Registration Dossier

Administrative data

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

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1998
Report Date:
1998

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPP 83-4 (Reproduction and Fertility Effects)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid

Test animals

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

Administration / exposure

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.
Doses / concentrationsopen allclose all
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

Examinations

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

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

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 / performance (P0)

Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed

Details on results (P0)

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.

Effect levels (P0)

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

Target system / organ toxicity (P0)

Critical effects observed:
yes
Lowest effective dose / conc.:
1 500 ppm
Organ:
kidney
liver
Treatment related:
yes
Dose response relationship:
not specified

Results: P1 (second parental generation)

Effect levels (P1)

Dose descriptor:
NOEL
Effect level:
150 ppm (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic

Target system / organ toxicity (P1)

Critical effects observed:
yes
Lowest effective dose / conc.:
1 500 ppm
Organ:
kidney
liver
Treatment related:
yes
Dose response relationship:
not specified

Results: F1 generation

General toxicity (F1)

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

Details on results (F1)

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.

Effect levels (F1)

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

Results: F2 generation

Effect levels (F2)

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

Overall reproductive toxicity

Reproductive effects observed:
no

Applicant's summary and conclusion

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.