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Toxicological information

Developmental toxicity / teratogenicity

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developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
May 12, 1981
GLP compliance:
Limit test:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:
- Chemical name: 5-Brom-5-nitro- 1,3-dioxan
- Trade name: Bronidox
Specific details on test material used for the study:
Batch 11 38 232
Stored in glass at room temperature
protected from light
white crystalline powder

Test animals

Details on test animals or test system and environmental conditions:
- Source: Charles River WIGA GmbH, Sulzfeld (D).
- Age at study initiation: not given
- Weight at study initiation: 200-240 g
- Fasting period before study: N/A
- Housing: Makrolon cage type 3, Litter: softwood granulate, autoclaved,
- Diet (e.g. ad libitum): Pelleted, low-germ, low-nitrosamine diet Altromin N-1324, Lot 1450, Altromin GmbH, 4937 Lage (D), ad libitum.
- Water (e.g. ad libitum): municipal tap water ad libitum
- Acclimation period: 19 days

- Temperature (°C): 21.5 - 23.5
- Humidity (%): 54
- Air changes (per hr): not given
- Photoperiod (hrs dark / hrs light): 12-hour artificial lighting / day, illuminance
30 - 550 Lux, depending on location.

IN-LIFE DATES: From: 14/12/1983 To: 09/02/1984

Administration / exposure

Route of administration:
oral: gavage
Details on exposure:
Number and frequence or application:
10 applications in 24 hours intervals from day 6 to day 15 or
gestation. Group 4 : 3 applications only because of the lethal


The solutions were freshly prepared each day. For applications over the weekend preparations were used, which were scheduled Fridays around 15 clock. The stability of the test substance in the solution was checked.

solutions prepared at 0.05, 0.15 and 0.45 % w/v to be dosed at 10ml/kg bw
Analytical verification of doses or concentrations:
Details on analytical verification of doses or concentrations:
The analytical upper test of the test concentrations was carried out 3 times
during the study by photometric determination of Bronidox K in
aqueous solution at 203 nm. For this purpose, 250 μl of each application solution were used
diluted to 25 ml in the flask and the extinctions are determined.
Details on mating procedure:
Mating, the female rats were used in groups of 3 animals / Makrolon cage type 3, the male rats in groups of 4 animals / Makrolon cage type 3.
At the beginning of the mating, 3 female and 1 male animals were assembled. After being diagnosed, the female animals were housed individually in Makrolon cage type 3. The animals were transplanted twice a week.
- Pairing:
Sexually mature females and females were housed in proportion 3: 1 from Monday 8.00 am to Friday 8.00 am.
The insemination was checked by daily checking of the vaginal smear and the vaginal plug. The timing of the appearance of sperm in the vaginal swab or finding the
Vaginal plug was taken as day 0 of pregnancy.
Duration of treatment / exposure:
10 days
Frequency of treatment:
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (actual dose received)
Dose / conc.:
5 mg/kg bw/day (actual dose received)
Dose / conc.:
15 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
30 (thirty)
Control animals:
yes, concurrent vehicle
Details on study design:
Choice of dosages and the type of application
The highest dose represents about 1/10 of the LD50 value for rats,
the dose of 100/200 mg / kg / day was requested after oral administration
proved to be cumulatively toxic in the long-term trial.


Maternal examinations:
- Time schedule: twice daily

- Time schedule: twice daily

- Time schedule for examinations: GD 0, 6, 15 and 19

- Sacrifice on gestation day # 20
- Organs examined: ovaries and uterus

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
- Other: - Number and positions of the implants divided into:
- live fetuses
- dead fetuses early in the uterus
- early-late intrauterine dead fetuses
- Intrauterine dead fetuses
- Total weight uterus with fetuses
- Weight of the placentas
Fetal examinations:
- External examinations: Yes: [all per litter ]
- Soft tissue examinations: Yes: [all per litter ]
- Skeletal examinations: Yes: [all per litter ]
- Head examinations: Yes: [all per litter]
student's t-test for body weights and Wilcoxon U-test,
Mann and Whitney for late resorptions
Implantations possible:
[Number of implants/Number of corpora lutea] x100

Fetal viability:
[Number of living fetuses/Number of implants] x 100

% of losses before implantation:
{[Number of corpora lutea - number of implants]/Number of corpora lutea} x 100

% of losses after implantation:
{[Number of implants - number of living fetuses]/ Number of implants}x 100

