Registration Dossier

Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 January 1997 to 23 June 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1997
Report Date:
1997

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
other: CrI:CD BR VAF/Plus (Sprague-Dawley)
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc., Kingston, New York
- Age at study initiation: 65 days (arrival)
- Weight at study initiation: 217 to 247g (females); 418-934g (males at cohabitation) (Note: Male rats were used only for the purposes of breeding and are
not considered part of the Test System.)
- Housing: Rats were individually housed except during the co-habitation period. During cohabitation, each pair of male and female rats was housed in the male rat's
cage. All cage sizes and housing conditions were in compliance with the Guide for the Care and Use of Laboratory Animals, NIH Publication No. 86-23c8).
- Diet: Rats were given ad /ibHum access to Certified Rodent Diet #5002 (Purina Mills, Inc ) in individual feeders.
- Water: Local water that had been processed by passage through a reverse osmosis membrane CR.O. water) was available to the rats ad /ibitum from an automatic watering system. Chlorine was added to the processed water as a baoteriostat

ENVIRONMENTAL CONDITIONS
- Temperature: 64 - 79°F (±2%);
- Humidity (%):30% to 70% (±3%)
- Air changes (per hr): ten changes per hour of 100% fresh air that had been passed through 99.97% HEPA Biters (Airo Clean rooms)
- Photoperiod: An automatically-controlled fluorescent light cycle was maintained at 12-hours light:12-hours dark, with each dark period beginning at 1900 hours EST.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Formulations of the test article were prepared twice at the Testing Facility. The test article was considered 100% active for the purpose of dosage calculations. Dosages of 0 (Vehicle), 15, 45 and 150 mg/kg bw/day of the test article were administered at a dosage volume of 5 mL/kg, adjusted daily on the basis of the individual body weights recorded before intubation. The rats were intubated once daily at approximately the same time each day.

VEHICLE
- Mazola corn oil from Best Foods Division, CPC International, Inc., USA stored at room temperature.
- Lot/batch no.: 92488
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Recovery: Recovery of the high range validation (10 – 130 mg/mL) varied from 93.7% to 100.6% over the analysis range with a mean of 97.4% ±2.7% RSD. Recovery of the low range validation (2.7 – 35 mg/mL) varied from 94.8% to 104.6% over the analysis range with a mean of 99.4% ±4.1% RSD.

Homogeneity: Homogeneity was determined for the 0, 12, 40, 120 and 400 mg/mLformulations. Mean results from samples taken from the top, middle, and bottom the formulation were calculated. Homogeneity RSD was calculated by determining the percent relative standard deviation of the three mean values. The values obtained were all below 5% RSD except for the 120 mg/mL formulation which had a result of 7.64% This indicates the formulations are homogeneous except for the 120 mg/mL formulation.

Concentration Verification Results:
The musk ketone samples prepared on 02/10/97 which were used for dosing were analysed on 02/11/97. The results were all within ±10% of the theoretical value. There were no of interest found in the vehicle sample (Group I).

The mush ketone samples prepared on 02/18/97, which were used for dosing, and 02/10/97, which were used to determine stability, were analysed on 19/97. The results were all within ±10% of the theoretical value. There were no peaks of interest found in the vehicle samples (Group I).

Refer to Appendix E for further details.

Details on mating procedure:
After acclimation, 215 healthy virgin female rats were placed into cohabitation for a maximum of 5 days with 215 breeder male rats (one male rat per female rat in the male rat cage). Female rats with spermatozoa observed in a smear of the vaginal contents or a copulatory plug in situ were considered to be at DG 0.
Duration of treatment / exposure:
DG 7 -17
Frequency of treatment:
Daily
Duration of test:
Approximately three weeks
Doses / concentrationsopen allclose all
Dose / conc.:
15 mg/kg bw/day (nominal)
Dose / conc.:
45 mg/kg bw/day (nominal)
Dose / conc.:
150 mg/kg bw/day (nominal)
No. of animals per sex per dose:
25 females
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: Oral (gavage) dosage-range developmental toxicity study of musk ketone in rats in "Any other information on materials and methods incl. tables below."

