Tetrapotassium pyrophosphate

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:

weight of evidence

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 and corpora lutea not determined One third used for visceral examination; should be 50% 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

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
See read-across justification report under Section 13 ‘Assessment Reports’.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
In accordance with REACH Annex XI, Section 1.5, of Regulation (EC) No. 1907/2006 (REACH) the standard testing regime may be adapted in cases where a grouping or read-across approach has been applied.

The similarities may be based on:
(1) a common functional group
(2) the common precursors and/or the likelihood of common breakdown products via physical or biological processes, which result in structurally similar chemicals; or
(3) a constant pattern in the changing of the potency of the properties across the category

(1) The source and target substances are both inorganic salts of a monovalent cation from Group 1A of the periodic table, sodium or potassium, and pyrophosphoric acid. Thus, they all share the Na+ or K+ cation and the P2O74- anion as common functional groups.
(2) All members of the group will ultimately dissociate into the common breakdown products of the Na+ or K+ cations and the P2O74-anion.
(3) The pyrophosphate ion is the simplest form of a condensed phosphate group. A condensed phosphate anion has one or several P-O-P bonds. As the group contains only two phosphate groups, both of the phosphorus ions are classified as “terminal phosphorus”. The pyrophosphate can undergo ionisation with loss of H+ from each of the two –OH groups on each P and therefore can occur in the -1, -2 -3 or -4 state. The degree of ionisation is dependent upon the associated cations and the ambient pH (if in solution). Therefore the above substances have a pyrophosphate anion that is likely to behave in a similar way. In addition, the sodium and potassium cations are key elements in various cellular processes their import and export over cell membranes is regulated via pore systems and usually tightly regulated. As such, the presence of varying quantities of such cations is not expected to have an impact on the genotoxicity of the substances therefore as the both ionic components of the substance are common the results of toxicity studies can be reliably read-across within the group.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See read-across justification report under Section 13 ‘Assessment Reports’.

3. ANALOGUE APPROACH JUSTIFICATION
See read-across justification report under Section 13 ‘Assessment Reports’.

4. DATA MATRIX
See read-across justification report under Section 13 ‘Assessment Reports’.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

other: no data

Deviations:

not specified

Principles of method if other than guideline:

Adult female albino (Wistar derived stock) rats were mated with young adult males. Observation of a vaginal sperm plug was considered as Day 0 of gestation. Dosing by oral intubation with a control (Vehicle at level equivalent to group receiving the highest dose or aspirin at 250 mg/kg) or test article in a water suspension at 1.69, 9.24, 42.95 and 169.0 mg/kg was carried out daily on Days 6 to 15 of gestation. Observations of body weight, appearence, behaviour, and food consumption were performed. Daily room temperature was recorded. On Day 20 of gestation all dams underwent Caesarean section. Number of 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. One third foetuses of each litter underwent detailed visceral examination and the remaining two thirds 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:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Outbred
- Age at study initiation: No data
- Weight at study initiation: 214 - 225 g
- Fasting period before study: No data
- Housing: Individual housing in mesh bottom cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: No data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): Not recorded
- Humidity (%): Not recorded

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: No data
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy

Duration of treatment / exposure:

10 days (Day 6 to Day 15 of gestation)

Frequency of treatment:

Daily

Duration of test:

20 days

No. of animals per sex per dose:

Table 1 Number of animals dosed
Material Dose (mg/kg) Total
Mated Pregnant
Sham 0.0 25 23
Aspirin 250.0 24 21
FDA 71-61 1.69 25 24
9.24 25 24
42.95 24 24
169.0 25 21

Control animals:

yes, sham-exposed

other: positive control: 250 mg/kg aspirin

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, 11, 15 and 20.
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- 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: No
- Number of implantations: Yes
- Number of resorptions: Yes

Fetal examinations:

- External examinations: Yes: one third per litter
- Soft tissue examinations: Yes: one third per litter
- Skeletal examinations: Yes: two thirds per litter
- Head examinations: Yes: two thirds per litter

