Potassium trifluorozincate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

75 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

GLP compliant guideline study, klimisch 1

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 GLP compliant combined oral repeated dose toxicity study with reproduction/developmental toxicity screening test performed according to OECD 422, potassium trifluorozincate (KZnF3) was administered daily by oral gavage to Wistar rats. The animals (12 per sex per dose) were exposed to 0 (control), 7.5, 25 and 75 mg/kg bw/day KZnF3 dissolved in water. Male animals were dosed during a 2-week premating period, during mating and up to day 30 (the day before sacrifice on day 31). The female animals were dosed with the test substance during a 2-week premating period, and during mating, gestation and lactation up to the day before sacrifice (approx. day 4 of lactation). At the end of the premating period, each female was caged with one male from the same group. Animals were caged together until mating occurred or 1 week had elapsed. Upon evidence of copulation the females were caged individually for the birth and rearing of their pups. Sperm positive females that turned out to be non-pregnant were killed not earlier than 24 days after copulation. Females that did not show evidence of copulation after the end of the one-week mating period were also housed individually until sacrifice (25 days after the last day of the mating period). Dams were allowed to raise their litter until sacrifice on day 4 of lactation or shortly thereafter.The following endpoints were evaluated to assess general toxicity: daily clinical observations, neurobehavioural examination, body weight, food consumption, routine haematology and clinical chemistry, organ weights, macroscopic examination and histopathological examination of a wide range of tissues and organs (except for the stomach which was examined in all groups, only high-dose animals and controls were subjected to histopathology).Endpoints to assess reproductive / developmental toxicity included parental fertility and reproductive performance (weight and morphology of sex organs, mating index, pre-coital time, male and female fertility indices, gestation index and length, pre- and post-implantation loss) and litter data (numbers of stillborn, live and dead pups, external abnormalities, pup weight on lactation days 0 and 4, necropsy of stillborn pups and pups that died during the study).Three rats died during the study, two females in the high-dose group and one male in the mid-dose group. The death of one of these high-dose females was caused by myocardial mineralization, a chance finding which was not ascribed to treatment. The cause of death of the other high-dose female and the mid-dose male could not be established. Because there were no signs of a dosing error, these deaths are ascribed to the treatment. White discoloration of the incissors (fluorosis) was noted in all males and in all females of the mid and high-dose group. These findings were confirmed at macroscopic examination. These mild changes are considered not to be adverse when they do not affect the functional structure of the teeth. The decreased body weights and feed consumption, observed in males of the high-dose group are ascribed to the treatment. Males and females of the high-dose group and males of the mid-dose group showed decreased levels of total protein and albumin in plasma. The differences from controls increased with dose. Because these effects occurred in both sexes and were not within the range of historical control values, they were ascribed to the treatment. Data from the present study did not indicate a plausible mechanism for these decreases in plasma proteins; the present study revealed no clear evidence of hepatotoxicity, as assessed by liver weight, pathology and relevant clinical chemistry values. Microscopic findings in the kidneys could not explain the decrease in plasma protein either. The relative weight of the kidneys was elevated in the high-dose group. Although not corroborated by microscopic findings in the kidneys, the increase in kidney weight was ascribed to treatment. The significance of the increased relative weight of the adrenals in males of the high-dose group is not clear. Treatment of the animals with the test substance caused a range of pathological changes in the stomach in all test groups. Based on the presence of inflammation, hyperaemia and epithelial vacuolization in several low-dose animals, a no-observed-adverse-effect-level could not be established. These changes in the stomach are considered local effects resulting from direct contact of the test substance with the stomach wall. Microscopic findings in the other organs examined revealed no treatment-related changes. There were no effects of the test substance on fertility and reproductive performance, litter data or pup observations in any group. In conclusion, no treatment-related effects were seen in any of the reproductive or developmental endpoints. Hence, the no-observed-adverse-effect-level (NOAEL) for reproductive or developmental effects was placed at the highest level tested, namely 75 mg/kg bw/day. Based on mortality and decreased plasma levels of total protein and albumin in the mid- and high-dose group, the NOAEL for systemic effects was placed at 7.5 mg/kg bw/day. Because of pathological changes in the stomach in all test groups, the NOAEL for local effects was below 7.5 mg/kg bw/day.

