Cyclohexadecen-1-one

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-04-19 to 2002-05-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study performed according to OECD test guideline No. 414 and in compliance with GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

22 January 2001

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

UK GLP Compliance Programme (inspection date: 2002-12-02)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

A mixture of: (E)-oxacyclohexadec-12-en-2-one; (E)-oxacyclohexadec-13-en-2-one; a) (Z)-oxacyclohexadec-(12)-en-2-one and b) (Z)-oxacyclohexadec-(13)-en-2-one

EC Number:

422-320-3

EC Name:

A mixture of: (E)-oxacyclohexadec-12-en-2-one; (E)-oxacyclohexadec-13-en-2-one; a) (Z)-oxacyclohexadec-(12)-en-2-one and b) (Z)-oxacyclohexadec-(13)-en-2-one

Molecular formula:

C15H26O2

IUPAC Name:

Reaction mass of (E)-oxacyclohexadec-12-en-2-one and (E)-oxacyclohexadec-13-en-2-one and (Z)-oxacyclohexadec-(12)-en-2-one and (Z)-oxacyclohexadec-(13)-en-2-one

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Limited, Margate, Kent - U.K.
- Age at study initiation: not mentioned in study report. The females were delivered to the study laboratory between Day 1 and 3 of gestation.
- Weight at study initiation: 171 to 263 g at female allocation
- Housing: females were caged individually in polypropylene cages with solid floors and stainless steel grid tops. Softwood chips were used as bedding material.
- Diet: ad libitum (pelleted diet (Rat and Mouse VRF1-C Diet, Charles River UK Limited, Margate, Kent)
- Water: ad libitum (drinking water)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23
- Humidity (%): 40-70 (On occasions the temperature and/or relative humidity were not within prescribed limits. This did not affect the purpose of the study)
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: from 2002-04-19 to 2002-05-15

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test material was suspended daily in 0.5% (w/v) carboxymethyl cellulose (vehicle). For each dose level, an appropriate aliquot of test material was weighed into a glass jar and a small volume of vehicle was added to make the calculated final volume. Homogeneity was assured by mixing the formulations using a Silverson mixer/homogeniser.

VEHICLE
- Justification for use and choice of vehicle (if other than water): test compound of low solubility in
water
- Dose volume: 5 mL/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The concentration of the test material in formulations was determined by gas chromatography (GC) using an external standard technique. Analysis of homogeneity, stability & concentrations in formulations gave good results as shown hereafter:

HOMOGENEITY: The test material formulations were mixed thoroughly using a homogeniser and samples were taken from the top, middle and bottom of the container, mixing in between sampling. Sampling was performed in triplicate. Measured concentrations were: 91.9-93.6%, 84.8-93.4% and 94-99% of nominal concentrations for 10, 50, 200 mg/mL nominal concentrations respectively.

STABILITY: The test material formulations were sampled and analysed initially and then after storage at approximately +4°C in the dark for fourteen days. Measured concentrations were >94 % of nominal concentrations of 10, 50 and 200 mg/mL.

TEST MATERIAL FORMULATIONS: the test material formulations were sampled and analysed within 2 days (Day 1 & Day 4) of preparation. Measured concentrations were 92, 97 and 101% of nominal concentrations for nominal concentrations of 10, 50 and 200 mg/mL on Day 1 and 98, 85 and 83% of nominal concentrations for nominal concentrations of 10, 50 and 200 mg/mL on Day 4.

Details on mating procedure:

Not provided in the study report. Pregnant females were delivered directly to the Testing Laboratory between Day 1 and 3 of gestation from Charles River (UK) Limited, that supplied pregnant female rats prepared in accordance with OECD 414 Guideline requirements.

Duration of treatment / exposure:

From Day 5 to 19 of gestation inclusive.

Frequency of treatment:

Daily

Duration of test:

15 days

No. of animals per sex per dose:

24 females/dose

Details on study design:

- Dose selection rationale: The concentrations tested in this study were determined from a subchronic 90-day oral toxicity study (OECD 408 Guideline) performed with the same test material on the same rat strain and for which a NOEL of 1000 mg/kg bw/day was determined.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily during the normal working week and once daily at weekends

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All females were observed once daily, in the morning from the day of delivery throughout gestation and, additionally, one hour after dosing, throughout the dosing period, for clinical signs of toxicity.

BODY WEIGHT: Yes
- Time schedule for examinations: All females were weighed on Day 3, Day 6 to Day 9, Day 12, Day 15, Day 18 and Day 20 of gestation.

FOOD CONSUMPTION: Yes
Food consumption for individual animals was recorded for discrete periods throughout the study on Days 3 to 6, Days 6 to 9, Days 9 to 12, Days 12 to 15, Days 15 to 18 and Days 18 to 20 of gestation.

POST-MORTEM EXAMINATIONS: Yes (Each animal was examined externally and internally for macroscopic abnormalities)
- Sacrifice on gestation day # 20
- Organs examined: ovaries and uteri (were examined and following data were recorded: i) Gravid uterus weight, ii) Number of corpora lutea, iii) number, position and type of intrauterine implantation)

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

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: half per litter

Statistics:

Data were processed to give litter mean values, group mean values and standard deviations. The following parameters were analysed statistically, where appropriate using the test methods out lined below: Female bodyweight change and food consumption: Bartlett's test for homogeneity of variance and
one way analysis of variance; followed by Dunnett's multiple comparison test; or a pairwise 'T' test where unequal variances are assumed. All caesarian necropsy parameters, foetal parameters: Kruskal-Wallis non-parametric analysis of variance; and a subsequent pairwise analysis of control values against treated values using the Man n-Whitney 'U' test, where significance was seen. Foetal evaluation parameters, including skeletal or visceral findings: Kruskal-Wallis nonparametric analysis of variance and Mann-Whitney 'U' test.

