Magnesium bis(dihydrogenorthophosphate)

Developmental toxicity / teratogenicity

Administrative data

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

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. Both substances are inorganic salts of a monovalent cation from Group 2 of the periodic table, calcium or magnesium, and phosphoric acid. Thus, they all share the Ca2+ or Mg2+ cation and the PO43- anion as common functional groups.
2. Both substances will ultimately dissociate into the common breakdown products of the Ca2+ or Mg2+ cations and the PO43- anion.
3. Calcium and magnesium orthophosphates have been shown to have a similar toxicological profile and physicochemical nature and therefore this data is considered to be adequate and reliable for use in read-across. In accordance with the provisions set out in Annex XI, Section 1.5, the results of the studies used for assessment and read-across are adequate for the purpose of classification and labelling and/or risk assessment; have adequate and reliable coverage of the key parameters addressed in the corresponding test method; cover an exposure duration comparable to or longer than the corresponding test method; and adequate and reliable documentation of the applied method is provided in the technical dossier. Orthophosphates are not considered to be genotoxic and are essential micronutrients. As such the reproductive toxicity will be predominantly determined by the presence of the Mg2+ cation.

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’.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

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 The reliability has been amended in accordance with 'practical guide 6: How to report read-across and categories' which states that the maximum reliability for a read-across study is 2. JUSTIFICATION FOR READ ACROSS; calcium and magnesium orthophosphates. The following substances are considered to be similar enough to facilitate read across for systemic toxicity endpoints: Calcium bis(dihydrogenorthophosohate, EC No: 231-837-1 Calcium hydrogenorthophosphate. EC No: 231-826-1 Tricalcium bis(orthophosphate), EC No: 231-840-8 Pentacalcium hydroxide tris(orthophosphate), EC No: 235-330-6 Magnesium hydrogenorthophosphate, EC No: 231-823-5 Trimagnesium bis(orthophosphate), EC No. 231-824-0 Magnesium bis(dihydrogenorthophosphate), EC No. 236-004-6 All of the above substances have exhibited similar toxicity in acute oral and dermal studies. Read across is justified on the following basis: 1. Low systemic toxicity in acute oral studies. A number of studies are provided to show that calcium and/or magnesium inorganic orthophosphates exhibit low acute oral toxicity. These data are provided in Section 7.2.1 of this dossier. The information provided in these records is considered to be of suitable relevance and reliability to underpin the read across for the acute dermal and inhalation endpoints. 2. Substance similarities All substances are ionic and will readily dissociate to their ionic forms in aqueous environments. The orthophosphate ion can under go ionisation with loss of H+from each of the three –OH groups and therefore can occur in the -1, -2 or -3. The degree of ionisation is dependant upon the associated cation and the ambient pH (if in solution). The ionic form of the Group 1ii alkali metals is M2+.Calcium, magnesium and phosphate are key elements in various cellular processes their import and export over cell membranes is regulated via pore systems and usually tightly regulated. Orthophosphate salts of these types are not considered to differ in their systemic toxicity profiles. Differences arise in their local effects profile due differences in pH and buffering capacities. This does not have an effect on systemic toxicity.

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. Both substances are inorganic salts of a monovalent cation from Group 2 of the periodic table, calcium or magnesium, and phosphoric acid. Thus, they all share the Ca2+ or Mg2+ cation and the PO43- anion as common functional groups.
2. Both substances will ultimately dissociate into the common breakdown products of the Ca2+ or Mg2+ cations and the PO43- anion.
3. Calcium and magnesium orthophosphates have been shown to have a similar toxicological profile and physicochemical nature and therefore this data is considered to be adequate and reliable for use in read-across. In accordance with the provisions set out in Annex XI, Section 1.5, the results of the studies used for assessment and read-across are adequate for the purpose of classification and labelling and/or risk assessment; have adequate and reliable coverage of the key parameters addressed in the corresponding test method; cover an exposure duration comparable to or longer than the corresponding test method; and adequate and reliable documentation of the applied method is provided in the technical dossier. Orthophosphates are not considered to be genotoxic and are essential micronutrients. As such the reproductive toxicity will be predominantly determined by the presence of the Mg2+ cation.