Short description of key information:
A NOAEL of 7.5 mg/kg bw for systemic effects and a NOAEL of 75 mg/kg bw for fertility and developmental toxicity was established in a combined oral repeated dose toxicity study with reproduction/developmental toxicity screening test (OECD 422, GLP).

Justification for selection of Effect on fertility via oral route:
GLP compliant guideline study with a reliability score of 1.

Effects on developmental toxicity

Description of key information

A NOAEL of 25 mg/kg bw for systemic maternal effects and a NOAEL of 75 mg/kg bw for developmental toxicity was established in a combined oral repeated dose toxicity study with reproduction/developmental toxicity screening test with KZnF3 (OECD 422, GLP). Supporting developmental studies with the individual ions (zinc and fluoride) of KZnF3 show that these ions are not developmental toxicants.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

75 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

One GLP compliant OECD 422 study with a reliability score of 1 performed with KZnF3 is available. Furthermore, several developmental studies are available on sodium fluoride and zinc sulphate to assess the developmental toxicity of the ions (fluoride and zinc) of KZnF3.

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

In addition to the combined oral repeated dose toxicity study with the reproduction / developmental toxicity screening test performed with potassium trifluorozincate, additional information has been collected to assess the developmental toxicity of potassium trifluorozincate. Once dissolved, potassium trifluorozincate is ionized to its ions Zn2+, F-, and K+. Therefore studies on the developmental effects of zinc and fluoride were reviewed.

In the combined oral repeated dose toxicity study with the reproduction / developmental toxicity screening test with potassium trifluorozincate no developmental toxicity was observed up to the highest dose tested (75 mg/kg bw). In the three available studies with sodium fluoride no developmental toxicity was observed up to the highest dose tested. Five out of six studies performed with zinc sulphate also showed no developmental toxicity up to the highest dose tested. Two of these studies were performed in rats and the other three in either hamster, mice or rabbit. In a developmental toxicity study with Cheviot sheep, at a concentration of 750 mg/kg bw ZnSO4, reproductive performance was severely impaired. However, at this dose level also maternal toxicity has been observed as the exposure to zinc resulted in copper deficiency.

In summary, since no developmental effect were observed in the OECD 422 study performed with potassium trifluorozincate and since no developmental toxicity was observed in the absence of maternal toxicity of the individual ions of potassium trifluorozincate it can be concluded that potassium trifluorozincate does not have to be classified for developmental toxicity.

Below the results of the studies with potassium trifluorozincate, sodium fluoride and zinc sulphate are described.

