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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No GLP, no guidelines followed, poorly details on test conditions Read across from a similar substance which has the same main component and with a different counter ion that doesn't influence the characteristics related to the specific end-point
Reason / purpose for cross-reference:
reference to same study

Data source

Reference Type:
Report date:

Materials and methods

Principles of method if other than guideline:
Malachite Green was administrated to Rabbits by oral gavage. Thalidomide was used as positive control and untreated animals as untreated control.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
Malachite Green Oxalate
Malachite Green Oxalate
Details on test material:
- Name of test material: Malachite Green Oxalate
- Form: crystals
- Source: Matheson, Coleman and Bell

Test animals

New Zealand White
Details on test animals or test system and environmental conditions:
- Specie: Oryctolagus cuniculus
- Source: commercial laboratory supplier Scott Rabbit Products, Langley, Washington
- Age at study initiation: time-pregnant
- Housing: all animals were housed individually
- Diet: Purina Laboratory Rabbit Chow supplemented by fresh greens
- Water: water ad libitum

- Group: two control group were used: one untreated and one like positive control (treated by Thalidomide, a known teratogen)

Administration / exposure

Route of administration:
oral: gavage
Details on exposure:
- Dose: 5, 10, 20 mg/kg
- Solution: Malachite Green was administrated as an aqueous solution.
- Administration: orally by gavage on days 6 through 18 of gestation
- N. initial animals: 20

- Solution: thalidomide was used as a positive control
- Preparation: Thalidomide was prepared as a suspension in corn oil
- Dose: 150 mg/kg
Duration of treatment / exposure:
18 days of gestation; orally administration by gavage on days 6 through 18 of gestation
Frequency of treatment:
Doses / concentrationsopen allclose all
Doses / Concentrations:
5, 10, 20 mg/kg
nominal in diet
Malachite Green solution
Doses / Concentrations:
150 mg/kg
nominal in diet
Positive control
No. of animals per sex per dose:
At dose 5 mg/kg 16 animals; at 10 mg/kg 21; at 20 mg/kg 16.
Control animals:
yes, concurrent vehicle
Details on study design:
Consequently, doses of 2, 50, and 75 mg/kg were selected to determine the maximum dose to be used with rabbits. Three young, nonpregnant adult New Zealand white rabbits were dosed daily for 13 days in each treatment. Data from this limited study indicated that nonpregnant female rabbits could tolerate 13 consecutive daily doses of 50 mg/kg of Malachite Green. Stanford Research Institute experience has been that pregnant rabbits are much more sensitive to drugs than nonpregnant ones so 20 mg/kg was selected as the maximum level to be used in the teratology study.


Maternal examinations:

- Time schedule for examinations: were recorded gestation days 0, 6, 9, 12, 15 and 18 and one day 29

- Sacrifice on gestation day 29
- Examination: on day 29 the animals were sacrificed and progeny were delivered by caesarean section. During delivery, all resorptions in each doe were recorded.

Young were thoroughly examined at delivery, weighed and incubated for 24 hours. During incubation they were observed hourly for viability during the first 4 hours and again at 24 hours
Fetal examinations:
- External examinations: Yes
- Skeletal examinations: Yes
- Visceral examination: Yes

Results and discussion

Results: maternal animals

Maternal developmental toxicity

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

Details on maternal toxic effects:
Treated adult animals were consistently lower in average total body weight than the untreated controls at the end of the study, but there were no overt signs of toxicity.

Effect levels (maternal animals)

Remarks on result:
other: See report below

Results (fetuses)

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

Details on embryotoxic / teratogenic effects:
Foetal toxicity was evident in the reproductive performance of does treated with Malachite Green (MG). At all three dosage levels of MG, there were significant increases in pre-implantation losses and in the ratio of dead implants to total implants and decrease in the number of living fetuses (P = 0.05). Early resorption accounted for most of the dead implants.
At the time of caesarean section mean body weights of progeny were significantly less in the thalidomide positive control and 5 mg/kg MG groups than in the untreated controls. Weights of foetuses from the 20 mg/kg MG group were also significantly lighter, but the difference was not as extreme.
Significant effects were observed in all three types of anomalies: gross, visceral and skeletal. Groups treated with 5 and 20 mg/kg MG showed significant differences from control animals in skeletal deviations. All treated groups showed significantly more progeny with deviations than were observed in the controls. Although delayed ossification is not an anomaly, this response was observed in varying ratios among all MG treated lots.

Effect levels (fetuses)

Dose descriptor:
Effect level:
> 5 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: teratogenicity

Fetal abnormalities

not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

During treatment with malachite green, the does showed a greatly reduced intake of dry food. This reduced food consumption is believed to have been related to the chemical treatments rather than the result of an incomplete diet.

Applicant's summary and conclusion

Malachite Green produced significant tetratological affects at all levels of treatment at dose as low as 5mg/kg. Abnormalities noted in rabbits were anomalies most frequently involved the skeleton, liver, heart, and kidneys.
Executive summary:

Malachite Green Oxalate caused significant developmental abnormalities when administered to pregnant New Zealand whiter rabbits Oryctolagus cuniculus. All dose levels affected foetal development of rabbits. At the dosages given, the incidence of anomalies caused by Malachite Green was about half that observed in thalidomide-treated positive controls and two to three times that in untreated controls.