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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
December 1999 - September 2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Sufficiently compliant to GLP; adequate coherence between data, comments and conclusions. The top-dose was not based on dose-limiting toxicity but on antithyroid effects (not verified in this study), limiting the sensitivity of the study for Developmental Effects classification. Loss indices were not reported but could be determined by Summary author. The other deviations to OECD 414 guideline have no impact on the reliability and completeness of the conclusions.
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000
Report Date:
2000

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: EPA OPPTS 870.3700 (Reproduction and Fertility effects)
Deviations:
not applicable
Remarks:
the guideline quoted does not exist (mistake in report)
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
Treatment period exceeds requirements. Temperature (°C): 18-26 instd. of 19-25. Highest dose did not induce clinical signs or lower weight gain and was < 1000 mg/kg/day. % Pre/Post-implantation loss not reported. Historical control data are inadequate.
GLP compliance:
yes
Remarks:
No laboratory compliance certificate. Analytical certificate does not check test item purity. Perchlorate concentrations were outside the range validated for stability during about half of the study, at the top-dose.
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Substance type: MCP
- Physical state: solid powder
- Nominal purity: 99.8% (not verified)
- Lot/batch No.: 03907LF
- Expiration date of the lot/batch: not indicated
- Stability under test conditions: not indicated but stability verified in drinking water
- Storage condition of test material: at room temperature

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
NB: The whole summary ignores male rats (although they were exposed during mating) since they are normally not included in a teratogenicity study.

TEST ANIMALS
- Source: Charles River Laboratories
- Age at study initiation: 8-9 weeks
- Weight at study initiation: 213-237 g
- Fasting period before study: no
- Housing: stainless steel wire-bottomed cages, individual except during mating
- Diet (e.g. ad libitum): PMI Certified Rodent Diet, ad libitum
- Water (e.g. ad libitum): reverse osmosis water, ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18-26
- Humidity (%): 30-70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 2000-01-25 To: 2000-03-15

Administration / exposure

Route of administration:
oral: drinking water
Vehicle:
water
Details on exposure:
VEHICLE
- Nature: reverse osmosis drinking water
- Justification for use and choice of vehicle: high solubility of the test item in water
- Lot/batch no. (if required): not applicable
- Purity: not applicable
- Less than 0.5 mg/L (LOD) of nitrate, a possible interference ion for perchlorate

PREPARATION OF TREATED DRINKING WATER:
- Dilution from a stock solution at 10 mg/mL
- Concentration adapted weekly (using body weight and water consumption) to reach the target dose-levels in mg/kg/day: 0.06-242 µg/mL
- Frequency of preparation: at least once a week (diluted solutions)
- Storage: refrigerated (stock solutions) / room temperature (diluted solutions)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Methods:
- validated ion chromatography method
- LOD for perchlorate and nitrate (interference ion): 0.005 µg/mL

Results:
- at all doses: concentrations within +/- 5% of nominals
- at 0.05 and 200 µg/mL: stable over 109 days at 21-22°C under light (12h/day) - demonstrated in another study (7.5.1)

Comments:
- For 3 out of 6 preparation occasions, the target concentrations at the high-dose were above the maximal concentration demonstrated to be stable (200 µg/mL).
- This validation otherwise adequately covers the study's test item use conditions.
Details on mating procedure:
- Impregnation procedure: cohoused with treated males
- M/F ratio per cage: 1:1
- Length of cohabitation: 9 days
- No replacement of males or further mating, as only presumably pregnant females were assigned to gestation study.
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug or sperm in vaginal smear; referred to as day 0 of pregnancy
Duration of treatment / exposure:
36 to 44 days: 14 days prior to mating, 1-9 days of mating, and 21 days of gestation before sacrifice
Frequency of treatment:
Continuous (treated water ad libitum)
Duration of test:
See in-life dates
Doses / concentrations
Remarks:
Doses / Concentrations:
0.01, 0.1, 1 and 30 mg/kg/day
Basis:
other: nominal dose; achieved dose within +/- 10% of nominal
No. of animals per sex per dose:
24 females, among which 17 to 20 per group were considered pregnant and therefore analysed by cesarian section.
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: 10 mg/kg/day resulted in antithyroid effects in pups in a neurobehavioral study, and in adults in a 90-day study (7.5.1)
- Rationale for animal assignment: random

