Dipotassium [[N,N'-ethylenebis[N-(carboxylatomethyl)glycinato]](4-)-N,N',O,O',ON,ON']zincate(2-)

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Several studies with chelates, including metal chelate) are available (EDTA-CaNa2, EDTA-Na2H2, EDTA-MnNa2).

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

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 EDTA-CaNa2 at dietary levels providing daily doses of approximately 50, 125, and 250 mg/kg bw (Oser et al., 1963). No significant differences in behavior or appearance nor adverse effects on the growth or on the longevity of the rats in any of the generations or among the various dose levels were reported. Evaluations of various tissues and organs (weight, histopathologic examinations) including gonads (testes) gave negative results even in the high dose group. Criteria for reproductive and lactational effects were evaluated as proportion of matings resulting in pregnancy (fertility index), proportion of pregnancies resulting in live litters (gestation index), proportion of pups that survive 4 days or longer (viability index), and proportion of rats alive at 4 days that survive to weaning. Poor responses with respect to some of the criteria of reproductive performance occurred occasionally but were not correlated with dosage or with the number of generations through which dosage continued. The overall data for two matings in the four successive generations did not give evidence for significant treatment related differences in either of these indexes. The authors concluded that the No Observed Adverse Effect Level of EDTA-CaNa2 was observed as measured by any of the usual indices of reproduction or lactation efficiency even under the stresses of repeated pregnancies and lactation. The NOAEL derived from this study is therefore at least 250 mg/kg bw/day for the parent and F1 to F3 generation.

Studies with EDTA-Na2H2 were not taken into consideration for setting a NOAEL because of methodological flaws. Studies with other metal-chelates such as EDTA-MnNa2 showed effects on fertility only at very levels of 1500 mg/kg bw but not at 500 mg/kg bw. But although effects on sperm were

seen at the highest dose of EDTA-MnNa2 (1500 mg/kg bw), it did not result in effects on reproduction as there were no changes in reproductive performance in animals of these groups. A study with EDTA-FeNa did not show effects up to the highest tested dose of 250 mg/kg bw.

Hence the NOAEL for EDTA-ZnK2 is at least 500 mg/kg bw/day but is expected to be higher as problems on fertility are due to zinc-binding and as such zinc shortage which is not the case with EDTA-ZnK2.

Short description of key information:

Fertility studies with EDTA-CaNa2, EDTA-Na2H2, EDTA-MnNa2 and EDTA-FeNa were used for risk assessment (for read-across justification also refer to section 13). Data from a multigeneration study on rats with EDTA-CaNa2 did not give evidence for adverse effects on reproductive performance and outcome for doses of up to 250 mg/kg bw/day. The studies with EDTA-Na2H2 were not taken into consideration for setting a NOAEL because of methodological flaws. The study with EDTA-MnNa2 showed effects only at a very high level (1500 mg/kg bw); the NOAEL in this study was 500 mg/kg bw. For EDTA-FeNa no effects were seen at the highest dose tested (250 mg/kg bw).

Effects on developmental toxicity

Description of key information

Results are available on several EDTA-compounds. After repeated treatment of dams withseveral of the non-metal EDTA chelates during various periods of gestation and with the use of different routes of substance application (diet, gavage, s.c., i.m.) impaired embryo/fetal development and the induction of a pattern of gross malformations were observed during these investigations with the exception of one gavage study (Schardein et al ., 1981). Gross malformations, comprised cleft palate, severe brain deformities, eye defects, micro- or agnathia, syndactyly, clubbed legs and tail anomalies. These effects were almost exclusively exhibited in studies using maternally toxic dosage levels. With the exception of one oral (single-dose/gavage) study, during which no teratogenic effects were induced, the fetotoxic and teratogenic effects are occurring at exposure levels of approximately 1,000 mg/kg bw/day and above. This was confirmed by a study with EDTA-MnNa2 in rats that showed developmental toxicity only at 1500 mg/kg bw. In rabbits, developmental effects were seen in the presence of maternal toxicity.Two subcutaneous injection studies with DTPA-CaNa3 and DTPA-ZnNa3 showed developmental effects in the case of DTPA-CaNa3 but not with DTPA-ZnNa3.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Several well performed studies available with several (metal) chelates.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

EDTA and four of its salts were evaluated for their teratogenic potential in CD albino rats (Schardein et al., 1981). Groups of 20 females were treated by gavage during g.d. 7 to 14 with 1,000 mg EDTA/kg bw/day as well as with equimolar doses of EDTA-Na2H2, EDTA-Na3H, EDTA-CaNa2 and EDTA-Na4. The dose level had been selected from preliminary studies with edetic acid in which there had been some evidence of both maternal and fetotoxicity under the same experimental conditions. For the dams significant drug-related reactions including diarrhea and depression of activity were reported. The former occurred in all drug groups with highest incidences for tetrasodium edetate (90%) and edetic acid (80%) and lowest incidence for calcium disodium edetate (10%). Three dams died during treatment with disodium edetate. Besides slightly decreased food intake in all test groups, treatment with all of the test compounds caused reduced weight gain in the dams during the treatment period. The mortality index of offspring in all treated groups as measured by postimplantation loss was comparable to that of the vehicle and untreated control group. None of the test compounds significantly affected litter size at term or mean fetal body weight when compared to either control. Fetuses were examined for external, visceral and skeletal anomalies. Incidental findings of skeletal anomalies did not reveal a definitive pattern regarding treatment with a particular compound. The authors stated that under these experimental conditions no teratogenic effects were evidenced even at maternally toxic doses.

