Succinic anhydride

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1982

Report date:

1982

Reference 2

Reference Type:

publication

Title:

Teratology and multigeneration reproduction studies with maleic anhydride in rats

Author:

Short R.D. et al

Year:

1986

Bibliographic source:

Fundamental and Applied Toxicology 7, 359-66

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

yes

Remarks:

proportion Male/female during mating 1/2; oestrus cycle and sperm parameters not analyzed

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Maleic anhydride

EC Number:

203-571-6

EC Name:

Maleic anhydride

Cas Number:

108-31-6

Molecular formula:

C4H2O3

IUPAC Name:

furan-2,5-dione

Specific details on test material used for the study:

- Appearance: White briquettes
- Purity: > 99%.

TREATMENT OF TEST MATERIAL PRIOR TO TESTING:
Briquettes of maleic anhydride were finely ground with a mortar and pestle and suspended in corn oil with the aid of a tissue homogenizer. All doses were prepared daily in corn oil in order to minimize problems with stability. The concentration was varied so that the desired dose could be administered orally in a volume of 10 ml/kg.

Test animals

Species:

rat

Strain:

other: Charles River CD rats

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: The Charles River Breeding Laboratories, Inc ., Portage, Michigan
- Age at study initiation: (P/F0): 5-6 wks; (F1): 22 days
- Weight at study initiation: (P) Males: 142-143 g; Females: 127-130 g; (F1) Males: 85-113 g; Females: 84-100 g
- Housing: single (besides mating and lactation period)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 16 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23
- Humidity (%): 25-60
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Briquettes of maleic anhydride were finely ground with a mortar and pestle and suspended in corn oil with the aid of a tissue homogenizer. All doses were prepared daily in corn oil in order to minimize problems with stability.

VEHICLE
- Justification for use and choice of vehicle (if other than water): In order to minimize problems with stability.
- Concentration in vehicle: The concentration of maleic anhydride was varied so that the desired dose could be administered orally in a volume of 10 mL/kg bw.

Details on mating procedure:

Rats, in groups of 10 males and 20 females represented the F0 generation, and females were bred twice with males in the same dose group to produce F1a and F1b litters. Then 10 males and 20 females were randomly selected from the F1b litter to become parents of the F2a and F2b litters.
- M/F ratio per cage: 1/2
- Length of cohabitation: maximum of 15 days
- Proof of pregnancy: vaginal plug in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged: individually

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Each generation was dosed a minimum of 80 days with maleic anhydride before its members were mated.
P/F0: from study initiation to the end of the generation (at least 80 days prior to mating and continued to termination);
F1: at 22 days of age and continued throughout the end of the generation (premating exposure period:a minimum of 80 days and treatment throughout mating, gestation and lactation)

Frequency of treatment:

Daily

Details on study schedule:

P/F0 rats were bred twice to produce the F1a and F1b litters. At weaning, ten males and 20 females from each dose group of the F1b litters were randomly selected to become parents of the F2a and F2b litters. A minimum of nine additional male and eight additional female pups per group were randomly selected to be used as replacements for animals dying prior to initiation of the generation.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

20 mg/kg bw/day (nominal)

Remarks:

Low dose

Doses / concentrations 3

Dose / conc.:

55 mg/kg bw/day (nominal)

Remarks:

Mid dose

Doses / concentrations 4

Dose / conc.:

150 mg/kg bw/day (nominal)

Remarks:

High dose

No. of animals per sex per dose:

10 males, 20 females

Control animals:

yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice a day

BODY WEIGHT: Yes
- Time schedule for examinations: weekly (additionally, female body weights were measured at intervals during gestation and lactation)

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

OTHER:
Male and female fertility, mean gestation length

Oestrous cyclicity (parental animals):

not examined

Sperm parameters (parental animals):

not examined

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes
- If yes, maximum of 10 pups/litter (5/sex/litter as nearly as possible); excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in [P/F0 and F1] offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities (besides organ weights); possible cause of death was determined for pups born or found dead

Postmortem examinations (parental animals):

