Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

In a two-generation reproduction study, the NOEL for reproductive toxicity was found to be 1500 ppm, i.e. up to 95.45 mg/kg bw/day for males and 107.49 mg/kg bw/day for females.

Link to relevant study records
Reference
Endpoint:
two-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 30 July, 1996 to 18 July, 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EPA OPP 83-4 (Reproduction and Fertility Effects)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Source: Charles River Laboratories, Raleigh, NC, USA
Acclimation Period (F0): Approx 2 weeks
Age at Study Start (F0): Approx 7 weeks
Weight Range at Study Start: Males-198.9 to 254.2 g, females: 168.7 to 199.7 g
Housing for Premating and Growth Phase: Individual suspended stainless steel cages over paper bedding. During mating, females were housed in the cage of the male.
Housing for Gestation through Lactation: Dams were housed in cages with solid bottoms containing appropriate bedding material
Water Availability: Ad libitum
Food Availability: Ad libitum
Light Cycle: 12 h light /12 h darkness
Route of administration:
oral: feed
Details on exposure:
The premix (highest dose level) was prepared weekly by mixing the specified amount of the test substance with approx 300 g of PM1 Certified Rodent #5002 Diet in a Waring blender. The premix was added to the required amount of feed and mixed further using a Hobart HCM-450 mixer. The diets for the lower doses were made by diluting the premix with the appropriate amounts of feed and mixing further.
Details on mating procedure:
-Cohabitation: 1: 1 mating: maximum 21 d. Rehoused with new mate after 14 d. F0 mated once. F1 A mated twice. Different male assigned to pair for F2A and F2B matings.
- Culling (F1A and F2A): Reduce litters to 8 pups at lactation Day 4
- Pup selection: Random selection for F1A of up to 2 pups/sex/litter on postnatal Day 21 (random number table)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Neat test substance stability: Gas chromatography (GC) using an electron capture detector. Comparison was made to an added analytical reference standard.
Homogeneity of diet mixtures: Analysis of duplicate diet samples from the 15, 150 and 1500 ppm levels taken from the top, middle and bottom of the mixer was performed.
Diet mixture stability: Samples from the 15 and 1500 ppm levels were kept at room temperature (in an open container for 7 and 21 d) or frozen (in a closed container for 35 d) and analyzed. Dietary stability was repeated after completion of the in-life phase of the study to confirm that the variability in results was due to instability in the extraction medium and not instability in the diet.
Verification of dietary concentration: Dietary concentrations from at least one sample/week were verified throughout the study.
Duration of treatment / exposure:
Throughout 2-generation
Frequency of treatment:
Ad libitum
Details on study schedule:
After approx 10 or 11 weeks of administration (F0 and F1A generation, respectively), males and females were paired (1 : 1) for mating. Females were allowed to litter and rear their offspring to weaning. Litter size was standardised to eight pups (four/sex, where possible) on Day 4 post-partum. After weaning (Day 21 post-partum), F1A pups were selected to represent the F1A generation. F1A adults produced two litters; the second litter (F2B) was produced because a low pregnancy rate was observed in the control group from the first F1A mating. Offspring from the second F1A mating were sacrificed immediately after birth, without necropsy. Selected organs/tissues were weighed and preserved from adult animals in both generations. Culled pups, weanling F1A offspring not selected for the F1A generation and, all weanling F2A pups were subject to a gross necropsy.
Remarks:
Doses / Concentrations:
0, 15, 150 and 1500 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
0, 0.96, 9.68, 95.45 and 0, 1.11, 10.96. 107.49 mg/kg/day for F0 males and females, respectively
Basis:
actual ingested
Remarks:
Doses / Concentrations:
0, 0.89, 8.97 and 92.39 and 0, 1.07, 10.67 and 106.42 mg/kg/day for F1A males and females, respectively
Basis:
actual ingested
No. of animals per sex per dose:
30/sex/dose
Control animals:
yes, plain diet
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once weekly

BODY WEIGHT: Yes
- Time schedule for examinations: Adult males - once weekly (throughout dietary exposure); adult females - weekly until beginning of mating, then on Days 0,7, 14, 21 of gestation and lactation when copulation and/or delivery were confumed. Females were weighed again at least once prior to necropsy, following the last possible delivery date. Fl A and F2A pups were weighed on Days 0, 4 (pm and post-culling), 7, 14 and 21 of lactation. F2B pups were humanely sacrificed immediately after birth without weighing.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Adult males - weekly until mating; adult females - weekly until mating. After copulation was confirmed. maternal food consumption was measured for Days 0-7, 7- 14 and 14-21 of gestation and lactation.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

Sperm parameters (parental animals):
Parameters examined in [P] male parental generations: Testis weight, epididymis weight
Litter observations:
Pup counts and observations: In the F0 and first F1A mating, the number of pups was counted and recorded on postnatal day (PND) 0 (live and dead), 4 pre- and post-cull, 7, 14 and 21. The sex of live pups was determined. Observations for abnormal behavior or development were recorded if noted. In the second F1A mating, the total number of pups of each sex was counted but it was not determined whether the pups were born alive. Missing pups were presumed cannibalized.
Culling of litters: On PND 4, litters were culled randomly to eight pups, maintaining equal numbers of each sex where possible (unless fewer than 8 pups were alive or if there were fewer than 4 of either sex).
Weaning of pups: On PND 21, at least 1 but not more than 2 pups/sex/litter were selected randomly (using random number tables) from F1A litters to provide 30 pups/sex/group for the next parental generation. The remaining pups were humanely euthanized and given a complete necropsy. All F2A pups were humanely euthanized following weaning on PND 21 and given a complete necropsy. All F2B pups were humanely euthanized and discarded without necropsy immediately after birth.
Postmortem examinations (parental animals):
Gross Pathology:
-Unscheduled necropsies: Adults that died or were sacrificed in a moribund condition were given a gross necropsy, and tissues listed below were saved. F1A and F2A pups found dead were given a gross necropsy but no tissues were saved. In order to establish if a dead pup was born dead or died after birth, lung tissue was examined to determine if breathing had occurred. No organs were weighed at unscheduled necropsies. There was no necropsy of the F2B pups.
-Scheduled sacrifice: A gross necropsy was performed on all surviving adults. Culled pups, weanling F1A pups not selected for mating, and all F2A weanling pups were examined grossly.
-Extent of examination: External and internal. Internal cavities were opened, and organs were examined in place and then removed. Hollow organs were opened and examined. Organs Weighed (Scheduled Sacrifice of Adults): Testes, ovaries, kidneys and liver were weighed from the adults. All adults were fasted prior to scheduled necropsy.
-Tissues retained: Adults (unscheduled deaths and scheduled sacrifice) – coagulating gland, ovaries (with oviducts), pituitary, prostate, seminal vesicles, skin/mammary gland, testes, epididymides, uterus (corpus. cervix/vagina), kidneys, liver, spleen, adrenals, brain, thymus and gross lesions; weanlings - tissues were saved at the discretion of the trained necropsist. In addition, lungs were saved from F1A adults.
-Fixatives: Testes: Bouin’s fixative; Other tissues: 10% buffered neutral formalin

