2,2-dimethyl-1,3-dioxolan-4-ylmethanol

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From 13 March 2013 to 19 November 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted according to OECD Guideline 422 without any major deviation

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificat n° 2012/96 ; 10 January 2013

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,2-dimethyl-1,3-dioxolan-4-ylmethanol

EC Number:

202-888-7

EC Name:

2,2-dimethyl-1,3-dioxolan-4-ylmethanol

Cas Number:

100-79-8

Molecular formula:

C6H12O3

IUPAC Name:

(2,2-dimethyl-1,3-dioxolan-4-yl)methanol

Test material form:

liquid

Specific details on test material used for the study:

- Analytical purity: 99.9%
- Composition of test material, percentage of components: 99.9% 2,2-Dimethyl-1,3-dioxolane-4-methanol; water: 0.02%; Acidity (Acetic acid): 0.0021%
- Lot/batch No.: BR12K853
- Expiration date of the lot/batch: 05 November 2013
- Storage condition of test material: at room temperature

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories Italia, Calco, Italy.
- Age at study initiation: Males: 10 weeks; Females: 9 weeks
- Weight at study initiation: Males: 388 g (331 to 440 g); females: 230 g (194 to 264 g)
- Housing: Individually, except during pairing and lactation, in polycarbonate cages (Tecniplast 2154, 940 cm²) with stainless steel lids and containing autoclaved sawdust (SICSA, Alfortville, France). Toward the end of gestation and during lactation, autoclaved wood shavings (SICSA, Alfortville, France) were provided to females and their litter as nesting material.
- Diet: SSNIFF R/M-H pelleted maintenance diet (SSNIFF Spezialdiäten GmbH, Soest, Germany), ad libitum
- Water: Drinking water filtered with a 0.22 µm filter, ad libitum
- Acclimation period: 8 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 2°C
- Humidity: 50 ± 20%
- Air changes: 12 air changes per hour of filtered, non-recycled air
- Photoperiod: 12 h dark / 12 h light

IN-LIFE DATES: From 19 March 2013 to 10 May 2013.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

physiological saline

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test item was administered as a solution in the vehicle. The test item was dissolved with the required quantity of vehicle to give the required concentrations of 50, 100 and 200 mg/mL. The formulations were prepared for up to 9 days, divided into daily aliquots and stored at room temperature and protected from light. For each dosing, daily aliquots were delivered to the study room protected from light

VEHICLE
- Concentration in vehicle: 50, 100 and 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg bw.

Details on mating procedure:

- M/F ratio per cage: 1: 1
- Length of cohabitation: Overnight
- Proof of pregnancy: presence of a vaginal plug or for sperm in a vaginal lavage referred to as Day 0 p.c..
- Each female was placed with the same male until mating occurs. The pre-coital time was calculated for each female. The estrous cycle stage was determined from a fresh vaginal lavage (stained with methylene blue), each morning during the pairing period, until the females were mated.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

- The concentrations of the dose formulations were checked in study weeks 1, 3 and 6 by a validated analytical method (CiToxLAB France/Study No. 39832 VAA).
- Acceptance criterion: measured concentration = nominal concentration ± 10%
- The pH of the obtained solutions used throughout the study was measured by means of a pH-meter.
- Results: The test item concentrations in the administered dose formulations analyzed in weeks 1, 3 and 6 were within an acceptable range of variation (i.e. -2% to +8%) when compared to the nominal values (± 10%); pH was close to neutrality.

Duration of treatment / exposure:

- Males: 2 weeks before pairing, during the pairing period (up to 5 days), until sacrifice (5 weeks in total).
- Females: 2 weeks before pairing, during the pairing period (up to 5 days), during gestation, during lactation until day 5 post partum (p.p.) inclusive.
- Day 1 corresponds to the first day of the treatment period.

Frequency of treatment:

Once daily

Doses / concentrations

Remarks:

Doses / Concentrations:
250, 500 or 1000 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The dose-levels were selected in agreement with the Sponsor, following the results of a previous 2-week toxicity study performed with the same species at the dose-levels of 250, 500 or 1000 mg/kg bw/day (Study No. 39834 TSR). In this study, no toxicologically relevant findings, but a slight decrease in body weight in females given 1000 mg/kg bw/day when compared to controls were observed.
- Rationale for animal assignment: during the acclimation period, the required number of animals (40 males and 40 females) was selected according to body weight and clinical condition. The animals were allocated to groups (by sex) according to computerized stratification procedure based on body weight, so that the average body weight of each group was similar.