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes - Time schedule: The female rats were observed for viability at least twice each day of the study
and for general appearance twice during acclimation and on DG 0.

DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule: The rats were also examined for clinical observations of effects of the test article before and approximately one hour post-intubation. These observations were also concluded once daily during the post-dosage period (DGs 18 through 20).

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were recorded twice during acclimation, on DG 0 and daily during the dosage and post-dosage periods.

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes
- Feed consumption values were recorded on DGs 0, 7, 10, 12, 15, 18 and 20.

POST-MORTEM EXAMINATIONS: Yes / No / No data
- Sacrifice on gestation day #: All rats were sacrificed by carbon dioxide asphyxiabon on DG 20
- Organs examined: A gross necropsy of the thoracic, abdominal and pelvic viscera was performed. Uteri from rats that appeared non-pregnant were stained with 10% ammonium sulfide) , to confirm the absence of implantation sites. Tissues with gross lesions were preserved in neutral buffered 10% formalin for possible future evaluation; all other maternal tissues were discarded.

OTHER: The rats were also examined for abortions, premature deliveries and deaths before and approximately one hour post-intubation. These observations were also concluded once daily during the post-dosage period (DGs 18 through 20).

Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included: The number of corpora lutea in each ovary was recorded. The uterus of each rat was excised and examined for pregnancy, number and distribution of implantations, live and dead fetuses and early and late resorptions. An early resorption was defined as one in which organogenesis was not grossly evident. A late resorption was defined as one in which the occurrence of organogenesis was grossly evident.

A live fetus was defined as a term fetus that responded to stimuli. Nonresponding term fetuses are considered to be dead (there were no dead fetuses). Dead fetuses and late resorptions are differentiated by the degree of autolysis present; marked to extreme autolysis indicated that the fetus was a late resorption.
Fetal examinations:
Approximately one-half of the fetuses in each liner were examined for soft tissue alterations by using a variation of the microdissection technique of Staples). The heads of these fetuses were fixed in Bouin's solution and subsequently examined by free-hand sectioning; sections were stored in alcohol. The decapitated carcasses were processed and retained in glycerin with thymol added as a preservative.

The remaining fetuses in each liner were eviscerated, cleared, stained with alizarin red S and examined for skeletal alterations. Skeletal preparations were retained in glycerin with thymol added as a preservative.
Statistics:
Clinical observation and other proportion data were analyzed using the Variance Test for Homogeneity of the Binomial Distribution.

Continuous data (e.g., maternal body weights, body weight changes, feed consumption values and litter averages for percent male fetuses, percent resorbed conceptuses, fetal body weights, fetal anomaly data and fetal ossification site data) were analyzed using Bartlett’s Test of Homogeneity of Variances and the Analysis of Variance, when appropriate [i.e., Bartlett's Test was not significant (p>O.05)]. If the Analysis of Variance was signifcant (p≤O.05), Dunnett's Test was used to identify the statistical significance of the individual groups. If the Analysis of Variance was not appropriate [i.e., Bartlett's Test was signi6cant (p≤O.05)], the Kruskal-Wallis Test was used, when less than or equal to 75% ties were present. In cases where the Kruskal-Wallis Test was statistically significant (p≤O.05), Dunn's Method of Multiple Comparisons was used to identify the statistical significance of the individual groups. If there were greater than 75% ties, Fishe’rs Exact Test was used to analyze the data.