Histopathology:
-Tissues examined: Retained tissues were examined from adults rats in the control and highest dietary level groups. In addition, liver was examined from males and females in all groups, epididymides were examined from all males, and kidneys from females in all groups. Lung sections were examined from F0 adults with grossly observed lesions in that tissue and from all F1A adults.
-Tissue Preparation: Tissues were rinsed, dehydrated, embedded in paraffin, and sectioned at approx 5 microns. Prepared slides were stained with hematoxylin and eosin.
-Examination: Light microscopy
Postmortem examinations (offspring):
Necropsy observations consisted largely of postmortem changes such as autolysis and cannibalization.
Statistics:
The following statistical procedures were used to detect statistically significant differences between treated animals and their respective controls:
-Dunnett’s multiple comparison test (two-tailed): In life body weights, cumulative body weight changes, and food consumption data. EHL decision-tree analysis (two-tailed): Non-categorical reproductive parameters (precoital length, gestational length, litter size, pup weights, dead pups/litter, pup survival), terminal body weights, absolute organ weights, and organ/body weight ratios were evaluated by decision-tree statistical analyses which, depending on the results of tests for normality and homogeneity of variances, utilized either parametric Dunnett’s Test and linear regression or nonparametric [Kruskal-Wallis, Jonckheere’s and/or Mann-Whitney Tests] routines to detect differences and analyze for trend.
-Uncorrected chi-square test: Categorical reproductive parameters (copulation, pregnancy. mating and fertility indices).
-Fisher’s exact test (one-tailed): Incidence of microscopic lesions. Prior to statistical analysis, a computer algorithm was applied with the intent of excluding from the analysis those data for which statistical analysis was inappropriate. An example of this would be a gross lesion examined microscopically in tissues not otherwise required by protocol. Grubbs’ test was used to detect outliers in organ weight data. Outliers were excluded from statistical analysis, if deemed appropriate by the study pathologist. All statistical tests to detect differences between treated groups and their respective controls and for trend were performed at the p≤0.05 and p≤0.01 levels of significance.
Reproductive indices:
Measured reproduction parameters included mating and fertility indices, pup-survival indices, maternal (gestation and lactation) and offspring body weights, and maternal (gestation and lactation) food consumption.
Offspring viability indices:
Yes
Clinical signs:
no effects observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Other effects:
effects observed, treatment-related
Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed
Body weight:
-Adults: In the F0 generation, reductions in mean weekly body weights or weight changes in males and females at the 1500 ppm level were attributed to treatment. In females the differences were statistically significant beginning in Week 3. The differences in cumulative weight gain for males fed 1500 ppm diets were slight (less than 10%), but statistically significant for males in Weeks 6, 20 and 21 and slight to moderate for females at the same dietary level (9.6-17.3%). The differences for females were statistically significant from Week 2 through the end of the 10 week premating period and in the last weighing period before sacrifice. In the F1A generation, significant differences in adult mean weekly body weights were observed in the 1500 ppm group males but not females after the 5th week of the growth phase and continuing through to the end of the study. In females, the mean body weights were similar at the 1500 ppm level to the controls with no statistically significant differences. There were significant differences in cumulative weight gains in the 1500 ppm level males group from the start of the growth phase and continuing through the 11 week premating period. In females the cumulative weight gain was significantly lower at the 1500 ppm level in the last three weeks of the premating period (up to 15.9% lower than control) as well as following the first mating (14.7% lower than control).
-Maternal - gestation and lactation: Treatment-related reductions in maternal body weights were apparent in the 1500 ppm level females in the F0 generation but not in the F1A generation during gestation and lactation. In F0 females although slight (8% or less), the differences in mean maternal weights during gestation and lactation were statistically significantly lower than controls. The mean maternal weight gains of the 1500 ppm level dams were different from control for Postnatal Day (PND) 0-7 interval and PND 14-21 interval, with the overall mean weight change for the lactation period greater at the 1500 ppm level (approx 19.23 g gain) than in control (approx 13.60 g loss). In the F1A generation the mean weights of treated groups were occasionally higher than control with no dose response and without relationship to treatment. The mean weight of the dams from the 150 ppm group was statistically significantly increased in the second mating of the F1A generation; however, this was not considered treatment-related based on the direction of change and the lack of a dose response.

Food Consumption:
-Adults: In the F0 generation, food consumption of males was generally similar in all groups after Week 1. Food consumption of the 1500 ppm level females was slightly (less than 10%) but consistently lower than controls throughout the 10 week growth phase with the differences statistically significant at Weeks 1, 3, 5, and 6. In the F1A growth phase, slight but significant differences in mean daily food consumption were seen in Weeks 7-11 at the 1500 ppm level in males. In F1A females, mean daily intake was variable with no treatment-related effects apparent.
-Maternal - gestation and lactation: There were no treatment related effects on maternal food consumption in any of the mating of either generation. Calculated daily and weekly food consumption in the F0 generation was reduced in the 1500 ppm level females during gestation and lactation. However, the differences were not consistent or clearly treatment related. Statistically significant reductions which occurred onn GD 0-7 and PND 7- 14 were considered spurious. In the F1A mating, significant differences in mean food consumption occurred during both gestation periods with no consistent pattern indicative of a treatment-related effect. During lactation, there were significant differences in the second week of lactation between the mid and high level groups and control that showed no dose response.

