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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
toxicity to reproduction
Remarks:
other: 28d gavage test in rats including fertility parameters
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2011-09-28 till 2011-11-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study with GLP and without deviations.
Cross-reference
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD 407 (Oct 2008), including fertility parameters
Deviations:
yes
Remarks:
The rats were about 8-9 weeks old at the start of the treatment period (rationale: to enable evaluation of the oestrus cycle during the last two weeks of the study).
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
technical product

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
The rats, 20 males and 20 females, were about 8-9 weeks old at the start of the treatment period (rationale: to enable evaluation of the oestrus cycle during the last two weeks of the study). The body weights at initiation of treatment were within ± 20% of the mean weight for each sex, and ranged from 235-286 g (mean 259 g) for males and from 165-196 g (mean 179 g) for females.
Details on mating procedure:
no mating
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The content, homogeneity and stability of the test substance in the carrier (tap water) were confirmed by HPLC-UV analysis.
Samples were taken from each dosing formulations prepared in the study. Analyses to determine the content, homogeneity and stability of the test substance in the carrier were conducted by HPLC-UV analysis (after storage in the animal room for approximately four hours and after storage in the refrigerator (2-10oC) for 7 days)
Duration of treatment / exposure:
28 consecutive days
Frequency of treatment:
once daily
Doses / concentrations
Remarks:
Doses / Concentrations:
50, 300, 1000 mg MPAAU/kg bw/day
Basis:
nominal conc.
No. of animals per sex per dose:
5 males and 5 females per group
Control animals:
yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:
General clinical observations
Each animal was observed daily in the morning hours by cage-side observations and, if necessary, handled to detect signs of toxicity. On working days, all cages were checked again in the afternoon for dead or moribund animals to minimize loss of animals from the study. On Saturdays, Sundays and public holidays only one check per day was carried out. All abnormalities, signs of ill health or reactions to treatment were recorded.

Neurobehavioural testing (arena testing, FOB and motor activity)
In addition to the above daily general clinical observations, detailed clinical examinations outside the home cage were performed on all rats prior to the first exposure and then once weekly throughout the study. In week 4 of the study, the detailed clinical observations were included in the Functional Observation Battery (FOB and motor activity assessment were investigated in all rats in week 4 of the study).

Body weight
The body weight of each animal was recorded at initiation of treatment (day 0), and twice per week thereafter. In addition, the animals were weighed on their scheduled necropsy date after overnight fasting in order to calculate the correct organ to body weight ratios.

Feed consumption
Feed consumption was measured per cage by weighing the feeders. The consumption was measured over successive periods of 3 or 4 days throughout the treatment period. The results were expressed in g per animal per day.

Haematology
Haematology was conducted on all surviving animals. At necropsy, blood samples were taken from the abdominal aorta of the rats whilst under CO2/O2 anaesthesia. The rats were fasted overnight before necropsy (water was freely available). EDTA was used as anticoagulant. In each sample the following determinations were carried: haemoglobin (Hb), packed cell volume (PCV), red blood cells (RBC), reticulocytes, total white blood cells (WBC), differential white blood cells, prothrombin time, thrombocytes.
The following parameters will be calculated:
mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC).

Clinical chemistry
Clinical chemistry was conducted on all surviving animals. At necropsy, blood samples were taken from the abdominal aorta of the rats whilst under CO2/O2 anaesthesia. The rats were fasted overnight before necropsy (water was freely available). The blood was collected in heparinized plastic tubes and plasma was prepared by centrifugation. The measurements listed below were made in the plasma: alkaline phosphatase activity (ALP) cholesterol (total), aspartate aminotransferase activity (ASAT) triglycerides, alanine aminotransferase activity (ALAT) phospholipids, gamma glutamyl transferase activity (GGT) creatinine, bilirubin (total) urea, bile acids inorganic phosphate, total protein calcium (Ca), albumin chloride (Cl), ratio albumin to globulin (calculated) potassium (K), (fasting) glucose sodium (Na).

Pathology
Gross necropsy
On day 28 of the study, after overnight fasting (water was freely available), the surviving animals were killed, in such a sequence that the average time of killing was approximately the same for each group. The animals were killed by exsanguination from the abdominal aorta under CO2/O2 anaesthesia and then examined grossly for pathological changes. A thorough necropsy was also performed on male rat no.34 that died accidentally on day 22 of the study.

