Magnesium fluoride

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Screening for reproductive / developmental toxicity (equivalent to OECD 416) (sodium fluoride)

NOAEL_reproduction> 250 ppm equal to >37.5 mg/kg bw (P generation, male, rat) (highest concentration tested)

NOAEL_reproduction> 250 ppm equal to >37.5 mg/kg bw (F1generation, male, rat) (highest concentration tested)

The study results are not considered reliable since the documentation is not adequate for assessment and the study is conducted of a read-across substance. As the NOAEL values are highest concentrations tested, these values are not used as starting point for DNEL derivation.

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

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:

Read-across justification is provided in Appendix 3 of the CSR.

The available toxicological data on the target and source substances is outlined in the data matrix (Table 8).
The toxicological properties of the target substance are related to the magnesium cations (Mg2+) and fluoride anions (F-). Thus, data on other magnesium salts (mainly magnesium chloride) and inorganic fluorides (mainly sodium fluoride) are justified in the human health hazard assessment.
Humans take in between 250 and 350 mg/day of magnesium and need at least 200 mg, but the body deals very effectively with this element, taking it form food when it can, and recycling what we already have when it cannot. There is no evidence that magnesium produces systemic poisoning although persistent over-indulgence in taking magnesium supplements and medicines can lead to muscle weakness, lethargy and confusion.
Chloride is relatively not toxic to human health but does pose organoleptic issues. Accordingly, EPA has set the potable limit for chloride in drinking water at 250 mg/L.

Experimental data obtained with the magnesium chloride indicate that it has low oral toxicity after repeated exposure. The available data does not show any test item related adverse effects on the highest doses (> 2000 mg/kg bw/day) tested. Sodium fluoride administration did not cause test item related adverse effects in rats dosed up to 175ppm for 2 years. Only exceptions were abnormalities in the teeth of rats in the two highest dose groups (100 and 175 ppm sodium fluoride).

Sodium is a compound of many foodstuffs, for instance of common salt. It is necessary for humans to maintain the balance of the physical fluids system. Sodium is also required for nerve and muscle functioning. Thus, there is no evidence that sodium produces systemic poisoning at reasonably possible exposures.

Fluoride has both positive and negative effects on human health, but there is a narrow range between intakes that are associated with these effects. Exposure to all sources of fluoride, including drinking-water and foodstuffs, is important There is little information to characterize the dose–response relationships for the different adverse effects. In particular, there are few data on total exposure, particularly with respect to intake and fluoride absorption. The most serious effect is the skeletal accumulation of fluoride from long-term excessive exposure to fluoride and its effect on non-neoplastic bone disease — specifically, skeletal fluorosis and bone fractures. There is clear evidence from India and China that skeletal fluorosis and an increased risk of bone fractures occur at total intakes of 14 mg fluoride/day and evidence suggestive of an increased risk of bone effects at total intakes above about 6 mg fluoride/day.
The data of repeated dose toxicity and reproduction toxicity are proposed to be used for read-across according to the information requirements of Annex VIII.

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Principles of method if other than guideline:

The study presents quantitative morphometric information on the testes of F1 generation rats exposed to one of four NaF concentrations in utero, during lactation, and for 14 weeks post weaning.

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

Test was conducted on a read-across substance sodium fluoride (CAS 7681-94-4; EC 231-667-8). Obtained from Sigma Chemical Co., MO, USA, Lot no. 109F0102. No trace element impurities were detected in the sample.

Species:

rat

Strain:

Sprague-Dawley

Remarks:

CD VAF+

Sex:

male/female

Details on test animals or test system and environmental conditions:

The male rats were from the larger two-generation reproduction study (Sprando et al. 1997). Male and female rats were obtained from Charles River Laboratories (Raleigh, NC, USA), 22 days old on arrival and quarantined for approximately 1 week. Individuals were identified by ear tags. Rats were housed under standard controlled temperature (19.4-23.3 degrees celcius), humidity (40-70%) and light (12 hour light:dark cycle). Rats were fed a low fluoride NIH-07 diet (7.95ppm fluoride). The diet was prepared by Ziegler Bros, Inc.

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

Sodium fluoride was dissolved in the rats drinking water, which was provided ad libitum. The water was obtained by filtering house-distilled water through a water purification system. The fluoride concentation in this water was determined to be less than 0.2ppm.