Chemical Consumption: Chemical consumption for the F0 premating period was estimated, based on weekly body weights, measured food consumption and target concentrations, to be 0, 0.96, 9.68 and 95.45 mg/kg bw/day for males and 0. 1.11. 10.96 and 107.49 mg/kg bw/day for females from the control, T1, T 2 and T3 groups, respectively. In the F1A premating period, the chemical consumption was estimated to be 0, 0.89, 8.97, and 92.39 mg/kg bw/day for males and 0, 1.07, 10.67, and 106.42 mg/kg bw/day for females.

Clinical Signs: There were no clinical signs in adults or offspring considered related to test substance exposure. There were incidents of malocclusion and injury to teeth that led to signs of perinasal encrustation and eye discharge that were not associated with treatment, but led to early termination of two males (M2 002 and M3 002). Another male, M2 024, had signs of malocclusion (periorbital and perinasal encrustation) but soft stool and decreased defecation lead to its early demise. The isolated occurrence of these findings indicated that these were not treatment related. No clinical signs were observed prior to the death of F1A male M2 067. In the F0 and the F1A generation, other observations were those commonly seen in rats of this age and strain.

Mortality adults: There were no deaths attributed to exposure to the test substance. In the F0 generation, two parental males, M2 002 and M3 002, were sacrificed and removed from the study following injury to their teeth. These deaths were considered non-test related. A third male, M2 024 was sacrificed in extremis. This death was also associated with malocclusion, and did not appear to be treatment related. A parental female, F3 012 was found dead. There were retained few placental remnants in the uterus and the death was associated with difficulty in delivering pups and not considered treatment related. Unscheduled deaths in the F1A generation were M2 067 and F2 055. The pups from the litter of F2 055 were also humanely euthanized following the moribund sacrifice of the dam.

Mating and fertility: There were no treatment-related effects on mating or fertility in this study. Significant differences in the pregnancy rates and male copulation indices, based both on the total group population (pregnant/total paired) and based on the number of matings confirmed (pregnant/confirmed copulation) were attributed to low rates in the control and not to treatment. Similarly, a significant increase in precoital length at the 1500 ppm level in the second F1A mating was reflective of the longer than expected control time. There was no indication of a dose response in any of the fertility parameters. In the F0 mating, the F3 female that died (F3 012) during delivering a litter was excluded from statistical evaluation of maternal data because the data were incomplete.

Pathology: Increases in absolute and relative kidney and liver weights were observed at the 1500 ppm level in males and/or females. The mean absolute kidney weight of F0 females and F1A males and females was slightly increased over controls. The difference was statistically significant and was considered toxicologically significant. The slight increase in the kidney/body weight ratio in both males and females at the 1500 ppm level was associated with a slight and statistically decreased terminal body weights. At the 150 ppm level, relative kidney weights were minimally increased over control. Absolute liver weights and liver/body weight ratios were statistically significantly increased in F0 and F1A adult males and females at the 1500 ppm level. At the 150 ppm level, increase absolute liver weights were observed in F1A females and relative liver weights observed in F1A males. Although statistically significant, the relationship of these increase organ weights to treatment is equivocal. The changes in organ weights were small (less than 10%) were not associated with any gross or microscopic pathology and therefore not considered an adverse finding. Similarly, a statistically significant increase in ovary weights in the F0 1500 ppm group females was observed which was not associated with any gross or microscopic pathology. Grossly visible enlargement of the liver of the 1500 ppm level males was the only necropsy finding attributed to treatment in the F0 parents. Enlargement of the livers in males from the 150 ppm level were not confirmed by increases in liver weights. Lung foci (white/gray) observed in animals of both sexes from all groups were attributed to a subclinical infectious process of unknown etiology which had no other effects on the study. Although the incidence in F0 control males was lower than F0 male treated groups, the incidence in F0 control females and in all Fl A adults equaled or exceeded the incidence in female treated groups+ supporting the conclusion of no treatment effect. In weanlings, the only remarkable finding was described as a mass in the liver of a low level male from the F1A generation and one hydrocephalus weanling pup in the F2A generation. Based on the isolated occurrence, these were considered spontaneous lesions, not attributed to treatment. Dilated renal pelves occurred in pups from the control and each of the treated groups and were considered incidental.

Microscopic pathology: Histomorphologic changes in the kidney and liver were observed in males and females from both the F0 and F1A parental generations at the 1500 ppm level. In the kidney, a significant increase in the incidence of nephropathy was observed in F0 females and F1A males and females at the 1500 ppm level, although the incidence in males was only minimally increased over controls. In the liver, bile ductule proliferation/cholangiofibrosis in males (F0); portal pigment deposition in males and females, and mononuclear cell infiltrate in the portal region (males): and hepatocellular hypertrophy in the periportal region were seen in one or both generations at 1500 ppm. Portal fibrosis and hepatocellular necrosis in both F0 and F1A females, as well as eosinophilic foci (F1A) were attributed to treatment. There were no treatment-related alterations in the reproductive organs. Pigment deposition in the uterus is an expected change in postpartum female rats. A slight increase in the control group compared with the 1500 ppm group was attributed to fortuitous sectioning and not considered a toxic change. Findings in those lungs examined from the F0 generation that were associated with the white foci observed grossly included the presence of interstitial pneumonia and mononuclear cell infiltrate in the perivascular region of the lungs males. There was an accumulation of macrophages in the lungs of females. Lungs of Fl A adults were examined from the control and high level group males and females with gross lesions. Interstitial infiltrate/pneumonia, perivascular mononuclear cell infiltrate/pleural fibrosis and an accumulation of alveolar macrophages were among the findings that occurred with low frequency and generally were at a higher incidence in the control than in test groups.
Dose descriptor:
NOEL
Effect level:
150 ppm (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
food consumption and compound intake
Critical effects observed:
yes
Lowest effective dose / conc.:
1 500 ppm
Organ:
kidney
liver
Treatment related:
yes
Dose response relationship:
not specified
Dose descriptor:
NOEL
Effect level:
150 ppm (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic
Critical effects observed:
yes
Lowest effective dose / conc.:
1 500 ppm
Organ:
kidney
liver
Treatment related:
yes
Dose response relationship:
not specified
Clinical signs:
not specified
Mortality / viability:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
no effects observed
Histopathological findings:
not specified
Litter Size, pup survival and growth: There were no adverse treatment-related effects on litter size or viability (the number of dead pups per litter) in either generation. Mean offspring survival was greater than 96% in control and treated groups both pre- and post culling in both generations. In the F0 generation, the mean number of females per litter in the 150 ppm level group was significantly greater than control at birth, but there were no significant differences in the F1A generation. The historical range of percent male pups per litter is 39 to 59.5% therefore this slight increase in the F0 generation was within expected range and attributed to biological variation. Treatment-related effects on weights of both the F0 and F1A generations occurred at the1500 ppm level at or after PND 4. In the F1A pups (F0 offspring), mean weights of 1500 ppm level males, females and both sexes combined were significantly lower than controls beginning at PND 4 and continuing to PND 21. In the second generation, the F2A pups (F1A offspring) had significant reductions in pup weights which occurred at PND 14 and 21. These reductions in mean pup weight at the high level were attributed to treatment. The mean weights of first generation female pups in the 150 ppm level group were significantly lower than control at PND 4 (postcull) only. This was not attributed to treatment based on its isolated occurrence.
Gross necropsy findings for culled pups and unscheduled deaths: There was no treatment-related gross necropsy findings in culled pups or pups found dead. Necropsy observations consisted largely of postmortem changes such as autolysis and cannibalization.
Dose descriptor:
NOEL
Generation:
F1a
Effect level:
150 ppm (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
Dose descriptor:
NOEL
Generation:
F2a
Effect level:
150 ppm (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
body weight and weight gain
Reproductive effects observed:
no
Conclusions:
Under the test conditions, the NOEL of MON 13900 for reproductive toxicity was 1500 ppm or up to 95.45 mg/kg bw/day for males and up to 107.49 mg/kg bw/day for females.
Executive summary:

A two-generation reproduction study was conducted to determine the effects of MON 13900 on growth, mating, gestation and lactation in rats according to the EPA OPP 83-4 Guideline in compliance with GLP.

 

30 Sprague-Dawley rats/sex/group were fed diets containing target levels of 0, 15, 150 and 1500 ppm of the test substance. After approx 10 weeks in the F0 generation and 11 weeks in the F1A generation, the males and females within each group were mated to produce the next generation. Pups were weaned at 21 d of age and pups from the F1A litters were selected to become the second parental generation. Because of a low pregnancy rate in the control group after mating for the F2A generation, all F1A adults were remated to produce F2B litters. Adults were sacrificed after completion of the gestation or lactation periods. Complete necropsies were performed on adults, and selected tissues were weighed and retained. F1A weanlings not selected for mating and all F2A weanlings were sacrificed and necropsied. F2B pups were not necropsied. Parental survival, body weights, food consumption, clinical observations, absolute and relative weights of specified organs, and gross pathology were evaluated for treatment-related effects. Histopathologic evaluation of specified tissues from adults was performed. Measured reproduction parameters included mating and fertility-indices, pup-survival indices, maternal (gestation and lactation) and offspring body weights, and maternal (gestation and lactation) food consumption.

 

Treatment-related effects at the 1500 ppm concentration were reductions in mean body weights, cumulative body weight gains, gestational weight gains, lactation weight gains and food consumption in adults. There were no effects on mating, fertility or offspring survival. The pup mean weights of F1A pups were significantly reduced, beginning at postnatal day (PND) 4 and F2A pups had reduced weights beginning at PND 14 in litters from the 1500 ppm group. Increases in absolute and relative liver and kidney weights and grossly enlarged livers were observed at 1500 ppm in F0 and F1A males and/or females. Microscopic findings in the liver included bile ductile proliferation /cholangiofibrosis (F0 males); portal pigment deposition (males and females); mononuclear cell infiltrate in the portal region and periportal hepatocellular hypertrophy (males); and hepatocellular necrosis, portal fibrosis and eosinophilic focus (F1A females) at the 1500 ppm level. In the kidneys, increased nephropathy occurred in males and females from the 1500 ppm group. There were no treatment-related effects on reproductive performance or offspring survival.

 

Under the test conditions, the NOEL for reproductive toxicity was 1500 ppm or up to 95.45 mg/kg bw/day for males and up to 107.49 mg/kg bw/day for females.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
95.45 mg/kg bw/day
Study duration:
chronic
Species:
rat
Quality of whole database:
The information requirements for this tonnage band is sufficiently met with the available data.
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

A two-generation reproduction study was conducted to determine the effects of MON 13900 on growth, mating, gestation and lactation in rats according to EPA OPP 83-4 Guideline in compliance with GLP. Thirty Sprague-Dawley rats/sex/group were fed diets containing target levels of 0, 15, 150 and 1500 ppm of the test substance. After approximately 10 weeks in the F0 generation and 11 weeks in the F1A generation, the males and females within each group were mated to produce the next generation. Pups were weaned at 21 d of age and pups from the F1A litters were selected to become the second parental generation. Because of a low pregnancy rate in the control group after mating for the F2A generation, all F1A adults were remated to produce F2B litters. Adults were sacrificed after completion of the gestation or lactation periods. Complete necropsies were performed on adults, and selected tissues were weighed and retained. F1A weanlings not selected for mating and all F2A weanlings were sacrificed and necropsied. F2B pups were not necropsied. Parental survival, body weights, food consumption, clinical observations, absolute and relative weights of specified organs, and gross pathology were evaluated for treatment-related effects. Histopathologic evaluation of specified tissues from adults was performed. Measured reproduction parameters included mating and fertility indices, pup survival indices, maternal (gestation and lactation) and offspring body weights, and maternal (gestation and lactation) food consumption. Treatment-related effects at 1,500 ppm were reductions in mean body weights, cumulative body weight gains, gestational weight gains, lactation weight gains and food consumption in adults. There were no effects on mating, fertility or offspring survival. The pup mean weights of F1A pups were significantly reduced, beginning at postnatal day (PND) 4 and F2A pups had reduced weights beginning at PND 14 in litters from the 1,500 ppm group. Increases in absolute and relative liver and kidney weights and grossly enlarged livers were observed at 1,500 ppm in F0 and F1A males and/or females. Microscopic findings in the liver included bile ductile proliferation /cholangiofibrosis (F0 males), portal pigment deposition (males and females), mononuclear cell infiltrate in the portal region and periportal hepatocellular hypertrophy (males) and hepatocellular necrosis, portal fibrosis and eosinophilic focus (F1A females) at 1,500 ppm. In the kidneys, increased nephropathy occurred in males and females from the 1,500 ppm group. There were no treatment-related effects on reproductive performance or offspring survival. Under the test conditions, the NOEL for reproductive toxicity was 1,500 ppm, i.e. up to 95.45 mg/kg bw/day for males and 107.49 mg/kg bw/day for females.