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:

read-across: supporting information

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 (10 mL/kg bw) at 2.17, 10.10, 46.7 and 217.0 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: 1.84 - 2.21 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 21 12
6-AN 2.5 18 9
FDA 71-81 2.17 21 12
10.10 27 17
46.7 15 10
217.0 27 10

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:

> 217 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:

> 217 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	2.17	10.10	46.7	217.0
Pregnancies
Total No.	12	9	12	17	10	10
Died or aborted (before Day 29)	2	0	1	4	0	0
To term (on Day 29)	10	9	11	13	10	10
Corpora Lutea
Total no.	160	117	132	191	110	121
Average/dam mated	11.4	9.75	9.43	9.55	8.46	6.37
Live litters
Total No.*	10	8	10	13	9	8
Implant Sites
Total No.	58	57	62	79	50	49
Average/dam*	5.80	6.33	5.64	6.08	5.00	4.90
Resorptions
Total No*	7	6	9	3	7	4
Dams with 1 or more sites resorbed	4	4	2	2	4	2
Dams with all sites resorbed	--	1	1	--	1	2
Per cent partial resorptions	40.0	44.4	18.2	15.4	40.0	20.0
Per cent complete resorptions	--	11.1	9.09	--	10.0	20.0
Live foetuses
Total No	51	49	49	76	43	45
Average/dam*	5.10	5.44	4.45	5.85	4.30	4.50
Sex ratio (M/F)	0.96	1.13	1.29	1.30	0.87	1.05
Dead Foetuses
Total No.*	--	2	4	--	--	--
Dams with 1 or more dead	--	2	1	--	--	--
Dams with all dead	--	--	--	--	--	--
Per cent partial dead	--	22.2	9.09	--	--	--
Per cent all dead	--	--	--	--	--	--
Average foetus weight (g)	39.6	37.0	39.3	39.7	36.0	39.7

* 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	2.17	10.10	46.7	217.0
Live foetuses examined (at term)	51/10	49/8	49/10	76/13	43/9	44/8
Sternebrae
Incomplete oss.	1/1			1/1	1/1
Scrambled
Bipartite
Fused
Extra					3/1	1/1
Missing						1/1
Other
Ribs
Incomplete oss.
Fused/split
Wavy
Less than 12
More than 13
Other
Vertebrae
Incomplete oss.
Scrambled
Fused
Extra ctrs. oss.
Scoliosis
Tail defects		1/1		1/1	1/1
Other
Skull
Incomplete closure				3/1
Missing
Craniostosis
Other; facial bones, inc
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 No soft tissue abnormalities observed.

Conclusions:

Under the conditions of the study, the test material administered to pregnant rabbits for 13 days up to a dose level of 217 mg/kg bw showed no maternal or developmental toxicity. The NOAEL for both maternal and developmental toxicity is > 217 mg/kg bw.

Cross-reference 2

Reason / purpose for cross-reference:

reference to same study

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

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. Both substances are inorganic salts of a monovalent cation from Group 2 of the periodic table, calcium or magnesium, and phosphoric acid. Thus, they all share the Ca2+ or Mg2+ cation and the PO43- anion as common functional groups.
2. Both substances will ultimately dissociate into the common breakdown products of the Ca2+ or Mg2+ cations and the PO43- anion.
3. Calcium and magnesium orthophosphates have been shown to have a similar toxicological profile and physicochemical nature and therefore this data is considered to be adequate and reliable for use in read-across. In accordance with the provisions set out in Annex XI, Section 1.5, the results of the studies used for assessment and read-across are adequate for the purpose of classification and labelling and/or risk assessment; have adequate and reliable coverage of the key parameters addressed in the corresponding test method; cover an exposure duration comparable to or longer than the corresponding test method; and adequate and reliable documentation of the applied method is provided in the technical dossier. Orthophosphates are not considered to be genotoxic and are essential micronutrients. As such the reproductive toxicity will be predominantly determined by the presence of the Mg2+ cation.

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:

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 4.1, 19.1, 88.5 and 410.0 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: 216 - 224 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: From: 12/01/1975 To: 06/02/1975

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 21
Aspirin 250.0 25 21
FDA 71-81 4.1 28 22
19.1 29 21
88.5 25 19
410.0 25 22

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:

> 410 mg/kg bw/day

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:
The results indicate that the number of wavey ribs (47 foetuses affected/ 12 litters) observed at the highest dose level in the study (410.0 mg/kg) might be significant in relation to the sham control. However, the same result is not observed in either of the other two species tested (mice and rabbit) so can be discounted.

