Nickel di(acetate)

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1985-1986

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Meets generally accepted scientific standards with acceptable restrictions Test animals experienced decreased water comsumption due to taste aversion; Animal room climate controls failed at one point during study

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1988

Report date:

1988

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

yes

Remarks:

included F1b and F2b generations for ancillary assessments

Principles of method if other than guideline:

The study design exceeded the guideline through the inclusion of F1b and F2b generations for ancillary assessments. These assessments included a complete developmental toxicity assessment in the F2b generation.

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Nickel dichloride

EC Number:

231-743-0

EC Name:

Nickel dichloride

Cas Number:

7791-20-0

Molecular formula:

Cl2Ni

IUPAC Name:

Nickel (II) chloride hexahydrate

Specific details on test material used for the study:

- Name of test material (as cited in study report): Nickel Chloride Hexahydrate (7791-20-0)
- Molecular formula (if other than submission substance): not different than submission substance
- Molecular weight (if other than submission substance): not different than submission substance
- Smiles notation (if other than submission substance): not different than submission substance
- InChl (if other than submission substance): not different than submission substance
- Structural formula attached as image file (if other than submission substance): not different than submission substance
- Substance type: pure product
- Physical state: green, deliquescent crystals or crystalline powder
- Solubility: water (20°C) 254 g/100 ml
- Other details on test material are included in the study report

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animals and Husbandry
The experimental animals in the present study were viral antibody free (VAF/Plus) @ Crl:CD (SD)BR outbred albino rats supplied by Charles River Breeding Laboratories. Inc. (Kingston, NY). The Charles River CD rat was selected as the experimental animal assigned to this investigation. Males and females were 27-32 days old at the time of arrival at RTI.

During the quarantine period (10-14 days), animals were randomly assigned to cages. and individually coded tags were affixed to one ear of each rat. All animals were singly housed throughout the study in solid bottom polycarbonate or polypropylene cages (8" x 19" x 10 1/2") with stainless steel wire lids and molded filter tops. Ab-Sorb-Dri cage litter was used in all cages.

Purina Certified Rodent Chow (No. 5002, pelletized) was available ad libitum throughout the study. Rodent chow was stored at 55-60°F and the period of use did not exceed five months after receipt at RTI. Deionized/filtered water was available ad libitum during the quarantine period. During the exposure period animals were given ad libitum access to either control water (i.e., deioniied/filtered water with pH=4.0-6.0 adjusted with hydrochloric acid) or to an aqueous solution of nickel chloride. Clear plastic water bottles with stainless steel sipper tubes were used throughout this investigation. The animal holding room assigned for this study was equipped with individual temperature and humidity controls.

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

RTI (1988) administered nickel chloride hexahydrate to male and female CD rats (30/sex/dose) at (0, 7.3, 30.8 and 51.6 mg Ni/kg bw/day, estimated overall) in a 2-generation study. An additional dose level of 1000 ppm was eliminated after 2 weeks due to excessive toxicity. The parental animals were exposed beginning 11 weeks before cohabitation, and exposure continued for a total of 24 weeks (males) or 30 weeks (females). Groups of 10 rats/sex comprised a satellite subchronic non breeder study. The average nickel consumption reported by the authors varied by more than a factor of 2, with the highest consumption at the beginning of the premating exposure and during the latter part of the lactation period. As a conservative estimate, the average exposure during gestation, which was on the low end of overall exposure levels, was used as the dose level for each group. This choice also takes into account the possibility that gestational exposure alone could have accounted for observed the effects. Thus, the estimated doses were 0, 6.0, 25, and 42 mg Ni/kg bw/day.

Details on mating procedure:

1 male and 1 female cohabited for up to 2-weeks; mating confirmed by positive spermatozoa on vaginal lavage

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

- Analytical purity: 99% as reported by vendor; >98% as reported by ICP analysis at RTI
- Stability: stability of aqueous solutions for 15 days under the anticipated conditions of use was verified by RTI for concentrations of 100 ppm Ni++ and greater
- Vehicle: Filtered/deionized water. Durham, NC city tap water was pre-filtered with 0.5 micron Nucleopore membrane filters to remove fine particulate matter. Organics were removed by charcoal adsorption. Then water was deionized by passage through two mixed-bed ion exchangers. The filtration and deionizing systems were purchased from and are routinely serviced by Hydro Ultrapure Water Systems, Inc., P. O. Box 2855, Durham, NC 27705

Duration of treatment / exposure:

Parental animals were exposed beginning 11 weeks before cohabitation and exposure continued for a total of 24 weeks (males) or 30 weeks (females).