Effects on developmental toxicity

Description of key information

In a pre-natal developmental toxicity study with rats, the NOEL for developmental toxicity was 75 mg/kg bw/day and the NOEL for maternal toxicity was 10 mg/kg bw/day.

According to the OECD TG 414 the test substance was suspended in 0.5% aqueous methylcellulose and administered daily by gavage (5 ml/kg) to 4 groups of 20 artificially inseminated New Zealand White rabbits during gestation days 7 through 19. Dose levels were 0, 2, 10 and 50 mg/kg/day.

The test substance produced maternal toxicity at the highest dose level tested, 50 mg/kg/day, as indicated by weight loss and decreased food consumption. Slight developmental toxicity, as indicated by slightly increased postimplantation loss and slightly decreased fetal weights, was seen in the 50 mg/kg/day dose group. There were no developmental malformations associated with exposure to the test substance. The No Observable Effect Level (NOEL) for maternal and developmental toxicity was therefore 10 mg/kg/day.

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March - April 1990
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no
Species:
rat
Strain:
other: Crl:CD BR Sprague-Dawley
Details on test animals and environmental conditions:
Source: Charles River Breeding Laboratories, Inc., Portage, MI
Age: 83 days on first day of mating
Weight: 206-276 g on GD 0
Males used: Resident, untreated, sexually mature
Animal husbandry: Food (#5002: Purina Certified Rodent Chow) and tap water were available ad libitum throughout the study. A 12-h light/dark cycle was maintained. Temperature and humidity ranges were 70-75°F and 33-74%, respectively. Fresh air changes were 10-15/h.
Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
Doses were administered daily via gavage from GD 6 through 15 in a volume of 5 mL/kg. The most recently recorded body weights were used to calculate the concentration of the doses. Dosing suspensions were not adjusted for active ingredient; were prepared once during the study; and were stored at room temperature. Prior to study initiation, homogeneity (low- and high-dose groups) and concentration (all dose groups) of the test substance in the vehicle were determined. Stability (low- and high-dose groups) was determined at the end of the study by analyzing the suspensions on the last day of dosing. Duplicate samples of the dosing solutions were analyzed by gas chromatography/flame ionization detection.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The concentrations of all dose levels were verified analytically prior to the initiation of dosing. Duplicate samples of the dosing solutions were analyzed by gas chromatography/flame ionization detection.
Details on mating procedure:
Following 12 d of acclimatization, females were mated 1:1 with males of the same strain and source. Females were checked daily for the presence of vaginal sperm or a (copulatory plug). The day on which mating was confirmed was designated Day 0 of gestation.
Duration of treatment / exposure:
GD 6 through 15, inclusive
Frequency of treatment:
Single daily dose
Duration of test:
10 d
Remarks:
Doses / Concentrations:
0, 10, 75, and 175 mg/kg bw/day
Basis:
nominal conc.
No. of animals per sex per dose:
25/female/group
Control animals:
yes, concurrent vehicle
Details on study design:
Concentrations of the doses were selected based upon the results of a range-finding study conducted in the same strain of eight mated rats per group at dose levels of 0, 10, 25, 75, or 150 mg/kg bw/day. In the range-finding study, maternal toxicity, evident at 150 mg/kg bw/day, was manifested as increased liver weight and clinical signs and slightly (non-significant) decreased body weight gain from GD 6 through 9. Developmental toxicity was not observed.
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS: Yes

BODY WEIGHT: Yes

FOOD CONSUMPTION: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation Day 20
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
Fetal examinations:
- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
- Head examinations: Yes
Statistics:
-Maternal body weight and bodyweight change, fetal body weight, food consumption, gravid uterus and organ weights, and numbers of corpora
lutea, implantation sites, and live fetuses--ANOVA and Dunnett’s test
-Litter proportions of intra-uterine data--Kruskal Wallis test
-Early and late resorption, dead fetuses, postimplantation losses-Mann-Whitney U-test
-Fetal sex ratios--Chi-square test with Yate’s correction factor
-Malformations and variations--Fischer’s exact test
Historical control data:
Yes
Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
A body weight loss was recorded in animals at 175 mg/kg bw/day for the first three days of treatment, and a moderate decrease in body weight gain was observed for the overall treatment period. Gravid uterine weights were slightly decreased at the high dose compared to control. Food consumption was severely decreased at 175 mg/kg bw/day during the first 3 d of treatment, but returned to near control levels for the remainder of the study. Body weights and food consumption were unaffected at 10 and 75 mg/kg bw/day. Other evidence of maternal toxicity at 175 mg/kg bw/day included hair loss on various body surfaces and decreased defection and urination. No treatment-related clinical signs were observed at 10 and 75 mg/kg bw/day.
Dose descriptor:
dose level: 175 mg/kg bw
Effect level:
175 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
clinical signs
body weight and weight gain
food consumption and compound intake
organ weights and organ / body weight ratios
early or late resorptions
Dose descriptor:
LOEL
Effect level:
75 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
organ weights and organ / body weight ratios
early or late resorptions
Dose descriptor:
NOEL
Effect level:
10 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
organ weights and organ / body weight ratios
Abnormalities:
not specified
Localisation:
not specified
Details on embryotoxic / teratogenic effects:
Details on embryotoxic / teratogenic effects:
Fetal body weights were slightly decreased at 175 mg/kg bw/day. No effects on fetal body weight were observed at other dose levels. Post implantation loss was increased at 75 and 175 mg/kg bw/day (1.0 and 1.3 postimplantation losses/dam, respectively) compared to the concurrent control value (0.5 losses/dam). However, both treatment values were within historical control range. Twenty percent of the historical control studies had post-implantation values equal to or greater than the value at 75 mg/kg bw/day. Therefore, the effect at 75 mg/kg bw/day was not considered related to treatment. The post-implantation loss at 175 mg/kg bw/day was at the upper end of the historical control range and only 3% of the studies had equal or greater values. The effect at 175 mg/kg bw/day was considered equivocal. There were no treatment-related effects on the number of implantations, fetal viability or sex ratios at any dose level. Total malformations (external, visceral and skeletal) occurred in 2, 5, 0, and 7 fetuses in 2, 4, 0 and 5 litters from the 0, 10, 75 and 175 mg/kg bw/day groups, respectively. The fetal and litter incidence rates at the high dose were not statistically higher than concurrent control, but were outside of historical control range. The malformations observed at 175 mg/kg bw/day was primarily observed in three of the seven affected fetuses and no single malformation was statistically increased compared to control. A dose of 175 mg/kg bw/day was considered to have produced an equivocal effect on malformations. The malformation incidence observed at 10 mg/kg bw/day was not considered related to treatment due to the lack of an effect at 75 mg/kg bw/day. Several external malformations occurred with a single incidence at the high dose only including: umbilical herniation of the intestine, fetal anasarca, micromelia, bradydactyly, omphalocele and tarsal flexure. Five fetuses in three litters at 175 mg/kg bw/day exhibited tail anomalies (curly, filamentous or bent). Visceral malformations observed as a single incidence at the high dose and not seen in the control were situs inversus and interrupted aortic arch. Malpositioned uteri and ovaries were noted in two high dose fetuses in two litters, and this litter incidence was outside of historical control range. The skeletal malformation, vertebral agenesis, occurred in two fetuses in two litters at the high dose, and this litter incidence was outside of historical control range. There were no external variations in any group, and there were no visceral variations considered related to treatment. One skeletal variation, sternebrae #1, 2, 3 and/or 4 unossified was increased in incidence for fetuses and litters at the high dose. There were no treatment-related increases in skeletal variations at lower dose levels.
Dose descriptor:
LOEL
Effect level:
175 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
not specified
Basis for effect level:
fetal/pup body weight changes
other: delayed ossification in the sternebrae at a significantly increased litter rate
Dose descriptor:
NOEL
Effect level:
75 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
not specified
Basis for effect level:
fetal/pup body weight changes
other: specific malformations
Abnormalities:
effects observed, treatment-related
Localisation:
other: An equivocal increase in the incidence of total (external, visceral and skeletal) malformations and an increase in one skeletal variation (vertebral agenesis)
Developmental effects observed:
yes
Lowest effective dose / conc.:
175 mg/kg bw/day (actual dose received)
Treatment related:
yes
Relation to maternal toxicity:
developmental effects as a secondary non-specific consequence of maternal toxicity effects