Count data obtained at Caesarean-sectioning of the dams were evaluated using the procedures described above for the Kruskal-Wallis Test.
Historical control data:
Historical control data from the period June 1994 - June 1996 for the CD rat is provided in Appendix G.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Increased incidences of dried feces (5/5) and perioral substance (2/25) occurred in the 45 mg/kg bw/day dosage group; these two adverse clinical observations, as well as urine-stained abdominal fur, excessive salivation, dehydration, red substance (presumably blood) on forepaws and tremors occurred in significantly increased numbers (p≤O.01) in the 150 mg/kg bw/day dosage group rats. Two 150 mg/kg bw/day dosage group rats also had chromorhinorrhea or chromodacryorrhea. Effects were first observed on gestation days (DGs) 13 and 7 in the 45 and 150mg/kg bw/day dosage groups, respectively. Urine-stained abdominal fur, perioral substance, dehydration and dried feces continued to occur in a few 150 mg/kg/day dosage group rats during
the postdosage period (DGs 18 to 20). (Summaries - Tables 1 and 2; Individual Data - Tables 14 and 15 in Results_Main study_32108)

All other clinical observations and all necropsy observations were considered unrelated to the test article because: 1) the incidences were not dosage dependent; and/or 2) the observations occurred in only one rat in any dosage group. These observations included chromorhinorrhea or a lesion on the right
forelimb of a control group rat, localized alopecia in a 150 mg/kg bw/day dosage group rat and red perivaginal substance associated with impending delivery In a 150 mg/kg bw/day dosage group rat. The apparent vaginal peripartum bleeding in the 150 mg/kg bw/day dosage group rat (12994) was associated with the presence of approximately 5 mL of red viscous fluid in the left uterine horn and paleness of the placentae in this horn, the liver lobes and cortex of each kidney.


Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
No deaths occurred during the study. All rats survived until scheduled sacrifice.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Dosage dependent, statistically significant (p≤O.05 to p≤O.01) reductions in weight gains for the entire dosage period (calculated as DGs 7 to 18) occurred in the 45 and 150 mg/kg bw/day dosage groups. These effects of the test articlereflected reduced weight gains in the 45 mg/kg bw/day dosage group on DGs 7 to 15 and, in the 150 mg/kg bw/day dosage group, a significant weight loss (p≤O.01) on DGs 7 to 10 followed by significantly reduced (p≤O.05 to p≤O.01) weight gains for the remainder of the dosage period (DGs 10 to 18). These two dosage groups had significant increases (p≤O.05 to p≤O.01) in body weight gains after completion of the dosage period (DGs 18 to 20), rebound phenomena that commonly occur in these types of studies. Despite these rebound phenomena, body weight gains for the entire period after initiation of dosage (DGs 7 to 20) and for the entire pregnancy (DGs O to 20) were reduced in the 45 mg/kg/day dosage group and significantly reduced (p≤O.O1) in the 150 mg/kg bw/day dosage group. Body weights were generally significantly reduced (p≤O.05 to p≤O.O1) on DGs 8 to 20 in the 45 and 150 mg/kg/day dosage groups. (Figure 1; Summaries - Tables 3 and 4; Individual Data - Table 16 in Results_Main study_32108

Body weight gains and body weights were unaffected by the 15 mg/kg/day dosage of the test article.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
The 45 and 150 mg/kg bw/day dosage groups had dosage dependent, statistically significant (p≤O.05 to p≤O.O1) reductions in absolute (g/day) and relative
(g/kg/day, 150 mg/kg bw/day dosage group only) feed consumption values for the entire dosage period (calculated as DGs 7 to 18). These effects of the test
article reflected significantly reduced (p≤O.O1) absolute and relative feed consumption values in the 45 mg/kg bw/day dosage group on DGs 7 to 10 and
throughout the dosage period in the 150 mg/kg bw/day dosage group. After completion of the dosage period (DGs 18 to 20), the 45 and 150 mg/kg bw/day
dosage groups had significant increases (p≤O.05 to p≤O.O1) in absolute and relative feed consumption values, rebound phenomena that commonly occur in
these types of studies. The absence of a dosage-dependency for the absolute feed consumption values reflects the severity of the weight depression in the
150 mg/kg/ bw/day dosage group Despite these rebound phenomena, absolute and relative feed consumption values for the entire period after initiation of dosage (DGs 7 to 20) and for the entire pregnancy (DGs O to 20) were reduced or significantly reduced (p≤O.05 to p≤O.O1) in the 45 and 150 mg/kg bw/day dosage
groups. (Summaries – Tables 5 and 6; Individual Data – Table 17).

