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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study is comparable to OECD Guideline 414 with acceptable restrictions (food consumption not examined; no data about corpora lutea; minor restrictions: no data about acclimatization of mice or age at initiation) Phenol is a major component of the reaction mass so that phenol hazard data are applied in the hazard assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1983
Report Date:
1983

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
not specified
Remarks:
but quality assurance similar to GLP standards
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Analytical purity: 99.9% (gas chromatography)
- Purity test date: 29 May 1981
- Lot/batch No.: 187130-280
- Source: Fluka AG
- Stability under test conditions: formulations were analysed by HPLC methods; ca. 10 months after formulation 83-105% of the theoretical concentration was measured.

Test animals

Species:
mouse
Strain:
CD-1
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Lab, Kingsten, NY, USA
- Age at study initiation: males 10-12 weeks and females 6-7 weeks at arrival (no further data)
- Weight at study initiation: pregnant females at gestation day 0: 24.0-32.5 g.
- Fasting period before study: no data
- Housing: 10 per cage, individual ear-coding
- Diet ad libitum: certified rodent chow
- Water ad libitum: deionized/filtered water
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 72+-2
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
Phenol dissolved in distilled water (concentration see below); dams dosed once daily on gestation day (GD) 6 through 15; volume for administration: 10 ml/kg bw.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
nominal concentration: 0, 7, 14, 28 g/l
analytical concentration: 0, 7.1-7.3, 13.6-13.7, 26.5-27.8 g/l
(3 independent aliquots per formulation; HPLC method)
Details on mating procedure:
Females were "primed" (one male in a wire-mesh cage inside the home cage with 10 females). 48 h later one male placed together with 2 females overnight in a cage; examined for copulation plugs the next morning (GD 0).
Duration of treatment / exposure:
GD 5-15
Frequency of treatment:
once daily
Duration of test:
GD 17
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 70, 140, 280 mg/kg bw
Basis:
actual ingested
No. of animals per sex per dose:
22-29 pregnant mice at sacrifice
Control animals:
yes, sham-exposed
Details on study design:
In a pilot study the dose range for the main study was determined.
Pilot study: 6-8 pregnant mice per dose were gavaged on GD 5-15 once daily with 0, 100, 200, 230, 250, 275, 300, 400 mg/kg bw/day in 4 subgroups and sacrificed on GD 17. Mortality: no deaths up to 250 mg/kg bw/day but 2/13, 5/20 and 2/5 at 275, 300, and 400 mg/kg bw/day, respectively. Developmental effects were detected at >= 200 mg/kg bw/day.

Examinations

Maternal examinations:
Dams weight on GD 0, 6-15 (daily), and 17; clinical signs recorded once daily; necropsy of mice found dead or at termination; at sacrifice liver and gravid uterine weight measured as well as examination of the status of implantation sites.
Ovaries and uterine content:
status of implantation sites determined
Fetal examinations:
fetuses weighed, sexed and examined for external malformations; all live fetuses examined for visceral malformations (Staples, 1974); half of fetuses decapitated and heads fixed in Bouins solution for free hand sectioning and examination (Wilson, 1965); carcasses (50% without head) examined for skeletal malformations (Crary, 1962).
Statistics:
Suitable methods used for each parameter:
Kruskal-Wallis one-way analysis, Mann-Whitney U test, Jonckheere's test, Fisher's Exact test.
Level of significance: p<0.05
Indices:
see results
Historical control data:
available

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
Mortality
31-36 plug-positive mice in each treatment group at GD0; 5 deaths in the high dose group, 4/35 deaths were treatment related (11%); no treatment related deaths in other groups;

Maternal body weight
no effects up to GD 6; during exposure and at sacrifice body weight was significantly decreased at 280 mg/kg bw as well as body weight gain.

Gravid uterine weight
Significantly reduced in the high dose group.

Liver weight
Significant trend with increasing doses (decrease in liver weight) but no significant difference between groups.

Clinical signs
No effects at low dose.
140 mg/kg bw: mild tremor after application on GD 6-8 in all rats but not on subsequent days of treatment.
280 mg/kg bw: tremors, ataxia, lethargy, irritability.
Vaginal bleeding was found in 4 mice but this effect was not clearly treatment related.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
140 mg/kg bw/day (actual dose received)
Basis for effect level:
other: developmental toxicity
Dose descriptor:
NOAEL
Effect level:
140 mg/kg bw/day (actual dose received)
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
No effects on implantation sites. No teratogenic effects (except cleft palate in high dose group). Pregnancy rates at termination were found to be 84%, 84% and 71% in the dosed groups and 83% in the control group (not significant). No effects on sex ratio.

280 mg/kg bw/day: The average fetal body weight per litter was significantly reduced; incidence of cleft palate was increased but did not reach statistical significance (a malformation for which the CD-1 mouse is predisposed under conditions of maternal stress), incidence: 0 in 308 fetuses, 1/290, 1/280, 8/214, respectively.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Embryotoxicity in CD-1 mice following maternal exposure to Phenol

Oral dose in mg/kg bw/day via gavage

Parameter

0

70

140

280

Pregant mice at GD 17

29

26

25

22

Implantation sites per litter

12.1+-0.44

12.0+-0.50

12.3+-0.27

12.4+-0.49

No. of litters with resorptions

16

11

12

14

No. of litters with dead

1

3

4

4

%dead fetuses per litter

12.9+-3.3

8.3+-3.8

9.0+-3.1

23.0+-6.8

Live fetuses per litter

10.6+-0.57

11.6+-0.42

11.2+-0.46

10.7+-0.79

Average fetal body weight

1.026+-0.022

0.989+-0.022

0.996+-0.013

0.842+-0.028*

*: p<0.001

 

Applicant's summary and conclusion

Conclusions:
Development effects like reduced average fetal body weight and cleft palate were detected at dosages of 280 mg/kg bw/day that also led to maternal toxicity. The NOAEL for developmental and maternal effects is 140 mg/kg bw/day.
Executive summary:

The study is comparable to OECD Guideline 414 with acceptable restrictions (food consumption not examined; no data about corpora lutea; minor restrictions: no data about acclimatization of mice or age at initiation).

CD-1 mice received phenol in distilled water via gavage at doses of 0, 70, 140, and 280 mg/kg bw in a volume of 10 ml/kg bw daily during gestation days (GD) 6 -15. 22 -29 pregnant mice per group were sacrificed on GD17. Maternal toxicity was observed at the high dose level including increased mortality (11%), reduced body weight and reduced weight gain as well as clinical signs like tremor and ataxia. No effects were detected on prenatal mortality or the incidence of teratogenic effects in any of the dosed groups, except for an increase in cleft palate at the highest dose level, a malformation for which the CD-1 mouse is predisposed under conditions of maternal stress. At 280 mg phenol/kg bw the mean gravid uterine weight and the average fetal body weight per litter was statistically significantly reduced.

Conclusion: Development effects like reduced average fetal body weight and cleft palate were detected at dosages of 280 mg/kg bw/day that also led to maternal toxicity. The NOAEL for developmental and maternal effects is 140 mg/kg bw/day.