SACRIFICE
- all P/F0 parents

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations

HISTOPATHOLOGY / ORGAN WEIGHTS
These tissues were prepared for microscopic examination and weighed, respectively: adrenal, colon, heart, ileum, duodenum, kidney, liver, lung, bone marrow (sternum), brain, eye, mesenteric lymph node, mammary gland, pituitary, pancreas, salivary gland, skin, ovary, spleen, stomach, testis (with epididymis), thyroid (with a section of thrachea and esophagus), spinal cord (cervical), urinary bladder, prostate, uterus, all other gross lesions including tissue masses

Postmortem examinations (offspring):

SACRIFICE
- all F1 parents
- The F1 offspring not selected as parental animals and all F2 offspring were sacrificed

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

HISTOPATHOLOGY / ORGAN WEIGTHS
These tissues were prepared for microscopic examination and weighed, respectively: adrenal, colon, heart, ileum, duodenum, kidney, liver, lung, bone marrow (sternum), brain, eye, mesenteric lymph node, mammary gland, pituitary, pancreas, salivary gland, skin, ovary, spleen, stomach, testis (with epididymis), thyroid (with a section of thrachea and esophagus), spinal cord (cervical), urinary bladder, prostate, uterus, all other gross lesions including tissue masses

Statistics:

All statistical analyses compared the treatment groups with the control group, with a level of significance at p<0 .05. Significance at p<0 .01 was also indicated. 1. Parental Body Weights: The parental body weights by sex were analysed by one-way analysis of variance, Bartlett's test for homogeneity of variances, and the appropriate t-test (for equal or unequal variances). Significant differences were determined using Dunnett's multiple comparison tables. Analyses for the P/F0 generation were conducted at one week prior to the F1a mating (week 11) and at termination of the generation (week 32). Analyses for the F1 generation were conducted at the first week of the generation (week 30), one week prior to the F2a mating (week 41) and at the termination of the generation (week 61). 2 . Male and Female Fertility: Male and female fertility indices were compared using the Chisquare test criterion with Yates' correction for 2 x 2 contingency tables and/or Fisher's exact probability test to judge levels of significant differences. 3. Pup Survival indices: The proportion of live pups at birth per total number born and the survival indices at lactation days 4, 7, 14 and 21 were compared by the Mann-Whitney U-test to judge significant differences. 4. Litter Size and Pup Body Weights: The mean number of liveborn pups per litter and mean body weights of pups were analysed by one-way analysis of variance, Barlett's test for homogeneity of variances, and the appropriate t- test (for equal or unequal variances). Significant differences were determined using Dunnett's multiple comparison tables. 5. Organ Weights: Absolute and relative organ weights (P/F0, F1, F2a and F2b) were compared by analysis of variance (one-way classification), Bartlett's test for homogeneity of variances and the appropriate t-test (for equal or unequal variances) using Dunnett's multiple comparison tables to judge significance of differences.

Reproductive indices:

Percentages for pregnant females and fertile males were calculated

Offspring viability indices:

Mean live pups/litter on day 0, 4 and 21 after birth were recorded

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Description (incidence and severity):

A few cases of respiratory rales occured. Clinical appearance and behavior of P0 rats were similar to controls.

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

For further details see section "Details on results" below

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Food consumption and compound intake (if feeding study):

no effects observed

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:

effects observed, non-treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Histopathological findings: neoplastic:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

effects observed, non-treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Details on results (P0)

CLINICAL SIGNS (PARENTAL ANIMALS): With the exception of a few cases of respiratory rales, the clinical appearance and behaviour of all treated animals were not remarkably different from the controls.

MORTALITY (PARENTAL ANIMALS): Mortality of adult males and females was 0 to 10% in the low and mid dose group and 65 to 70% in the high dose group.Intubation error was the cause of death for both low and mid dose rats and a single high dose male.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS): P/F0 body weights in the high-dose group were significantly reduced by week 11 (males: -14.1%; females: -10.4%) in both sexes and this reduction increased as the generation progressed (males: -19.7% on study week 32; females: -18%). The mid-dose group means were low but not statistically significantly different from the controls, except at the end of the generation in the females. No effects in the low dose group in either sex during both generations. Mean maternal body weight gain during gestation and lactation during the Fla and Flb matings was unaffected by the administration of Maleic anhydride at all treatment levels tested.
No treatment-related effects on food consumption were observed in any group during the study (a slight decrease in mean female food consumption (both g/rat/day and g/kg/day) was observed throughout the P/F0 generation in the 20 mg/kg/day group, but this was considered as not treatment-related.