Organ weights
At scheduled necropsy, the following organs were weighed (paired organs together) as soon as possible after dissection to avoid drying, and the relative organ weights (g/kg body weight) were calculated based on the terminal body weight of the rats:
adrenals prostate brain seminal vesicles (with coagulating glands) epididymides spleen heart testes kidneys thymus liver uterus ovaries

Tissue preservation
Samples of the following tissues and organs of all animals were preserved in a neutral aqueous phosphate-buffered 4% solution of formaldehyde.
adrenals oesophagus axillary lymph nodes ovaries brain pituitary* caecum prostate colon rectum duodenum seminal vesicles + coagulating glands epididymides 4 skeletal muscle (thigh) eyes spinal cord GALT (gut associated lymphoid tissue, spleen including Peyer's patches) sternum with bone marrow heart stomach ileum testes jejunum thymus kidneys thyroid liver trachea/bronchi lung urinary bladder mammary gland (females) uterus (with cervix) mandibular (cervical) lymph nodes* vagina mesenteric lymph nodes all gross lesions nerve-peripheral (sciatic)
The carcass containing any remaining tissues was also retained in formalin, but discarded after completion of the histopathological examination.

Histopathological examination
The tissues to be examined microscopically were embedded in paraffin wax, sectioned at 5 μm and stained with haematoxylin and eosin. Histopathological examination (by light microscopy) was performed on all tissues and organs listed above (except those marked with an asterisk) of all animals of the control group and the high-dose group, Gross lesions were examined in rats of all dose groups.
Oestrous cyclicity (parental animals):
Vaginal smears to evaluate the oestrus cycle length and normality were made daily from day 15 until sacrifice on day 28. Smears were made and stained of all females, but evaluated only in the control and high-dose group.
Sperm parameters (parental animals):
Epididymal sperm motility, count and morphology
At scheduled necropsy, epididymal sperm was derived from the left cauda epididymis of all males of all groups, and the motility was measured. The cauda epididymidis was dissected, weighed and thereafter minced in 3 ml M199 medium containing 0.5% BSA. Sperm motility and, after sonification and DNA-staining, the cauda epididymal sperm reserves (sperm count) were measured for all males of all groups with the Hamilton Thorne Integrated Visual Optical System (IVOS).
In addition, a smear of the sperm solution was prepared and stained for all males, and two hundred spermatozoa of the smear of each male of the control group and high-dose group were analysed.
Litter observations:
no mating/offspring
Postmortem examinations (parental animals):
Testicular sperm count
At scheduled necropsy, the left testis of all males of all groups was placed on dry ice and subsequently stored in a freezer (<-70°) for later determination of the number of homogenization-resistant spermatids. Before analysis the testis was thawed and the tunica albuginea removed. After weighing, testicular parenchyma was minced and homogenized in 25 ml Saline Triton X-100 solution. Following DNA-staining, the homogenization-resistant sperm heads were enumerated using the IVOS in males of the control group and high-dose group. The daily sperm production was calculated as ‘number of spermatozoa per gram testicular parenchyma / 6.1’ (WF Blazak et al.; in Male Reproductive Toxicology, eds. RE Chapin and JJ Heindel, Methods in toxicology volume 3A, 1993).
Postmortem examinations (offspring):
no mating/offspring
Statistics:
Numerous tests are performed as two-sided tests with results taken as significant where the probability of the results is <0.05 or <0.01.
Because numerous variables are subjected to statistical analysis, the overall false positive rate (Type I errors) is greater than suggested by a probability level of 0.05. Therefore, the final interpretation of results is based not only on statistical analysis but also on other considerations such as dose-response relationships and whether the results are significant in the light of other biological and pathological findings.
Reproductive indices:
no mating/offspring
Offspring viability indices:
no mating/offspring

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
There were no indications of adverse effects of treatment on general condition or mortality.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There were no treatment-related or statistically significant changes in mean body weights.
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
effects observed, non-treatment-related
Description (incidence and severity):
ALAT activity was statistically significantly increased in females of the high-dose group. This finding occurred in one sex only and was not accompanied by corroborative changes in other parameters. There were no other statistically significant changes in clinical chemistry variables.
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
The results of the neurobehavioural observations and motor activity assessment did not indicate any neurotoxic potential of MPAAU in rats.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Description (incidence and severity):
Smears obtained during the last 14 days prior to sacrifice of all control females and high-dose females were evaluated. The number of acyclic females, the mean length of the longest cycle, the number of cycles per animal and the number of females with a prolonged estrus period were comparable in both groups.
Reproductive function: sperm measures:
no effects observed
Description (incidence and severity):
Epididymal sperm motility: Statistical analysis of sperm motility data indicated no significant differences between the test groups and the controls.