Positive control:

Not applicable

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS (PARENTAL ANIMALS): Yes
- Time schedule:
Viability / Mortality: Once a day before the treatment period and twice a day during the treatment period. A female of group 4 showing signs of poor clinical condition (immobilized hindlimbs), was humanely sacrificed on day 4 p.c., and was subjected to a macroscopic post-mortem examination.
Clinical Signs: Once daily, during acclimatization and up to day of necropsy. As a male from the control group displayed liquid feces on day 22, decision was taken to weigh and to examine the animal closely on day 23.

DETAILED CLINICAL OBSERVATIONS (PARENTAL ANIMALS): Yes
- Time schedule: Detailed clinical examinations were performed on all animals once before the beginning of the treatment period and then once a week until the end of the study. Observations included (but were not limited to) changes in the skin, fur, eyes, mucous membranes, occurrence of secretions and excretions and autonomic activity (e.g. lacrimation, piloerection, pupil size, unusual respiratory pattern). Changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypes (e.g. excessive grooming, repetitive circling) or bizarre behavior (e.g. self-mutilation, walking backwards) were also recorded.

NEUROBEHAVIOURAL EXAMINATION (PARENTAL ANIMALS): Yes
- Time schedule: The first five males and the first five females to be sacrificed on day 6 p.p. from each group were evaluated once at the end of the treatment period. For females, this was performed on day 5 p.p. after sacrifice of the pups.
- Animals were observed for the following:
Cage-side observations: "touch escape" or ease of removal from the cage.
Hand-held observations: fur appearance, salivation, lacrimation, piloerection, exophthalmos, reactivity to handling, pupil size (presence of myosis or mydriasis).
Standard arena (2-minute recording) observations: grooming, palpebral closure, defecation, urination, tremors, twitches, tonic and clonic convulsions, gait, arousal (hypo- and hyper- activity), posture, stereotypy, behavior, breathing, ataxia and hypotonia.
Reactivity to manipulation and to different stimuli: The following parameter measurements, reflexes and responses were recorded: touch response, forelimb grip strength, pupillary reflex, visual stimulus response, auditory startle reflex, tail pinch response, righting reflex, landing foot splay, at the end of observation: rectal temperature.
Motor activity: Finally, motor activity was measured once by automated infra-red sensor equipment over a 60-minute period.


OPHTHALMOSCOPIC EXAMINATION: No data

BODY WEIGHT (PARENTAL ANIMALS): Yes
- Time schedule for examinations: The body weight of each male was recorded on the first day of treatment (day 1), then once a week until sacrifice. The body weight of each female was recorded on the first day of treatment (day 1), then once a week until mated, on days 0, 7, 14 and 20 post-coitum (p.c.) and days 1 and 5 p.p..
- The body weight of each animal sacrificed as scheduled after the end of the pairing period for males or on day 6 p.p. for females was recorded before sacrifice.

FOOD CONSUMPTION (PARENTAL ANIMALS): Yes
- Time schedule for examinations: The quantity of food consumed by each male was measured once a week, over a 7-day period, from the first day of treatment until the start of the pairing period. The quantity of food consumed by each female was measured once a week, over a 7-day period, from the first day of treatment until the start of the pairing period, during pregnancy for the intervals days 0-7, 7-14 and 14-20 p.c. and during lactation for the interval days 1-5 p.p.

HAEMATOLOGY (PARENTAL ANIMALS): Yes
- Time schedule for collection of blood: from the first five males and the first five females to be sacrificed on day 6 p.p. from each group on the day of sacrifice.
- Anaesthetic used for blood collection: Yes (isoflurane)
- Blood samples were taken from the orbital sinus of the animals, under light isoflurane anesthesia, into appropriate tubes.
- Animals fasted: Yes; an overnight period of at least 14 hours
- How many animals: five males and five females
- Parameters checked: Erythrocytes, Mean cell volume, Packed cell volume, Hemoglobin, Mean cell hemoglobin Concentration, Mean cell hemoglobin, Thrombocytes, Leucocytes, Differential white cell count with cell morphology (neutrophils, eosinophils, basophils, lymphocytes and large unstained cells, monocytes), Reticulocytes, Prothrombin time, Fibrinogen, Activated partial thromboplastin time.

