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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:
1983-12-21 to 1984-06-21
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1984
Report Date:
1984
Reference Type:
publication
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Principles of method if other than guideline:
Method: guideline comparable inhalation teratogenicity test
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Isophorone: batch no. # 3, purity 96.8 % according to correspondence from the sponsor;
- description: pale yellow liquid
- specific gravity: 0.92 at 20°C
- storage: room temperature, under Nitrogen

Test animals

Species:
rat
Strain:
Fischer 344
Details on test animals and environmental conditions:
TEST ORGANISMS
- Source: Harlan Sprague Dawley Inc.
- Age at study initiation: 11 weeks
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 15 days
- Housing: animals were contained in a 12.9 m3 stainless steel and glass chamber and exposed either to conditioned air or to an atmosphere of
isophorone suspended in air

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
other: air
Details on exposure:
ADMINISTRATION / EXPOSURE
- Vehicle: no vehicle
- Concentrations: 0 / 25 / 50 / 115 ppm (corresponds to 0, 144, 289 and 664 mg/m3)
- Type or preparation of particles: vapor
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
All chambers were routinelly sampled on approximately an hourly basis by gas chromatograpgy.
Study mean concentrations as determined by GC were: group I = 0 ppm, group II = 27 ppm, group III = 52 ppm, group IV = 111 ppm

Details on mating procedure:
MATING PROCEDURES: 
Virgin female Fischer rats (approximately 11 weeks of  age) were paired with similar males for mating. Females were confirmed to  have mated by 
observation of a copulatory plug in the vagina or by  observation of sperm in a vaginal rinse. Confirmed mated females were assigned to groups
randomly.
Duration of treatment / exposure:
6th to 15th day of gestation
Frequency of treatment:
6 h/d
Duration of test:
Rats were sacrified by methoxyflurane inhalation and examined by gross necropsy on the 20th day of gestation.
No. of animals per sex per dose:
22 female rats
Control animals:
other: yes, concurrent conditioned air
Details on study design:
Sex: female
Duration of test: section on the 20th d of gestation

Examinations

Maternal examinations:
PARAMETERS ASSESSED DURING STUDY: 
- Body weight gain: each 3rd day
- Food consumption: 3 day intervals
- Clinical observations: each 3rd day

Ovaries and uterine content:
- Examination of uterine content: identified as live fetuses, dead  fetuses, late resorptions, and early resorptions at end of study
(day 20  of gestation). The uterus of each animal was stained in 10 % aqueous  ammonium sulfide and further examined for confirmation of 
implantation  sites. Corpora lutea were counted.
Fetal examinations:
Examination of fetuses: Live and dead fetuses were weighed, examined  externally for gross abnormalities, and crown-rump distances were  
determined. One half of the fetuses from each litter were decapitated, the heads were preserved and subsequently sectioned and examined, viscera
of these fetuses were examined by the Staples technique. All fetuses were eviscerated and processed for skeletal staining . Only those fetuses which
had not been decapitated were examined for skeletal malformations and ossification  variations.
Statistics:
STATISTICAL METHODS: 
- Bartlett's test of homogeneity of variance: body weight, body weight  change, food consumption, number of implantation sites,  ratio of live 
fetuses to implantation sites, ratios of resorptions to implant sites,  malformations per litter.
- Kruskal-Wallis test if variances were not equivalent.
- Standard nested analysis of variance for fetal weights.
Indices:
no data
Historical control data:
no data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
MATERNAL TOXIC EFFECTS BY DOSE LEVEL: 
- Mortality and day of death: no mortalities
- Number pregnant per dose level: 22
- Number of resorptions: no statistically significant differences between  treated and control groups
- Number of implantations: no statistically significant differences  between treated and control groups
- Number of corpora lutea: no statistically significant differences  between treated and control groups
- Duration of Pregnancy: no statistically significant differences between  treated and control groups
- Body weight: reduced in days 12 (-6.1 %) and 15 (-6.8 %) rats in 664  mg/m3 dose group
- Food/water consumption: reduced food consumption in 664 mg/m3 dose group
- Clinical signs: alopecia and cervical or anogenital staining (each  dose-related).

Effect levels (maternal animals)

Dose descriptor:
NOAEC
Effect level:
289 mg/m³ air
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
FETAL DATA: 
No statistically significant differences between treated and control  groups:
- Litter size and weights
- Number viable
- Sex ratio
- Grossly visible abnormalities
- External abnormalities
- Soft tissue abnormalities
- Skeletal abnormalities

Effect levels (fetuses)

Dose descriptor:
NOAEC
Effect level:
>= 664 mg/m³ air
Basis for effect level:
other: teratogenicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

NOAEL (maternal): based on reduced body weight, clinical signs are not considered

Applicant's summary and conclusion

Conclusions:
In this inhalation teratogenicity study with rats, isophorone elicited a clinical effect in the pregnant dams in the form of decreased food consumption
(664 mg/m3, days 6-20 and 0-20), lower body weights (664 mg/m3, days 12 and 15 of gestation), and dose related increases in alopecia and
staining of the cervical and anogenital areas.
During the conduct of the probe study there was one instance of exencephaly noted in a rat fetus. Based on the observations made in this study the
authors do not believe that this anomaly was related to the test material.
Within the framework of the dose levels and test methods used, it is concluded, that isophorne was not teratogenic or fetotoxic in rats.
Executive summary:

Pregnant Fischer 344 rats were treated daily for 6 hours by inhalation (whole body) with isophorone from day 6 to day 15 of gestation to examine potential developmental toxicity effects of the test substance. Dosages used were 0 (conditioned air control), 144, 289 and 664 mg/m3, respectively (22 animals per dose level).

There was a significant reduction in food consumption of rats of the highest dose group. Body weight was also reduced in animals of the highest dose group (gestation day 12: -6.1%; gestation day 15: -6.8%). Additionally, a dose related increase in alopecia was observed, as well as a discoloration of the cervical and aogenital region. Adverse effects on the fetuses were not observed.

Therefore, under the conditions of this inhalation teratogenicity study with rats, the NOAEC for maternal toxicity was determined to be 289 mg/m3 (based on < 7% reduction in body weight gain). Isophorone was neither embryotoxic nor teratogenic up to the highest test concentration of 664 mg/m3 isophorone.