Potassium trifluorozincate

In a GLP compliant combined oral repeated dose toxicity study with reproduction/developmental toxicity screening test performed according to OECD 422, potassium trifluorozincate (KZnF3) was administered daily by oral gavage to Wistar rats. The female animals (12 per dose) were exposed to 0 (control), 7.5, 25 and 75 mg/kg bw/day KZnF3 dissolved in water. The female animals were dosed with the test substance during a 2-week premating period, and during mating, gestation and lactation up to the day before sacrifice (approx. day 4 of lactation). At the end of the premating period, each female was caged with one male from the same group. Animals were caged together until mating occurred or 1 week had elapsed. Upon evidence of copulation the females were caged individually for the birth and rearing of their pups. Sperm positive females that turned out to be non-pregnant were killed not earlier than 24 days after copulation. Females that did not show evidence of copulation after the end of the one-week mating period were also housed individually until sacrifice (25 days after the last day of the mating period). Dams were allowed to raise their litter until sacrifice on day 4 of lactation or shortly thereafter. The following endpoints were evaluated to assess general toxicity: daily clinical observations, neurobehavioural examination, body weight, food consumption, routine haematology and clinical chemistry, organ weights, macroscopic examination and histopathological examination of a wide range of tissues and organs (except for the stomach which was examined in all groups, only high-dose animals and controls were subjected to histopathology). Endpoints to assess reproductive / developmental toxicity included maternal fertility and reproductive performance (morphology of sex organs, mating index, pre-coital time, fertility indices, gestation index and length, pre- and post-implantation loss) and litter data (numbers of stillborn, live and dead pups, external abnormalities, pup weight on lactation days 0 and 4, necropsy of stillborn pups and pups that died during the study). Two females in the high-dose group died during the study. The death of one of these high-dose females was caused by myocardial mineralization, a chance finding which was not ascribed to treatment. The cause of death of the other high-dose female could not be established. Because there were no signs of a dosing error, this death is ascribed to the treatment. White discoloration of the incissors (fluorosis) was noted in all females of the mid and high-dose group. These findings were confirmed at macroscopic examination. These mild changes are considered not to be adverse when they do not affect the functional structure of the teeth. No treatment related effects on female body weights and feed consumption were observed. Females of the high-dose group showed decreased levels of total protein and albumin in plasma. The differences from controls increased with dose. Because these effects were not within the range of historical control values, they were ascribed to the treatment. Data from the present study did not indicate a plausible mechanism for these decreases in plasma proteins; the present study revealed no clear evidence of hepatotoxicity, as assessed by liver weight, pathology and relevant clinical chemistry values. Microscopic findings in the kidneys could not explain the decrease in plasma protein either. The relative weight of the kidneys was elevated in the high-dose group. Although not corroborated by microscopic findings in the kidneys, the increase in relative kidney weight was ascribed to treatment. Treatment of the animals with the test substance caused a range of pathological changes in the stomach in all test groups. Based on the presence of inflammation, hyperaemia and epithelial vacuolization in several low-dose animals, a no-observed-adverse-effect-level could not be established. These changes in the stomach are considered local effects resulting from direct contact of the test substance with the stomach wall. No treatment-related microscopic changes were observed in the other organs examined. There were no effects of the test substance on fertility and reproductive performance, litter data or pup observations in any group. In conclusion, based on mortality and decreased plasma levels of total protein and albumin in the high-dose group, the maternal no-observed-adverse-effect-level (NOAEL) for systemic effects was placed at 25 mg/kg bw/day. Because of pathological changes in the stomach in all test groups, the NOAEL for local effects was below 7.5 mg/kg bw/day.No treatment-related effects were seen in any of the developmental endpoints and therefore the developmental NOAEL was 75 mg/kg bw (the highest dose tested).

Sodium fluoride

Pregnant Sprague-Dawley CD rats were exposed to sodium fluoride in their drinking water at concentrations of 0, 50, 150 or 300 ppm daily between gestation days 6 and 15 (Heindel 1996). Maternal weight gain was significantly reduced at 300 ppm during the first two days of exposure (days 6 to 8). Maternal water consumption (grams/kg/day) during exposure was significantly decreased in the animals exposed to 300ppm NaF. Post-exposure water consumption was normal in these animals indicating the probability of decreased palatability of the 300ppm solution. Necropsy of the maternal animals revealed no effects on kidney or liver weights. NaF exposure did not significantly affect post-implantation loss, mean fetal body weight per litter, or external, visceral, or skeletal malformations. This study established a NOAEL for maternal toxicity of 150 ppm (18 mg NaF/kg bw/day, ~8.4mg fluoride/kg bw/day) and a NOAEL of 300 ppm for developmental toxicity (27 mg NaF/kg bw/day, ~12.3 mg fluoride/kg bw/day) when administered in drinking water to pregnant CD rats during organogenesis.

In another developmental toxicity study with sodium fluoride mated female Sprague-Dawley rats were exposed via the drinking water at concentrations of 0, 25, 100, 175 and 250 ppm on gestation days 0 -20 (Collins 1995). Caesarean sections were performed on gestation day 20 and foetuses were examined. Sodium fluoride was not teratogenic at any dose tested. There was no effect on the development of specific bones including sternebrae. Foetal growth was not affected by sodium fluoride, even in dams exhibiting significantly decreased food and water consumption (250ppm; decreased feed and water consumption, 175ppm decreased water consumption). A significant increase was seen in the average number of foetuses with three or more skeletal variations in the 250 ppm group, however the number of affected litters was not significantly increased. There was no dose-related effect of sodium fluoride on the incidence of soft tissue variations. Therefore the developmental NOAEL was determined to be 250 ppm (~11.1 mg fluoride/kg bw/day).