CLINICAL CHEMISTRY (PARENTAL ANIMALS): Yes
- Time schedule for collection of blood: from the first five males and the first five females to be sacrificed on day 6 p.p. from each group on the day of sacrifice.
- Anaesthetic used for blood collection: Yes (isoflurane)
- Blood samples were taken from the orbital sinus of the animals, under light isoflurane anesthesia, into appropriate tubes.
- Animals fasted: Yes; an overnight period of at least 14 hours
- How many animals: five males and five females
- Parameters checked: Sodium, Potassium, Chloride , Calcium, Inorganic phosphorus, Glucose, Urea, Creatinine, Bilirubin (total), Cholesterol (total), Triglycerides, Aspartate aminotransferase, Alanine aminotransferase, Alkaline phosphatase, Protein (total), Albumin, Albumin/Globulin ratio and Bile acids

URINALYSIS: No data

PREGNANCY AND PARTURITION:
- Females were allowed to litter normally and rear their progeny until day 5 p.p.. Any sign of a difficult or prolonged parturition was recorded. The morning when the parturition was completed was designated day 1 p.p.. The length of gestation was calculated.

Oestrous cyclicity (parental animals):

The estrous cycle stage was determined from a fresh vaginal lavage (stained with methylene blue), each morning during the pairing period, until the females were mated.

Sperm parameters (parental animals):

Parameters examined in male parental generations: testis weight, epididymis weight, detailed histological examination of the testes and epididymides with special emphasis on stages of spermatogenesis and histopathology of interstitial testicular cell structure.

Litter observations:

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
- Litters were examined for litter size, sex of each pup and any gross anomalies.
- The litters were observed daily in order to note the number of live, dead and cannibalized pups.
- The pups were observed daily for clinical signs, abnormal behavior and external abnormalities.
- The body weight of each pup was recorded on days 1 and 5 p.p..

GROSS EXAMINATION OF DEAD PUPS:
yes, for external abnormalities

Postmortem examinations (parental animals):

SACRIFICE (PARENTAL ANIMALS)
- On completion of the treatment period, after at least 14 hours fasting, all surviving F0 animals were deeply anesthetized by an intraperitoneal injection of sodium pentobarbital and sacrificed by exsanguination: males: after the end of the pairing period (5 weeks of treatment in total); females: on day 6 p.p..
- One female was prematurely sacrificed during the gestation period. This female was deeply anesthetized by an intraperitoneal injection of sodium pentobarbital and sacrificed by exsanguination.

GROSS PATHOLOGY: Yes
- All parent animals were submitted to complete macroscopic post-mortem examination, either at the scheduled necropsy or during the study if death occurred to establish, if possible, the cause of death. This included examination of the external surfaces, all orifices, the cranial
cavity, the external surfaces of the brain and spinal cord, the thoracic, abdominal and pelvic cavities with their associated organs and tissues and the neck with its associated organs and tissues. Special attention was paid to the reproductive organs.
- For prematurely sacrificed animals the pregnancy status was determined. The presence of implantation scars on the uterus was checked using the ammonium sulphide staining technique. Implantation sites and corpora lutea were counted and recorded for females sacrificed as scheduled on day 6 p.p..

ORGAN WEIGHTS
Body weight of each animal was recorded before sacrifice and the organs specified in the table 7.8.1/2 were weighed. The ratio of organ weight to body weight (recorded immediately before sacrifice) was calculated.