Frequency of treatment:

Daily

Details on study schedule:

F1b males and females of the RTI (1988) study were randomly mated on postnatal day 70 and their offspring (F2a and F2b) were evaluated through postnatal day 21. This phase included teratological evaluations of F2b fetuses.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 250, or 500 ppm nickel in drinking water (0, 7.3, 30.8 and 51.6 mg Ni/kg bw/day, estimated overall)
Basis:
nominal in water

No. of animals per sex per dose:

30/sex/dose

Control animals:

yes, concurrent no treatment

Details on study design:

None

Positive control:

None

Examinations

Parental animals: Observations and examinations:

Daily cage-side Morbidty/Mortality and Clinical Signs of Toxicity

Oestrous cyclicity (parental animals):

Not evaluated

Sperm parameters (parental animals):

Not evaluated

Postmortem examinations (parental animals):

Gross examination of all organs at necropsy. Histopathology was performed for liver, kidney, lungs, heart, pituitary, adrenals and reproductive organs.

Postmortem examinations (offspring):

Gross examination of all organs at necropsy. Histopathology was performed for liver, kidney, lungs, heart, pituitary, adrenals and reproductive organs.

Statistics:

When the data were expected to violate the assumptions of the parametric tests, then similar nonparametric tests were used. When data were continuous or approximately continuous but not normally distributed, the KruskalWallis (Siegel, 1956), Mann-Whitney U (Siegel, 1956), and Jonckheere's (Jonckheere, 1954) tests were used to examine the experiMent-wise effect of dose, the pair-wise effect of dose, and the dose response trend, respectively. For nonparametric pair-wise cOMparisons of individual groups against the controls, the following tests were used: (I) for data with a significant Kruskal-Wallis Test (p<0.05) and evidence of a trend (p<0.10, Jonckheere's Test), Shirley's multiple comparison procedure (Shirley, 1977) was used to determine the smallest dose at which there was a statistically significant effect, or (2) for data with a significant Kruskal-Wallis Test (p<0.05) and no evidence of a trend (p>O.IO, Jonckheere's Test), Dunn's Test, a nonparametric analogue to Dunnett's Test was applied (Dunn, 1964). Index (categorical) data were analyzed using the Chi-Square Test for Independence (Snedecor and Cochran, 1967), Fisher's Exact Probability Test (Snedecor and Cochran, 1967), and the Test for Linear Trend on Proportions (Snedecor and Cochran, 1967) for the detection of the experiment-wise, pair-wise, and trend effects of dose, respectively.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

An additional dose level of 1000 ppm was eliminated after 2 weeks due to excessive toxicity.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At the 500 ppm (~42 mg/kg) dose level there was a statistically significant decrease in parental body weight in males and females (95% and as low as 80% of controls, respectively)

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

At the 500 ppm (~42 mg/kg) dose level there was a statistically significant decrease in parental body weight in males and females (95% and as low as 80% of controls, respectively)

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Description (incidence and severity):

Test substance intake: Average nickel consumption varied by more than 2-fold, with the highest consumption at the beginning of the premating exposure and during the latter part of lactation. As a conservative estimate, the average exposures doses were 0, 6.0, 25, & 42 mg Ni/kg.

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

RTI (1988) administered nickel chloride hexahydrate to male and female CD rats (30/sex/dose) at 0, 50, 250, or 500 ppm nickel in drinking water (0, 7.3, 30.8 and 51.6 mg Ni/kg bw/day, estimated overall) in a 2-generation study. An additional dose level of 1000 ppm was eliminated after 2 weeks due to excessive toxicity. The parental animals were exposed beginning 11 weeks before cohabitation, and exposure continued for a total of 24 weeks (males) or 30 weeks (females). Groups of 10 rats/sex comprised a satellite subchronic non-breeder study.

The average nickel consumption reported by the authors varied by more than a factor of 2, with the highest consumption at the beginning of the premating exposure and during the latter part of the lactation period. As a conservative estimate, the average exposure during gestation, which was on the low end of overall exposure levels, was used as the dose level for each group. This choice also takes into account the possibility that gestational exposure alone could have accounted for the observed effects. Thus, the estimated doses were 0, 6.0, 25, and 42 mg Ni/kg bw/day.

At the 500 ppm dose level there were statistically significant decreases in both parental generation body weights in males and females (95% and as low as 80%, respectively), along with decreased absolute and relative liver weights in the females (90% and 80% of controls, respectively), but not in the males. Females also show the most pronounced effects on body weight during the premating exposure period and during lactation in both breeding generations.

Thus, 250 ppm (25 mg Ni/kg bw/day) was a NOAEL for breeders. Histopathology was performed for liver, kidney, lungs, heart, pituitary, adrenals and reproductive organs to make this assessment. There was no treatment-related effect on reproductive performance indices (mating success, rate of impregnation), reproductive organ weights or histopatholgy of reproductive organs. Therefore, the NOAEL for fertility in this study is 42 mg Ni/kg bw/day and a LOAEL was not identified. However, it should be noticed that effects on sperm quality and oestrus cyclicity were not investigated in this study.