Test substance analysis: Analysis conducted on dosing suspensions for concentration and homogeneity ranged from 93.4% to 100% of target. Stability of low and high-dose suspensions after 20 d in room temperature revealed values from 84.3% to 106% of target.

Conclusions:
Under the conditions of the study, the NOELs of MON 13900 for maternal and developmental toxicity were found to be 10 and 75 mg/kg bw/day, respectively in rats.
Executive summary:

A study was to evaluate the developmental toxicity potential of MON 13900 according to the EPA OPP 83-3 Guideline in compliance with GLP.

 

The test substance in the vehicle, corn oil, was administered orally by gavage once daily at the dose levels of 0, 10, 75, and 175 mg/kg bw/day to 4 groups of 25 mated female Charles River CD(SD)BR rats during gestation days 6 through 15. These dose levels were selected based on results from a pilot rat teratology study. Analytical concentrations of the test substance were acceptably close to target levels. Homogeneity and stability of dosing solutions were also acceptable. Maternal toxicity was evidenced at 175 mg/kg bw/day by an initial body weight loss and a decreased body weight gain for the overall treatment period, by various clinical signs and by increased liver weights. Liver weights were also increased at 75 mg/kg bw/day. Developmental toxicity was indicated at 175 mg/kg bw/day by decreased fetal weights, an equivocal increase in post-implantation loss, an equivocal increase in the incidence of total (external, visceral and skeletal) malformations and an increase in one skeletal variation.

Therefore, the NOEL for developmental toxicity was 75 mg/kg bw/day and the NOEL for maternal toxicity was 10 mg/kg bw/day.

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
June - July 1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EPA OPP 83-3 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
May 12, 1981
GLP compliance:
yes (incl. certificate)
Limit test:
no
Specific details on test material used for the study:
For the purposes of dose calculation the test material was considered to be 100% MON 13900.
- Final preparation of a solid: suspension
Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
- Source: Hazleton Research Products, Inc., Denver, Pennsylvania,
- Age upon receipt: 7 months
- Weight at study initiation: approx. 3900 gr
- Fasting period before study: restricted to approx. 150 g/animal/day during acclimation period
- Housing: individually in clean, stainless-steel wire bottom cages suspended above ground corn cob bedding
- Diet (e.g. ad libitum): yes
- Water (e.g. ad libitum): yes
- Acclimation period: six weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 68 - 72
- Humidity (%): 54-90%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:
oral: gavage
Vehicle:
other: 0.5% aqueous methylcellulose
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
To prepare each liter of the vehicle (0.5 % aqueous methylcellulose), 1000 ml of deionized water was heated to approximately 70°C and 5.0 g of the control material powder was gradually added; the mixture was stirred until clear. The vehicle was prepared prior to study initiation and stored refrigerated between periods of use. An appropriate amount of the vehicle (3500 ml) was dispensed into a storage container. A magnetic stir bar was added and the vehicle was stirred continuously during the dosing procedure. An appropriate amount of the test material, MON 13900, was weighed for each group into a tared weigh boat. The test material was transferred to a mortar, ground to a fine powder and triturated with the vehicle (0.5%methylcellulose) until a slurry was formed. This mixture was transferred to a graduated cylinder via vehicle rinses and was then brought to volume (2000ml) with the vehicle. The graduated cylinder was inverted several times, then the dosing preparation was transferred to a storage container. The graduated cylinder was rinsed with an additional 1500 ml of the vehicle, which was then added to the storage container to attain a total volume of 3500 ml. The preparation was mixed on a Polytron PT6000 homogenizer for approximately five minutes to reduce particle size. A magnetic stir bar was added and the mixture was stirred continuously throughout the sampling and dosing procedures. An adequate amount of the preparations for each group was dispensed daily for dosing. Dosing preparations were made twice during the treatment period (June 9 and June 18, 1992) and were stored at room temperature.