HISTOPATHOLOGY: Yes
- Samples of the tissues specified in the table 7.8.1/2 were preserved in 10% buffered formalin (except for the testes and epididymides which were fixed in modified Davidson's fixative).
- All tissues required for microscopic examination were trimmed, embedded in paraffin wax and sectioned at a thickness of approximately four microns and stained with hematoxylin-eosin (except testes and epididymides which were stained with hematoxylin/PAS). Microscopic examination was performed on all tissues listed in the table 7.8.1/2 from the first five sacrificed as scheduled males and the first five females sacrificed on day 6 p.p. of the control and high-dose groups (groups 1 and 4) and from the prematurely sacrificed female, and on all macroscopic lesions of all groups. Based on the microscopic findings seen in the kidneys of high-dose males, a microscopic examination was performed on the kidneys from group 2 and group 3 males. Special emphasis was paid to the stages of spermatogenesis in the male gonads and histopathology of interstitial testicular cell structure.

Postmortem examinations (offspring):

SACRIFICE (LITTER):
- Surviving pups were sacrificed by an intraperitoneal injection of sodium pentobarbital on day 5 p.p..

GROSS NECROPSY (LITTER):
- A macroscopic post-mortem examination of the principal thoracic and abdominal organs was performed on all found dead pups and on all pups sacrificed on day 5 p.p.. Special attention was paid to the reproductive organs and to whether the pup has fed (e.g. presence of milk in the stomach). No tissues were preserved.

Statistics:

- Data are expressed as group mean values ± standard deviation (body weight, body weight change, food consumption, number of corpora lutea, number of implantation sites, number of pups and pup body weight, gestation length) or as proportions (pre-implantation loss, post-implantation loss, pup observations, mating index, fertility index, gestation index, live birth index, viability index). Whenever appropriate, the experimental unit of comparison was the litter. Data of the non-pregnant female are not included in group mean calculations such as body weight, body weight change, food consumption.
- Body weight, food consumption and reproductive data are compared by one-way analysis of variances and Dunnett test (mean values being considered as normally distributed, variances being considered as homogenous) or by Fischer exact probability test (proportions).
- Hematology and blood biochemistry data are compared by various tests according to a decision tree: Dunnett-test, Dunn test or Mann-Whitney / Wilcoxon test (according to variance homogeneity between groups) were applied if the variables could be assumed to follow a normal distribution for the comparison of the treated groups and the control groups. Mann-Whitney / Wilcoxon test or Dunn test were applied when the data could not be assumed to follow a normal distribution.
- PathData software (version 6.2d2) was used to perform the statistical analysis of organ weight data (level of significance: 0.05 or 0.01) by Dunn test if >2 groups or Wilcoxon test if 2 groups and Dunnett test if >2 groups or t-test if 2 groups, based on normal distribution and homogeneity of variance.

Reproductive indices:

Pre-implantation loss = (Number of corpora lutea - Number of implantation sites)/ Number of corpora lutea x 100
Post-implantation loss (calculated manually) = (Number of implantation sites - Number of live pups)/ Number of implantation sites x 100
Mating index = Number of mated animals / Number of paired animals x 100
Fertility index = Number of pregnant female partners / Number of mated pairs x 100
Gestation index = Number of females with live born pups / Number of pregnant females x 100

Offspring viability indices:

Live birth index = Number of live born pups / Number of delivered pups x 100
Viability index = Number of surviving pups on day 4 p.p. / Number of live born pups x 100

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
- There were no deaths considered as test item-related. One female given 1000 mg/kg/day was prematurely sacrificed on day 4 p.c. on ethical grounds as this animal displayed hindlimb immobilized before sacrifice. No necropsy findings were noted. In view of the duration of the treatment, and absence of pre-neoplastic or neoplastic hematopoietic lesions in other test item-treated animals, this isolated finding was considered to be fortuitous. There were no other unscheduled deaths during the study.
- There were no test item treatment-related clinical signs.

BODY WEIGHT AND WEIGHT GAIN (PARENTAL ANIMALS)
- There were no test item treatment-related effects on mean body weight or mean body weight gain.
- When compared with the control group, a slightly lower mean body weight gain was observed in females treated at 1000 mg/kg/day during the whole pre-mating period (+30 g and +18 g between Days 1 – 15, respectively). When compared with the control group, the opposite trend was noted in all test item-treated males with a statistical significance over the last 3 weeks at 250 and 1000 mg/kg/day (+31 g, +50 g and +49 g between Days 15 – 36, respectively). Since these differences were not dose-related and of opposite tendency and since these differences had no impact on the final body weights, they were considered not to be relevant.

