Bumetrizole

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Treatment of dams was limited to gestation periods Day 6-15 of gestation only as opposed to a day before scheduled kill - certain maternal parameters not checked e.g corpora lutea was not determined.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1976

Report date:

1976

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

(test substance administered on day 6-15 of gestation only, certain maternal parameters not checked e.g corpora lutea was not determined)

Principles of method if other than guideline:

The test compound was administered orally to pregnant rats from day 6 until 15 of gestation. Dams were observed during the pregnancy and then killed on day 21 of the pregnancy and an autopsy performed to examine the dam and the foetuses.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Bumetrizole

EC Number:

223-445-4

EC Name:

Bumetrizole

Cas Number:

3896-11-5

Molecular formula:

C17 H18 Cl N3 O

IUPAC Name:

2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol

Test material form:

solid

Specific details on test material used for the study:

- Name of test material (as cited in study report): TK 10048
- Physical state: solid
- Lot/batch No.: EN 26580 (1/75)

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Closed SPF breeding colony
- Age at study initiation: not stated
- Weight at study initiation: 240 g
- Fasting period before study: not stated
- Housing: Macrolon cages
- Diet: ad libitum; Nafag No. 890
- Water: ad libitum; tap water
- Acclimation period: not stated

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 0.5
- Humidity (%): 60 ± 5
- Air changes (per hr): air-conditioned room
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

(2%, aqueous)

Details on exposure:

VEHICLE
- Justification for use and choice of vehicle (if other than water): not stated
- Amount of vehicle (if gavage): 1mL/100 g bw
- Lot/batch no. (if required): not stated
- Purity: not stated

Analytical verification of doses or concentrations:

no

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:3
- Length of cohabitation: overnight
- Further matings after two unsuccessful attempts: no data
- Verification of same strain and source of both sexes: yes, the albino rats were Sprague -Dawley derived and obtained from a closed SPF breeding colony
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

Day 6 until day 15 of pregnancy inclusive.

Frequency of treatment:

once daily

Duration of test:

21 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

3 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

25 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: not stated
- Rationale for animal assignment (if not random): not stated

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Daily

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: daily

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, a mean food consumption graph was present in the study, but no details about individual animal food consumption.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No, as not a feeding study.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: Assessment of the dam's organs, especially the ovaries and uterus.

OTHER:The foetuses were subjected to careful external inspection and the condition of their body orifices was checked. They were then weighed individually followed by examination of the viscera and skeletal assessment.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Not stated
- Number of corpora lutea: No
- Number of implantations: Yes
- Number of early resorptions: Yes
-Number of late resorptions: Yes

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: 1/3 per litter
- Skeletal examinations: Yes: 2/3 per litter
- Head examinations: No

Statistics:

Some statistics were present in the tables, although not in much detail. Standard deviation was only applied to weight of live foetuses. Confidence limits of the CMC-control for the skeletal assessment was present.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
No reactions to treatment were observed. Body-weight gain and food consumption were comparable for all groups.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

3 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

3 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The implantation ratio and embryolethality were comparable for all groups. The average body weights of foetuses in each group were not significantly different from controls. Histopathology revealed the following minor anomalies: Two foetuses of one litter from the 300 mg/kg dose group showed either hypoplasia of the lungs or slight oedema-like changes of subcutaneous tissue (anasarca). One foetus from the 3000 mg/kg dose group and one from the vehicle control also showed hypoplasia. The aforementioned types of minor anomalies were also found in the cumulative control at incidences of 0.4% (hypoplasia of lungs) and 1.3% (anasarca). Based on these findings, no substance-related effect on embryonic or foetal development is assumed.

Skeletal assessment did not reveal any clearcut differences between the foetuses of the experimental group and those of the vehicle control.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

3 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Any other information on results incl. tables

Table 1: Results of uterus examinations. 

	Dose groups (mg/kg bw)
	Historical controls	300	1,000	3,000	Control
No. of dams	510	25	25	25	25
Spontaneous deaths	0	0	0	0	0
No of females with implantations	453^a	24	24	24	23
Mean No. of implantations	13.18	14.33	14.13	13.88	12.87
Embryonic resorptions (%)	6.7	9.0	11.2	7.2	11.8
Foetal resorptions (%)	0.1	0.3	0.3	0	0.3
Dead foetuses (%)	0.1	0.6	0	0	0.3
Live foetuses (%)	93.1	90.1	88.5	92.8	87.9
Live foetuses with malformations	10 / 5,546^b	0 / 310	0 / 300	0 / 309	0 / 259
Mean weight of live foetuses (g)	5.25 ± 0.44	5.19 ± 0.39	5.18 ±0.38	5.28 ± 0.39	5.20 ± 0.45

 

(a) Including one female with totally aborted litter (not taken into further consideration of data)

(b) Two cleft palates (one associated with mandibular hypoplasia), 2 mandibular aplasias, 3 general oedemas, 3 “open eyes”

Table 2: Skeletal changes in the foetuses.

Dose group (mg/kg bw)	No. of skeletons examined	Phalangeal nuclei^a		Calcaneus^a	Sternebrae^d	Vertebrae^e	Vertebrae^f	Sternebrae^g	Ribs
		Fore limb	Hind limb
Control	173	3 (1.7)	39 (22.5)	33 (19.1)	48 (27.7)	0	1 (0.6)	1 (0.6)	1 (0.6)^j
300	208	4 (1.9)	69 (33.2)	75 (36.1)	56 (26.9)	1 (0.5)	0	0	0
1,000	200	2 (1.0)	34 (17.0)	48 (24.0)	60 (30.0)	1 (0.5)	0	0	1 (0.5)^h
3,000	205	6 (2.9)	32 (15.6)	23 (11.2)	73 (35.6)	0	0	0	1 (0.5)^i
99 % confidence limits of the controls n= 170		0.2 – 6.31	15.15 – 32.21	12.19 – 28.29	19.22 – 37.3	0.00 – 3.07	0.00 – 4.29	0.00 – 4.29	0.00 – 4.29

 

Figures in parenthensis represent %.

a)     ossification

b)     proximal phalanges V

c)     proximal phalanges

d)     particularly ossification centres of the 5^thsternebrae still incompletely ossified (bipartite)

e)     centres of some throracic vertebrae still dumbbell-shaped

f)       centres of some throracic vertebrae bipartite

g)     centres displaced and irregularly ossified

h)     Basal fusion of left ribs 10 + 11

i)       Bifurcation of right rins no. 13

j)       Navy rib no. 13 (right)