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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
one-generation reproductive toxicity
Remarks:
based on generations indicated in Effect levels (migrated information)
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
Not reported
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1986

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Males rats were fed diet supplemented with the test material for specific period and then mated with normal females. Males were sacrificed after mating and effect on sperm motility/viability and zinc concentration in reproductive organs observed. Females were allowed to have full term gestation and effect on conception and litter viability were determined.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Anhydrous zinc sulphate

Test animals

Species:
rat
Strain:
other: Charles-Foster
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Weight at study initiation: (P) Males: 162 g
- Diet: Crushed rat feed of Hindustan Lever (India); ad libitum

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
DIET PREPARATION
- Mixing appropriate amounts with (Type of food): Crushed rat feed

Details on mating procedure:
- M/F ratio per cage: 1:1
- Length of cohabitation: 1 d
- Proof of pregnancy: Sperm in vaginal smear (mating performed only once irrespective of results)

Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
No data
Duration of treatment / exposure:
30-32 d before mating to males only
Frequency of treatment:
Daily, ad libitum
Details on study schedule:
Following the day of mating, males were sacrificed and sperm was immediately collected from epididymis for motility and viability studies. Reproductive organs were dissected out for estimation of zinc. Mated females were allowed to have full term gestation.
Doses / concentrations
Remarks:
Doses / Concentrations:
4,000 ppm zinc as zinc sulphate
Basis:
nominal in diet
No. of animals per sex per dose:
Control group: 15
Treatment group: 18
Control animals:
yes, plain diet
Details on study design:
None
Positive control:
None

Examinations

Parental animals: Observations and examinations:
No data
Oestrous cyclicity (parental animals):
No data
Sperm parameters (parental animals):
Parameters examined in male parents:
Sperm motility and viability
Litter observations:
PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
Number of pups, stillbirths, live births and malformation


Postmortem examinations (parental animals):
- Male animals: All animals sacrificed following the day of mating and reproductive organs (testis, epididymis, seminal vesicle and prostate) were dissected out for estimation of zinc
- Maternal animals: Not sacrificed
Postmortem examinations (offspring):
No data
Statistics:
Fischer's one sided T test
Reproductive indices:
None
Offspring viability indices:
None

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
not specified
Body weight and weight changes:
not specified
Food consumption and compound intake (if feeding study):
not specified
Organ weight findings including organ / body weight ratios:
not specified
Histopathological findings: non-neoplastic:
not specified
Other effects:
not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
effects observed, treatment-related
Reproductive performance:
effects observed, treatment-related

Details on results (P0)

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS): Motility of the sperm was significantly reduced in the zinc treated rats at all time intervals viz. 30 min., 2 h and 4 h. The percentage reduction as compared to the controls was 8.5, 25 .3 and 29 .0 respectively. Sperm viability was unaffected. (See Table 3 for details)

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): Mating by zinc treated males caused significant lowering of incidence of conception and number of live births per mated female. Only 11 females conceived out of 18 mated by zinc treated males whereas all females mated with control rats conceived. (See Table 1 for details)

OTHER FINDINGS (PARENTAL ANIMALS): Zinc content was significantly increased only in the testis (25 %) and sperm (18 %) of the zinc treated rats. (See Table 2 for details)

Effect levels (P0)

open allclose all
Dose descriptor:
dose level: 4,000 ppm zinc
Sex:
male
Basis for effect level:
other: overall effects sperm characterization; other: zinc concentration in reproductive organs
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)
Dose descriptor:
other: Not treated but mated with males fed 4,000 ppm zinc
Sex:
female
Basis for effect level:
other: Overall effects incidence of conception
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
not specified
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Histopathological findings:
not specified

Details on results (F1)

VIABILITY (OFFSPRING): No stillbirth in any of the groups

OTHER FINDINGS (OFFSPRING): No malformed litter in any of the groups

Effect levels (F1)

Dose descriptor:
other: Offsprings of 4,000 ppm zinc treated males
Generation:
F1
Sex:
male/female
Basis for effect level:
other: overall effects live births; offspring malformation
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Table 1: Outcome of mating by zinc treated male rats

 

Mating males

 

Control

Experimental

Number of females mated

15

18

Number of females conceived

15

11

Normal live litter

Total number

101

61

Number / mated female

6.73

3.38*

*Difference was significant at 5% level

Table 2: Zinc content of the reproductive tissues of zinc treated male rats

 

Control

Experimental

Testis

28.1± 1.63 (15)

35.3 ± 2.13 (18)*

Epididymis

58.3 ± 3.46 (10)

61.4 ± 6.63 (10)

Seminal vesicle

24.4 ± 3.25 (10

33.8 ± 5.96 (10)

Prostate (whole)

48.8 ± 6.90 (10)

51.7 ± 6.36 (10)

Sperm

559 ± 14.8 (10)

658 ± 24.7 (10)*

Results expressed as Mean ± SEM in µg/g, except for sperm in µg/g dw, for the number of

rats shown in parentheses.

* P < 0.02

Table 3: Motility and viability of the sperm of zinc treated rats

 

Control (15)

Experimental (18)

Motility (Emmen's unit)

 

 

30 min

25.9 ± 0.57

23.7 ± 0.47*

2 hours

23.7 ± 0.58

17.7 ± 1.15**

4 hours

17.2 ± 1.10

12.2 ± 1.42*

% viable at 4 hours

55.7 ± 4.80

49.0 ± 4.60

Values expressed as Mean ± SEM for the number of rats shown in parentheses.

* P < 0.01 

**P < 0.001

Applicant's summary and conclusion

Conclusions:
Dietary zinc supplementation at 4,000 ppm reduced male fertility in rats under the conditions of the study.
Executive summary:

A study was conducted to determine the effects of dietary zinc supplementation on male fertility in Charles-Foster rats.

4,000 ppm zinc as zinc sulphate was fed to 18 test males in diet for 30 -32 d. 15 control males were fed normal diet for the same duration. All animals mated with individual normal females once between Day 30 and 32. After mating, males were sacrificed for sperm characterization and zinc concentration analysis in different reproductive organs. Mated females were allowed to have full term gestation.

Mating by treated males caused significant lowering of incidence of conception and number of live births per mated female. However, no stillbirth or malformed litter was observed. Motility of the sperm was significantly reduced in the treated rats but viability was unaffected. Zinc content was significantly increased only in the testis and sperm of the treated rats.

The results indicate that dietary zinc supplementation at 4,000 ppm reduced male fertility in rats under the conditions of the study.