FOOD CONSUMPTION (PARENTAL ANIMALS)
- When compared with the mean control values, females treated at 500 and 1000 mg/kg/day had statistically significantly lower food consumption (23 g/rat/day, 20 g/rat/day and 21 g/rat/day between Days 1 – 8 of Pre-mating, respectively). As this effect was minimal, not dose-related and limited to the first week of the pre-mating period, it was considered to be of no toxicological importance. There were no effects on mean food consumption at these dose-levels in males.
- The test item did not affect the food consumption at any of the dose-levels employed.

NEUROBEHAVIOURAL EXAMINATION (PARENTAL ANIMALS)
- No relevant findings were noted during functional observational battery testing in test item-treated groups when compared with the control groups.

LABORATORY INVESTIGATIONS (PARENTAL ANIMALS)
- There were no test item-related findings on hematology parameters. Lower mean values of Mean Cell Hemoglobin, prothrombin and activated partial thromboplastin times recorded in males given the high dose-level were considered to be of no toxicological importance as they were minimal, with no biological significance and/or isolated variations.
- When compared with the mean control values, the cholesterol concentration of males treated at 1000 mg/kg/day was 77% higher (2.3 vs. 1.3 mmol/L, p<0.01). In absence of treatment-related microscopic findings in the liver, these variations were considered to be of minor toxicological importance.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
- There were no evident signs of disturbances of the estrus cycle. There were no test item-related effects on mating and fertility data.
- At 1000 mg/kg/day, the higher pre-implantation loss (11.2% instead of 5.2 % in control group) was considered to be fortuitous in origin and not considered to be related to the test item administration since the number of pups per litter was unaffected. There were no effects on the mean numbers of corpora lutea, implantations or pups at any dose-level, nor on the duration of gestation or the extent of post-implantation losses.

ORGAN WEIGHTS (PARENTAL ANIMALS)
- Test item-related changes were observed for the liver in males. There were no test item-related organ weight changes in females. When compared with controls, there was a slight increase in the mean absolute and relative liver weights in males given the test item at 1000 mg/kg/day (+31% and +26%, respectively), reaching statistical significance for the relative weight only. A minimal trend was also present at 500 mg/kg/day (+22% and + 18%, respectively), but the differences were not statistically significant. These variations were considered to be related to the test item but were considered not to be adverse in view of the slight magnitude of the changes.
- The mean absolute and relative spleen weights were slightly higher in males given the test item at 1000 mg/kg/day compared with controls (up to +29%). This correlated at microscopic examination with increased congestion in two animals, and was considered to be an agonal phenomenon related to euthanasia with pentobarbital.
- Other occasional organ weight changes were not considered to be related to the test item as they were small in amplitude, had no gross or microscopic correlates, and/or were not dose-related in magnitude.

GROSS PATHOLOGY (PARENTAL ANIMALS)
- In the vagina of the female given 1000 mg/kg/day prematurely sacrificed on day 4 p.c., there was a slight subacute inflammation, and moderate mucification of the mucosal epithelium. Low development of the corpora lutea in the ovaries and slight glandular atrophy in the stomach (fundus) may have been secondary to stress and poor clinical condition of this animal. None of these findings were attributed to the test item.
- There were no macroscopic findings attributed to the test item administration. The thymus was reduced in size in a single female in each of the 500 and 1000 mg/kg/day dose-groups.
This correlated at microscopic examination with lymphoid atrophy. However lymphoid atrophy was recorded with similar incidence in controls and high-dose females. These macroscopic findings were therefore considered to be incidental and unrelated to the test item administration.