ORGAN WEIGHT (PARENTAL ANIMALS):
There were no obvious toxicologically significant variations in either mean absolute or relative (% body weight) organ weights for animals receiving 20, 55 or 150 mg/kg/day of maleic anhydride. There were statistically significant differences observed primarily for mean relative weights. The differences were contributed to the decrease in body weight gain and were not the result of a direct effect on the organs. There was also a statistically significant variation in the mean absolute and relative weight of the thyroid/parathyroid complex for females in the 20 mg/kg/day dosage group. there were no remarkable findings, however, microscopically. A biological significance is therefore doubtful.

GROSS PATHOLOGY (PARENTAL ANIMALS)/HISTOPATHOLOGY (PARENTAL ANIMALS):There were compound"related changes observed during postmortem examination of animals dying on study (DOS) or sacrificed at its termination (SAC). The changes included hydronephrosis/dilated pelvis, mottled kidneys/irregular surface and urinary calculi. Although, the incidences were small and randomly distributed among males and females (DOS/SAC) in the 20, 55 and 150 mg/kg bw/day dosage groups. Their toxicological significance was confirmed during microscopic examination. There was also a remarkaible incidence of gastric thickening, ulcerations, erosions and gaseous distension observed during macroscopic examination among animals in the 55 and 150 mg/kg bw/day dosage groups. A variety of gastritides were observed during microscopic examination. The primary cause(s), however, was not established. Thelesions were thereefore considered to be equivocally compound-related. There were other macroscopic changes observed in various organs. they were considered to be incidental and unrelated to the adminstration of maleic anhydride.
There were compound-related degenerative/inflammatory changes observed histologically in the kidney and urinary bladder of animals in the FO generation which died on study (DOS) or were sacrificed at the termination (SAC). In addition, there were inflammatory changes observed in the stomach of males and females (SAC/DOS) which had received 20, 55 or 150 mg/kg bw/day of maleic anhydrideThe changes were considered to be equivocally compound-related because their pathogenic origin was not clearly established.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): Male and female fertility indices were reduced in the 20 and 150 mg/kg bw/day groups in the F1a mating when compared with the control group. The relation of these findings to treatment is doubtful since the F1b mating fertility indices were generally comparable at all treatment levels. No difficulties were observed at parturition among the treated and control females in either the F1a or F1b matings. There were no significant differences in the mean length of gestation between the 20, 55 and 150 mg/kg bw/day females and control group females in the F1a and F1b matings.

Effect levels (P0)

1

Key result

Dose descriptor:

NOAEL

Remarks:

(fertility)

Effect level:

55 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Remarks on result:

other: No effects; highest dose tested without complete maternal mortility

2

Dose descriptor:

LOAEL

Remarks:

(systemic)

Effect level:

20 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

3

Dose descriptor:

LOEL

Remarks:

(local)

Effect level:

20 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: inflammatory changes in stomachs (it was not possible to conclude they were directly related to maleic anhydride)

Target system / organ toxicity (P0)

Critical effects observed:

no

Results: P1 (second parental generation)

General toxicity (P1)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

For further details see section "Details on results" below

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Food consumption and compound intake (if feeding study):

no effects observed

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:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Reproductive function / performance (P1)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

effects observed, non-treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Details on results (P1)

CLINICAL SIGNS: Clinically, in both parental generations (P0/P1), respirator rales was observed with increased frequency among treated animals when compared to the control group. In addition, treated P1/F1 parental rats vigorously resisted the physical dosing procedure.

MORTALITY: Most of these deaths were attributed to gavage-related injuries . If these deaths are omitted, then a 0 to 10% mortality was observed in both the low and mid dose groups, and significant mortality was produced only in the high dose group (100% among high-dose females). As a result of poor survival, the high dose group was terminated in the F1 generation, and the study was reduced from a three generation to a two generation study

