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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Valid guideline study under GLP-conditions.
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report date:
2008

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Deviations:
no
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Bis(4-chlorophenyl) sulphone
EC Number:
201-247-9
EC Name:
Bis(4-chlorophenyl) sulphone
Cas Number:
80-07-9
Molecular formula:
C12H8Cl2O2S
IUPAC Name:
1-chloro-4-(4-chlorobenzenesulfonyl)benzene
Details on test material:
- Name of test material: 4,4'-dichlorodiphenyl sulfone
- Physical state: white solid pellets
- Analytical purity: >98.4 %
- Batch No.: LP070811
- Storage condition: at room temperature in the dark

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, UK
- Age at study initiation: approximately 8 weeks old
- Weight at study initiation: 286-361 g (males), 192-233 g (females)
- Housing: in solid floor polypropylene cages with stainless steel grid tops and softwood flake bedding (Datesand Ltd, Cheshire, UK); in groups of 5 animals/sex/cage premating, or 1 male and 1 female/cage during the mating period, or 1 mated female/cage during gestation and lactation
- Diet: pelleted diet (Rodent PMI 5002 certified diet, BCM IPS Limited, London, UK), ad libitum
- Water: mains drinking water supplied from polycarbonate bottles, ad libitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 2 °C
- Humidity: 55 ± 15 %
- Air changes: 15 air changes/hour
- Photoperiod: 12 hours dark / 12 hours light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
arachis oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS
The test material was prepared at the appropriate concentrations as a suspension in Arachis oil BP. The stability and homogeneity of the dose formulations were determined. Formulations were shown to be stable for at least 14 days. Samples were taken of each formulation and analysed for DCDPS concentration.

VEHICLE
- Justification for use and choice of vehicle: Arachis oil BP is a standard vehicle in studies of this type
- Concentration in vehicle: 0, 1.25, 3.75 or 12.5 mg/mL
- Amount of vehicle: a dose volume of 4 mL/kg bw was used
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The concentration of DCDPS in the test material formulations was determined by high performance liquid chromatography (HPLC) using an external standard technique. The test material formulations were extracted with acetonitrile to give a final, theoretical test material concentration of approximately 0.1 mg/mL. Standard solutions of test material were prepared in acetonitrile at a nominal concentration of 0.1 mg/mL. The standard and sample solutions were then analysed by HPLC. The analytical method has been satisfactorily validated in terms of linearity, specificity and accuracy for the purposes of the study.
Details on mating procedure:
- M/F ratio per cage: 1:1 within each dose group
- Length of cohabitation: max. 14 days
- Proof of pregnancy: vaginal plug and sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
42 days
Total observation time up to 54 consecutive days (including a two week maturation phase, pairing, gestation and early lactation for females)
Frequency of treatment:
once daily
Duration of test:
up to 54 consecutive days of dosing
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 5, 15, and 50 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
10 animals
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on previous toxicology studies

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS:
- Time schedule: before dosing and up to 5 hours (workdays) or 1 hour (weekend) thereafter

BODY WEIGHT:
- Time schedule for examinations: day 1, weekly thereafter (males); weekly until mating, GD 0, 7, 14, 20, PPD 1 and 4

FOOD CONSUMPTION :
- Food consumption for each group determined and mean daily diet consumption calculated as g food/rat/day: Yes, premating and 3 weeks after and individual for females during pregnancy.

FEED EFFICIENCY:
Body weight gain/feed intake: for periods of measured feed consumption

WATER CONSUMPTION:
Visual observation only

POST-MORTEM EXAMINATIONS:
Full external and internal examination for macroscopic anomalies.
Organ weights: epididymes, testes, liver
Histopathology: coagulation gland, liver, ovaries, pituitary, prostate, seminal vesicles, testes, uterus/cervix, vagina
Ovaries and uterine content:
The ovaries and uterine content was examined after termination.
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: Yes
- Number of implantations: Yes
Fetal examinations:
Full external and internal examination for macroscopic anomalies
Statistics:
Standard methods such as linear regression, ANOVA, Dunntett's, Mann Whitney U test for parametric values, Chi square and Kruskall Wallis for non parametric data.
Indices:
Percent post-implantation loss, live birth index, viability index, sex ratio plus weights and righting reflex on day 4.
Historical control data:
Historical control data for the same strain were included in the report.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
none

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
50 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOEL
Effect level:
15 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Mean offspring body weight gain between days 1 and 4 of lactation were statistically significantly reduced for offspring from litters treated with 50 mg/kg bw/day. No such effects were detected in offspring from litters treated with 15 or 5 mg/kg bw/day.