Details on mating procedure:

Mating took place over a 3-week period. Pregnancy was determined by the presence of sperm plugs in the cage and the presence of sperm in the vagina.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Sodium fluoride concentrations for both the control and treated groups were performed at the FDA by potentiometric titration of the fluoride ion with a fluoride ion electrode. Sodium fluoride concentrations for both control and treated groups were determined using an EA 940 pH/ISE meter with appropriate electrodes and filling solutions for fluoride analysis. Sodium fluoride concentrations were determined each time dosing solutions were prepared for any treatment group including the control.

Duration of treatment / exposure:

Approximately 14 weeks per generation

Frequency of treatment:

Daily

Details on study schedule:

The parent (P) generation received sodium fluoride in their drinking water (provided ad libitum) for approximately 14 weeks; 10 weeks pretreatment, 3 weeks mating (to non-siblings), and 1 week post-mating. Pregnant P females continued to be exposed from gestation day 0 until the end of lactation. On post-partum day 4, litters were culled to 10 pups per litter (5 males and 5 females) where possible using a random number table. At day 21, males and females were randomly selected to represent the F1 generation from as many litters as possible. The weanlings remained in the same treatment group as their parents and were exposed to sodium fluoride for approximately 14 weeks.

Remarks:

0, 25, 100, 175 or 250 ppm

No. of animals per sex per dose:

P generation total: 64 male rats (0 ppm n=12, 25 ppm n=13, 100 ppm n=13, 175 ppm n=12, 250 ppm n=14); F1 generation total: 60 male rats (12 rats per dose). The same number of female rats were used, but no examinations were conducted on these rats.

Control animals:

yes, concurrent vehicle

Details on study design:

P generation rats were assigned to treatment groups by weight using a random experimental stratified procedure. On post-partum day 4, F1 litters were culled to 10 pups per litter (5 males and 5 females) where possible using a random number table. At day 21, males were randomly selected to represent the F1 generation from as many litters as possible.

Parental animals: Observations and examinations:

Reported in Sprando et al 1997

Oestrous cyclicity (parental animals):

Not examined

Sperm parameters (parental animals):

Reported in Sprando et al 1997

Postmortem examinations (parental animals):

Reported in Sprando et al 1997

Postmortem examinations (offspring):

The male F1 rats were weighed prior to anaesthesia. Trunk blood was collected from the right ventricle. The left testis and epididymis were removed. The left epididymis was weighed then discarded. The left testis was homogenised and the number of homogenisation-resistant spermatids per testis determined. The right testis was perfusion fixed.

Statistics:

All the variables except body weight were analysed using ANCOVA, with body weight as a covariate. Body weight data were analysed in an ANOVA. P values equal to or less than 0.05 were considered significant.

Reproductive indices:

Not examined

Offspring viability indices:

Not examined

Clinical signs:

not examined

Body weight and weight changes:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

not examined

Results from the P generation are reported in Sprando et al 1997.

Dose descriptor:

NOAEL

Effect level:

250 ppm (nominal)

Sex:

male

Basis for effect level:

other: Spermatogenesis and endocrine function

Key result

Critical effects observed:

no

Clinical signs:

not examined

Mortality / viability:

not examined

Body weight and weight changes:

effects observed, treatment-related

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

not examined

Histopathological findings:

no effects observed

A significant difference in body weight was observed between the controls and the treated rats in the 100, 175ppm and a borderline significant effect was observed in the 250 ppm group, however this decrease in body weight was not dose related. Statistically significant differences in testis weight, volume or specific gravity were not observed between treated and control rats. There was a statistically significant reduction in the volume composition of the lymphatic endothelium in the 175 and 250ppm groups, and in the testicular capsule of the 100ppm group, compared to controls. No other significant differences relating to volumetric composition of the testis were found. There were no significant differences in the mean numbers of Sertoli cell nuclei counted per cross-sectioned seminiferous tubules, the seminiferous tubule diamters, the height of the seminiferous epithelium, the mean absolute seminiferous tubule lengths or mean absolute surface areas.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

250 ppm

Based on:

test mat.

Sex:

male

Basis for effect level:

histopathology: non-neoplastic

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Reproductive effects observed:

no

The significant reduction in the absolute volume of the testicular capsule in the 100 ppm group was not considered treatment related because no dose relationship was observed, the authors conclude it is likely to be a sampling error. The absolute volumes of nearly all testicular components examined (seminiferous tubule, tubular lumen, interstitium, Leydig cells, blood vessels) were not sigificantly different than control values.

Conclusions:

The quantitative information obtained in this study confirms earlier findings (Sprando et al 1997), that sodium fluoride does not affect spermatogenesis in the rat up to a dose of 250 ppm.

