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Key value for chemical safety assessment

Toxicity to reproduction: other studies

Description of key information

It was observed from this exploratory investigation that embryos cultured in the presence of propylal exhibited no adverse effects on growth, development or morphology. It was concluded, therefore, that propylal showed no potential embryo toxicity or teratogenicity.

Link to relevant study records
Reference
Endpoint:
toxicity to reproduction: other studies
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental start date: 5 April 2016, Experimental completion date: 20 May 2016.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: INVITTOX protocol no. 123.
Deviations:
yes
Remarks:
please see any other information on methods and materials section
GLP compliance:
yes (incl. certificate)
Type of method:
in vitro
Specific details on test material used for the study:
Test substance: Propylal
Test substance identity (including alternative names): Dipropoxymethane
CAS number: 505-84-0
Intended use: solvent
Appearance: Colourless liquid
Storage conditions: Refrigerated (2-8°C), protected from light.
Batch number: 1602181700R
Expiry date: 18 February 2017
Purity: 99.6658%
Species:
rat
Strain:
other: Crl:CD (SD)
Details on test animals and environmental conditions:
Animal supply, acclimatisation and allocation
Strain/Species Crl:CD(SD) rat.
Supplier Charles River (UK) Ltd.
Number of animals ordered 80 females.
Duration of acclimatisation At least 1week before commencement of pairing.
Age of the animals ordered Approximately 9 weeks old.

Mating
Male/female ratio 1:1 with identified stock males.
Daily checks for evidence of mating Ejected copulation plugs in cage tray and vaginal smear.
Day 0 of gestation When positive evidence of mating was detected.

Allocation and identification
Allocation On the day of positive evidence of mating (Day 0).
Identification of animals Each animal was assigned a number and identified uniquely within the study by a tail tattoo.

Environmental control
Rodent facility Full barrier - to minimise entry of external biological and chemical agents and to minimise the transference of such agents between rooms.
Air supply Filtered fresh air which was passed to atmosphere and not recirculated.
Temperature and relative humidity Monitored and maintained within the range of 19-23ºC and 40-70%, respectively.
There were no deviations from these ranges.
Lighting Artificial lighting, 12 hours light : 12 hours dark, with lights on at 01:00 GMT.
Window blinds remained open for the first three days allowing light ingress during the dark period. Blinds were closed prior to 13:00 GMT on 1st April 2016.
Electricity supply Public supply with automatic stand-by generators.

Animal accommodation
Cages Cages comprised of a polycarbonate body with a stainless steel mesh lid; changed at appropriate intervals.
Solid (polycarbonate) bottom cages were used during the acclimatisation and gestation periods.
Grid bottomed cages were used during pairing. These were suspended above absorbent paper which was changed daily during pairing.
Bedding (solid bottom cages) Wood based bedding which was changed at appropriate intervals each week.

Environmental enrichment
Aspen chew block Provided to each animal throughout the study and replaced when necessary.
Plastic shelter Provided to each cage throughout the study and replaced when necessary.

Diet supply
Diet SDS VRF1 Certified pelleted diet.
The diet contained no added antibiotic or other chemotherapeutic or prophylactic agent.
Availability Non-restricted.

Water supply
Supply Potable water from the public supply via polycarbonate bottles with sipper tubes. Bottles were changed at appropriate intervals.
Availability Non-restricted.


Route of administration:
other: Roller bottle culture technique
Vehicle:
corn oil
Details on exposure:
The roller bottle culture technique was used (New 1978). Embryos were cultured in the presence of each test substance for a period of approximately 48 hours at a temperature of 37.0 ± 1.0°C.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
48 hours
Duration of test:
48 hours
Dose / conc.:
0 other: µg/mL
Dose / conc.:
30 other: µg/mL
Dose / conc.:
100 other: µg/mL
Dose / conc.:
300 other: µg/mL
Dose / conc.:
1 000 other: µg/mL
No. of animals per sex per dose:
3 embryos per dose for preliminary study.
7 embryos per dose for main study
Control animals:
yes, concurrent vehicle
Details on study design:
A preliminary test (0, 1, 10, 100 and 1000 µg/mL) was used to establish suitable treatment levels for the Main study. Propylal and Butylal showed little or no adverse effect on embryonic growth or development at dose levels up to 1000 μg/mL

Culture medium
The culture medium consisted of equal volumes of homologous rat serum, heat inactivated at 56.0 ± 0.5°C for 40 minutes, and HEPES-buffered Eagle’s minimum essential medium.

