Bromoacetic acid

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From August to October 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD, EPA, etc)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Bromoacetic acid

EC Number:

201-175-8

EC Name:

Bromoacetic acid

Cas Number:

79-08-3

Molecular formula:

C2H3BrO2

IUPAC Name:

2-bromoacetic acid

Test material form:

other: White to yellow crystalline solid

Details on test material:

- Name of test material (as cited in study report): Bromoacetic acid
- Substance type: White to yellow crystalline solid
- Physical state: solid
- Purity test date: 98%
- Lot/batch No.: 210892
- Stability under test conditions: Stable at room temperature
- Storage condition of test material: at 20°C

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Wiga, Sulzfeld, Germany
- Age at study initiation: About 14 weeks old
- Weight at study initiation: 190.5-249.8 g
- Housing: Upon arrival in the study room, the males were housed individually in suspended stainless steel cages fitted with wire mesh fronts and floors of 18x32x18 cm and the females were housed in groups of four per sex in similar cages of 45x32x18 cm. During mating, 2 females were caged with a male. During gestation, the females were housed individually in cages of l8x32x18 cm.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.5-24°C
- Humidity (%): 50-70%
- Air changes (per hr): 10 changes/hour
- Photoperiod (hrs dark / hrs light): 12 hours light

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: the test substance was administred dissolved in tap water.

VEHICLE: Tap water

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Drinking water containing test substance was prepared twice and samples for analyses were taken once.

Details on mating procedure:

Females were placed with males, i.e. two females with one male. vaginal smears were taken the next morning to determine whether mating had occurred. If no sperm cells were detected, the female in question was placed again with the male until observation of a vaginal smear or vaginal plug (several days) (considered as the day 0 of gestation)

Duration of treatment / exposure:

The test substance solutions were offered from day 6 up to and including day 15 of gestation.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0, 4.7, 11.6, 21.9 mg/kg bw
Basis:
other:

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0, 40, 120, 360 mg/kg
Basis:
nominal in water

No. of animals per sex per dose:

96 females - 24 number of animals per group

Control animals:

yes

Details on study design:

On day 21 of gestation the females were killed by cervical dislocation preceded by ether anaesthesia, opened through a midline incision in the abdominal and thoracic wall and examined for gross abnormalities. Subsequently, the uterus and ovaries were removed for further examination.
The fetuses were removed from the uterus, dried of amniotic fluids and examined grossly, upon which they were further processed.

Examinations

Maternal examinations:

- Body weight: On day 0, 6, 11, 16 and 21 of gestation.
- Food consumption: Periods day 0-6, 6-11, 11-16 and 16-21
_ Clinical signs/ checked daily, twice daily during weekdays, once daily on weekends.

Ovaries and uterine content:

- Gravid uterine weight, net uterine weight
- Placental weight
- Number of corpora lutea
- Number of implantations

Fetal examinations:

- Litter Size,
- Nr. of dead Foetuses,
- Foetal Weight, length
- Sex Ratio
- Grossly vivible malformations

Statistics:

- Clinical findings of the female rats were evaluated by Fisher's exact probability test.
- Body weights and food and water consumption were subjected to one-way analysis of variance (ANOVA) followed by Dunnett's Multiple Comparison test.
- The mating data were calculated for the females from each group and compared by Fisher's exact test.
* Day 21 sacrifice data:
- Mean gravid and empty uterus weight, mean ovary and carcass weight were analysed for each group by ANOVA + Dunnett-test.
- Numbers of corpora lutea, implantation sites, resorptions, and live and dead fetuses were analysed for each group by the Kruskal-Wallis test followed by the Mann Whitney U-test.
- Mean fetal body weights and lengths, and placenta weights were calculated for each litter and subjected to ANOVA + Dunnett-test.
- Numbers of male and female fetuses, and visceral and skeletal findings were analysed by the Fisher exact test.

Indices:

- Pre implantation loss (%) = (a-b)/a x 100
- Post implantation loss (%) = (b-c)/b x 100
where:
a = number of corpora lutea
b = total number of implantation sites
c = number of live fetuses

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes. Remark: For details, see below