Executive summary:

A quantitative examination of the testes of F1 generation males was made, following prolonged exposure to sodium fluoride in the drinking water at 0, 25, 100, 175 or 250ppm. The rats were exposed in utero, during lactation, and directly in their drinking water for 14 weeks after weaning. At the end of the exposure period testicular tissues were perfusion fixed and examined. There were no statistically significant differences between controls and treated rats in almost all the parameters evaluated. A significant decrease in the absolute volume and volume percent of the lymphatic endothelium was observed in the 175 and 250ppm groups, and in the testicular capsule in the 100ppm group. The authors report that the significance of this finding is not clear, and overall the results suggests that exposure to NaF does not adversely affect testis structure or spermatogenesis in the rat.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

37.5 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

No specific reproductive toxicity studies have been conducted for Magnesium fluoride. Weight of evidence approach is used to evaluate the reproductive toxicity of the target substance. Two reproduction toxicity studies summarised below, are conducted for similar substance (sodium fluoride).

The first study presents quantitative morphometric information on the testes of F1 generation rats exposed to one of four Sodium Fluoride (NaF) concentrations (25, 100, 175 or 250 ppm equal to 3.8 , 15, 26.2 or 37.5 mg/kg bw) in utero, during lactation, and for 14 weeks post weaning (Sprando et al. 1998). A significant difference in body weight was observed between the controls and the treated rats in the 100, 175ppm and a borderline significant effect was observed in the 250 ppm group, however this decrease in body weight was not dose related. Statistically significant differences in testis weight, volume or specific gravity were not observed between treated and control rats. There was a statistically significant reduction in the volume composition of the lymphatic endothelium in the 175 and 250 ppm groups, and in the testicular capsule of the 100 ppm group, compared to controls. The significant reduction in the absolute volume of the testicular capsule in the 100 ppm group was not considered treatment related because no dose relationship was observed. No other significant differences relating to volumetric composition of the testis were found. There were no significant differences in the mean numbers of Sertoli cell nuclei counted per cross-sectioned seminiferous tubules, the seminiferous tubule diameters, the height of the seminiferous epithelium, the mean absolute seminiferous tubule lengths or mean absolute surface areas. Overall, the results suggest that exposure to NaF does not adversely affect testis structure or spermatogenesis in the rat.

In the other study, the study design is comparable to a standard two-generation reproductive toxicity study, however this study focuses on investigations of the effects on spermatogenesis in male rats following administration of Sodium Fluoride over two generations (Sprando et al, 1997). The potential of sodium fluoride to affect spermatogenesis and endocrine function was assessed in P and F1 generation male rats. Male and female rats received sodium fluoride in their drinking water at 0, 25, 100, 175 or 250 ppm (equal to 3.8 , 15, 26.2 or 37.5 mg/kg bw). P generation rats were exposed for 10 weeks, then for 3 weeks during mating. Reproductive tissues were collected from P males 1 week after mating (after approximately 14 weeks of NaF treatment). Pregnant females (P) were exposed to NaF during gestation and lactation. F1 weanling males were exposed to NaF for 14 weeks, at which time reproductive tissues were collected. Dose-related effects were not observed within the P and F1 treatment groups in testis weights, prostate/seminal vesicle weights, non-reproductive organ weights, testicular spermatid counts, sperm production per gram of testis per day, sperm production per gram of testis, LH, FSH or serum testosterone concentrations. Histopathological changes in testicular tissues were not observed. Prolonged exposure to NaF in drinking water up to a dose of 250 ppm does not adversely affect spermatogenesis or endocrine function in P and F1 generation male rats.

Effects on developmental toxicity

Description of key information

Prenatal developmental toxicity (equivalent to OECD 414) (sodium fluoride)

NOAEL > 300 ppm, > 45 mg/kg bw/day (rat) (highest concentration tested)

NOAEL 175 ppm, 25 mg/kg/day (rat)

The study results are not considered reliable since the documentation is not adequate for assessment and the study is conducted of a read-across substance. As the NOAEL values are highest concentrations tested, these values are not used as starting point for DNEL derivation.

 

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Justification for type of information:

Read-across justification is provided in Appendix 3 of the CSR.