In a further developmental study pregnant Sprague-Dawley rats were exposed during various periods of gestation to purified diets adjusted to either 100 or 1,000 ppm zinc (provided as zinc carbonate) and containing 2 or 3% Na2EDTA corresponding to 1000 or 1500 mg/kg bw daily intake (Swenerton and Hurley, 1971). The groups of 8 to 16 females had been set on the control diet at least 5 days before breeding and mated to normal stock-fed males. The evaluation of treatment related effects to the dams was not indicated in this study, except for the report on moderate to severe diarrhea in all females that were fed diets containing Na2EDTA. While obviously complete reproductive failure occurred with the 3% Na2EDTA/100 ppm zinc diet fed during g.d. 0-21, with the 2% Na2EDTA/100 ppm zinc diet reproductive outcome was essentially comparable to that of controls, however with lower mean body weight of the pups and with 7% malformed of the fullterm fetuses. Exposure to the 3% Na2EDTA/100 ppm zinc diet during the period of g.d. 6-14, and 6-21 resulted in respectively 40% and 54% dead or absorbed fetuses, reduced number of dams with live pubs, clearly reduced mean fetal body weight and ratios of respectively 87% and 100% malformed living offspring. Gross malformations comprised cleft palate, severe brain deformities, eye defects, micro- or agnathia, syndactyly, clubbed legs and tail anomalies. The reported fetotoxic and teratogenic effects were similar to those from earlier experiments with zinc deficient diets administered to pregnant rats for various periods of during gestation (Hurley, 1966). In contrast, the live offspring of dams fed 3% Na2EDTA supplemented with 1,000 ppm zinc from g.d. 6-21 did not exhibit any malformations, and the mean number of live pups/litter and the mean fetal body weight were comparable to those of controls. The authors concluded from this study that Na2EDTA ingested during pregnancy was teratogenic, whereas supplementation with zinc prevented the detrimental effects of EDTA. It was suggested that the congenital anomalies caused by EDTA were due specifically to zinc deficiency. This was also supported by zinc analyses of fetuses (Hurley and Swenerton, 1966), where clearly lower zinc contents were found in fetuses from deficient mothers in comparison to those from zinc supplemented dams, indicating that the reported effects rather occur because of a direct lack of zinc in fetal tissues than from indirect effects of maternal metabolism on fetal development.

The toxic and teratogenic effects of Na2EDTA were studied in female CD rats following different routes of administration (dietary, gavage, s.c) during g.d. 7-14 (Kimmel, 1977). Dietary exposure to 3% Na2EDTA amounting to an average dose of 954 mg Na2EDTA/kg bw/day resulted in reduced food intake, severe diarrhea and severe weight loss in the dams during treatment and produced a significant proportion of fetal deaths (about 33% resorptions/litter), significantly lower average fetal weight and gross external, internal and skeletal malformations in about 71% of the survivors. Treatment with 1,500 or 1,250 mg Na2EDTA/ kg bw/day administered by gavage (respectively 625 mg/kg and 750 mg/kg twice daily) resulted in severe toxicity to the dams (7 out of 8 animals died in the 1,500 mg dose group), in particular 36% maternal deaths, significantly reduced weight gain, and diarrhea in the 1,250 mg dose group and a significantly higher proportion of (about 21%) malformed survivors. Treatment with 375 mg/kg bw administered subcutaneously produced signs of severe pain (vocalisations and shock) to the dams and resulted in 24% maternal deaths, significantly reduced food intake and maternal weight loss during the period of treatment. Fetal toxicity (about 32% resorptions/litter, significantly reduced fetal weight) and a rate of about 4% malformed survivors/litter were reported for this route of application.

EDTA-MnNa2 showed developmental effects in rats only at 1500 mg/kg bw. The effects observed following treatment with EDTA-MnNa2 consisted of a decreased number of females with live born pups, decreased number of (live) pups, increased postimplantation loss. No such effects were seen at 500 mg/kg bw. In rabbits, changes consisted of a slightly decreased fetal body weight and a slightly increased incidence of a skeletal variation at 100 mg/kg bw (with and without extra zinc). Retarded skeletal ossification was only seen at 100 mg/kg bw without extra zinc; the developmental effects were seen in the presence of maternal toxicity. Because of the higher affinity of EDTA for Zn it can also be expected that at the high level of 1500 mg/kg bw, sufficient Mn will be exchanged for Zn and as such Zn-deficiency may also occur as has occurred with the 'empty' (non-metal containing) chelates. The affinity of EDTA for Ca is even lower. Two subcutaneous injection studies with DTPA-CaNa3 and DTPA-ZnNa3 showed developmental effects in the case of DTPA-CaNa3 but not with DTPA-ZnNa3 confirming the notion that Zn-binding and subsequent Zn shortage is the cause of the effects. See also read across document in section 13.

Justification for classification or non-classification

Effects on reproduction and effects on fetal development in rats have only been observed at high levels of the (metal) chelates, i.e. at levels of approximately 1000 mg/kg bw and above, and are considered to be due to zinc deficiency. No such effects were seen in the case of sufficient zinc and a subcutaneous injection study with DTPA-ZnNa3 did not show developmental effects even at a very high level. Therefore, based on the results obtained in all these studies and taking into account the provisions laid down in Council Directive 67/548/EEC and CLP, classification with regard to toxicity to reproduction is not required for EDTA-ZnK2.