BODY WEIGHT:
At the 20 mg/kg/day level, no effect on mean male body weight was observed throughout the F1 generation (percentage difference -2 .6 on study week 61). The 55 mg/kg bw/day group exhibited moderate to slight decreases in mean male body weight which decreased in magnitude as the F1 generation progressed (i.e., percentage difference -10 and -5 .4 on study weeks 41 and 61, respectively). Marked reductions in mean male body weight were observed at the 150 mg/kg/day level (percentage difference -12 .9 on study week 41) prior to sacrifice of the remaining males.
Females in the 20 and 55 mg/kg bw/day groups showed no adverse effects/regarding mean body weight throughout the F1 generation ; values for these treated groups generally exceeded corresponding control group values . At the 150 mg/kg bw/day level, slight to moderate inhibition of mean female body weight was observed until study week 42 when mortality reached 100% . Percentage differences for these females ranged from -12 .5 to -6 .2% on weeks 30 and 35, respectively . No statistical significance was observed at any of the F1 points of analysis .
Mean maternal body weight gain during gestation in the 20 and 55 mg/kg bw/day groups was comparable to the control group during the F2 matings (F2a and F2b). The 20 mg/kg/day group exhibited mean maternal body weight gain in excess of the control group during lactation in the F2a mating and mean loss in maternal body weight during lactation in the F2a . mating . Slight reduction of mean maternal body weight gain and no gain in mean maternal body weight were observed during lactation in the F2a and F2b mating respectively, at the 55 mg/kg bw/day level.

ORGAN WEIGHT AND HISTOPATHOLOGY: In the F1 generation, kidney weights were significantly increased in females from the low and mid dose group ; however, there were no microscopic changes observed in these kidneys.

REPRODUCTIVE PERFORMANCE:
Male and female fertility indices for the 20 and 55 mg/kg bw/day groups for the F2a and F2b mating were comparable to those of the control group . In addition, these values were generally within the range of historical control values. It was noted that fertility in this study was reduced in all groups including the control when compared to control groups of previous studies. However, this generalized reduction is not considered an effect of treatment since the control group also had reduced fertility indices. The general reduction in fertility observed throughout the P0 and P1 generations and mortality contribute to a significant reduction in the available sample size of the data with regard to reproductive and litter parameters . In the P1 generation, 17 litters were available at the 55 mg/kg bw/daylevel with 100% mortality among the 150 mg/kg bw/day females by the time of the first F1 mating.
Findings with regards to parturition and length of gestation for the Fl generation were similar to the FO generation.No dystocia was observed of the F2a and F2b matings and the mean length of gestation of the treated females was comparable to the control group during both matings of the F1generation.

Effect levels (P1)

1

Key result

Dose descriptor:

NOAEL

Remarks:

(fertility)

Effect level:

55 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Remarks on result:

other: Since 100% mortality was observed among female rats at 150 mg/kg bw/day.The high dose group was terminated in the F1 generation, and and 55 mg/kg bw/day was the highest dose tested in the F1 generation.

Remarks:

Since 100% mortality was observed among female rats at 150 mg/kg bw/day.The high dose group was terminated in the F1 generation, and and 55 mg/kg bw/day was the highest dose tested in the F1 generation.

2

Key result

Dose descriptor:

LOAEL

Remarks:

(systemic)

Effect level:

20 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Target system / organ toxicity (P1)

Critical effects observed:

no

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

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:

no effects observed

Anogenital distance (AGD):

not specified

Nipple retention in male pups:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

Histopathological findings:

no effects observed

Other effects:

no effects observed

Developmental neurotoxicity (F1)

Behaviour (functional findings):

not specified

Developmental immunotoxicity (F1)

Developmental immunotoxicity:

not examined

Details on results (F1)

MORTALITY/VIABILITY (OFFSPRING):
- Pup viability (birth):There were no biologically meaningful or statistically significant differences between the treated and control rats in the mean numbers of viable or stillborn pups on lactation day 0 in the F1a and F1b litter.
- Pup survival to weaning:Treeatment with maleic anhydride at levels of 20, 55 or 150 mg/kg bw/day had no apparent adverse affect on pup survival to weaning in the F1a or F1b litters.

BODY WEIGHT: In the F1a litters, mean pup body weight at birth was comparable to the control group at the 20 and 55 mg/kg bw/day levels but significantly reduced (p<0.01) in the 150 mg/kg/day group. This effect was not observed in the F1b litters; mean pup body weight at birth in all treated groups of the F1b litters was comparable to the control groups.
Pup growth during lactation was unaffected by treatment with Maleic anhydride at dosage levels of 20 and 55 mg/kg bw/day in both mating of the P0 generation. However, at the 150 mg/kg/day level, inhibition of pup body weight was observed throughout lactation [with statistical significance on days 7, 14 and 21 (by sex),] in the F1a litters and after day 7 of lactation in the F1b litters.