Effect levels (P0)

Dose descriptor:

LOAEL

Effect level:

ca. 42 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: perinatal lethality/fertility

Remarks on result:

other: NOAEL 25 mg/kg bw/day (parental animals)

Target system / organ toxicity (P0)

Critical effects observed:

not specified

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

mortality observed, treatment-related

Description (incidence and severity):

increased perinatal mortality in the high exposure group

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

decreased weight in the high exposure group

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Details on results (F1)

In the RTI (1987) F1a generation (postnatal days 1-4) at the 500 ppm dose level the number of live pups/litter was significantly decreased, pup mortality was significantly increased, and average pup body weight was significantly decreased in comparison with controls. Similar effects were seen with F1b litters of Po dams exposed to 500 ppm nickel. In the 50 and 250 ppm dose groups increased pup mortality and decreased live litter size was observed in the F1b litters. However, these effects seen with F1b litters are questionable because the room temperature tended to be 10 degrees F higher than normal at certain times (gestation-postnatal days) along with much lower levels of humidity. As evidenced in the literature, temperatures that are 10 degrees F above normal during fetal development cause adverse effects (Edwards, 1986). Therefore, the above results seen at 50 and 250 ppm cannot be considered to be genuine adverse effects.

Effect levels (F1)

Dose descriptor:

LOAEL

Generation:

F1

Effect level:

500 ppm

Sex:

not specified

Basis for effect level:

mortality

Remarks on result:

other: F1a generation

Results: F2 generation

Target system / organ toxicity (F2)

Critical effects observed:

not specified

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

RTI (1988) administered nickel chloride hexahydrate to male and female CD rats (30/sex/dose) at 0, 50, 250, or 500 ppm nickel in drinking water in a 2-generation study. An additional dose level of 1000 ppm was eliminated after 2 weeks due to excessive toxicity. The parental animals were exposed beginning 11 weeks before cohabitation, and exposure continued for a total of 24 weeks (males) or 30 weeks (females). Groups of 10 rats/sex comprised a satellite subchronic non breeder study. The average nickel consumption reported by the authors varied by more than a factor of 2, with the highest consumption at the beginning of the premating exposure and during the latter part of the lactation period. As a conservative estimate, the average exposure during gestation, which was on the low end of overall exposure levels, was used as the dose level for each group. This choice also takes into account the possibility that gestational exposure alone could have accounted for observed the effects. Thus, the estimated doses were 0, 6.0, 25, and 42 mg Ni/kg bw/day.

 

At the 500 ppm dose level there was a statistically significant decrease in the Po body weight in males and females (95% and 90% of controls, respectively), along with decreased absolute and relative liver weights in the females (90% and 89% of controls, respectively), but not in the males. Thus, 250 ppm (25 mg Ni/kg bw/day) was a NOAEL forbreeders. There was no treatment-related effect on reproductive performance indices (mating success, rate of impregnation), reproductive organ weights or histopatholgy of reproductive organs. Therefore, the NOAEL for fertility in this study is 42 mg Ni/kg bw/day and a LOAEL was not identified. However, it should be noticed that effects on sperm quality and oestrus cyclicity were not investigated in this study.

 

In the F1a generation at the 500 ppm dose level, the number of live pups/litter was significantly decreased, pup mortality was significantly increased, and average pup body weight was significantly decreased in comparison with controls. Although there was no statistically significant effect at 250 ppm, there was some indication of decreased number of live pups/litter. Similar effects were seen with FIb litters ofdams exposed to 500 ppm nickel. In the 50 and 250 ppm dose groups, increased pup mortality and decreased live litter size was observed in the F1b litters. However, these effects seen in the F1b litters are somewhat questionable because the room temperature was 3-5° C higher than normal at certain times (gestation-postnatal days) along with lower levels of humidity. Therefore, the above results seen at 50 and 250 ppm may not be adverse effects of nickel only.

 

F1b males and females were randomly mated (19-30/sex/group) on postnatal day 70 and their offspring (F2a and F2b) were evaluated through postnatal day 21 or on gestational day 21. This phase included teratological evaluations of F2b foetuses. The average gestational nickel consumption of F1b dams was 0, 6.2, 23, and 42 mg Ni/kg. Evaluation of the data indicated that the 500 ppm dose caused significant body weight depression of both mothers and pups and increased neonatal mortality during the postnatal development period. No effects on prenatal growth or viability were observed in F2b. The percent foetuses malformed per litter were significantly increased at 50 ppm, due primarily to a higher incidence of short rib in that group. In the absence of similar effects at higher doses, the increased incidence at 50 ppm is probably not due to exposure to nickel.