Pregnant New Zealand White rabbits were exposed to sodium fluoride in their drinking water at concentrations of 0, 100, 200 or 400 ppm daily between gestation days 6 and 19 (Heindel 1996). There was evidence of minimal maternal toxicity but no definitive evidence of developmental toxicity with levels of sodium fluoride in drinking water as high as 400ppm (resulting in an average exposure of 29 mg/kg bw/d) although the palatabillity of a 400 ppm sodium fluoride solution apparently reduced water consumption. This study established a NOAEL for maternal toxicity at 200 ppm NaF in drinking water (approximately 18 mg/kg bw/d) and a NOAEL for developmental toxicity of 400ppm NaF in drinking water (approximately 29 mg/kg bw/d, ~13.2 mg fluoride/kg bw/day) when administered to pregnant NZW rabbits during organogenesis.

Zinc sulphate

In the EU-RAR risk assessment document for Zinc Chloride prepared by the Netherlands Organization for Applied Scientific Research (TNO) and the National Institute of Public Health and Environment (RIVM) (http://esis.jrc.ec.europa.eu/doc/risk_assessment/REPORT/zincchloridereport075.pdf), several studies investigating the developmental toxicity of zinc sulfate have been summarised. These summaries are presented below. It is concluded in the EU-RAR document that neither fertility nor developmental toxicity are considered endpoints of concern for humans and that based on the available information there is no reason to classify metallic zinc nor any of the zinc compounds considered for reproductive toxicity.

Female CD-1 mice (25-30 animals/group) received daily doses of 0.3, 1.4, 6.5 and 30 mg unspecified ZnSO4/kg bw by gavage during days 6-15 of gestation. A control group was included. All animals were observed daily for appearance and behaviour with particular attention to food consumption and body weight. Body weights were recorded on day 0, 6, 11, 15 and 17 of gestation. The females were sacrificed at day 17. The urogenital tract of each animal was examined in detail. Between 21 and 23 females were pregnant at term in all groups. No clearly discernible effects on maternal survival, body weight gains, number of corpora lutea, implantations and resorptions were observed. The number of live litters, live and dead foetuses, the foetus weights and sex ratio were not affected by treatment. No difference in number or kind of abnormalities (in either soft or skeletal tissues) was found between exposed and control groups. It can be concluded that the administration of up to 30 mg/kg bw of unspecified zinc sulphate (≈12 mg or 6.8 mg Zn2+/kg bw, for anhydrate and heptahydrate, respectively) had no adverse effects on adult mice and their foetuses (Food and Drug Research Labs., Inc., 1973).

Female Wistar rats (25-28 animals/group) received daily doses 0.4, 2.0, 9.1 and 42.5 mg unspecified ZnSO4/kg bw by gavage during days 6-15 of gestation. A control group was included. All animals were observed daily for appearance and behaviour with particular attention to food consumption and body weight. Body weights were recorded on day 0, 6, 11, 15 and 20 of gestation. The females were sacrificed at day 20. The urogenital tract of each animal was examined in detail. At term 25 females were pregnant in all groups. No clearly discernible effects on maternal survival, body weight gains, number of corpora lutea, implantations and resorptions were observed. The number of live litters, live and dead foetuses, the foetus weights and sex ratio were not affected by treatment. No difference in number or kind of abnormalities (in either soft or skeletal tissues) was found between exposed and control groups. It can be concluded that the administration of up to 42.5 mg/kg bw of unspecified zinc sulphate (≈17 mg or 9.6 mg Zn2+/kg bw, for anhydrate and heptahydrate, respectively) had no adverse effects on adult rats and their foetuses (Food and Drug Research Labs., Inc., 1973).