ORGAN WEIGHTS (OFFSPRING): In the F1 generation, the absolute kidney weights of adult females in the low- and mid-dose groups were significantly increased to 108 and to 111%, respectively, of the control value.

GROSS PATHOLOGY (OFFSPRING)/HISTOPATHOLOGY (OFFSPRING): - F1: Low incidence of mineralization (2/12 males; 3/21 females) and nephrosis (2/12 males ; 5/21 females) in the kidney of animals receiving 150 mg/kg/day. There were no microscopic changes in these kidneys.

OTHER FINDINGS (OFFSPRING): No treatment-related effects were observed on indices of fertility for males and females in the F1 generation. No adverse effects on litter size and on pup survival were observed at doses up to 150 mg/kg bw/day in the F1 litters, or at 55 mg/kg bw/day in the F2 litters.

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

150 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects on litter size and on pup survival were observed with maleic anhydride at doses up to 150 mg/kg/day in F1 a and F1b litters

Target system / organ toxicity (F1)

Critical effects observed:

no

Results: F2 generation

General toxicity (F2)

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, treatment-related

Description (incidence and severity):

The high-dose group was terminated during the second generation due to treatment-related mortality in adults.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

For further details see section "Details on results" below

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:

no effects observed

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Description (incidence and severity):

The examination of tissues from F2b pups revealed no compound-related changes in incidences of microscopic lesions.

Other effects:

not specified

Developmental neurotoxicity (F2)

Behaviour (functional findings):

not examined

Developmental immunotoxicity (F2)

Developmental immunotoxicity:

not examined

Details on results (F2)

MORTALITY/VIABILITY:
- Pup viability (birth): Very slight reductions in the mean number of viable pups at birth in the F2a litters were observed at the 20 and 55 mg/kg bw/day levels; there was no similar increase in the mean number of stillborn pups. These very slight reductions were not considered to represent a test article-related effect since values for both the 20 and 55 mg/kg bw/day groups (12.2 and 12.0, respectively) were comparable to the historical control value (12.3) and no similar decreases were noted in theF2b litters. The mean numbers of viable and stillborn pups at birth in the 20 and 55· mg/kg bw/day groups were comparable to the. control group in the F2b litters.
- Pup survival:There were no statistically significant differences in pup survival to weaning between treated and control litters in both matings of the FI generation at doses of 55 mg/kg/day and less.

BODY WEIGHT: Mean pup body weight at birth of treated litters in both matings of the Fl generation was statistically comparable to the control group. In the F2a litters, mean pup body weights In the low and intermediate dose groups were generally comparable to the control through lactation. However, in the F2b litters, slight to moderate reductions in mean pup body weight were observed in the 20 and 55 mg/kg/day groups throughout lactation. These reductions were statistically significant on days 14 (combined weights) and 21 (females only) of lactation in the 20 mg/kg/day group and days 4 before reduction (females only) and 21 (females only) of lactation at the 55 mg/kg/day level.

Effect levels (F2)

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

55 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

sexual maturation

Remarks on result:

other: Since 100% mortality was observed among parental F1 female rats at 150 mg/kg bw/day. The high dose group was terminated in the F1 generation, and 55 mg/kg bw/day was the highest dose tested in the F1 and F2 generation.

Overall reproductive toxicity

Reproductive effects observed:

no

Any other information on results incl. tables

The high dose group (150 mg/kg bw/day) during the second generation was terminated due to treatment-related mortality in F1. The lack of adverse findings in the reproductive toxicity study with maleic anhydride is also seen in1 carcinogenicity studies with succinic anhydride. No adverse findings in reproductive organs were observed in rats or mice in 2-year studies with succinic anhydride (NTP, 1990). No treatment-related effects on reproduction were observed with maleic anhydride at doses up to 55 mg/kg bw/day over two generations.