VEHICLE
- Amount of vehicle (if gavage): A dose volume of 5 ml/kg was used for all dose levels
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples of the test material preparations were analyzed at WL Researchbboratories, Inc. Samples were drawn from all groups, including the control group, from the first batch preparation to verify concentration. Homogeneity was verifed in the low and high dose groups only. Samples were drawn from each dose group from the second batch preparation to verify concentration.Concentration analyses for the high dose group were repeated twice due to apparently unrepresentative aliquot samples. On the last day of dosing, aliquots were taken from the low and high dose group preparations and analyzed for stability. The dosing preparations were homogeneous, contained the designated amount of test material specified in the protocol and were stable for the duration of dosing.
Details on mating procedure:
- Impregnation procedure: artificial insemination (the day of insemination was designated gestation day 0.)

Duration of treatment / exposure:
during gestation days 7 through 19
Frequency of treatment:
once a day
Duration of test:
29 days
Dose / conc.:
0 mg/kg bw/day
Dose / conc.:
2 mg/kg bw/day
Dose / conc.:
10 mg/kg bw/day
Dose / conc.:
50 mg/kg bw/day
No. of animals per sex per dose:
20/female/group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: Based on the results of a preliminary range-finding study with the substance (WIL-50207; no further information availlable)
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes, twice daily (

DETAILED CLINICAL OBSERVATIONS: Yes, daily (prior to compound administration during dosing period and approximately one hour following dosing)

BODY WEIGHT: Yes, on gestation days 0, 7, 10, 13, 19, 24, and 29

FOOD CONSUMPTION: Yes, during days 0-29

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation Day 29
- Organs examined: liver, kidney, spleen,and uterus weights; livers from control and high-dose animals were examined histopathologically
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
Fetal examinations:
Fetuses were weighed and examined for external malformations and variations. Crown-rump lengths were recorded for late resorption and then the tissues were discarded. Each viable fetus was examined viscerally to determine the sex and to assess development of internal organs including heart, kidney and brain. Skeletal development was evaluated following staining with Alizarin Red S

.- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: all per litter
Statistics:
- Mann-Whitney U-test
- ANOVA (two-tialed) with Dunnett’s test
-Kruskal-Wallis test
Historical control data:
Yes
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Decreased defecation was noted in all dose groups, including the control group. However, the greatly increased frequency of this finding during the dosing period (gestation days 7-19) in the 50 mg/kg/day group was indicative of a treatment-related effect.
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Two females in the 10 mg/kg/day group aborted, one each on gestation days 26 and 27. One 2 mg/kg/day group female aborted on gestation day 29. No abortions were observed at the higher dose level of 50 mg/kg/day and one control group female aborted on gestation day 28. Therefore, no relationship to treatment was apparent. One control group female died on gestation day 22. All other animals survived to the scheduled necropsy.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Substantial mean body weight losses occurred in the 50 mg/kg/day group throughout the treatment period (gestation days 7-10, 10-13, 13-19 and 7-19). The differences between the control group and the 50 mg/kg/day were statistically significant at p< 0.01. During the post-treatment period gestation days 19-29),an increased mean body weight gain in the 50 mg/kg/day group was statistically significant at p <0.01 when compared to the control group value. Mean body weights in the 50 mg/kg/day group were slightly lower than the control group values on gestation days 10, 13, 19, 24 and 29. The gestation day 19 value was statistically sigignificant (p< 0.01). Mean gravid uterine weight in the 50 mg/kg/day group was comparable to the control group value. However, the mean net body weight in this group was dereased and the mean net body weight loss was greater than the loss observed in the control group. The difference in net body weight losses was statistically significant at p< 0.05.No adverse effects on mean body weights, body weight changes, gravid uterine weights, net body weights or net body weight losses were observed at dose levels of 2 and 10 mg/kg/day. None of the differences from the control group were statistically significant.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Food consumption, evaluated as g/animal/day and g/kg/day, in the 50mg/kg/day group was reduced and statistically significant at p <0.01 throughout the treatment period (gestation days 7-10, 10-13, 13-19 and 7-19) when compared to the control group. Food consumption in this group was comparable to that in the control group during the overall post-treatment period (gestation days 19-29). No adverse effects on food consumption (g/animal/day and g/kg/day) were apparent in the 2 and 10 mg/kg/day groups.
Food efficiency:
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:
effects observed, treatment-related
Description (incidence and severity):
Mean liver weight in the 50 mg/kg/day group was increased 10% when compared to the control group value. The difference was not statistically significant. Mean liver weights in the 2 and 10 mg/kg/day groups were comparable to the control group value. No remarkable differences were observed in mean kidney and spleen weights between the control and treated groups.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
At the scheduled necropsy, no internal findings related to compound administration were observd at any dose level.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, non-treatment-related
Description (incidence and severity):
Microscopic tissue changes in the liver at a dose level of 50 mg/kg/day were comparable to the changes observed in the control group. These changes consisted of cytoplasmic vacuolation and fatty change.
Number of abortions:
effects observed, non-treatment-related
Description (incidence and severity):
Abortions occurred in 1, 1, 2 and 0 females in the control, 2, 10 and 50mg/kg/day groups, respectively. No relationship to treatment was evident.
Pre- and post-implantation loss:
effects observed, treatment-related
Description (incidence and severity):
Postimplantation loss in the 50 mg/kg/day group (1.4 losses/dam) was increased when compared to the control group value (0.5 losses/dam); the difference was not statistically significant. The 50 mg/kg/day group value was within the range of the WIL historical control data (0.1 - 1.9 losses/dam).
Total litter losses by resorption:
not specified
Early or late resorptions:
not specified
Dose descriptor:
NOAEL
Effect level:
10 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
clinical signs
body weight and weight gain
food consumption and compound intake
pre and post implantation loss
Abnormalities:
not specified
Localisation:
not specified
Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Mean fetal body weight in the 50 mg/kg/day group (37.2 g) was slightly lower (not statistictiy significant) than the control group value (42.1 g), but was within the range of the WIL historical control data (34.5 -47.8 g).
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
The only external malformation observed in this study was macroglossia in one 10 mg/kg/day group fetus. No external developmental variations were observed in fetuses at any dose level.
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Skeletal malformations were observed in O, 3, 3 and 2 fetuses in the control, 2, 10 and 50 mg/kg/day groups, respectively. In the 50 mg/kg/day group, two fetuses (nos. 13870-8 and 13942-3) had spherical enlargements on right rib nos. 7, 8 and/or 9. The percentage of fetuses affacted in the 50mg/kg/day group (1.4%) was within the range of the historical control data (0.0 % - 1.9%). An extra site of ossification anterior to sternebra no. 1 was observed in one 2 mg/kg/day group fetus (no. 13922-4) and two 10-mg/kg/day group fetuses (nos. 13882-4 and 13932-1). One fetus in each of the 2 and 10 mg/kg/day groups had vertebral anomalies without associated rib anomalies. For fetus no. 13885-9 in the 2 mg/kg/day group, these anomalies consisted of extra lumbar arches and centra and lumbar arches and centra that were located more anterior or more posterior than normal. For fetus no.13945-5 in the 10 mg/kg/day group, these anomalies consisted of thoracic centra that were absent, smaller than normal or located more anterior or more posterior than normal. The remaining skeletal malformation was observed in2 mg/kg/day group fetus no. 13905-7. This fetus had rib anomalies, including a malformed rib, a bifurcated rib and fused costal cartilage. The percentages of fetuses with individual skeletal malformations in the 2 and 10 mg/kg/day groups were within the ranges of the historical control data. Skeletal variants occurred in all dose groups, including the control group, and consisted primary of 13th full and rudimentary ribs and 27 presacral vertebrae. No remarkable differences were observed between the control and treated groups in the percentages of fetuses (litters) affected. Other skeletal variants in the treated groups occurred at a similar frequency in the control group, were observed at a limited frequency (in one or two fetuses per group),and/or were within the ranges of the WIL historical control data. No relationship to treatment was evident.
Visceral malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Soft tissues malformations were observed only in the 50 mg/kg/day group. Cataracts were noted in both eyes of fetus no. 13866-5. Heart and great vessel anomalies were observed in another 50 mg/kg/day group fetus (no.13901-2). These anomalies consisted of a bulbous ascending aorta and aortic arch, a rudimentary pulmonary trunk, md an interventricular septal defect. The percentages of fetuses (litters) with these malformations in the 50mg/kg/day group were within the ranges of the WL historical control dam. The primary soft tissue development variations in all groups, including the control group, consisted of non dose-related occurrences of accessory spleens and major blood vessel variations (in all cases the Ieft carotid arose from the brachesephalic trunk). Other soft tissue variants in the treated groups (a hemorrhagic ring around the iris, retrocaval ureters, renal papillae not developed and a small gallbladder) occurred infrequently, occurred similarly in the control group and/or within the ranges of the WL historical control data. No relationship to treatment was evident.
Details on embryotoxic / teratogenic effects:
Fetal growth and survival were unaffected by compound administration at dose levels of 2 and 10 mg/kg/day. Intrauterine parameters (postimplantation loss, live litter size, fetal body weights, fetal sex ratios and numbers of corpora lutea and implantation sites) were assessed as appropriate, on a group mean basis or as a proportional (%) litter comparison. The only statistically significant differences from the control group were the following. A slightly increased (p <0.05) mean number of corpora lutea was observed in the 10 mg/kg/day group. The numbers of corpora lutea that are present are determined prior to the initiation of treatment. A fetal sex ratio that was slightly skewed toward females (p <0.05) occurred in the 10 mg/kg/day group. A similar trend was not observed at the higher dose level of 50 mg/kg/day and no relationship to treatment was evident.
Dose descriptor:
NOAEL
Effect level:
10 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
female
Basis for effect level:
fetal/pup body weight changes
Abnormalities:
effects observed, non-treatment-related
Description (incidence and severity):
No indication of developmental toxicity was expressed in fetuses at any dose level at the morphological evaluation. The types of malformations in the treated groups were not dose-related. The variations expressd in the treated groups were also not present in a dose-dependent manner but were generally similar to those present in the control group.
Developmental effects observed:
yes
Lowest effective dose / conc.:
50 mg/kg bw/day (actual dose received)
Treatment related:
yes
Relation to maternal toxicity:
developmental effects as a secondary non-specific consequence of maternal toxicity effects
Executive summary:

According to the OECD TG 414 the test substance was suspended in 0.5% aqueous methylcellulose and administered daily by gavage (5 ml/kg) to 4 groups of 20 artificially inseminated New Zealand White rabbits during gestation days 7 through 19. Dose levels were 0, 2, 10 and 50 mg/kg/day.

The test substance produced maternal toxicity at the highest dose level tested, 50 mg/kg/day, as indicated by weight loss and decreased food consumption. Slight developmental toxicity, as indicated by slightly increased postimplantation loss and slightly decreased fetal weights, was seen in the 50 mg/kg/day dose group. There were no developmental malformations associated with exposure to the test substance. The No Observable Effect Level (NOEL) for maternal and developmental toxicity was therefore 10 mg/kg/day.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
10 mg/kg bw/day
Study duration:
subacute
Species:
rabbit
Quality of whole database:
The information requirements for this tonnage band is sufficiently met with the available data.
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

A study was conducted to evaluate the developmental toxicity potential of MON 13900 according to EPA OPP Guideline 83-3 in compliance with GLP. The test substance was administered in corn oil by gavage once daily at 0, 10, 75 and 175 mg/kg bw/day to 4 groups of 25 mated female Charles River CD(SD) BR rats during Gestation Days 6 to 15. These dose levels were selected based on results from a pilot rat teratology study. Analytical concentrations of the test substance were acceptably close to target levels. Homogeneity and stability of dosing solutions were also acceptable. Maternal toxicity was evidenced at 175 mg/kg bw/day by an initial body weight loss and a decreased body weight gain for the overall treatment period, various clinical signs and increased liver weights. Liver weights were also increased at 75 mg/kg bw/day. Developmental toxicity was indicated at 175 mg/kg bw/day by decreased fetal weights, an equivocal increase in post-implantation loss, an equivocal increase in the incidence of total (external, visceral and skeletal) malformations and an increase in one skeletal variation. Therefore, the NOEL for developmental toxicity was 75 mg/kg bw/day and the NOEL for maternal toxicity was 10 mg/kg bw/day.

Justification for classification or non-classification

The available data suggests that MON 13900 is not a reproductive or developmental toxicant. Therefore, no classification is required according to CLP criteria (EC 1272/2008).