Acetaldehyde oxime

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

one-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP. Study conducted according to OECD guideline.

Qualifier:

according to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: (P) x wks; (F1) x wks
- Weight at study initiation: (P) Males: x-x g; Females: x-x g; (F1) Males: x-x g; Females: x-x g
- Housing: During the quarantine, acclimatization and premating periods, the animals were housed in groups of 4/sex in macrolon cages type 3. For mating one male and one female were housed together in type 3 cages. Mated females were housed individually in type 3 cages, which were placed in another cage rack.
- Diet: ad libitum (Rat&Mouse No. 3, Breeding Diet, RM3, SDS Special Diets Services, Witham, England)
- Water: ad libitum (tap water)
- Acclimation period: yes

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70 (with exceptions)
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: To:

Route of administration:

oral: gavage

Vehicle:

water

Remarks:

tap water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Concentration in vehicle:
- Amount of vehicle (if gavage): 2 mL/kg bw, the dose volumes were not adjusted after gestation day 14

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: until pregnancy occurred or 2 weeks had elapsed
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged (how): individually in type 3 cage
- Non-mated females: sacrificed and necropsied about 3 weeks after the last day of the mating period

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis to determine the stability, homogeneity and content of the test substances in the dosing solutions were conducted by quantitative determination of the test substance by HPLC.

Duration of treatment / exposure:

Females: the test substance was administered during at least 10 weeks premating, during the mating, gestation and lactation period
Males: the test substance was administered during at least 10 weeks premating and during the mating (shortly after mating, males were euthanized)

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
10, 30, 100 mg/kg bw/day
Basis:
actual ingested

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on results of dose-range finding study
- Rationale for animal assignment (if not random): The animals (males and females) separately were allocated to the various groups by computer randomization and proportionately to body weight.

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least daily

BODY WEIGHT: Yes
- Time schedule for examinations: male and female animals shortly before the start of the study, male animals weekly until sacrifice, females weekly during the premating and mating period, mated females were weighed on GD 0, 4, 7, 10, 14, 17 and 21 and on PN 1, 4, 7, 10, 14, 17 and 21, non-mated females weekly until sacrifice, all animals on the day of sacrifice

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

Oestrous cyclicity (parental animals):

3 weeks prior to the mating period, vaginal smears were made of all females of both generations to evaluate the estrus cycle length and normality. The estrus cycle length and normality were determined in the smears of the control and high-dose group.

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: Yes
- If yes, maximum of 8 pups/litter (4/sex/litter as nearly as possible); excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, pups showing abnormalities or malformations, weight

GROSS EXAMINATION OF DEAD PUPS: YES

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals, shortly after mating
- Maternal animals: All surviving animals. Non-mated females were sacrificed and necropsied about 3 weeks after the last day of the mating period.

GROSS NECROPSY
- Gross necropsy consisted of [external and internal examinations including the cervical, thoracic, and abdominal viscera.]

ORGAN WEIGHTS
ovaries, uterus with cervix, testes, epididymides, seminal vesicles, prostate, brain, liver, kidneys, spleen, pituitary, thyroid, adrenal glands

HISTOPATHOLOGY
vagina, ovaries, uterus with cervix, testes, epididymides, seminal vesicles, prostate, liver, kidneys, spleen
Tissues were embedded in paraffin wax, sectioned at 5 μm, and stained with haematoxylin and eosin, except for sections of the testes, which were stained with PAS haematoxylin.
Microscopic examination was performed on the collected organs of all rats of the control and high-dose groups. Based on the increased organ weight, and after consultation with the sponsor, the spleen of the male and female animals of the low- and mid-dose groups were microscopically examined.
Based on the histopathological effects found in the liver (male and female animals) the microscopical examination was extended to the low and mid-dose groups.

HAEMATOLOGY: Yes
- Blood collected at autopsy from the abdominal aorta
- Fasted: No
- Parameters checked: red blood cells, haemoglobin, packed cell volume, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, reticulocytes, thrombocytes, prothrombin time, white blood cells, eosinophils, neutrophils, lymphocytes, monocytes, basophils

Postmortem examinations (offspring):

SACRIFICE
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows: All stillborn pups, pups found dead and pups that were terminated in a moribound condition during the study were examined microscopically for structural abnormalities or pathological changes. Organs and tissues that showed macroscopic abnormalities were preserved in a neutral aqueous phosphate-buffer 4% solution of formaldehyde and examined microscopically. At weaning on PN21 or shortly thereafter, 1 male and 1 female pup were subjected to a thorough necropsy. Special attention was paid to the organs of the reproductive system. Pups were selected randomly at or shortly after PN14; in case a selected pup died before the necropsy this pup was replaced by another randomly chosen pup.

