5,7-dichloro-4-(4-fluorophenoxy)quinoline;quinoxyfen (ISO)

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPP 83-3 (Prenatal Developmental Toxicity Study)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: 87/302/EEC Part B, Methods for the determination of toxicity, teratogenicity test - rodent and non-rodent.

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF Notice 59, NohSan N4200

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

124495-18-7

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

Substance ID: TSN 100097
Name of substance: XDE-795 (Technical grade)
Purity: 97.4%

Test animals

Species:

rat

Strain:

other: Crl: CD(SD) BR VAF/Plus

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, UK Limited, Manston Road, Margate, Kent, England.
- Age at study initiation: 8-10 weeks old
- Housing: The animals were housed individually in suspended stainless-steel cages equipped with solid sides and wire grid front, back, floor and top. The cages constituting each treatment group were dispersed within the batteries so that possible environmental influences arising from their spatial distribution were equilibrated as far as possible for all treatments.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: Not specified

ENVIRONMENTAL CONDITIONS
- Temperature: 18-23°C
- Humidity: 45-60%
- Photoperiod: 12 hrs dark /12 hrs light

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1% methylcellulose

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Dose suspensions were prepared daily and used within 4 hours of preparation. The test substance was ground in a mortar with a small amount of the vehicle, 1% methylcellulose, until a smooth paste was formed. The formulation was then gradually made up to volume and mixed using a high shear homogeniser. A series of suspensions was made by serial dilution to achieve the required concentrations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The achieved concentration of prepared formulations was assessed on the first day of treatment and results for all groups were within the range -1% to +5% of nominal.

Details on mating procedure:

- Impregnation procedure: Purchased timed pregnant
- Verification of same strain and source of both sexes: Yes
- Proof of pregnancy: Vaginal plug / sperm in vaginal smear referred to as day 0 of pregnancy
- Any other deviations from standard protocol: None

Duration of treatment / exposure:

GD6 to GD15

Frequency of treatment:

Daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day

No. of animals per sex per dose:

30 time mated females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dosages of 0, 100, 300 and 1000 mg/kg/day were selected on the basis of a preliminary study where no conclusive toxicity was apparent at dosages up to 750 mg/kg/day.

Examinations

Maternal examinations:

CLINICAL OBSERVATIONS
- Time schedule: All animals were regularly handled and observed daily for obvious changes or signs of reaction to treatment.

BODY WEIGHT
- Time schedule for examinations: All animals were weighed by the supplier on the day of mating (Day 0 of pregnancy), on receipt at test facility (Day 1, batch A or Day 2, batch B of pregnancy) and on Days 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20.

FOOD CONSUMPTION
- Food consumption for each animal determined and mean daily diet consumption calculated as g/rat/day

POST-MORTEM EXAMINATIONS
- Sacrifice on gestation day # 20
- Organs examined: Liver, ovaries, uteri

Ovaries and uterine content:

The ovaries and uterine content was examined after termination include:
- Gravid uterus weight: No data
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: number and distribution of live young, individual foetal weight (from which the litter weight was calculated) and foetal abnormalities

Fetal examinations:

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

Statistics:

Significance tests, employing analysis of variance or covariance followed by an intergroup comparison with the control, were performed on the following parameters and results are presented in relevant tables of this report:
bodyweight change, food consumption, liver weight, litter data, sex ratios, foetal anomalies and variants.
For maternal parameters the tests employed were dependent on the heterogeneity of variance between treatment groups. Parametric tests (analysis of variance or covariance (Snedecor and Cochran, 1967) followed by Williams' test (Williams, 1971/2) or non-parametric tests (Kruskal-Wallis (Hollander and Wolfe, 1971) followed by Shirley's test (Shirley, 1977) were used to analyse these data, as appropriate. For litter data and foetal changes, the basic sample unit was the litter and, due to the preponderance of non-normal distributions the above mentioned non-parametric analyses were used. Analysis of malformations and anomalies was performed using a trend test on the number of litters affected followed by a 2 sample permutation test (Edgington, 1980; Franck, 1986).
All significant (i.e., P ≤0.05) intergroup differences from the control were reported and are supported by a significant analysis of variance (p ≤0.05.
Where a non-parametric test was usually employed but 75% or more of the values for a given variable were the same (i.e., late embryonic deaths), a Fisher's exact test (Fisher, 1950) was used.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, non-treatment-related

Mortality:

mortality observed, non-treatment-related

Description (incidence):

There was a single mortality at 1000 mg/kg/day, one female died prior to dosing on Day 12 post coitum during weighing. Clinical findings noted immediately prior to death were pallor, lethargy and respiratory distress. Post mortem examination indicated this death was due to an intubation error, probably on Day 11 post coitum and not, therefore, related to treatment.

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:

no effects observed

Description (incidence and severity):

Liver weight, as assessed at Day 20 of pregnancy (5 days after the end of the dosing period), showed no notable or significant (P>0.05) intergroup differences.

Gross pathological findings:

no effects observed

Maternal developmental toxicity

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

There was one notable litter with a single viable implantation. Preimplantation loss, which is considered to occur prior to the start of treatment, was very high for this litter and influenced other values, especially size and weight of the litter.

Total litter losses by resorption:

no effects observed

Effect levels (maternal animals)

Key result

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Remarks on result:

other: Highest dose tested

Results (fetuses)

Fetal body weight changes:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

At 100 mg/kg/day (the low dosage), the 6 malformed foetuses came from one litter. Findings in these foetuses included translucent or mottled white appearance to skin, brachygnathia, cleft palate, mal rotated hindlimbs, apparent ring of constriction around lower thorax and symphalangy, oligodactyly or syndactyly. Microscopic examination of abdominal skin from one of these foetuses with mottled appearance, revealed marked dermal oedema with absent hair follicles/adnexa. In view of the absence of similar effects at this or higher dosages and considering this event as an isolated cluster of foetuses in a single litter showing the same syndrome of defects, no association with treatment was indicated.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

At 1000 mg/kg/day, there was a slightly higher number of foetuses with extra (14) ribs but differences did not attain statistical significance, were well inside the historical control range and were considered not to be treatment-related.

Effect levels (fetuses)

Key result

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: Highest dose tested

Overall developmental toxicity

Key result

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

NOEL (Rat, maternal and developmental toxicity): 1000 mg/kg/day (highest dose tested)

Executive summary:

This study was conducted to assess the effect of the test substance on pregnancy of the rat according to the guidelines OECD 414 and EPA OPP 83-3. Dosages of 0 (Control), 100, 300 or 1000 mg/kg/day were administered by gavage to groups of 30 time-mated CD rats from Day 6 to 15 of pregnancy, inclusive. The animals were killed on Day 20 of pregnancy and in utero development was assessed by determination of litter values and subsequent examination of foetuses for visceral or skeletal abnormalities.

No effects of treatment on maternal clinical signs, bodyweight gain, food intake, liver weight or macroscopic abnormalities at autopsy were observed.

No effects of treatment on in utero development were observed. Litter size, pre- and post-implantation losses, litter and mean foetal weight, sex ratio and the distribution of foetuses with abnormalities were considered unaffected by treatment.

Treatment of parent females with the test substance at dosages up to 1000 mg/kg/day was determined as being without adverse effect on the mother or developing conceptus in this study.