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily for viability

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily during pregnancy only

BODY WEIGHT: Yes
- Time schedule for examinations: twice during acclimation and daily throughout exposure period

FOOD CONSUMPTION: Yes
- Time schedule: daily throughout exposure period

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: weekly, individually
- Calculated as mg/kg/day from body weight data

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: gross necropsy of all viscera.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: placental abnormalities
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: half per litter
Statistics:
See page 24 of study report
Indices:
% Pre-implantation loss and % Post-implantation loss were not calculated in the report. Recalculated by RSS author as:
% Pre-implantation loss = 100 * (Number of corpora lutea - Number of implantation sites) / Number of corpora lutea
% Post-implantation loss = 100 * (Number of implantation sites - Number of live fetuses) / Number of implantation sites
Historical control data:
Provided; same type of data, from the same laboratory in the same strain.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
Alopecia in 3 top-dose females, not toxicologically relevant.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
>= 30 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
>= 30 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes. Remark: minimal & non adverse

Details on embryotoxic / teratogenic effects:
There appeared to be an increase in % pre- and post-implantation losses* and a decrease in number of live fetuses, but dose-relationship was unclear and the number of implantation sites was unaffected by treatment. The effects are not considered as being toxicologically relevant. NB: an absence of impact on number of pups has been confirmed in a 2-generation study in rats treated at up to 30 mg/kg/day (see 7.8.1).
*: comparison with historical control impossible since these indices were not calculated in historical data.

There are 3% and 8% fewer ossification sites in sternum and forelimb phalanges, respectively, at 30 mg/kg/day vs. controls.** This effect is minimal, and not adverse: it represents a slight delay in development which is usually reversible.
**: the control group was already outside the historical range for sternal ossification sites: historical control data inadequate for interpretation.

No teratogenic effects.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Reproductive indices and ossification sites in rats treated with ammonium perchlorate

Dose (mg/kg/day) 0 0.01 0.1 1 30
Corpora lutea 19.3 17.9 18.1 19.8 19.8
Implantations 17.0 14.7 14.4 16.6 14.8
Live fetuses 16.6 14.3 13.9 16.2 14.1*
% Pre-implantation loss @ 11.9 17.9 20.4 16.2 25.3
% Post-implantation loss @ 2.4 2.7 3.5 2.4 4.7
Ossification sites (per fetus per litter):
- Sternal center 4.00 3.93 3.97 3.96 3.88**
- Forelimb phalanges 6.97 6.78 6.68 7.01 6.43*

@: no statistical analysis performed since these data were not in the original report

*: p<0.05; **: p<0.01

Applicant's summary and conclusion

Conclusions:
Maternal NOAEL set at 30 mg/kg/day in the absence of relevant maternal effects.
Developmental NOAEL set at 30 mg/kg/day in the absence of adverse developmental abnormalities.
The top-dose was not based on dose-limiting toxicity but on antithyroid effects (not verified in this study), limiting the sensitivity of the study for Developmental Effects classification.
Executive summary:

Ammonium perchlorate was provided to groups of 24 female rats via drinking water, at dose-levels of 0 (control), 0.01, 0.1, 1 and 30 mg/kg/day before (2 weeks before mating, complete mating) and during gestation (21 days). Effects on thyroids were not investigated.

  • At 30 mg/kg/day, there was no maternal toxicity. Pre- and Post-implantation loss indices were higher than in controls but this was not considered to represent relevant resorptions when considering the number of resorptions, implantation sites, live and dead fetuses. There was a minor indication of delayed ossification (fewer ossification sites). No developmental abnormalities were noted.
  • At 0.01 to 1 mg/kg/day, neither maternal nor embryo-/feto- or developmental toxicities were noted.