Statistics:

The resulting data were analyzed using the methods mentioned below. Other statistical tests may be performed when considered appropriate. P<0.05 was considered as a level of significance. - Clinical findings were evaluated by Fisher's exact probability test. - Body weight, body weight gain, organ weights and food consumption data were subjected to one-way analysis of variance (ANOVA) followed by Dunnett's multiple comparison tests - Fisher's exact probabillity test was used to evaluate the number of mated and pregnant females and females with live pups. - Number of implantations sites, live and dead pups were evaluated by Kruskal-Wallis nonparametric analysis of variance followed by the MannWhitney U-test. - Red blood cell and coagulation variables, total white blood cell counts, absolute differential white blood cell counts were evaluated by one-way ANOVA followed by Dunnett's multiple comparison tests (treatment period). Reticulocytes and relative differential white blood cell counts: Kruskal-Wallis non-parametric ANOVA followed by Mann-Whitney U-tests. - Estrus cycle: ANOVA followed by Dunnett's multiple comparison test - Histopathological changes: Fisher's exact probability test.

Reproductive indices:

pre-coital time, duration of gestation, mating index, male fertility index, female fertility index; female fecundity index, gestation index, live birth index, pup mortality day n, sex ratio day n, number of lost implantations, post-implantation loss

Clinical signs:

effects observed, treatment-related

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

Description (incidence and severity):

liver and spleen of males and females

Other effects:

not examined

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
After dosing on the first day of the study all animals of the 100 mg AAO group showed decreased activity or sedation.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
The decrease in mean body weights and body weight changes as observed in the male animals of the high-dose groups (100 mg AAO) was considered to be related to treatment.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
No effect on the fertility and reproductive performance of the male and female animals and on the estrus cycle of the female animals.

ORGAN WEIGHTS (PARENTAL ANIMALS)
The increase of absolute and relative spleen weight of males and females of the 30 and 100 mg AAO groups were considered to be related to treatment. The increased relative liver weight of the male animals of the 100 mg AAO group (<10%) was considered to be a treatment-related effect since histopathologic effects were also observed on the livers of male animals of this dose group.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Microscopic examination did reveal treatment-related findings in the liver and spleen of males and females of the mid- and high dose group and in the spleen of low-dose males.
In the liver focal to multifocal pigmented Kupffer cells were observed in all males and 27 females of the high-dose group and in 10 males and 7 females of the mid-dose group.
The changes in the spleen were characterized by slight increased brown pigment accumulation and a statistically significantly increased incidence of (very) slight increased extramedullary hematopoiesis, i.e. predominantly erythropoiesis, in the red pulp.

HAEMATOLOGY (PARENTAL ANIMALS)
Effects on red blood cell variables were observed in the 30 and 100 mg AAO groups in both sexes. In the male 10 mg AAO group, only a decrease in mean corpuscular haemoglobin concentration was observed. Male and female animals of the 100 mg AAO group showed some effects on total and differential white blood cell parameters.

Dose descriptor:

LOAEL

Effect level:

10 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: NOAEL for 50% solution of AAO in water. Decrease in mean corpuscular haemoglobin concentration and histopathological changes in spleen

Dose descriptor:

LOAEL

Effect level:

5 mg/kg bw/day (nominal)

Based on:

act. ingr.

Sex:

male

Basis for effect level:

other: LOAEL for AAO (undilluted). Decrease in mean corpuscular haemoglobin concentration and histopathological changes in the spleen.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

incidental findings

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

CLINICAL SIGNS (OFFSPRING)
Some incidental findings such as pale pup, subcutaneous haemorrhage, small eye and kinked tail were noted in 1 pup of the AAO treated groups. Missing/dead tail tip was noted in 1 pup of the 30 mg AAO and in 2 pups of the 100 mg AAO groups.

ORGAN WEIGHTS (OFFSPRING)
Absolute weights and relative weight of the spleen, thymus and brain of 1 randomly selected pup of each sex was comparable among the groups.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: NOAEL for 50% solution of AAO in water.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

50 mg/kg bw/day (nominal)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: NOAEL for AAO (undilluted).

Reproductive effects observed:

not specified

Conclusions:

Based on the decrease in mean corpuscular haemoglobin concentration and histopathological changes in the spleen of the males of the 10 mg AAO / kg bw group (equal to 5 mg active ingredient), the No Observed Adverse Effect Level (NOAEL) for parental toxicity of AAO is lower than 10 mg/kg bw/day.
Since no effects on reproduction of the parental animals were observed, the NOAEL for AAO based on the results of this study is 100 mg/kg bw/day (equal to 50 mg active ingredient).

Executive summary:

Based on the results of the dose-range finding study, in consultation with the sponsor, the following dose levels were chosen for the one-generation reproduction toxicity study: 0, 10, 30 and 100 mg AAO/kg bw for the control, low-, mid- and high-dose groups, respectively.

Apart from the decreased activity and/or sedation of the animals of the 100 mg AAO group after dosing on the first day, no treatment-related clinical signs were observed during the premating, mating, gestation and lactation periods of the adult animals.

