Difluoroacetic acid

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Data source

Reference

Reference Type:

publication

Title:

Developmental toxicity of dichloroacetate in the rat

Author:

Smith M.K., Randall, J.L. Read, E.J. and Stober, J.A.

Year:

1990

Bibliographic source:

Teratology, 46 (3), 217-23. Year: 1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other:

Principles of method if other than guideline:

The developmental toxicity effect of dichloroacetic acid to Long-Evans rat was assessed in a parental generation of rat.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Dichloroacetic acid

EC Number:

201-207-0

EC Name:

Dichloroacetic acid

Cas Number:

79-43-6

IUPAC Name:

dichloroacetic acid

Test material form:

other: Liquid

Details on test material:

- Name of test material (as cited in study report): Dichloroacetic acid
- Molecular formula (if other than submission substance): C2H2Cl2O2
- Molecular weight (if other than submission substance): 128.94
- Substance type: Organic
- Physical state: Liquid
- Impurities (identity and concentrations): -----

Test animals

Species:

rat

Strain:

Long-Evans

Details on test animals or test system and environmental conditions:

Source: Charles River Breeding Laboratories
Weight range: Not available
Housing: groups of three in plastic cages with corn cob bedding (Bed O'Cobs, Anderson Cob Div., Maumee, OH), and maintained on Purina Rodent Laboratory Chow No. 5001 (St. Louis, MO)
Diet (e.g. ad libitum): Purina Rodent Laboratory Chow No. 5001, ad libitum
Water: ad libitum (distilled water)

ENVIRONMENTAL CONDITIONS:
Temperature: Temp. 70-74°F
Humidity (%): 40-60%
Photoperiod: 12-h light cycle (0630 lights on).

Administration / exposure

Route of administration:

oral: gavage

Type of inhalation exposure (if applicable):

not specified

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Dosing solutions were prepared daily and their purity and stability confirmed using ion chromatography.
DCA of >99% purity was dissolved in water and adjusted to pH 7 with sodium hydroxide, such that the desired dosage, adjusted daily, could be administered at 10 ml/kg body weight.
Rate of preparation of diet (frequency):
Dosing solutions were prepared daily and their purity and stability confirmed using ion-chromatography.

Amount of dose: 10 ml/kg body weight.

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- M/F ratio per cage: 1 female: 1 male
- Length of cohabitation: At 2:00 PM and checked for the presence of sperm at 9:00 AM on the following morning.
(19 Hrs)
- Proof of pregnancy: [vaginal plug / sperm in vaginal smear] referred to as [day 0 / day 1] of pregnancy Sperm-positive females were considered to be in day 0 of pregnancy and were singly housed for the duration of the study.
- After … days of unsuccessful pairing replacement of first male by another male with proven fertility. Not Available
- Further matings after two unsuccessful attempts: [no / yes (explain)] Not Available
- After successful mating each pregnant female was caged (how): Not Available
- Any other deviations from standard protocol: Not Available

Duration of treatment / exposure:

10 days

Frequency of treatment:

Daily

Duration of test:

10 days

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 14, 140 or 400 mg/kg-bw/day
Basis:
nominal in water

No. of animals per sex per dose:

80 rats
0mg/kg-bw/ day: 20
14 mg/kg-bw/ day: 20
140 mg/kg-bw/ day: 20
400 mg/kg-bw/ day: 20

Control animals:

yes, concurrent vehicle

Examinations

Maternal examinations:

Analysis of the average percent maternal weight gain from days 0-20, adjusted for gravid uterine weight, revealed a statistically significant difference from the controls in 140 and 400 mg/kg/day, but not in the lowest dose group (14 mg/kg/day).
Reductions in weight gain, particularly during the initial phases of dosing, were seen in 140 mg/kg/day except at the 14-mg/kg/day dose.
The weight of the maternal liver (relative to body weight) was elevated above control values at all dose levels

The total number of implants per litter was unaltered by treatment with the exception of an apparently spurious reduction at 400 mg/kg/day