Relevant data are summarised in tabular form in section "Any other information on results incl. tables"

Effect levels (fetuses)

Dose descriptor:
other: Reduced body weight gain in pups
Basis for effect level:
fetal/pup body weight changes
Remarks on result:
not determinable
Remarks:
No distinct causal relation is evident for the reduced body weight gain (developmental effect) in pups except the association with maternal toxicity. A plausible hypothesis is to see it as a consequence of effects upon maternal metabolism. The altered metabolism may have limited the ability of the female to provide sufficient nutrition to the offspring.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Offspring body weight and body weight change

Dose level

[mg/kg bw/day]

Offspring body weight [g]

Offspring body weight change [g]

Day 1

Day 4

Days 1-4

Males

Females

Males

Females

Males

Females

0 (control)

7.3 ± 0.9

6.8 ± 0.8

10.5 ± 1.5

9.9 ± 1.5

3.2 ± 0.7

3.1 ± 0.8

5

6.8 ± 0.6

6.4 ± 0.6

9.7 ± 1.3

9.0 ± 1.2

2.9 ± 0.8

2.6 ± 0.7

15

6.8 ± 0.6

6.6 ± 0.5

9.3 ± 0.9

8.9 ± 0.8

2.5 ± 0.5

2.4 ± 0.5

50

7.0 ± 0.7

6.6 ± 0.6

9.3 ± 1.3

8.7 ± 1.2

2.3 ± 0.6 *

2.1 ± 0.7 **

All values are mean ± standard deviation of 10 animals

* Significantly different from control group p<0.05

** Significantly different from control group p<0.01

Applicant's summary and conclusion

Conclusions:
All doses induced effects in the parental generation, which were significantly adverse in the males. Reduced body weight gain was noted in the offsping of mothers treated at 50 mg/kg bw/day (developmental effect). In the absence of any other treatment related finding in the offspring, reduced body weight gain was considered to be secondary to changes in maternal metabolism, but this can not be finally assessed based on the available data.
Executive summary:

In a reproduction/developmental toxicity screening study (Safepharm Ltd, 2008), DCDPS (>98.4 %) in arachis oil was administered to 10 Sprague-Dawley rats/sex/dose level by oral gavage (4 mL/kg bw) at dose levels of 0 (vehicle only), 5, 15 or 50 mg/kg bw/day. Rats were dosed with DCDPS for two weeks maturation, pairing and pregnancy up to day 4 post partum, thus a total of 42 days. In the developmental screening part of the study, there were no treatment related effects noted on mortality, clinical aspects, food and water consumption as well as food efficiency, reproductive performance/fertility and offspring litter size and viability. Males treated with 50 mg/kg bw/day showed a reduction in cumulative body weight gain throughout the treatment period and a reduction in weekly body weight gain during the first two weeks of treatment. Offspring from litters treated with 50 mg/kg bw/day showed a reduction in body weight gain considered as developmental effect. At necropsy, enlarged livers were seen in males at 15 mg/kg bw/day and in males and females at 50 mg/kg bw/day. Animals of either sex from all treatment groups showed an increase in liver weight. Dose-dependent centrilobular hepatocyte enlargement was seen in all treated groups. Centrilobular hepatocyte vacuolation was noted at 50 mg/kg bw/day being more prevalent in males. Based on these results, the NOAEL for parental toxicity was established at 15 and 50 mg/kg bw/day for male and female animals, respectively. The NOEL for developmental toxicity/teratogenicity was set at 15 mg/kg bw/day based on reduced body weight gain in the offspring at 50 mg/kgbw/day.

This screening study is acceptable and satisfies the requirement for test guideline OECD 421.