 

In the male animals of the 100 mg AAO group a statistically significant decrease in body weight (days 7-21) and body weight change (day 0-7) were observed.

 

During the first week of the study a statistically significant decrease in the food consumption was observed in the male and female animals of the 100 mg AAO group.

 

Oral administration of AAO for one generation did not affect fertility and reproductive performance of the male and female animals and estrus cycle of the female animals.

 

No treatment-related effects were observed on the size of the litters, the number of stillborn-, missing- and dead pups during the lactation period and on the sex ratio, pup abnormalities or pup weight during lactation.

Macroscopic observations of the pups and absolute and relative organ weights (brain, spleen and thymus) at sacrifice, PN 21 or 22, did not reveal any treatment-related findings.

 

Effects on red blood cell variables were observed in the 30 and 100 mg AAO group in both sexes. In male animals of the 10 mg AAO group, only a decrease in mean corpuscular haemoglobin concentration was observed. Male and female animals of the 100 mg AAO group showed some effects on total and differential white blood cell parameters.

 

The increase of absolute and relative spleen weights of males and females of the 30 and 100 mg AAO groups was considered treatment-related. The increased relative liver weight of the male animals of the 100 mg AAO group (<10%) was considered to be a treatment-related effect of the test substance since histopathological effects were also observed on the livers of male animals of this dose group.

 

Microscopic examination of the organs and tissues of parental animals revealed treatment-related histopathological changes in the spleen of males of the low dose-group and in the spleen and liver of mid-, and high dose animals (both sexes).

The changes in the spleen were characterized by increased brown pigment accumulation and increased extramedullary hematopoiesis, i.e. predominantly erythropoiesis, in the red pulp.

In the liver focal to multifocal pigmented Kupffer cells were observed. The phagocytized pigment was present as very small greenish granula of varying size in the cytoplasm of the Kupffer cells, not accompanied by any other morphological change.

In conclusion, based on the decrease in mean corpuscular haemoglobin concentration and histopathological changes in the spleen of the males of the 10 mg AAO / kg bw group (equal to 5 mg active ingredient), the No Observed Adverse Effect Level (NOAEL) for parental toxicity of AAO is lower than 10 mg/kg bw/day.

Since no effects on reproduction of the parental animals were observed, the NOAEL for AAO based on the results of this study is 100 mg/kg bw/day (equal to 50 mg active ingredient).

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Toxicity to reproduction was evaluated in a one-generation reproduction study in rats (Wolterbeek and Waalkens-Berends 2005). Based on the results of a dose-range finder study the following dose levels were chosen for the main study:0, 10, 30 and 100 mg test substance/kg bw. The test substance contained 50% AAO and 50% water.

 

The test substance did not affect fertility and reproductive performance of the male and female animals and estrus cycle of the female animals.

 

No treatment-related effects were observed on the size of the litters, the number of stillborn, missing and dead pups during the lactation period and on the sex ratio, pup abnormalities or pup weight during lactation. Macroscopic observation of the pups and absolute and relative organ weights (brain, spleen and thymus) at sacrifice, PN21 or 22, did not reveal any treatment-related findings.

 

Effects on red blood cell variables were observed in the mid and high dose groups in both sexes. In the low dose group, a significant affected haematological parameter, a decrease in mean corpuscular haemoglobin concentration, was only observed in the male animals. Male and female animals of the high dose group showed some effects on total and differential white blood cell parameters.

 

The increase of absolute and relative spleen weights of males and females of the mid and high dose group was considered to be related to treatment. Microscopic examination revealed treatment-related histopathological changes in the spleen in males of the low dose group and in the spleen and liver of mid and high dose groups (both sexes). The changes in the spleen were characterized by increased brown pigment accumulation and increased extramedullary haematopoiesis, i.e. predominantly erythropoiesis, in the red pulp.

 

In the liver focal to multifocal pigmented Kupffer cells were observed. The phagocytised pigment was present as very small greenish granula of varying size in the cytoplasm of the Kupffer cell, not accompanied by any other morphological change.

 

Based on the decrease in mean corpuscular haemoglobin concentration and histopathological changes in the spleen of the males of the low dose group (10 mg test substance/kg bw) the NOAEL for parental toxicity could not be derived for this study and consequently was lower than 10 mg test substance/kg bw (equal to approximately 5 mg AAO/kg bw).

 

Since no effects on reproduction of the parental animals and development of the pups were observed, the NOAEL for reproductive toxicity is 100 mg test substance/kg bw (equal to approximately 50 mg active ingredient.

Justification for selection of Effect on fertility via oral route:
Key study.

Effects on developmental toxicity

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Justification for classification or non-classification

Since no effects on reproduction of the parental animals and development of the pups were observed, classification of AAO as a reproductive toxicant is not required.