were potentially exposed to the test substance in utero and through lactational transfer.

Frequency of treatment:

Once daily for 7 days per week, approximately the same time each day with a maximum of 6 hours difference between the earliest and latest dose.
Animals were dosed up to the day prior to scheduled necropsy.

Duration of test:

Males: 29 days
Females: 41-55 days

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
Dose levels were based on results of a 28-day oral toxicity study with Ditetrahydrofurylpropane (NOTOX Project 484766)

Parturition:
The females were allowed to litter normally. Day 1 of lactation was defined as the day when a litter was found completed (i.e. membranes, placentas cleaned up, nest built up and/or feeding of pups started). Females that were littering were left undisturbed.

Identification of pups:
On Day 1 of lactation, all pups were randomized per litter and individually identified by means of subcutaneous injection of Indian ink.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS
- Time schedule: At least twice daily.

DETAILED CLINICAL OBSERVATIONS
- Time schedule: At least once daily, detailed clinical observations were made in all animals. The time of onset, grade and duration of any observed sign was recorded. Signs were graded for severity. On Day 3 of the mating period all animals were observed under Project number 495179 instead of Project number 495227. Clinical signs recorded under the incorrect number were transferred to the correct number afterwards.

BODY WEIGHT
- Time schedule for examinations: Males and females were weighed on the first day of exposure and weekly thereafter. Mated females were weighed on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum, and during lactation on Days 1 and 4.
Inadvertently, the body weight from one female of Group 1 was determined on Lactation Day 2 instead of lactation Day 1. Given that recording of body weight occurred only one day later than intended, this is considered to provide sufficient information on body weight development of this animal during the lactation phase.

FOOD CONSUMPTION
Weekly, for males and females. Food consumption was not recorded during the mating period. Food consumption of mated females was measured on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum and on Days 1 and 4 of lactation.

FOOD EFFICIENCY
(Average food consumption [per animal per day]/average body weight per cage)x1000

WATER CONSUMPTION
Subjective appraisal was maintained during the study, but no quantitative investigation introduced as no effect was suspected.

OPHTHALMOSCOPIC EXAMINATION
No

HAEMATOLOGY
No

CLINICAL CHEMISTRY
No

URINALYSIS
No

NEUROBEHAVIOURAL EXAMINATION
No

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: No
- Number of late resorptions: No

Fetal examinations:

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross abnomalies, weight gain, physical or behavioural abnormalities.

- Mortality: The numbers of live and dead pups on Day 1 of lactation and daily thereafter were determined. If possible, defects or cause of death were evaluated.
- Clinical signs: At least once daily, detailed clinical observations were made in all animals.
- Body weights: Live pups were weighed on Days 1 and 4 of lactation.
- Sex: Sex was determined for all pups on Days 1 and 4 of lactation (by assessment of the ano-genital distance).

GROSS EXAMINATION OF DEAD PUPS
Yes, if possible, defects or cause of death were evaluated.

Statistics:

- If the variables could be assumed to follow a normal distribution, the Dunnett-test (Dunnett, 1955) (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex. (Ref. 1)
- The Steel-test (Miller, 1981) (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution. (Ref. 3)
- The Fisher Exact-test (Fisher, 1950) was applied to frequency data. (Ref. 2)

All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance. Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. No statistical analysis was performed on histopathology findings.

References:
Ref. 1 Dunnett C.W., A Multiple Comparison Procedure for Comparing Several Treatments with a Control, J. Amer. Stat. Assoc. 50, 1096-1121 (1955).
Ref. 2 Fisher R.A., Statistical Methods for Research Workers, Oliver and Boyd, Edinburgh (1950).
Ref. 3 Miller R.G., Simultaneous Statistical Inference, Springer Verlag, New York (1981).

Indices:

Reproductive indices; For each group, the following calculations were performed:
- Mating index: Number of females mated/Number of females paired x 100
- Fertility index: Number of pregnant females/Number of females paired x 100
- Conception index: Number of pregnant females/Number of females mated x 100
- Gestation index: Number of females bearing live pups/Number of pregnant females x 100
- Duration of gestation: Number of days between confirmation of mating and the beginning of parturition

Offspring indices:
- Percentage live males at First Litter Check: Number of live male pups at First Litter Check/Number of live pups at First Litter Check x 100
- Percentage live females at First Litter Check: Number of live female pups at First Litter Check/Number of live pups at First Litter Check x 100
- Percentage of postnatal loss Days 0-4 of lactation: Number of dead pups on Day 4 of lactation/Number of live pups at First Litter Check x 100
- Viability index: Number of live pups on Day 4 of lactation / Number of pups born alive x 100

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

No clinical signs of toxicity were noted during the observation period.

Salivation seen after dosing among all animals at 50 and 150 mg/kg was considered to be a physiological response rather than a sign of systemic toxicity considering the nature and minor severity of the effect and its time of occurrence (i.e. after dosing). This sign may be related to irritancy/taste of the test substance.

Alopecia and scales observed among females at 50 and 150 mg/kg occurred within the range of background findings to be expected for rats of this age and strain which are housed and treated under the conditions in this study. At the incidence observed, these were considered signs of no toxicological relevance.