% Sex distribution coefficient:
Number of male fetuses/ Number of fetuses x 100

Number of female fetuses / Number of fetuses x 100

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
From the second application the first symptoms of poisoning appeared.
The intensity of the symptoms as well as the number of affected animals was
dose-dependent. In group 4 (45 mg/kg bw/day) treatment was discontinued after 3 applications for severe general and nervous symptoms.
Dermal irritation (if dermal study):
not examined
mortality observed, treatment-related
Description (incidence):
1 animal died in the 15 mg/kgbw/day group and 4 died in the 45 mg/kg bw/day group. the dosing of the high dose group was suspended in extremis following the 3rd dose
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
significant decreases in bodyweight gain (P<0.05) in the high dose group on Gestation days 15 and 19
Food consumption and compound intake (if feeding study):
not examined
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):
effects observed, treatment-related
Description (incidence and severity):
Group 2: Occasional vocalizations, abnormal gait, vocalization when touched,
Group 3: Isolated vocalizations, vocalization when touched, reduced activity, eg. T. prone position, aggressiveness,
Group 4: Isolated vocalizations, Increased/decreased activity, abnormal gait, decreased reflexes, vocalization when touched, aggressiveness,

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

Maternal developmental toxicity

Number of abortions:
no effects observed
Pre- and post-implantation loss:
effects observed, treatment-related
Description (incidence and severity):
Maternal toxicity is manifested by increased levels of implantation losses (33 in total) at the highest dose level, with 15 and 5 resorptions/implantaiton losses at the low and mid doses respectively
Total litter losses by resorption:
no effects observed
Description (incidence and severity):
There were no total litter losses by resorption
Early or late resorptions:
not specified
Description (incidence and severity):
The timing of the observed resorptions was not specified
Dead fetuses:
effects observed, treatment-related
Description (incidence and severity):
Maternal toxicity is manifested by increasing numbers of dead fetuses at the highest dose levels compared to other doses administered.
Changes in pregnancy duration:
no effects observed
Changes in number of pregnant:
no effects observed
Details on maternal toxic effects:
4 maternal animals died in the high dose group and the remaining 26 animals exhibited symptoms of toxicity. One animal died in the mid-dose groups and 7 other exhibited signs of toxicity.

Effect levels (maternal animals)

Key result
Dose descriptor:
Effect level:
ca. 5 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
clinical signs

Maternal abnormalities

no effects observed

Results (fetuses)

Fetal body weight changes:
not examined
Reduction in number of live offspring:
effects observed, treatment-related
Description (incidence and severity):
offspring viability reduced to 87.73% compared to 97.63% in control ( not statistically significnat)
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
not examined
External malformations:
no effects observed
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
one instance of ex-encephaly and two instances of thoracic spina bifida, including one with absence of lumbar and sacral vertebra in mid-dose group
Visceral malformations:
no effects observed

Effect levels (fetuses)

Key result
Dose descriptor:
Effect level:
ca. 15 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
reduction in number of live offspring

Fetal abnormalities

effects observed, non-treatment-related
skeletal: skull
skeletal: sternum
skeletal: vertebra

Overall developmental toxicity

Key result
Developmental effects observed:
Lowest effective dose / conc.:
45 mg/kg bw/day (actual dose received)
Treatment related:
Relation to maternal toxicity:
developmental effects as a secondary non-specific consequence of maternal toxicity effects
Dose response relationship:
Relevant for humans:

Applicant's summary and conclusion

Based on the study described Bronidox K is to be classified as maternally cumulatively toxic, non-embryolethal as well as non-teratogenic. Anyfetal effects (resorptions/fetal deaths) observed are a direct result of non-specific secondary consequence of maternal toxicity.
Executive summary:

Bronidox K was applied orally in doses of 5, 15 and 45 mg/kg body weight/day once daily to groups of pregnant rats from day 6 to day 15 of pregnancy. Control animals were treated simltaneously with the vehicle. All dosages resulted in general symptoms of intoxication with one death in the median dose group of 15 mg/kg/day, and 4 animals died after 2 to 3 applications of the highest dose of 45 mg/kg/day. An influence of the test substance on fetal parameters was recognisable only at the highest dosage by an increased resorption rate after implantation and by increased rate of retardation. The investigation of the foetuses yielded no indication of direct embryotoxic or teratogenic effects. Based on the study subsequently described Bronidox K is to be classified as maternally cumulatively toxic, non-embryolethal as well as non-teratogenic.