Ovaries and uterine content:

Reproductive outcome in pregnant Long-Evans hooded rats following exposure to dichloroacetic acid on days 6-15 of gestation

Treatment
(mg/kg/day) Sperm positive females treated Deaths Pregnant Viable litters Body weight
D0 G±SD
D20 % Wt Gain
±SD Adjusted
% Wt Gain
±SD
H2O 19 00 19 19 226.7±18 343.0±27 51.5±8 21.0±6
DCA 14 19 00 18 18 223.7±22 348.5±30 49.7±12 20.3±6
DCA 140 20 00 19 19 228.3±22 337.2±31 48.0±8 16.2±5
DCA 400 19 00 19 19 227.7±17 326.8±28 43.6±8 13.3±5

Live fetuses showed dose-dependent reductions in weight and length at doses above 140 mgkg

Fetal examinations:

Dose-related increases were seen in external, total soft tissue, cardiovascular, urogenital and orbital malformations.

Statistics:

Not Available

Indices:

Not Available

Historical control data:

Not Available

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
Maternal livers, spleens and kidneys showed dose-related hypertrophy, and at all except the lowest dose (14 mg/kg/day) the adjusted percentage body weight gain in the dams was significantly reduced in comparison with the controls.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

14 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Remarks on result:

other: not specified

2

Dose descriptor:

NOAEL

Effect level:

14 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Remarks on result:

other: not specified

Maternal abnormalities

Abnormalities:

not specified

Localisation:

not specified

Description (incidence and severity):

not specified

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes. Remark: no dose-related trend in sex ratio alteration was seen at the 14 mg/kg/day

Details on embryotoxic / teratogenic effects:
no dose-related trend in sex ratio alteration was seen at the 14 mg/kg/day

Effect levels (fetuses)

1

Dose descriptor:

LOEL

Effect level:

140 mg/kg bw/day

Based on:

test mat.

Sex:

not specified

Basis for effect level:

other: embryotoxicity

Remarks on result:

other: not specified

2

Dose descriptor:

LOEL

Effect level:

140 mg/kg bw/day

Based on:

test mat.

Sex:

not specified

Basis for effect level:

other: teratogenicity

Remarks on result:

other: not specified

Fetal abnormalities

Abnormalities:

not specified

Localisation:

other: not specified

Description (incidence and severity):

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Treatment related:

not specified

Relation to maternal toxicity:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Applicant's summary and conclusion

Conclusions:

The Dichloroacetic acid treated on Long-Evans rat had shown NOAEL (no observed adverse effect level) for maternal and developmental toxicity in Long-Evans rats treated with dichloroacetic acid was found to be 14 mg/kg bw/day, while the LOEL (Low observed effect level) for embryotoxicity and teratogenicity was 140 mg/kg bw/day.

Executive summary:

The developmental toxicity of DCA (Dichloroacetic acid) was assessed in a one generation study with pregnant Long-Evans rats at dose levels of 0, 14, 140 or 400 mg/kg/day. The rats were orally administrated with DCA in distilled water on gestation days 6-15. Maternal observations included clinical signs, weight change, and gross evaluation of organ weights and uterine contents at necropsy (day20).Corpora lutea were counted and uteri stained for implantation sites. Live fetuses were examined for external, skeletal, and soft tissue malformations.While in increased post-implantation resorptions at 900+ mg/kg bw per day, reduced fetal body weights at 400+ mg/kg bw per day, maternal toxicity at 14+ mg/kg bw per day malformations shown in cardiovascular at 400+ mg/kg bw per day soft tissue at 140+ mg/kg bw per day urogenital at 1400+ mg/kg bw per day. Liver, spleen, and kidney weights increased in a dose-related manner. The mean percentage of resorbed implants per litter was significantly elevated at 2900 mg/kg/day

The No observed adverse effect level (NOAEL)for maternal and developmental toxicity was found to be 14 mg/kg-bw/day, and the Low observed effect level (LOEL)for embryotoxicity and teratogenicitywas 140 mg/kg-bw/day.