Disodium dihydrogen ethylenediaminetetraacetate

Toxicity to reproduction

Administrative data

Endpoint:

multi-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Data source

Reference

Reference Type:

publication

Title:

Safety Evaluation Studies of Calcium EDTA

Author:

Oser, B.L. et al.

Year:

1963

Bibliographic source:

Toxicology and Applied Pharmacology 5, 142-162 (1963)

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

In a 2-year feeding study on Wistar rats including reproductive and lactation experiments in four successive generations, groups of 25 male and 25 female animals were exposed to CaNa2EDTA at dietary levels providing daily doses of approximately 50, 125, and 250 mg/kg bw.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium calcium edetate

EC Number:

200-529-9

EC Name:

Sodium calcium edetate

Cas Number:

62-33-9

Molecular formula:

C10H12CaN2O8.2Na

IUPAC Name:

calcium disodium 2,2',2'',2'''-(ethane-1,2-diyldinitrilo)tetraacetate

Test material form:

solid

Test animals

Species:

rat

Strain:

other: FDRL (derived from Wistar strain)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Housing: individually
- Diet: "natural type diet" ad libitum
- Water: ad libitum

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on mating procedure:

After approximately 13 weeks after the start of the exposure (when the rats were about 120 days of age and sexually mature) matings were set up with one male and two females per cage. As pregnancy was recognized (visually, by palpation, or by weight increments) the dam was transferred to an individual cage. If pregnancy was not established by the third week, the male was replaced. A female was regarded as infertile and matings were discontinued after two successive mating failures. Lactation was allowed to continue for 3 weeks, the pups being weighed at 4, 12, and 21 days.
After weaning, death, or destruction of their litters, the females were allowed a 1-week rest period before remating. In successive matings the males were rotated among females within their respective test groups.
Ten rats of each sex selected from as many litters as possible and representative of the average weight within the litters were assigned to the F1 generation groups. They were raised to maturity in accordance with the same program as the parent generation. Similarly, groups of rats from second litters of the F1 generation and, in turn, the F2 and F3 generations, were each carried through the production of two litters. When the F0 rats reached 2 years on test, the entire study was terminated.
The rats selected from each generation for breeding were continued on their respective diets for a 1 2-week feeding period, as described for the F0 generation. Following the weaning of the second litters in the descendant generation rats at the 50- and 125-mg/kg dosage levels were sacrificed and examined grossly post mortem, but the control and highest dosage level groups were continued without change in dietary treatment until about the end of the 2-year study.

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

2 years

Frequency of treatment:

continuously

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

50 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

125 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

250 mg/kg bw/day (nominal)

No. of animals per sex per dose:

23

Control animals:

yes, plain diet

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
BODY WEIGHT: Yes
- Time schedule for examinations:

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 / No / No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data

HEMATOLOGY
BLOOD CHEMICAL
URINARY EXAMINATIONS

Postmortem examinations (parental animals):

SACRIFICE
- Representative animals of the F0 generation were sacrificed 12 weeks after the start of the exposure. At the end of year one, two males and two females of each dose level were sacrificed and at the end of the study 10 or more rats of the control and the 250 mg/kg bw dose group.

WEIGHT
- of liver, kidneys, spleen, heart, adrenals, thyroids and gonads

HISTOPATHOLOGY
- in the animals which died or were sacrificed during the study: liver and kidney at the lower dose levels
- in the animals which were sacrificed at the end of the study: liver, anterior pituitaries, adrenals, kidneys, pancreas, heart, spleen, lungs, marrow, stomach, small and large intestines,
gonads, thyroid, parathyroid, Iymph nodes, spinal cord, and tibias of the control and the 250 mg/kg bw dose group

ADDTIONAL EXAMINATIONS
- determination of the ash content of the tibials of rats in the highest dose group and control group
- microscopic examination of the jaws of representative animals for evidence of dental caries
- xanthine oxidase determination in the liver
- carbonic anhydrase determination in serum

Statistics:

- Duncan multiple rank and multiple F test

Reproductive indices:

Fertility Index (FI): the proportion of matings resulting in pregnancy
Gestation Index (GI): the proportion of pregnancies resulting in live litters

Offspring viability indices:

Viability Index (VI), the proportion of rats born that survive 4 days or longer;
Lactation Index (LI), the proportion of rats alive at 4 days that survive to weaning.

Results and discussion

Results: P0 (first parental generation)

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

>= 250 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

haematology

urinalysis

organ weights and organ / body weight ratios

gross pathology

histopathology: non-neoplastic

reproductive performance

Results: F1 generation

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

>= 250 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

haematology

urinalysis

organ weights and organ / body weight ratios

gross pathology

histopathology: non-neoplastic

Results: F2 generation

Effect levels (F2)

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

>= 250 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

haematology

urinalysis

organ weights and organ / body weight ratios

neuropathology

histopathology: non-neoplastic

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

MORTALITY

At 1.5 years survival in all groups ranged from 62 to 86%. Within the last half year of the study deaths were mor frequent, however this was not an effect of the treatment (average survival in the 250 mg/kg bw dose group: 61%; in the control 45%)

BEHAVIOR

- No significant abnormalities or differences in behavior or appearance of the rats in any of the generations or among the various dose levels were observed.

