Disodium dihydrogenpyrophosphate

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because a pre-natal developmental toxicity study is available

Cross-reference

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Meets generally accepted scientific standards with acceptable restrictions. Deficiencies: Food consumption not reported Uterine weights not determined Test substance identification (Batch etc) missing No details on housing conditions/source of animals Administration only during periods of organogenesis, not until day before pregnancy

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: no data

Deviations:

not specified

Principles of method if other than guideline:

Adult female Dutch-belted rabbits were dosed on Day 0 with a single injection of 0.4 mL human chorionic gonadotropin (400 IU) via the marginal ear vein. After three hours each doe was artificially inseminated with 0.3 mL diluted semen from a donor buck using 20 x 10E06 motile sperm. Dosing by oral intubation with a control (Vehicle at level equivalent to group receiving the highest dose) or test article in a water suspension at 1.28, 5.95, 27.6 and 128.0 mg/kg was carried out daily on Days 6 to 18 of gestation. The positive control 6-aminonicotinamide at 2.5 mg/kg was dosed on Day 9. Observations of body weight, appearence, behaviour, and food consumption were performed. On Day 29 all does underwent Caesarean section. Number of corpora lutea, implantation sites, resorption sites and live/dead foetuses recorded. Body weights of live pups recorded. Urogenital tract of each dam examined for anatomical normality. All foetuses examined grossly for presence of external congenital abnormalities. Live foetuses of each litter were then placed in an incubator for 24 hours for evaluation of neonatal survival. All pups underwent detailed visceral examination. All foetuses were cleared in potassium hydroxide, stained with alizarin red S dye and examined for skeletal defects.

GLP compliance:

no

Remarks:

Study predates GLP

Limit test:

no

Species:

rabbit

Strain:

Dutch

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Outbred
- Age at study initiation: No data
- Weight at study initiation: 2.17 - 2.51 kg
- Fasting period before study: No data
- Housing: Individually housed in mesh-bottomed cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: No data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): No data
- Humidity (%): No data

IN-LIFE DATES: No data

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
VEHICLE: Water
- Amount of vehicle (if gavage): 1 mL/kg bw at doses equal to or below 250 mg/kg bw and 2 mL/kg at doses up to 500 mg/kg bw

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: artificial insemination
- Proof of pregnancy: No data

Duration of treatment / exposure:

13 days (Day 6 to Day 18 of gestation)

Frequency of treatment:

Daily

Duration of test:

29 days

No. of animals per sex per dose:

Table 1 Number of animals dosed
Material Dose (mg/kg) Total
Mated Pregnant
Sham 0.0 17 11
6-AN 2.5 15 10
FDA 71-61 1.28 15 12
5.95 16 12
27.6 20 9
128.0 15 11

Control animals:

yes, sham-exposed

other: positive control: 2.5 mg/kg 6-aminonicotinamide (6-AN)

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Appearence, behaviour, food consumption and weight observed daily.
DETAILED CLINICAL OBSERVATIONS: No
BODY WEIGHT: Yes
- Time schedule for examinations: Body weights recorded on days 0, 6, 12, 18 and 29.
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: uterus and urogenital tract

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of resorptions: Yes

Fetal examinations:

- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
- Head examinations: Yes

Statistics:

No data

Indices:

No data

Historical control data:

No

Details on maternal toxic effects:

Maternal toxic effects:no effects

Dose descriptor:

NOAEL

Effect level:

> 128 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: no effects observed

Abnormalities:

no effects observed

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No dose related response observed.

Dose descriptor:

NOAEL

Effect level:

> 128 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed

Abnormalities:

no effects observed

Developmental effects observed:

no

Table 2 Reproduction data

Dose (mg/kg)	Sham	6-AN	1.28	5.95	27.6	128.0
Pregnancies
Total No.	11	10	12	12	9	11
Died or aborted (before Day 29)	1	0	0	2	0	0
To term (on Day 29)	10	10	12	10	9	11
Corpora Lutea
Total no.	175	132	146	191	140	159
Average/dam mated	14.6	12.0	12.2	13.6	9.33	12.2
Live litters
Total No.*	10	6	12	9	9	11
Implant Sites
Total No.	53	42	70	64	44	80
Average/dam*	5.30	4.20	5.83	6.40	4.89	7.27
Resorptions
Total No*	--	18	3	9	1	7
Dams with 1 or more sites resorbed	--	6	2	3	1	5
Dams with all sites resorbed	--	4	--	1	--	--
Per cent partial resorptions	--	60.0	16.7	30.0	11.1	45.5
Per cent complete resorptions	--	40.0	--	10.0	--	--
Live foetuses
Total No	52	19	67	55	43	73
Average/dam*	5.20	1.90	5.58	5.50	4.78	6.64
Sex ratio (M/F)	0.73	5.00	0.63	1.04	1.26	0.92
Dead Foetuses
Total No.*	1	5	--	--	--	73
Dams with 1 or more dead	1	2	--	--	--	--
Dams with all dead	--	--	-	--	--	--
Per cent partial dead	10.0	20.0	--	--	--	--
Per cent all dead	--	--	--	--	--	--
Average foetus weight (g)	42.2	29.7	37.0	36.0	40.0	35.8

* Includes only those dams examined at term

** Positive control: 2.5 mg/kg 6-AN dosed on Day 9

 

Table 3 Summary of skeletal findings

Findings	Dose (mg/kg)
	Sham	6-AN	1.28	5.95	27.6	128.0
Live foetuses examined (at term)	52/10	19/6	67/12	55/9	43/9	72/11^a
Sternebrae
Incomplete oss.	2/2	1/1		1/1	2/2
Scrambled
Bipartite		1/1		1/1		1/1
Fused		3/2
Extra		1/1	2/1			6/4
Missing		2/2
Other
Ribs
Incomplete oss.
Fused/split		5/2			3/1
Wavy
Less than 12
More than 13
Other
Vertebrae
Incomplete oss.
Scrambled		4/2
Fused
Extra ctrs. oss.
Scoliosis		4/3
Tail defects		13/4			1/1	1/1
Other
Skull
Incomplete closure		1/1
Missing
Craniostosis
Other; facial bones, inc		1/1
Extremities
Incomplete oss.
Missing
Extra
Miscellaneous

* Numerator = Number of foetuses affected; Denominator = Number of litters affected

** Positive control: 2.5 mg/kg 6-AN dosed on Day 9

a One pup lost in processing

 

Table 4 Summary of soft tissue abnormalities

Material	Dose level (mg/kg)	Dam	Number of pups	Description
6-AN	2.5	Z 6479	1	Medial rotation of hind limbs
		Z 6488	1	Medial rotation of hind limbs
		Z 6489	1	Siamese pups (combined stomach and head)
		Z 6490	3	Anopia, Medial rotation of hind limbs
			2	Anopia
FDA 71-61	27.6	M 6051	2	Anopia

Conclusions:

Under the conditions of the study, the test material administered to pregnant rabbits for 13 days up to a dose level of 128 mg/kg bw showed no maternal or developmental toxicity. The NOAEL for both maternal and fetotoxicity is > 128 mg/kg bw.

Results and discussion

Overall reproductive toxicity

Reproductive effects observed:

not specified