Dose descriptor:

NOAEL

Effect level:

> 410 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	4.1	19.1	88.5	410.0
Pregnancies
Total No.	21	21	22	22	19	22
Died or aborted (before Day 20)	0	0	0	0	0	0
To term (on Day 20)	21	21	22	22	19	22
Live litters
Total No.*	21	19	22	22	19	22
Implant Sites
Total No.	235	235	257	257	196	244
Average/dam*	11.2	11.2	11.7	11.7	10.3	11.1
Resorptions
Total No*	2	63	3	3	3	2
Dams with 1 or more sites resorbed	2	13	3	3	2	1
Dams with all sites resorbed	--	2	--	--	--	--
Per cent partial resorptions	9.52	61.9	13.6	13.6	10.5	4.55
Per cent complete resorptions	--	9.52	--	--	--	--
Live foetuses
Total No	233	170	253	253	192	242
Average/dam*	11.1	8.10	11.5	11.5	10.1	11.0
Sex ratio (M/F)	1.33	1.07	0.92	0.92	0.92	0.87
Dead Foetuses
Total No.*	--	2	1	1	1	--
Dams with 1 or more dead	--	2	1	1	1	--
Dams with all dead	--	--	--	--	--	--
Per cent partial dead	--	9.52	4.55	4.55	5.26	--
Per cent all dead	--	--	--	--	--	--
Average foetus weight (g)	3.62	2.43	3.85	3.85	3.56	3.65

* Includes only those dams examined at term

** Positive control: 250 mg/kg

 

Table 3 Summary of skeletal findings

Findings	Dose (mg/kg)
	Sham	Aspirin	4.1	19.1	88.5	410.0
Live foetuses examined (at term)	165/21	124/19	174/22	162/21	133/19	168/22
Sternebrae
Incomplete oss.	45/18	49/16	31/12	36/16	42/15	45/15
Scrambled		1/1
Bipartite	1/1	13/7				1/1
Fused		1/1
Extra
Missing	27/12	92/18	6/4	5/4	22/10	16/7
Other
Ribs
Incomplete oss.		1/1				9/3
Fused/split		8/4
Wavy	17/10	51/14	16/9	15/7	11/8	47/12
Less than 12		1/1
More than 13	5/5	71/17	2/2	1/1	2/2	4/3
Other
Vertebrae
Incomplete oss.	26/14	92/19	10/6	6/5	22/11	29/10
Scrambled
Fused
Extra ctrs. oss.
Scoliosis
Tail defects
Other
Skull
Incomplete closure	29/12	38/12	25/11	12/6	14/10	28/10
Missing		1/1
Craniostosis
Other; facial bones, inc		9/6
Extremities
Incomplete oss.		6/3
Missing
Extra
Miscellaneous
Hyoid; missing	15/8	51/16	13/7	14/9	8/6	22/12
Hyoid; reduced	22/11	11/7	24/10	12/7	9/8	30/14

* 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 7065	1	Encephalomyelocele
		A 7066	1	Gastroschisis
		A 7070	1	Meningoencephalocele
		A 7076	2	Meningoencephalocele
FDA 71-81	4.1	H 6028	1	Hydrocephalus

 

Conclusions:

Under the conditions of the study, the test material administered to pregnant rats for 10 days up to a dose level of 410 mg/kg bw showed no maternal or developmental toxicity. The NOAEL for both maternal and developmental toxicity is > 410 mg/kg bw.

Cross-reference 3

Reason / purpose for cross-reference:

read-across: supporting information

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1974

Report date:

1973

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: no data

Deviations:

not specified

Principles of method if other than guideline:

Adult female albino CD-1 mice 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 150 mg/kg) or test article in a water suspension (10 mL/kg bw) at 4.65, 21.6, 100.0 and 465.0 mg/kg was carried out daily on Days 6 to 15 of gestation. Observations of body weight, appearence, behaviour, and food consumption were performed. On Day 17 of gestation all dams underwent Caesarean section. 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

Test material

Test material information

Constituent 1

Reference substance name:

calcium dihydrogenorthophosphate monohydrate

IUPAC Name:

calcium dihydrogenorthophosphate monohydrate

Constituent 2

Reference substance name:

Calcium bis(dihydrogenorthophosphate)

EC Number:

231-837-1

EC Name:

Calcium bis(dihydrogenorthophosphate)

Cas Number:

7758-23-8

Molecular formula:

CaH4O8P2

IUPAC Name:

calcium dihydrogen phosphate

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report): FDA 71-81 (Monocalcium phosphate; monohydrate)
- Physical state: Fine white crystalline material

Test animals

Species:

mouse

Strain:

other: albino CD-1

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Outbred
- Age at study initiation: No data
- Weight at study initiation: 29.2 - 30.6 g
- Fasting period before study: No data
- Housing: Gang housing in disposable plastic 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

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
VEHICLE: Water
- Amount of vehicle (if gavage): 10 mL/kg bodyweight

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- Impregnation procedure: cohoused
- 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:

17 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 22
Aspirin 150.0 25 20
FDA 71-81 4.65 25 24
21.6 26 19
100.0 23 22
465.0 25 23

Control animals:

yes, sham-exposed

other: positive control: 150 mg/kg aspirin

Examinations

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 17.
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 17
- 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

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

> 465 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: no effects observed

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

> 465 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects observed

Fetal abnormalities

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Any other information on results incl. tables

Table 2 Reproduction data

Dose (mg/kg)	Sham	Aspirin	4.65	21.6	100.0	465.0
Pregnancies
Total No.	22	20	24	19	22	23
Died or aborted (before Day 17)	0	1	0	0	0	0
To term (on Day 17)	22	19	24	19	22	23
Live litters
Total No.*	22	19	24	19	22	22
Implant Sites
Total No.	261	224	283	225	244	265
Average/dam*	11.9	11.8	11.8	11.8	11.1	11.5
Resorptions
Total No*	8	20	19	4	12	28
Dams with 1 or more sites resorbed	7	9	13	3	10	12
Dams with all sites resorbed	--	--	--	--	--	1
Per cent partial resorptions	31.8	47.4	54.2	15.8	45.5	52.2
Per cent complete resorptions	--	--	--	--	--	4.35
Live foetuses
Total No	252	201	261	221	230	233
Average/dam*	11.5	10.6	10.9	11.6	10.5	10.1
Sex ratio (M/F)	1.02	0.88	0.78	0.92	1.13	0.93
Dead Foetuses
Total No.*	1	3	--	--	2	4
Dams with 1 or more dead	1	3	--	--	2	3
Dams with all dead	--	--	--	--	--	--
Per cent partial dead	4.55	15.8	--	--	9.09	13.0
Per cent all dead	--	--	--	--	--	--
Average foetus weight (g)	0.84	0.81	0.88	0.87	0.82	0.85

* Includes only those dams examined at term

** Positive control: 150 mg/kg

 

Table 3 Summary of skeletal findings

Findings	Dose (mg/kg)
	Sham	Aspirin	4.65	21.6	100.0	465.0
Live foetuses examined (at term)	179/22	141/19	186/24	155/19	162/22	164/22
Sternebrae
Incomplete oss.	10/8	31/10	18/9	27/15	22/10	28/15
Scrambled
Bipartite	8/7	3/3	11/8	9/7	10/8	9/6
Fused
Extra		6/3
Missing	23/10	28/11	13/9	13/6	32/14	23/7
Other
Ribs
Incomplete oss.						9/4
Fused/split		2/2
Wavy		1/1	2/2
Less than 12	1/1		1/1			1/1
More than 13	48/18	30/12	42/18	18/11	32/15	34/17
Other
Vertebrae
Incomplete oss.	9/6	9/3	2/2	1/1	11/4	13/4
Scrambled
Fused
Extra ctrs. oss.
Scoliosis
Tail defects
Other
Skull
Incomplete closure		2/2
Missing			1/1
Craniostosis
Other; facial bones, inc						2/1
Extremities
Incomplete oss.	7/5	5/3	2/2		10/5	14/4
Missing
Extra
Miscellaneous
Hyoid; missing	37/16	33/11	31/15	22/12	52/15	33/13
Hyoid; reduced	17/11	25/12	17/11	21/14	15/11	27/14

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

** Positive control: 150 mg/kg

 

Table 4 Summary of soft tissue abnormalities

Material	Dose level (mg/kg)	Dam	Number of pups	Description
Aspirin	150.0	A 6068	1	Cleft palate; gastroschisis

Applicant's summary and conclusion

Conclusions:

Under the conditions of the study, the test material administered to pregnant mice for 10 days up to a dose level of 465 mg/kg bw showed no maternal or developmental toxicity. The NOAEL for both maternal and developmental toxicity is > 465 mg/kg bw.