GROWTH

- Growth in all groups and in all four generations proceeded at a normal rate, plateauing at about 1 year. In the F0 generation the growth responses within sexes at all levels were essentialiy equal up to the 76th week. During the final half-year the average body weights varied somewhat more because of premortal losses and deaths, but no significant variations occurred in the intergroup relationships. Growth data for the F1, F2, and F3 generation rats in the control and highest dosage test groups was as good as or better than that of the control group.

BLOOD PARAMETERS

- The hemoglobin, hematocrit, and red blood cell counts all fell within normal ranges up to 1 year. Following this there was a slight downward trend in hemoglobin and red blood cells with advancing age in all groups, including the controls, but there were no dose-related differences. The total and differential leucocyte counts likewise disclosed no effcts attributable to the test material. Prothrombin times, determined at 78 and 104 weeks in both the responses in both the 250 mg/kg bw group and the control wer in the normal range as well as blood sugar, nonprotein nitrogen and serum calcium levels.

URINARY ANALYSIS

-essentially normal.

REPRODUCTIVE PERFORMANCE

- Sometimes poor performance (see table 1) however they were not dose related.

ORGAN WEIGHTS

- No significant differences were found for the liver, kidneys, spleen, heart, adrenals, gonads or thyroid glands.

PATHOLOGY

By virtue of their diverse character and sporadic distribution among the groups the gross pathologic findings were considered not to be causally related to test dosage. Pulmonary changes were typical of the respiratory infection common in laboratory rats and their frequency in the test groups was, for the most part, less than in the controls. Liver abnormalities also correlated with occurred at least as frequently in the control as in the test groups. Except for mammary tumors which are fairly common in females with variance a history of continuous breeding, the character and number of tumors observed indicated them to be of an incidental nature. They occurred with a frequency comparable to that usually seen in this colony.

HISTOLOGY

Microscopically, no important aberrations were evident in the liver. kidneys, gastrointestinal tract, and tibias of the four rats in each group selected for sacrifice either at 12 weeks or at 1 year. In the 250-mg/kg bw group, in which 13 organs and tissues of each rat were examined, the findings were consistently negative.

In the histopathologic examinations of the F0 generation rats sacrificed at 2 years revealed changes in the anterior pituitaries (focal hyperplasia); adrenal cortex (focal hyperplasia); medulla (focal hyperplasia) and liver. However, they were not dose related.

Table 1: Reproduction and lactation data for four generations of rats fed withCaNa2EDTA

			Average litter size
Dose (mg/kg bw/day)	Generation	Total number of matings	At birth	At weaning	Average weight of pups at weaning (g)	F.I.	G.I.	V.I.	L.I.
None	F0	46	7.7	5.7	44.9	70	94	57	78
	F1	20	8.6	7.5	47.5	85	100	92	89
	F2	20	8.3	7.8	41.3	95	100	85	96
	F3	20	8.4	8.7	37.4	75	100	88	90
50	F0	41	8.3	7.3	41	90	100	69	82
	F1	20	5.8	5.7	46.5	65	92	76	89
	F2	20	7.7	6.5	44.7	80	100	90	88
	F3	20	9.8	9.2	39.7	95	95	96	97
125	F0	44	9.2	8.7	42	57	96	46	76
	F1	18	6.4	6.5	47.6	78	93	66	95
	F2	20	8.2	6.6	49.6	75	100	89	84
	F3	20	8.1	6.6	46.1	95	84	76	87
250	F0	46	8.9	6.9	42.8	85	100	70	72
	F1	19	5.5	6.3	45.3	58	100	67	93
	F2	12	10.5	8.1	40.5	92	100	92	86
	F3	20	6.8	6.3	49.4	70	93	79	93

F.I. = Fertility Index = (pregnancies/mating) x 100

G.I. = Gestation Index = (litters born/pregnancies) x 100

V.I. = Viability Index = (pups alive at 4 days/pups born) x 100

L.I. = Lactation Index = (pups weaned/pups alive at 4 days) x 100

RESULTS OF ADDITIONAL TESTS

- The tibias of rats sacrificed at the 12-week period showed no evidence of abnormal calcification.

- At the end of the 2-year period, the ash content of the tibias in the control and 250-mg/kg groups were approximately the same.

- There was no difference in either the incidence or severity of dental caries

- There were no significant differences in the two metallo-enzymes blood carbonic anhydrase and liver xanthine oxidase