The available toxicological data on the target and source substances is outlined in the data matrix (Table 8).
The toxicological properties of the target substance are related to the magnesium cations (Mg2+) and fluoride anions (F-). Thus, data on other magnesium salts (mainly magnesium chloride) and inorganic fluorides (mainly sodium fluoride) are justified in the human health hazard assessment.
Humans take in between 250 and 350 mg/day of magnesium and need at least 200 mg, but the body deals very effectively with this element, taking it form food when it can, and recycling what we already have when it cannot. There is no evidence that magnesium produces systemic poisoning although persistent over-indulgence in taking magnesium supplements and medicines can lead to muscle weakness, lethargy and confusion.
Chloride is relatively not toxic to human health but does pose organoleptic issues. Accordingly, EPA has set the potable limit for chloride in drinking water at 250 mg/L.

Experimental data obtained with the magnesium chloride indicate that it has low oral toxicity after repeated exposure. The available data does not show any test item related adverse effects on the highest doses (> 2000 mg/kg bw/day) tested. Sodium fluoride administration did not cause test item related adverse effects in rats dosed up to 175ppm for 2 years. Only exceptions were abnormalities in the teeth of rats in the two highest dose groups (100 and 175 ppm sodium fluoride).

Sodium is a compound of many foodstuffs, for instance of common salt. It is necessary for humans to maintain the balance of the physical fluids system. Sodium is also required for nerve and muscle functioning. Thus, there is no evidence that sodium produces systemic poisoning at reasonably possible exposures.

Fluoride has both positive and negative effects on human health, but there is a narrow range between intakes that are associated with these effects. Exposure to all sources of fluoride, including drinking-water and foodstuffs, is important There is little information to characterize the dose–response relationships for the different adverse effects. In particular, there are few data on total exposure, particularly with respect to intake and fluoride absorption. The most serious effect is the skeletal accumulation of fluoride from long-term excessive exposure to fluoride and its effect on non-neoplastic bone disease — specifically, skeletal fluorosis and bone fractures. There is clear evidence from India and China that skeletal fluorosis and an increased risk of bone fractures occur at total intakes of 14 mg fluoride/day and evidence suggestive of an increased risk of bone effects at total intakes above about 6 mg fluoride/day.
The data of repeated dose toxicity and reproduction toxicity are proposed to be used for read-across according to the information requirements of Annex VIII.

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Limit test:

no

Specific details on test material used for the study:

Test was conducted on a read-across material sodium fluoride (CAS 7681-49-4; EC 231-667-8).

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

Cesarean-originated, barrier sustained Crl:CD (BR) VAF/Plus outbred albino rats were obtained from Charles River Laboratories, Inc., Raleigh, NC.
Sperm-positive females were individually housed in solid-bottom polycarbonate cages with stainless-steel wire lids and Ab-Sorb-Dri cage litter.
NIH-07 Rodent chow and either deionized/fileterd water or the prepared sodium fluoride-spiked drinking water were available ad libitum throughout gestation.
12:12 hr light:dark cycle; average temperature 22 degrees celcius and average humidity 55%. All environmental conditions were monitored and controlled by computer.

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

Sodium fluoride was administered to rats in the drinking water, provided ad libitum.

Details on analytical verification of doses or concentrations:

The method detection limit was used to determine the level of NaF present in the control water, and this value was used to calculate the drinking water doses. The amount of F present in the standard diet was also determined.

Details on mating procedure:

After a 7-day quarantien period, individual breeding pairs of rats were cohabited overnight. In the first replicate study there was three consecutive breeding dates and five consecutive breeding dates in the second. The morning on which sperm were found in vaginal lavage was designated as Gestational Day (GD) 0.

Duration of treatment / exposure:

Timed-mated rats were allowed ad libitum access to deionized/filtered drinking water containing 0, 50, 150 or 300 ppm sodium fluoride from GD 6 to 15 (i.e. treated water was removed on the morning of GD 16).

Frequency of treatment:

Drinking water was available ad libitum.

Duration of test:

All animals were terminated on GD 20. On the second replicate of the study, 10 female rats were added and they were killed on GD 16 for blood collection.

Remarks:

0, 50, 150 or 300 ppm

No. of animals per sex per dose:

26 female rats per dose were used for the developmental toxicity study and an additional 10 rats per dose were used for blood collection. The study was performed in two replicates.

Control animals:

yes, concurrent vehicle

Details on study design:

26 pregnant female rats per dose were used for the developmental toxicity study and an additional 10 rats per dose were used for blood collection. Two replicates of the study were performed. Body weight, feed and water consumption development were followed during the study. Animals were terminated on GD 20. On the second replicate of the study, 10 female rats were added and they were killed on GD 16 for blood collection in order to determine serum fluoride levels. Gross pathology was performed for the maternal bodies. Gross pathology and histopahtological examinations were performed on featuses.