The 15 mg/kg bw/day dosage group had a slight, but significant (p≤0.05) reduction in absolute feed consumption (g/day) for the entire period after the first dosage was administered (DGs 7 to 20). This reduction reflected the cumulative effect of small reductions in absolute and relative feed consumption values, primarily on DGs 7 to 10 and to a lesser extent at other intervals. This observation was considered of no toxicological significance because: 1) the value was within 5% of the control group value, and thus not biologically important; and 2) the relative feed consumption value was unaffected.

Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
no effects observed
Description (incidence and severity):
No abortions or premature deliveries occurred during the study.
Pre- and post-implantation loss:
effects observed, treatment-related
Description (incidence and severity):
The 150 mg/kg bw/day dosage was associated with increased post-implantation loss [evident as significant increases (p≤O.05) in the liner averages for total and early resorptions, significantly increased numbers (p≤0.01) of dams and significantly increased numbers (p≤0.01) of dams with any resorptions (18 of 22 vs. 7 of 21), a slight tendency for increased late resorptions and percentage of resorbed conceptuses per liner, and/or dams with all conceptuses dead or resorbed] and significantly reduced (p≤0.01) fetal body weight. The values for the various parameters identifying post-implantation loss generally exceeded the historical
ranges of the Testing Facility but were not sufficiently severe to result in statistically significant or biologically important differences in live litter size. (Summaries - Tables 7 and 8; Individual Data - Tables 18 - 20 in Results_Main study_32108)
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
no effects observed
Changes in pregnancy duration:
no effects observed
Changes in number of pregnant:
effects observed, non-treatment-related
Description (incidence and severity):
Pregnancy incidences were comparable in the four dosage groups (21, 18, 18 and 22 female rats in the four respective dosage groups were pregnant). The non dosage-dependent reductions in pregnancy incidences in the 18 and 48 mg/kg/day dosage groups, as compared with the control and 180 mg/kg/day dosage groups were unrelated to the test article and reflected the random assignment of presumed pregnant dams to the four dosage groups. (Summaries - Tables 7 and 8; Individual Data - Tables 18 - 20 in Results_Main study_32108)
Other effects:
no effects observed
Description (incidence and severity):
All other Caesarean-sectioning and lifter parameters were unaffected by dosages of the test article as high as 45 mg/kg bw/day. No other dosage- dependent statistically significant or biologically important differences occurred in the liner averages for corpora lutea, implantations or percent male fetuses. As previously noted, two 150 mg/kg/day dams (12978 and 12987) had litters consisting of only resorbed conceptuses. There were no dead fetuses. All placentae appeared normal except those in the left uterine horn of the 150 mg/kg/ bw/day dosage group dam (12994) that had peripartum bleeding which appeared pale, as described previously. (Summaries - Tables 7 and 8; Individual Data - Tables 18 - 20 in Results_Main study_32108)

Details on maternal toxic effects:
The maternal NOAEL is 15 mg/kg bw/day. The 45 and 150 mg/kg bw/day dosages were toxic to the dams resulting in adverse clinical observations and reductions in maternal body weight gains, body weights and absolute and relative feed consumption values

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
15 mg/kg bw/day (nominal)
Basis for effect level:
clinical signs
body weight and weight gain
food consumption and compound intake