Mortality:

no mortality observed

Description (incidence):

No mortality occurred during the study period.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Body weights and body weight gain of treated animals remained in the same range as controls over the treatment period.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Food consumption before allowance for body weight was similar between treated and control animals.

Food efficiency:

no effects observed

Description (incidence and severity):

Food consumption after allowance for body weight was similar between treated and control animals.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Necropsy did not reveal any toxicologically relevant alterations.

Incidental findings among control and/or treated animals included red-brown discolouration of the epididymides, a yellowish nodule on the preputial glands, greenish nodules on the epididymides, reduced size of the prostate and seminal vesicles, a tan/red/brown focus on the clitoral glands and alopecia. The incidence of these findings was within the background range of findings that are encountered among rats of this age and strain, and did not show a dose-related incidence trend. These necropsy findings were therefore considered to be of no toxicological relevance.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There were no treatment-related microscopic findings.

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

The number of corpora lutea and implantation sites showed an apparent trend towards a decrease at 150 mg/kg. The lower mean number of implantation sites was due to one female of Group 4; the mean no. of implantations without this animal was similar to other groups, i.e. 12.8 ± 2.5. Control means of these parameters were considered to be slightly high and mean litter size at this dose level was within the normal range for rats of this age and strain. Also given that mating, fertility and conception indices were unaffected by treatment, no toxicological relevance was ascribed to these apparent differences in precoital time and number of corpora lutea and implantation sites.

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

Gestation index and duration of gestation were unaffected by treatment.
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): effects observed, non-treatment-related
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.DescriptionIncidenceAndSeverityEffectsOnPregnancyDuration): A trend towards an increase in precoital time was observed at 50 and 150 mg/kg. This was due to a higher precoital time of one pair at 50 mg/kg and two pairs at 150 mg/kg. Litter size of these females was normal, and the respective males showed no spermatogenic abnormalities. Moreover, precoital time of other animals of these dose groups was within the range of precoital times observed among control animals.

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

No signs of difficult or prolonged parturition were noted among the pregnant females. Examination of cage debris of pregnant females revealed no signs of abortion or premature birth. No deficiencies in maternal care were observed.

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

>= 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Results (fetuses)

Fetal body weight changes:

not examined

Description (incidence and severity):

Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Field "Description (incidence and severity)" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.DescriptionIncidenceAndSeverityFetalPupBodyWeightChanges): Body weights of pups were considered to have been unaffected by treatment.

Reduction in number of live offspring:

effects observed, non-treatment-related

Description (incidence and severity):

Two pups at 50 mg/kg and three pups at 150 mg/kg were found dead or missing during lactation. The pup missing at 50 mg/kg was most likely cannibalised. No toxicological relevance was attributed to these dead/missing pups since the mortality incidence did not show a dose-related trend and remained within the range considered normal for pups of this age.

Changes in sex ratio:

no effects observed

Description (incidence and severity):

Sex ratio was unaffected by treatment,

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

Postnatal loss was unaffected by treatment.

Changes in postnatal survival:

no effects observed

Description (incidence and severity):

Postnatal loss and the viability index were unaffected by treatment,

External malformations:

no effects observed

Description (incidence and severity):

Three pups found dead (one at 50 mg/kg and two at 150 mg/kg) had no milk in the stomach. No further macroscopic abnormalities were noted among the (surviving) pups.

Other effects:

no effects observed

Description (incidence and severity):

Incidental clinical symptoms of pups consisted of a wound on the right paw, a blue spot on the right shoulder or head and small size. The nature and incidence of these clinical signs remained within the range considered normal for pups of this age, and were therefore considered to be of no toxicological relevance.

Details on embryotoxic / teratogenic effects:

No toxicologically relevant effects on gestation index and duration, parturition, maternal care and early postnatal pup development (mortality, clinical signs, body weight and macroscopy) were observed.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

>= 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Based on these results of a reproduction/developental screening study performed according to OECD guideline 421 and GLP principles, a developmental No Observed Adverse Effect Level (NOAEL) of 150 mg/kg/day was derived.

Executive summary:

A reproduction/developmental toxicity screening test with Ditetrahydrofurylpropane in rats by oral gavagewas performed according toOECD guideline 421 and GLP principles. In a 28-day oral toxicity study with Ditetrahydrofurylpropane (NOTOX project 484766), a No Observed Adverse Effect Level (NOAEL) of 50 mg/kg was established, based on effects in liver and kidneys at 150 and 500 mg/kg. Based on these results, the dose levels for this reproduction/developmental toxicity screening test were selected to be 15, 50 and 150 mg/kg. After acclimatization, four groups of ten male and ten female Wistar Han rats were exposed by oral gavage to the test substance at 0, 15, 50 and 150 mg/kg/day. Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to termination. Females were exposed for 41 -55 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation. The following parameters were evaluated: mortality / viability, clinical signs, body weights, food consumption, reproduction/developmental parameters, observations pups, macroscopy, organ weights, and histopathology. Chemical analyses of formulations were conducted once during the study to assess accuracy and homogeneity.Accuracy, homogeneity and stability of formulations were demonstrated by analyses. No parental, reproduction or developmental toxicity was observedup to the highest dose level tested (150 mg/kg bw/day). Based on the parameters assessed in this study, a parental, reproduction and developmental No Observed Adverse Effect Level (NOAEL) of at least 150 mg/kg bw/day was derived.