Indices:

Percentage pre-implantation loss was calculated as: (Number of corpora lutea - Number of implantations)/ Number of corpora lutea x 100
Percentage post-implantation loss was calculated as: (Number of implantations - Number of live foetuses)/ Numer of implantations x 100

Historical control data:

Historical control were provided in the study (Foetal External and Visceral Findings, Foetal Skeletal Development, Foetal Skeletal Findings)

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

no effects observed

Description (incidence and severity):

There were no significant treatment-related clinical findings during the course of the study.

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Description (incidence):

There were no mortalities during the course of the study. No animals were observed to show evidence of ill-health.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no significant treatment-related effects upon female bodyweight gain throughout the study.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There were no significant treatment-related differences in female food consumption throughout 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

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

Examination of the uterine contents showed no significant treatment-related effects. At 1000 mg/kg there was a slight increase in pre-implantation loss. This was considered to be unrelated to treatment because of the lack of statistical significance, lack of dose-response relationship and no difference in the implantation count or live litter size when compared to control values. The increase in pre-implantation loss is a direct consequence of an elevated mean corpora lutea counts alone which may be a natural phenomenon. All other uterine parameters examined were comparable to control values.

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

For all dose groups, there were no significant treatment-related trends in the proportion of litters.

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

not examined

Other effects:

not examined

Effect levels (maternal animals)

1

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

mortality

2

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

maternal abnormalities

Maternal abnormalities

Key result

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

At 1000 mg/kg there was an increase in foetal weight compared to control values. The difference was statistically significant (p<0.001). There is an apparent "dosage-related" trend for increasing foetal weight. This is a totally fortuitous result and the margin of difference between all groups is unlikely to be the result of abnormal foetal development.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

no effects observed

Other effects:

not examined

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: no effects observed up to the highest dose tested

Fetal abnormalities

Key result

Abnormalities:

no effects observed

Overall developmental toxicity

Key result

Developmental effects observed:

no

Any other information on results incl. tables

The results of administration of the test material, throughout the majority of the gestation period, at dose levels up to 1000 mg/kg bw/ resulted in no effects in adults during the in-life phase of the study. This was demonstrated by the lack of effect upon female bodyweight gain and food consumption during the study period. No clinical signs of toxicity were observed during the dosing phase of the study and no significant macroscopic findings were seen at the post mortem examination of adults. Examination of the uterine contents showed no significant treatment-related effects. At 1000 mg/kg bw/d there was a slight increase in pre-implantation loss. This was considered to be unrelated to treatment because of the lack of statistical significance, lack of a dose-response relationship and no difference in the implantation count or live litter size when compared to control values. The increase in preimplantation loss is a direct consequence of elevated mean corpora lutea counts alone which may be a natural phenomenon. All other uterine parameters examined were comparable to control values. There were no significant treatment-related effects upon offspring growth and development during gestation. At 1000 mg/kg bw/d, a statistically significant increase in group mean foetal weight was observed. This was considered to be unrelated to treatment as subsequent foetal evaluations, particularly the evaluation of skeletal development suggests no significant precocious development of offspring. There were no significant increases in the type or incidence of visceral or skeletal anomalies observed. The types of anomalies seen are those commonly observed for this study type.

Applicant's summary and conclusion

Conclusions:

The oral administration of the test material at dose levels up to 1000 mg/kg bw/d, to pregnant rats from Day 5 to Day 19 of gestation resulted in no significant systemic effects on the adults. There were no significant effects on any of the uterine parameters examined. There were no significant effects upon offspring viability, growth or development. The No Observed Adverse Effect Level (NOAEL) for adult toxicity and developmental toxicity was ≥1000 mg /kg bw/d.

Executive summary:

In a developmental toxicity study conducted according to the OECD guideline No. 414 and in compliance with GLP, the test material diluted in carboxymethyl cellulose was administered to 24 females Sprague- Dawley CD rats/dose by gavage at dose levels of 0, 50, 250 or 1000 g/kg bw/d from day 5 of gestation through day 19 of gestation. Individual clinical observations, bodyweight and food consumption were recorded during the study. The females were killed on Day 20 of gestation, examined macroscopically and the uterine contents examined. The number of corpora lutea, implantation number, position and type, foetal and placental weights, foetal sex, and external appearance were recorded. All live foetuses were preserved, processed and subsequently examined for skeletal or visceral anomalies. At all dose levels up to and including 1000 mg/kg bw/d there were no significant treatment related effects on adult bodyweight gain and food consumption during gestation. There were no clinical signs of reaction to test material administration and no significant macroscopic findings at post mortem examination. At caesarian necropsy, there were no significant treatment-related effects on any of the parameters examined. At all dose levels up to and including 1000 mg/kg bw/d there were no significant treatment related effects upon foetal viability, growth and development. There was no effect upon the type or incidence of visceral or skeletal anomalies observed. The oral administration of the test material at dose levels up to 1000 mg/kg bw/d, to pregnant rats from Day 5 to 19 of gestation resulted in no significant systemic effects on the adults. There were no significant effects on any of the uterine parameters examined. There were no significant effects upon offspring viability, growth or development. The No Observed Adverse Effect Level (NOAEL) for adult toxicity and developmental toxicity was ≥ 1000 mg /kg bw/d. Under the test conditions, the test material is not classified according to the annex VI of the Regulation (EC) No. 1272/2008 (CLP) and of the Directive 67/548/EEC. This study is acceptable and satisfies the requirement for developmental toxicity endpoint.