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:

> 169 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

Dose descriptor:

NOAEL

Effect level:

> 169 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	Aspirin	1.69	9.24	42.95	169.0
Pregnancies
Total No.	23	21	24	24	24	21
Died or aborted (before Day 20)	0	1	0	0	0	0
To term (on Day 20)	23	20	24	24	24	21
Live litters
Total No.*	23	18	24	24	24	21
Implant Sites			293
Total No.	283	234	12.2	284	287	254
Average/dam*	12.3	11.7		11.8	12.0	12.1
Resorptions
Total No*	4	35	4	4	4	--
Dams with 1 or more sites resorbed	2	5	4	4	3	--
Dams with all sites resorbed	--	2	--	--	--	--
Per cent partial resorptions	8.70	25.0	16.7	16.7	12.5	--
Per cent complete resorptions	--	10.0	--	--	--	--
Live foetuses
Total No	279	197	288	280	283	254
Average/dam*	12.1	9.85	12.0	11.7	11.8	12.1
Sex ratio (M/F)	1.08	0.80	1.27	1.00	0.98	1.03
Dead Foetuses
Total No.*	--	2	1	--	--	--
Dams with 1 or more dead	--	2	1	--	--	--
Dams with all dead	--	--	--	--	--	--
Per cent partial dead	--	10.0	4.17	--	--	--
Per cent all dead	--	--	--	--	--	--
Average foetus weight (g)	3.65	2.41	3.71	3.78	3.78	3.75

* Includes only those dams examined at term

** Positive control: 250 mg/kg

 

Table 3 Summary of skeletal findings

Findings	Dose (mg/kg)
	Sham	Aspirin	1.69	9.24	42.95	169.0
Live foetuses examined (at term)	191/23	137/18	198/24	193/24	196/24	176/21
Sternebrae
Incomplete oss.	71/20	86/16	83/19	54/19	61/16	47/17
Scrambled
Bipartite		7/5			2/2	4/3
Fused
Extra
Missing	7/6	117/7	9/7	15/8	1/1	5/4
Other
Ribs
Incomplete oss.	1/1	3/2	3/2			1/1
Fused/split		14/4
Wavy	14/8	54/14	34/9	12/7	15/8	13/8
Less than 12
More than 13	1/1	89/15	6/5	3/3		6/5
Other
Vertebrae
Incomplete oss.	6/5	120/17	12/4	21/11	5/4	10/8
Scrambled		1/1
Fused			1/1
Extra ctrs. oss.
Scoliosis		3/3
Tail defects		1/1
Other
Skull
Incomplete closure	23/10	60/13	50/16	31/12	25/13	20/11
Missing		9/4
Craniostosis
Other		1/1
Extremities
Incomplete oss.		4/3
Missing
Extra
Miscellaneous
Hyoid; missing	19/11	69/17	37/15	14/9	26/13	7/6
Hyoid; reduced	7/5	20/8	38/14	27/12	35/16	28/12

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

** Positive control: 250 mg/kg

 

Table 4 Summary of soft tissue abnormalities

Material	Dose level (mg/kg)	Dam	Number of pups	Description
Aspirin	250.0	A 4910	1	Encepalomyelocele
		A 4913	1	Exencephaly; exophthalmos
		A 4917	1	Renal agenesis
		A 4921	1	Encephalomyelocele; gastroschisis
		A 4923	3	Encephalomyelocele
			1	Exophthalmos; gastroschisis
		A 4925	2	Encepalomyelocele
FDA 71-61	42.95	M 4076	1	Gastroschisis

Conclusions:

Under the conditions of the study, the test material administered to pregnant rats for 10 days up to a dose level of 169 mg/kg bw showed no maternal or developmental toxicity. The NOAEL for both maternal and fetotoxicity is > 169 mg/kg bw.

Results and discussion

Overall reproductive toxicity

Reproductive effects observed:

not specified