Maternal abnormalities

Abnormalities:
no effects observed

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
The 150 mg/kg bw/day dosage was associated with increased post-implantation loss and significantly reduced (p≤0.01) fetal body weight. Significant increases (p≤0.08 to p≤0.01) in fetal body weights in the 15 and 45 mg/kg bw/day dosage groups were considered unrelated to the test article because the values were not dosage-dependent and were generally within historical ranges of the Testing Facility. (Summaries - Tables 7 and 8; Individual Data - Tables 18 - 20 in Results_Main study_32108)
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
no effects observed
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
All gross external, soft tissue and skeletal malformations and variations in the fetuses were considered unrelated to the test article. The significant increase (p≤O.01) in the fetal incidence of anasarca (edematous body, p≤O.01) in the 150 mg/kg bw/day dosage group was considered unrelated to the test article because: 1) the litter incidence (two) for this malformation, the more relevant measure, did not significantly differ from the control group value; 2) this malformation was not observed in the range-finding study, in which dams were administered dosages of the test article as high as 2000 mg/kg bw/day; and 3) the high fetal incidence reflects the presence of anasarca in five littermates of the 150 mg/kg bw/day dosage group rat (12994) which had peripartum bleeding, approximately 5 mL of red viscous fluid in the left uterine horn and paleness of the placentae in this horn, the liver lobes and cortex of each kidney, as previously described. This high incidence of anasarca in one litter may indicate a genetic relationship for the malformation; the only other fetus with this malformation was from a different 150 mg/kg bw/day dosage group litter (12982), an incidence within the historical range of the Testing Facility. (Summaries - Tables 7 and 8; Individual Data - Tables 18 - 20 in Results_Main study_32108)

Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Description (incidence and severity):
As previously described, six fetuses (p≤0.01; 12982-3; 12994-9,-11,-12,-13,-15) from two 150 mg/kg bw/day dosage group liners had anasarca. One of these fetuses
(12982-3) also had a variation in sternal ossi6cation (an incompletely ossified Ist sternal centrum). One 15 mg/kg bw/day dosage group fetus (12934-9) had a kinked tail. No additional alterations were revealed by soft tissue examination of this fetus. (Summaries - Tables 9-13; Individual Data - Table 21 in Results_Main study_32108).

No other statistically significant or dosage-dependent increases occurred in the incidences of gross external, soft tissue or skeletal malformations or variations in the fetuses in this study. All other fetal alterations occurred at incidences within the ranges observed historically at this Testing Facility.
Details on embryotoxic / teratogenic effects:
The developmental NOAEL for musk ketone is 45 mg/kg/day. The 150 mg/kg/day dosage was associated with increased post-implantation loss
(total and early resorptions) and reduced fetal body weight. Based on these data, musk ketone is not selectively toxic to development. Adverse effects on embryo-fetal development (post-implantation loss and reduced fetal body weight) occurred only at the higher of two dosages that were toxic to the dams.

Effect levels (fetuses)

Dose descriptor:
NOAEL
Effect level:
45 mg/kg bw/day (nominal)
Basis for effect level:
fetal/pup body weight changes
other: increased postimplantation loss (total and early resorptions)

Fetal abnormalities

Abnormalities:
effects observed, non-treatment-related
Localisation:
other: anasarca at 150 mg/kg bw/day

Overall developmental toxicity

Developmental effects observed:
no
Lowest effective dose / conc.:
45 mg/kg bw/day (nominal)
Treatment related:
no

Applicant's summary and conclusion

Conclusions:
In an oral (gavage) pre-natal developmental study in CrI:CD BR VAF/Plus (Sprague-Dawley) rats, the maternal NOAEL is 15 mg/kg bw/day. The 45 and 150 mg/kg bw/day dosages were toxic to the dams resulting in adverse clinical observations and reductions in maternal body weight gains, body weights and absolute and relative feed consumption values.
The developmental NOAEL is 45 mg/kg/day. The 150 mg/kg bw/day dosage was associated with increased post-implantation loss (total and early resorptions) and reduced fetal body weight. Based on these data, musk ketone is not selectively toxic to development. Adverse effects on embryo-fetal development (post-implantation loss and reduced fetal body weight) occurred only at the higher of two dosages that were toxic to the dams.
Executive summary:

In a developmental toxicity study (32108) musk ketone was administered to 25 female CrI:CD BR VAF/Plus (Sprague-Dawley)/dose in corn oil by gavage at dose levels of 0, 15, 45, 150  mg/kg bw/day from days 7 through 17 of gestation.