 

Overall, the study shows that exposure to nickel can cause increased neonatal mortality at 42 mg Ni/kg bw/day and possibly at lower doses of 6 and 25 mg Ni/kg bw/day, but a reliable developmental NOAEL cannot be identified in this study. 

 

Table Litter size and pup mortality in RTI (1988) study

Dose (ppm Ni)	Live pups per litter, PND 1 (No. of litters)	Live pups per litter, PND 4	% mortality per litter, PND 1-4
F1a litters
0	13.3          (26)	13.0	2.1%
50	14.0          (25)	13.8	1.2%
250	11.5          (23)	11.3	1.7%
500	10.9*        (27)	8.8**	18.4%**
F1b litters
0	15.3          (15)	15.1	0.9%
50	11.8*        (19)	11.4*	7.2%
250	11.5*        (19)	11.3*	8.6%
500	9.5**        (15)	5.3**	53.3%**
F2a litters
0	13.6          (24)	12.3	12.9%
50	14.2          (28)	13.5	4.4%
250	12.4          (25)	11.7	9.8%
500	11.4*        (15)	8.3*	28.6%

* P < 0.05; ** P < 0.01

Applicant's summary and conclusion

Executive summary:

RTI (1988) administered nickel chloride hexahydrate to male and female CD rats (30/sex/dose) at 0, 50, 250, or 500 ppm nickel in drinking water(0, 7.3, 30.8 and 51.6 mg Ni/kg bw/day, estimated overall)in a 2-generation study. An additional dose level of 1000 ppm was eliminated after 2 weeks due to excessive toxicity. The parental animals were exposed beginning 11 weeks before cohabitation, and exposure continued for a total of 24 weeks (males) or 30 weeks (females). Groups of 10 rats/sex comprised a satellite subchronic non-breeder study.

 

The average nickel consumption reported by the authors varied by more than a factor of 2, with the highest consumption at the beginning of the premating exposure and during the latter part of the lactation period. As a conservative estimate, the average exposure during gestation, which was on the low end of overall exposure levels, was used as the dose level for each group. This choice also takes into account the possibility that gestational exposure alone could have accounted for the observed effects. Thus, the estimated doses were 0, 6.0, 25, and 42 mg Ni/kg bw/day.

 

At the 500 ppm dose level there were statistically significant decreases in both parental generation body weights in males and females (95% and as low as 80%, respectively), along with decreased absolute and relative liver weights in the females (90% and 80% of controls, respectively), but not in the males. Females also show the most pronounced effects on body weight during the premating exposure period and during lactation in both breeding generations.

 

Thus, 250 ppm (25 mg Ni/kg bw/day) was a NOAEL for breeders.Histopathology was performed for liver, kidney, lungs, heart, pituitary, adrenals and reproductive organs to make this assessment.There was no treatment-related effect on reproductive performance indices (mating success, rate of impregnation), reproductive organ weights or histopatholgy of reproductive organs. Therefore, the NOAEL for fertility in this study is 42 mg Ni/kg bw/day and a LOAEL was not identified. However, it should be noticed that effects on sperm quality and oestrus cyclicity were not investigated in this study.

 

In the F1a generation at the 500 ppm dose level, the number of live pups/litter was significantly decreased, pup mortality was significantly increased, and average pup body weight was significantly decreased in comparison with controls. Although there was no statistically significant effect at 250 ppm, there was some indication of decreased number of live pups/litter. Similar effects were seen with F1b litters of dams exposed to 500 ppm nickel. In the 50 and 250 ppm dose groups, increased pup mortality and decreased live litter size was observed in the F1b litters. However, these effects seen in the F1b litters are somewhat questionable because the room temperature was 3-5° C higher than normal at certain times (gestation-postnatal days) along with lower levels of humidity. Therefore, the above results seen at 50 and 250 ppm may not be adverse effects of nickel only.

 

F1b males and females were randomly mated (19-30/sex/group) on postnatal day 70 and their offspring (F2a and F2b) were evaluated through postnatal day 21 or on gestational day 21. This phase included teratological evaluations of F2b foetuses. The average gestational nickel consumption of F1b dams was 0, 6.2, 23, and 42 mg Ni/kg. Evaluation of the data indicated that the 500 ppm dose caused significant body weight depression of both mothers and pups and increased neonatal mortality during the postnatal development period. No effects on prenatal growth or viability were observed in F2b. The percent foetuses malformed per litter were significantly increased at 50 ppm, due primarily to a higher incidence of short rib in that group. In the absence of similar effects at higher doses, the increased incidence at 50 ppm is probably not due to exposure to nickel.

 

Overall, the study shows that exposure to nickel can cause increased neonatal mortality at 42 mg Ni/kg bw/day and possibly at lower doses of 6 and 25 mg Ni/kg bw/day, but a reliable developmental NOAEL cannot be identified in this study.