Maternal examinations:

Animals were observed daily for clinical signs of toxicity. Food and water intakes and body weights were recorded on gestation days 0, 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20. All animals were sacrificed on gestation day 20 and examined for maternal body and organ weights (liver, right kidney and intact uterus), implant status, foetal weight, sex and morphological development. An additional 10 mated animals per groups were subjected to the same experimental regimen but sacrificed on gestation day 16 for blood collection for determination of serum fluoride concentration.

Ovaries and uterine content:

Uterine contents were examined - implant status, foetal weight, sex and morphological development were recorded.

Fetal examinations:

Foetuses were examined for external, visceral or skeletal malformations, in addition to foetal body weights and sex.

Statistics:

General linear models (GLM) procedures were applied for the analyses of variance (NOVA) of maternal and fetal parameters. GLM-ANOVA analysis determined the significance of dose-response relationship and the significance of dose effects, replicate effects, and dose x replicate interactions. When ANOVA revealed a significant (p < 0.05) dose effect, Dunnett's test and Williams' test were used to compare treated to control groups. One-tailed tests were used for all pairwise comparisons except maternal body and organ weights, food and water consumption, fetal body weight and percentage of males per litter.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Water consumption and compound intake (if drinking water study):

effects observed, non-treatment-related

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS: No treatment related clinical signs were observed in confirmed-pregnant animals during or after administration of sodium fluoride.
MORTALITY: No animals died during the course of the study
BODY WEIGHT: Maternal body weight gain during the first 2 days of exposure (GD 6 to 8) was significantly reduced at 300 ppm relative to controls. The mean maternal body weight gain for the treatment period as a whole exhibited a decreasing trend, and the comparison among groups for an effect of dose approached statistical significance.
WATER CONSUMPTION: Maternal water consumption of the animals dosed with 300 ppm sodium fluoride was significantly decreased for each period of observation from GD 6 to 16. Maternal food consumption was also decreased in the animals given 300 ppm sodium fluoride from GD 8 to 10, but did not differ from controls for any other period of measurement.
ORGAN WEIGHT: Maternal liver and kidney weights on GD 20 were not different from control.

Dose descriptor:

NOAEL

Effect level:

300 ppm (nominal)

Based on:

test mat.

Basis for effect level:

other: this is the highest dose tested, no clear test item related adverse effects observed

Details on embryotoxic / teratogenic effects:

Sodium fluoride exposure did not affect the number of corpora lutea, implantations, live featuses or the percentage of early deaths or late fetal deaths per litter. In addition, no significant effects on external, visceral, or skeletal malformations were found.

Dose descriptor:

NOAEL

Effect level:

300 ppm

Sex:

male/female

Basis for effect level:

other: No addverse effects were observed. This is the maximum dose tested

Developmental effects observed:

no

Control water fluoride levels were <0.6 ppm NaF.

Food contained an average of 12.4 ppm F (11.6 -13.4 ppm F).

The calculated doses from drinking water were 7, 18 and 27 mg NaF/kg bw/d (3, 8 and 12 mg F/kg bw/d) for the low, intermediate and high-dose groups respectively. Intake from food added approximately 2 mg NaF/kg bw/d (1 mg F/kg bw/d) to the intake for each group.

Determination of serum fluoride levels in the 10 animals per group terminated on 16 revealed mean levels of 0.007 ± 0.002, 0.035 ± 0.040, 0.039 ± 0.039, and 0.187 ± 0.076F at the end of the exposure period.

Conclusions:

In conclusion, sodium fluoride in drinking water at doses up to 300 ppm rats throughout major organogenesis caused no definitive developmental toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

25 mg/kg bw/day

Study duration:

subacute

Species:

rat

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

No specific studies of toxicity on development have been conducted for Magnesium fluoride. Weight of evidence approach is used to evaluate the developmental toxicity of the target substance. Two developmental toxicity studies summarised below, are conducted for similar substance (sodium fluoride).

 

Sodium fluoride was administered to rats in the drinking water in concentrations of 50, 150 or 300 ppm (equal to 7,5 , 22.5 or 45 mg/kg bw), provided ad libitum from GD 6 to 15 (Heindel et al. 1996). All animals were terminated on GD 20. On the second replicate of the study, 10 female rats were added and they were killed on GD 16 for blood collection. Gross pathology was performed for the maternal bodies. Gross pathology and histopathological examinations were performed on foetuses. Sodium fluoride exposure did not affect the number of corpora lutea, implantations, live foetuses or the percentage of early deaths or late fetal deaths per litter. In addition, no significant effects on external, visceral, or skeletal malformations were found. In conclusion, sodium fluoride in drinking water at doses up to 300 ppm (corresponds actual intake of 27 mg/kg bw/day) throughout major organogenesis caused no definitive developmental toxicity.