Maternal euthanasia
Dams were anaesthetised with a mixture of isofluorane and oxygen on the afternoon of the ninth day of gestation and, after removal of the uterus, were killed by exsanguination and/or cardiac section.

Embryo preparation
Decidua were subsequently released from the uterus and the embryos dissected out. The parietal yolk sac was torn open and removed. Only overtly healthy embryos with the visceral yolk sac and ectoplacental cone intact were cultured.

Culture methods
Embryos were incubated at 37.0 ± 1.0°C in 30 mL glass bottles which were rotated continuously at 60 rev/min throughout the period of culture. Each bottle contained up to five embryos with 1 mL of culture medium per embryo and a gas phase. The gas phase was 5% O2, 5% CO2 and 90% N2 for approximately 20 hours followed by 20% O2, 5% CO2 and 75% N2. Each bottle was identified by indelible marker pen showing group number, compound name and dose level. Cultures were terminated after approximately 48 hours.
Temperature was monitored continuously but recorded daily. Since these data show that there were no significant deviations from target values they are not presented.
Dose descriptor:
NOAEL
Effect level:
> 1 000 other: μg/mL
Based on:
test mat.
Basis for effect level:
other: embryonic growth, development and morphology

Preliminary study

Embryos cultured in the presence of Propylal at doses up to 1000 μg/mL exhibited no adverse effect on embryonic growth, development or morphology. Findings at 1 μg/mL were not attributed to treatment.

Main Study

Embryos cultured in the presence ofPropylalat doses up to 1000 μg/mL exhibited no adverse effect on embryonic growth, developmentor morphology. Morphological observations were generally of a minor nature and were therefore considered incidental.

Discussion

Low incidences of minor morphological observations were recorded; these were mostly haemorrhages and common pericardial defects, which were considered unlikely to be related to treatment. 

For preliminary study cultures started on 19 April 2016, stoppers had fallen out of four bottles prior to the start of culture. The medium within these bottles appeared bright pink. Since there was insufficient time to prepare fresh medium these bottles were assigned to the lowest concentration level for material dosed on that day. Effects seen could be attributed to the change in the culture medium as they were not seen at the higher dose levels; hence for propylal, findings at 1 μg/mL were not attributed to treatment

No other effects were seen following treatment with propylal, hence this material was considered not to show developmental toxicity in vitro.

Conclusions:
It was observed from this exploratory investigation that embryos cultured in the presence of propylal exhibited no adverse effects on growth, development or morphology. It was concluded, therefore, that propylal showed no potential embryo toxicity or teratogenicity.
Executive summary:

Summary

The influence of Propylal, upon growth and development in vitro was assessed in Day 9.5 embryos from rats of the CD strain. Each test substance was added to the culture medium at concentrations of 1, 10, 100 and 1000 mg/mL in groups of 3 embryos in the preliminary study. In the main study groups of 7 embryos were administered each test substance at concentration levels of 30, 100, 300 and 1000mg/mL. The negative Control group received the vehicle corn oil at the same volume-dose. All embryos were evaluated after approximately 48 hours in culture.

Results

Propylal: No adverse effect on embryonic growth, development or morphology was observed at doses up to 1000 μg/mL.

Conclusion

It was observed from this exploratory investigation that embryos cultured in the presence of propylal exhibited no adverse effects on growth, development or morphology. It was concluded, therefore, that propylal showed no potential embryo toxicity or teratogenicity.

Justification for classification or non-classification

The test substance was considered to be non toxic or teratogenic under embryonic development test and is therefore not classified for reproductive toxicity.