Epididymal sperm count : No statistically significant effects on sperm counts were observed.

Epididymal sperm morphology: No statistically significant effect on sperm morphology was observed.

Testicular sperm count: No effects on the number of spermatozoa per gram testicular parenchyma or on daily sperm production were observed.
Reproductive performance:
not examined

Details on results (P0)

Fertility parameters
Estrous cyclicity: Smears obtained during the last 14 days prior to sacrifice of all control females and high-dose females were evaluated. The number of acyclic females, the mean length of the longest cycle, the number of cycles per animal and the number of females with a prolonged estrous period were comparable in both groups.

Sperm analysis
Epididymal sperm motility: Statistical analysis of sperm motility data indicated no significant differences between the test groups and the controls.
Epididymal sperm count: No statistically significant effects on epididymal sperm counts were observed.
Epididymal sperm morphology: No statistically significant effect on sperm morphology was observed.
Testicular sperm count: No effects on the number of spermatozoa per gram testicular parenchyma or on daily sperm production were observed.

Effect levels (P0)

Key result
Dose descriptor:
NOAEL
Effect level:
> 1 000 mg/kg bw/day (nominal)
Based on:
act. ingr.
Sex:
male/female
Basis for effect level:
other: no indications of adverse effects of treatment

Target system / organ toxicity (P0)

Key result
Critical effects observed:
no

Results: P1 (second parental generation)

General toxicity (P1)

Clinical signs:
not examined
Dermal irritation (if dermal study):
not examined
Mortality:
not examined
Body weight and weight changes:
not examined
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not examined

Reproductive function / performance (P1)

Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
not examined

Results: F1 generation

General toxicity (F1)

Clinical signs:
not examined
Dermal irritation (if dermal study):
not examined
Mortality / viability:
not examined
Body weight and weight changes:
not examined
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Histopathological findings:
not examined
Other effects:
not examined

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Results: F2 generation

General toxicity (F2)

Clinical signs:
not examined
Dermal irritation (if dermal study):
not examined
Mortality / viability:
not examined
Body weight and weight changes:
not examined
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Histopathological findings:
not examined
Other effects:
not examined

Developmental neurotoxicity (F2)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F2)

Developmental immunotoxicity:
not examined

Applicant's summary and conclusion

Conclusions:
In this sub-acute study, the safety of MPAAU was examined in Wistar rats (four groups of 5 males and 5 females each). The test substance was administered as a solution in tap water by daily oral gavage during 28 consecutive days, at levels of 0 (tap water only), 50, 300 or 1000 mg MPAAU/kg body weight/day. The dose volume was 10 ml/kg body weight/day in each group.
The content, homogeneity and stability of the test substance in the carrier were confirmed by analysis.
There were no adverse effects of treatment on general condition or mortality. One male rat of the high-dose group accidentally died on day 22 for reason unrelated to treatment. Neurobehavioural observations and motor activity assessment did not indicate any neurotoxic potential of the test substance.
Body weights and feed intake were not affected by the administration of the test substance.
Haematology was conducted in all rats at necropsy. There were no treatment-related changes in red blood cell variables, clotting potential or in total and differential white blood cell counts. A slight increase in the absolute number (but not in percentage distribution) of basophils in females of the high-dose group was considered a chance finding.
Clinical chemistry, conducted in plasma obtained from all rats at necropsy did not show any treatment-related changes. An elevated ALAT activity in females of the high-dose group was not corroborated by changes in other parameters and considered a chance finding.
There were no treatment-related changes in absolute organ weights or in organ to body weight ratios.
Macroscopic examination at necropsy and microscopic examination of organs and tissues did not reveal adverse effects.
There were no effects of the test substance on fertility parameters (oestrus cyclus, epididymal sperm motility, sperm count and sperm morphology, and testicular spermcount and daily sperm production).
Because the administration of the test substance did not induce any changes that were considered to be of toxicological significance, the no-observed-adverse-effect level (NOAEL) was placed at the highest dose level, 1000 mg MPAAU/kg body weight/day.