Details on maternal toxic effects:
- Clinical signs:
Alopecic areas were observed in 1 animal of the control group, the midand high-dose group respectively. No other clinical signs were observed.
- Marternal necropsy:
No remarkable findings were observed in most of the animals (23 of the control, 20 of the low and high dose group and 18 of the mid dose group). Four females with a pronounced lobular pattern in the liver were observed, 2 in the mid-dose and 2 in the high-dose group. One female in the mid-dose group was observed to have a stomach with a haemorrhagic content. Unilateral kidney cysts were observed in 3 females, one in the control group, mid-dose and high dose group respectively. Ovary cysts were observed of one animal in each the lowor mid-dose group. A swollen uterus was observed in 2 females of the low-dose and 1 female of the high-dose group and uteri of one female each of the low- or mid-dose group were observed to be filled with blood. None of the effects was considered to be related to the treatment. No other relevant observations were made at autopsy.
- Body weight:
Maternal body weight was statistically significantly decreased in the high-dose animals on gd 16. Body weight gain was affected in both the mid- and high-dose groups during the administration period. Mean body weight change was reduced compared to controls from day 6 to 11 in the mid dose group and from day 6 to 16 in the high dose group, whereas in the latter an increase in body weight change compared to controls was observed between gestation day 16 and 21.
- Food consumption:
At start of the study (day 0-6) food consumption was comparable between all groups.. A statistically significant reduction in food consumption was obseved in the mid dose group between day 6 and 11 of gestation and in the high dose group from day 6 to 16 of gestation, whereas it was significantly increased in the latter group from gd 16 to 21.
- Water consumption:
At start of the study (day 0-6) water consumption was comparable between all groups. Mean water consumption was statistically significantly reduced in the
mid-dose group between gestation days 6 and 11, and in the high-dose group between days 6 and 16. Mean water consumption was slightly increased in the high-dose group between day 16 and 21.
- Maternal performance and organ weights:
None of the females had an abortion or died during the study. In each group one female delivered before scheduled sacrifice, and 3 to 4 females per group were not pregnant. All pregnant females had litters with viable foetuses. No statistically significant differences were observed in mean gravid and mean empty
uterus weight and in mean ovary weight.
- Reproduction findings and litter data
No significant differences were observed between the dose groups and the control group concerning the numbers of corpora lutea, implantation sites, and live and dead foetuses, and in the pre- and postimplantation loss. The number of dead foetuses was very low (1 foetus only, in the low-dose group). The count of early and late resorptions alone or taken together did not show any differences amongst the groups. The sex ratio in all groups was, within the normal limits, close to 1:1.
- Autopsy findings:
Placental haemorrhages were observed on 3 occasions, in a single case of each treatment group. Fused placentas were observed on 1 occasion, in the high-dose group.

Effect levels (maternal animals)

1

Dose descriptor:

NOEL

Effect level:

21.9 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: other:

2

Dose descriptor:

NOEL

Effect level:

4.7 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

3

Dose descriptor:

LOEL

Effect level:

21.9 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

4

Dose descriptor:

LOEL

Effect level:

21.9 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: other:

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects. Remark: For details, see below

Details on embryotoxic / teratogenic effects:
- Autopsy findings:
Foetal crown-rump lengths, placental weight and fetal body weights were similar in all groups. At Caesarian section 842 foetuses were found in 78 litters. Only 1 foetus was dead (low-dose group). Umbilical hernia was observed in 1 foetus in the mid-dose group. Hypogenesis of the tail was observed in 1 foetus of the high-dose group. A swelling on the head was observed in 1 foetus of the high-dose group.
Flexed limbs were observed in 1 foetus of the control group, in 2 foetuses of the low-dose group and in 1 foetus of the mid-dose group. A dysmature appearance (i.e. a foetus smaller/lighter than 25/of the mean) was observed in 1 foetus of the low-dose group. A purple appearance was observed in 5 foetuses of the high-dose group and a pale appearance in 2 foetuses from low-dose group. One large foetus was observed (i.e. a foetus bigger/heavier than 25\ of the mean), in mid-dose group.
Subcutaneous haemorrhages were observed in many foetuses, distributed about equally over all groups. Due to the location, it could be decided that these haemorrhages were probably caused by the method with which the foetuses were identified individually. None of the observations described above, being few and distributed evenly over the groups, was considered to be related to the treatment.
- Visceral malformations:
The only malformation found was one case of encephalocele in the high dose group. This finding is not considered treatment related.
- Visceral anomalies:
The number of viceral anomalies was small and none of them was considered the result of treatment. One incidence each of defects of the retina or lens were observed in the control and high dose group respectively. One incident of haemorrhagein the brain was observed in the high dose group and haemorrhage in the liver was observed in one case in both the control and the high dose group. One incidence of hydronephrosis was reported in the high dose group and hydorurether was found in one fetus of the control and high dose group respectively. One incidence of thoracic cavity filled with blood was observed in the high dose group.
- Visceral variations:
The visceral variations observed included esophagectasia (2 incidences in the control, 1 in the high dose group), kidneys with increased pelvis cavitation (12 in the control, 9 in the high dose group), crooked tails (3 in both the control and high dose group), subcutaneous haemorrhages (1 in the control 7 in the high dose group), and a haemorrhage in the salivary gland in the control group. The number of visceral variations was small and none of the observed variations could be ascribed to the treatment.
- Skeletal malformations and variations:
Neither skeletal malformations nor variations were observed in the cotnrol and high dose group. Variations in ossification were present in approximately equal quantities in both groups.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The oral administration of bromoacetic acid, dissolved in the drinking water at levels up to 360 mg/kg water (mean actual daily intake: 21.9 mg/kg body weight) from day 6 through 15 of pregnancy induced no clinical signs and adverse findings at autopsy of the pregnant females.
In addition and on the basis of the results abtained it can be concluded that:
- bromoacetic acid is not embryo/fetotoxic and does not induce any teratogenic effect. Consequently, the no-adverse effect level for prenatal development is
21.9 mg/kg bw per day or higher.
- In view of the effects seen in the pregnant rats the no-adverse effect level of bromo acetic acid for maternal toxicity is 40 mg/kg water, which is equivalent to 4.7 mg/kg body weight per day.