No abortions, premature deliveries or deaths occurred during the study. All rats survived until scheduled sacrifice. Increased incidences of dried feces and perioral substance occurred in the 45 mg/kg bw/day dosage group; these two adverse clinical observations, as well as urine-stained abdominal fur, excessive salivation, dehydration, red substance on forepaws and tremors occurred in significantly increased numbers (p≤O.01) in the 150 mg/kg bw/day dosage group rats, and one or two 150 mg/kg bw/day dosage group rats also had chromorhinorrhea or chromodacryorrhea.  Effects were first observed on gestation days (DGs) 13 and 7 in the 45 and 150 mg/kg bw/day dosage groups, respectively.  Urine stained abdominal fur, perioral substance, dehydration and dried feces continued to occur in a few 150 mg/kg bw/day dosage group rats during the postdosage period (DGs 18 to 20).

Dosage-dependent, statistically significant (p≤O.05 to p≤O.01) reductions in weight gains and absolute Cg/day) and relative Cg/kg/day) feed consumption values for the entire dosage period (calculated as DGs 7 to 18) occurred in the 45 and 150 mg/kg bw/day dosage groups.  These effects of the test article were most severe on DGs 7 to 10, when signi6cant weight loss (p≤O.01) occurred in the 150 mg/kg bw/day dosage group.  These two dosage groups had significant increases (p≤O 05 to p≤O.01) in body weight gains and absolute and relative feed consumption values after completion of the dosage period (DGs 18 to 20), rebound phenomena that commonly occur in these types of studies. Despite these rebound phenomena, body weight gains and absolute and relative feed consumption values for the entire period after initiation of dosage (DGs 7 to 20) and for the entire pregnancy (DGs 0 to 20) were reduced or significantly reduced (p≤O.05 to p≤O 01) in the 45 and 150 mg/kg bw/day dosage groups.  Body weights were generally significantly reduced (p≤O.05 to p≤O.01) on DGs 8 through 20 in the 45 and 150 mg/kg bw/day dosage groups.

Pregnancy incidences were comparable in the four dosage groups. The 150 mg/kg bw/day dosage was associated with increased postimplantation loss [evident as significant increases (p≤O.05) in the litter averages for total and early resorptions, a tendency for increased late resorptions and percentage of resorbed conceptuses per litter, and increased numbers of dams with any resorptions or with all conceptuses dead or resorbed] and significantly reduced (p≤O.01) fetal body weight.  The values for the various parameters identifying postimplantation loss generally exceeded the historical ranges of the Testing Facility but were not sufficiently severe to result in statistically significant or biologically important differences in live litter size.  No dosage-dependent, statistically significant or biologically important differences occurred in the litter averages for corpora lutea, implantations or percent male fetuses. Two 150 mg/kg bw/day dams had litters consisting of only resorbed conceptuses.  There were no dead fetuses.  All placentae appeared normal except those of a 150 mg/kg bw/day dosage group dam that had peripartum bleeding, which appeared pale.

All gross external, soft tissue and skeletal malformations and variations in the fetuses were considered unrelated to the test article.

The maternal NOAEL is 15 mg/kg bw/day.  The 45 and 150 mg/kg bw/day dosages were toxic to the dams resulting in adverse clinical observations and reductions in maternal body weight gains, body weights and absolute and relative feed consumption values.

The developmental NOAEL is 45 mg/kg/day.  The 150 mg/kg bw/day dosage was associated with increased post-implantation loss (total and early resorptions) and reduced fetal body weight. Based on these data, musk ketone is not selectively toxic to development. Adverse effects on embryo-fetal development (post-implantation loss and reduced fetal body weight) occurred only at the higher of two dosages that were toxic to the dams.