Female hamsters (23-25 animals/group; outbred strain of golden hamster) received daily doses of 0.9, 4.1, 19 and 88 mg unspecified ZnSO4/kg bw by gavage during days 6-10 of gestation. A control group was included. All animals were observed daily for appearance and behaviour with particular attention to food consumption and body weight. Body weights were recorded on day 0, 8, 10 and 14 of gestation. The females were sacrificed at day 14. The urogenital tract of each animal was examined in detail. Between 21 and 24 females were pregnant at term in all groups. No clearly discernible effects on maternal survival, body weight gains, number of corpora lutea, implantations and resorptions were observed. The number of live litters, live and dead foetuses, the foetus weights and sex ratio were not affected by treatment. No difference in number or kind of abnormalities (in either soft or skeletal tissues) was found between exposed and control groups. It can be concluded that the administration of up to 88 mg/kg bw of unspecified zinc sulphate (≈35.2 mg or 19.9 mg Zn2+/kg bw, for anhydrate and heptahydrate, respectively) had no adverse effects on adult hamsters and their foetuses (Food and Drug Research Labs., Inc., 1973).

Female Dutch rabbits (14-19 animals/group) received daily doses of 0.6, 2.8, 13 and 60 mg unspecified ZnSO4/kg bw by gavage during days 6-18 of gestation. A control group was included. All animals were observed daily for appearance and behaviour with particular attention to food consumption and body weight. Body weights were recorded on day 0, 6, 12, 18 and 29 of gestation. The urogenital tract of each animal was examined in detail. The females were sacrificed at day 29. Between 10 and 12 females were pregnant at term in all groups. No clearly discernible effects on maternal survival, body weight gains, number of corpora lutea, implantations and resorptions were observed. The number of live litters, live and dead foetuses, the foetus weights and sex ratio were not affected by treatment. No difference in number or kind of abnormalities (in either soft or skeletal tissues) was found between exposed and control groups. It can be concluded that the administration of up to 60 mg/kg bw of unspecified zinc sulphate (≈24 mg or 13.6 mg Zn2+/kg bw, for anhydrate and heptahydrate, respectively) had no adverse effects on adult rabbits and their foetuses (Food and Drug Research Labs., Inc., 1974).

12 Female Charles-Foster rats received via diet 4,000 mg Zn2+ (as anhydrous ZnSO4)/kg feed (corresponding to 200 mg Zn2+/kg bw) from day 1 until day 18 post coitum and 15 animals received the same diet from day 21-26 prior to mating until sacrifice (day 18 post coitum). Control groups consisted of 12 and 11 animals, respectively. No stillbirths or malformed fetuses were recorded and there were no significant differences in the number of resorptions or the mean placental and fetal weights between the treated females and controls irrespective of the exposure regime (Pal and Pal, 1987).

Campbell and Mills (1979) examined the reproductive performance of Cheviot sheep (6/group) which received 30, 150 and 750 mg ZnSO4 (unspecified)/kg feed during pregnancy until parturition. A control group was included. High-dose sheep showed decreased food consumption, food utilisation and reduced body weight gains. Blood copper levels, plasma ceruloplasmin and amine oxidase were statistically significantly decreased and plasma zinc levels were greatly increased. The reproductive performance was severely impaired at the highest dose level: Most of the lambs were non-viable, and showed high zinc levels in the livers (this was also seen in the mid-dose) and low copper concentrations. These lambs also showed discontinuous growth of long bones, which was not observed in the lower dose groups. Copper supplementation (2.5 and 10 mg) at the high dose level prevented the development of copper deficiency, but not the other effects such as lamb viability and food consumption/utilisation.

Justification for selection of Effect on developmental toxicity: via oral route:
GLP compliant guideline study with a reliability score of 1.

Justification for classification or non-classification

Based on the absence of effects on fertility, reproductive performance and development in the combined oral repeated dose toxicity study with the reproduction / developmental toxicity screening test with KZnF3 and based on developmental toxicity studies performed with fluoride (sodium fluoride) and zinc (zinc sulfate), classification of KZnF3 for reproductive toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 and EU Directive 67/548/EEC is not warranted.