Developmental toxicity of sodium fluoride was assessed in rats that were given drinking water containing five different dose levels (10, 25, 100, 175 or 250 ppm) throughout gestation (days 0 to 20) (Collins, T.F. et al. 1995). The intakes of sodium fluoride in the study were 1.4, 3.9, 15.6, 24.7 or 25.1 mg/kg, respectively. Reproductive parameters included pregnancy rate, implantation efficiency, and foetal viability. Foetal development parameters included foetal body weight and growth measurements, number of runts and number of runts/litter. Developmental parameters included external variations, sternebral variations, soft tissue variations, and extensive skeletal variations. Foetal growth was not affected by sodium fluoride. A significant increase in the average number of foetuses with three or more skeletal variations and the number of litters with foetuses with three or more skeletal variations was increased in the 250 ppm group. However, there were no dose-related increases in the incidence of soft tissue variations, external anomalies, or effects on the development of specific bones, including sternebrae. In conclusion, no definitive treatment-related effects on foetal growth or on the incidence of external, visceral, or skeletal abnormalities at levels of sodium fluoride up to and including 250 ppm (25.1 mg/kg/day) were found.

Magnesium chloride has been investigated in a reproductive and developmental toxicity screening test in rats [OECD TG 421] (OECD 2011). Rats were treated by gavage at doses of 0, 250, 500 or 1 000 mg/kg bw/day. Males were dosed once daily for a total of 42 days (two weeks each prior to, during and post mating), and females once daily for two weeks prior to mating, throughout gestation and four days after delivery. During the study, no necropsy findings and histopathological changes in lungs were found in one dead male and three dead females dosed with 1,000 mg/kg bw/day. The mating and gestation periods, mating index, fertility index and gestation index did not show statistically significant differences between the dosed groups and the control group. Normal parturition, mean litter size, pre- and post-implantation loss rate, live birth index and viability index on postnatal Days 0 and 4 were observed in all the dosed groups compared to the control group. There were no effects on the sex ratio, external findings, body weights and clinical signs of pups. Moreover, no differences were noted in absolute and relative organ weights of testes, epididymis, uterus, and ovaries, and no histopathological changes were observed. No adverse effects were noted in reproduction parameters of parents or the development of the pups in any of the dosed groups. In conclusion, the NOAEL for reproductive and developmental toxicity was 1000 mg/kg bw/day.

The reproductive/developmental toxicity of magnesium sulphate has been investigated in a combined oral repeated dose/reproductive and developmental toxicity screening test in rats [OECD TG 422] (OECD 2010). Rats were treated by gavage at doses of 0, 50, 150, or 450 mg/kg bw/day. Males in the main group (13 rats per group) were administered for a total of six weeks (two weeks each prior to, during and post mating), and females in main group (13 rats per group) were administered for two weeks prior to mating, throughout gestation and five days (six days in twelve females) after delivery. No deaths were observed in either sex. The gestation indices were 100 %, and the pre-implantation loss rates were 10.5% and 4.8% in the control and 450 mg/kg bw/day groups, respectively. The post-implantation loss rates were 7.9% and 5.5% in the control and 450 mg/kg bw/day groups, respectively, and the live birth indices were 92.1% and 94.5% in the control and 450 mg/kg bw/day groups, respectively. In addition, the viability indices on postnatal day 0 were 97.6% and 99.0% in the control and 450 mg/kg, respectively, and the viability indices on postnatal day 4 were 99.6% and 96.8% in the control and 450 mg/kg bw/day groups, respectively. Furthermore, there were no effects in live birth index, sex ratio, mean litter size, and external findings including eye, ear, mouth, palate, absence of limbs and tail, position, size and shape. on day 0 and 4. No dose-related effects on reproductive and developmental parameters were observed up to the highest dose tested. There were no treatment related effects on parental animals observed at any dose. Based on these results, the NOAEL for reproductive and developmental toxicity was considered to be 450 mg/kg bw/day. Also, magnesium sulphate is not considered to be a reproductive and developmental toxicant.

Justification for classification or non-classification

Based on the observations made of reproduction data of sodium fluoride and magnesium salts there is no need to classify the target substance for reproduction toxicity in accordance with the criteria of CLP regulation 1272/2008.