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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:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Non-guideline study not performed under GLP. Non-standard study design. Low level of experimental detail reported. No data on purity, stability or origin of the test item. The route of administration was the diet. Dose levels of 0, 2% salicylamide in the diet. No data provided to show achieved concentration, homogeneity in the diet preparations. Animals were dosed from either day 5 to 11 of gestation or day 12 to 18 and all dams were terminated on day 18 of gestation. Critical elements of the study design were missing including, number of dams per dose group, therefore it is difficult to interpret the data as where means were calculated the number in each group is not shown, there are often very large standard deviations and the suitability of the statistical analysis is not clear.

Data source

Reference
Reference Type:
publication
Title:
Effects of salicylamide and protein restriction on the skeletal development of the rat fetus
Author:
Knight E, Roe DA
Year:
1978
Bibliographic source:
Teratology, 1978, 18(1), 17-22

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Pregnant Holtzman rats were fed a diet supplemented with 2% salicylamide either from day 5-11 or from day 12-18 of gestation. Weight gain of the dams was recoded throughout the feeding period. Dams were killed on gestation day 18 and fetuses and placentas were extracted and counted; placentas were weighted and examined on resorption sites. Fetuses were weighted, examined for gross malformations, and stained with Alizarin Red S.Stained fetuses were examined on skeletal abnormalities and centers of ossifications were counted.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): salicylaminde

Test animals

Species:
rat
Strain:
other: Holtzman
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: approximately 200-210 g
- Acclimation period: 1 day

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Analytical verification of doses or concentrations:
not specified
Details on mating procedure:
- Impregnation procedure: purchased pregnant
Duration of treatment / exposure:
One group fed 2% salicylamide on gestation day 5-11.
One group fed 2% salicylamide on gestation day 12-18
Frequency of treatment:
daily
Duration of test:
gestation day 5-18
No. of animals per sex per dose:
no data
Control animals:
yes, plain diet

Examinations

Maternal examinations:
BODY WEIGHT: Yes
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- number of placentas
- placental weight
- number of resorptions
Fetal examinations:
- Number of fetuses
- Viability
- External examinations
- Skeletal examinations
Statistics:
Differences in the outcome of gestation, the incidence of fetal skeletal defects and skeletal maturity were examined by ANOVA. Three factor interactions were analyzed by the G-test. Analysis of covariance was used to examine data on fetuses from individual dams.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

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

Details on maternal toxic effects:
At start of drug administration on gestation day 5 or 12, a transient decline in weight of the dams was visible. Subsequently, the drug-treated dams showed normal weight gain which, however, was less than weight gain of control animals.

Results (fetuses)

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

Details on embryotoxic / teratogenic effects:
Compared to the control group, mean placental and fetal weights were significantly lower in the group treated with salicylamide. This effect was more pronounced in animals receiving salicylamide from gestation day 12-18 than in animals receiving the compound on gestation day 5-11.
The percentage of resorptions was significantly increased by treatment with salicylamide.
External malformations were found in fetuses of dams receiving salicylamide from gestation day 5-11, and in some fetuses in the groups receiving salicylamide from gestation day 12-18.
Malformations included micromelia of the hind legs, phocomelia, syndactyly and short or absent tails. Skeletal malformations included missing and abnormal ribs, fused ileum, lordosis and absence of lumbar arches with number of malformations being higher in fetuses from rats receiving the drug from the fifth to eleventh days of gestation.
No malformed fetuses were observed in control rats.
Drug treatment during early gestation (days 5-11) significantly decreased the number of ossification centers; when the drug was administered in the late gestational period (days 12-18) no significant effect on the development of ossification centers was noticed.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table 1: Effect of salicylamide on placental and fetal weight

Treatment period

Drug level [%]

Placental weight [g]

Fetal weight [g]

gestation day 5-11

0

0.5421

±0.09

1.4570

±0.14

2

0.5012 *

±0.09

1.4100

±0.28

gestation day 12-18

0

0.5205

±0.09

1.5460

±0.2

2

0.480 *

±0.04

1.3450 **

±0.09

Significant difference to untreated control: * p< 0.05 ** p < 0.001

 

Table 3: External and skeletal malformations of fetuses

 

No. of fetuses examined

Malformed

Not malformed

External malformations

Control (no treatment)

90

0

90

2% salicylamide on gestation day 5-11

31

4

27

2% salicylamide on gestation day 12-18

52

1

51

Skeletal malformations

Control (no treatment)

59

0

59

2% salicylamide on gestation day 5-11

23

4

19

2% salicylamide on gestation day 12-18

32

1

31

 

Table 4: Effect of salicylamide on number of fetal ossification centers

Treatment period [gestation day]

Drug level [%]

Average number of ossification centers

5-18

0

22.72±5.0

5-11

2

17.26±8.0

12-18

2

21.00±2.1

Applicant's summary and conclusion

Conclusions:
The study is considered to be relevant, but not reliable or suitable for risk assessment or classification and labeling purposes with regard to developmental or reproductive toxicology.
Executive summary:

The effect of oral salicylamide administration on fetal development was assessed in a feeding study with rats. Salicylamide (2% in feed) was administered to pregnant Holtzman rats either during gestation day 5 -11 or during gestation day 12 -18. Parameters under investigation were maternal body weight, number and weight of placentas, number of resorptions and of fetuses, external and skeletal malformations.

There are serious shortcomings in study design as well as in reporting (e.g. feed consumption not measured, no information on the number of fetuses total/per litter, and so on); therefore, the study was deemed to be not reliable.

Results indicate that oral administration of salicylamide during gestation resulted in reduced placental and fetal weight. Salicylamide was found to be teratogenic, especially when administered during early organogenesis (gestation day 5-11). Malformations included especially abnormalities of the limbs but also short or missing tail, lordosis, or fused ileum. The number of ossification centers was reduced mainly in fetuses of dams receiving salicylamide during early organogenesis.