HISTOPATHOLOGY (PARENTAL ANIMALS)
- There were no effects on the genital organs examined in any groups. A careful qualitative histopathological examination of the testes was performed. There were no effects on the germ cells or interstitial (Leydig) cells.
- Test item-related microscopic findings occurred in the kidneys from males. There were no test item-related findings in females. In the kidneys, tubular hyaline droplets were seen with increased incidence and severity in males given the test item at 1000 mg/kg/day compared with controls. This was characterized by the presence of dense eosinophilic droplets in proximal tubular epithelium. These hyaline droplets, occasionally seen in untreated male rats, are consistent with α2u globulin. Although human excrete proteins of a similar nature, they are found in only trace amounts and therefore this finding is considered to be non-relevant for human. There were no significant findings at 250 and 500 mg/kg/day.
- Other microscopic findings noted in treated animals were considered incidental changes, as they also occurred in controls, were of low incidence, had no dose-relationship in incidence or severity, and/or are common background findings for the Sprague-Dawley rat.

Effect levels (P0)

1

Dose descriptor:

NOAEL

Remarks:

(systemic toxicity)

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

2

Dose descriptor:

NOEL

Remarks:

(reproductive toxicity)

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed on mating, fertility and delivery data in any group

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

OFFSPRING LITTER SIZE AND VIABILITY
- There were no effects on pup viability and none of the observed clinical signs were considered to be test item-related (comparable incidences in control pups or not dose-related).
- There were no effects of treatment with the test item on the percentage of male pups at birth at any dose-levels.

OFFSPRING GROWTH AND DEVELOPMENT
- There were no effects of treatment with the test item on mean body weight and mean body weight change in pups.
- The macroscopic findings were considered not to be of toxicological importance as these findings can appear spontaneously and as they were no test item-related (no dose-relationship and slight incidences).

Effect levels (F1)

Dose descriptor:

NOEL

Remarks:

(developmental toxicity)

Generation:

F1

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed on pups by day 5 post partum (viability, clinical signs, sex ratio, macroscopic post-mortem findings)

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:

Under the test condition, the dose-level of 1000 mg/kg/day was considered to be the No Observed Adverse Effect Level (NOAEL) for parental and systemic toxicity (based on findings in the kidneys of males) and the No Observed Effect Level (NOEL) for reproductive performance (mating and fertility) and for toxic effects on progeny.

Executive summary:

In a Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test conducted according to OECD Guideline 422 and in compliance with GLP, 2,2-Dimethyl-1,3-dioxolane-4-methanol diluted in Phosphate Buffer Saline solution was administered daily by oral gavage to male and female Sprague-Dawley rats (10/sex/dose), for 2 weeks before mating, during mating and (for females) throughout gestation and until day 5 post-partum, at dose-levels of 250, 500 or 1000 mg/kg bw/day. A control group was treated with Phosphate Buffer Saline solution. During the study, data was recorded on mortality, clinical signs, behavioural assessments, body weight change, food consumption, haematology, blood chemistry, mating performance, fertility and gestation length. All animals were subjected to a gross necropsy examination, selected organs were weighed and histopathological evaluation of selected tissues was performed. The clinical condition of offspring, litter size and survival, sex ratio and offspring bodyweight were assessed and macroscopic pathology investigations were undertaken.

 

No test item-related deaths or clinical signs were noted in any group and sex. No toxicologically relevant effects on mean body weight, mean food consumption, mean Functional Observation Battery and motor activity data and mean clinical pathology parameters in any group and sex. The increase in the absolute and relative liver weights recorded in males given 1000 mg/kg bw/day was considered not to be adverse in view of the slight magnitude of the changes and the absence of microscopic correlates. None of the macroscopic findings were attributed to the test item administration. At histopathology, tubular hyaline droplets in the kidneys (consistent with rat-specific alpha-2u-globulin) were seen with increased incidence and severity in males treated at 1000 mg/kg bw/day compared to controls (presence of dense eosinophilic droplets in proximal tubular epithelium). This finding was not observed at 250 or 500 mg/kg bw/day. These kidney effects were considered to be related to alpha-2u globulin nephropathy and of no relevance to humans. There were no toxicologically relevant effects on mean mating, fertility and delivery data in any group. There were no test item-related effects on pups by day 5 post partum (viability, clinical signs, sex ratio, macroscopic post-mortem findings).

 

Under the test condition, the dose-level of 1000 mg/kg/day was considered to be the No Observed Adverse Effect Level (NOAEL) for parental and systemic toxicity (based on findings in the kidneys of males) and the No Observed Effect Level (NOEL) for reproductive performance (mating and fertility) and for toxic effects on progeny.