Table 1. Mortality and body weight of adult rats treated with maleic anhydride during a multigeneration reproduction study

		Maleic anhydride (mg/kg/day)
F0 generation		0	20	55	150
Males	Mortality^a	0 (0)	10 (10)	10 (0)	70^b (60)^b
	Body weight^c	143, 502, 700	142, 524, 697	143, 506, 666	143, 431^b, 562^b
Females	Mortality^a	0 (0)	0 (0)	5 (0)	65^b (65)^b
	Body weight^c	129, 289, 368	130, 281, 345	130, 280, 337	127, 259^b,317^b
F1 generation
Males	Mortality^a	20 (0)	40 (40)^b	40 (0)	75^b (58)^b
	Body weight^d	113, 495, 722	107, 500, 703	103, 445, 683	85^b, 431,--
Females	Mortality^a	20 (0)	30 (5)	52^b (10)	100^b (14)
	Body weight^d	96, 265, 334	100, 272, 343	95, 265, 347	84, 247, --
^a Total dead/total treated x 100 (% mortality minus gavage-related deaths). Groups contained 10 to 12 males and 20 to 21 females; ^bSignificantly different from the appropriate control; ^cBody weight (g/rat) at weeks 0, 11 and 32 of study; ^dBody weights (g/rat) at weeks 30, 41 and 61 of study.

Table 2. Fertility of rats treated with maleic anhydride during a multigeneration reproduction study

		Maleic anhydride (mg/kg/day)
		0	20	55	150
Females	F1a	14/20 (70)^a	7/20 (35)^b	14/20 (70)	7/20 (35)^b
	F1b	10/20 (50)	8/2 (40)	11/19 (58)	6/10 (60)
	F2a	14/20 (70)	13/15 (87)	9/11 (82)	--
	F2b	12/16 (75)	12/14 (86)	8/10 (80)	--
Males	F1a	8/10 (80)^c	5/10 (50)	9/10 (90)	4/10 (40)^b
	F1b	6/10 (60)	5 /9 (56)	7/10 (70)	5/9 (56)
	F2a	9/10 (90)	6/6 (100)	6/6 (100)	--
	F2b	8/8 (100)	7/7 (100)	5/5 (100)	--
^a Number pregnant/number mated x 100 (% pregnant); ^bSignificantly different from control; ^cNumber fertile/number mated x 100 (% fertile)

Table 3. Litter size of rats treated with maleic anhydride during a multigeneration reproduction study

		Maleic anhydride (mg/kg/day)
Litter	Days after birth	0	20	55	150
F1a	0 4 21	12.2^a 12.0 (9.9)^b 9.9	11.0 10.5 (9.3) 9.3	11.6 11.2 (9.3) 8.8	13.1 13.4 (10.0) 10.0
F1b	0 4 21	13.3 13.0 (9.8) 9.8	10.3 9.6 (9.0) 8.9	13.4 13.2 (9.9) 9.8	11.3 10.8 (9.7) 9.3
F2a	0 4 21	13.4 13.1 (9.9) 9.9	12.2 11.6 (10.0) 9.9	12.0 11.8 (9.8) 9.8	------
F2b	0 4 21	10.5 10.4 (8.2) 8.2	13.6 13.3 (9.8) 9.7	14.0 13.8 (10.0) 9.0	------
^aMean live pups/litter on indicated day. The number of pregnant females that gave birth on day 0 is presented in Table 2; ^bMean live pups/litter before litter reduction (mean live pups/litter after reduction to five pups/sex/litter when possible)

Table 4. Body weight of pups from rats treated with maleic anhydride during a multigeneration reproduction study

		Maleic anhydride (mg/kg/day)
Litter	Days after birth	0	20	55	150
F1a	0 4 21	6.7^a 12 (11)^c 58 (56)	6.6 11 (11) 54 (53)	6.7 12 (11) 58 (55)	5.8^b 10 (9) 46^b(44)^b
F1b	0 4 21	6.4 11 (10) 53 (50)	7.1^b 12 (12) 54 (54)	6.2 11 (10) 51 (50)	6.3 10 (10) 47 (46)
F2a	0 4 21	6.6 11 (10) 47 (45)	6.4 10 (10) 47 (46)	6.7 10 (10) 46 (45)	------
F2b	0 4 21	6.8 11 (11) 50 (57)	6.4 10 (9) 45 (44)^b	6.1 9 (9) 43 (44)^b	------
^aMean weight (g) of both males and females; ^bSignificantly different from control;^cMean weight (g) of males (mean weight (g) of females)

Applicant's summary and conclusion

Conclusions:

With reference to fertility, neither a dose-related reduction nor a pattern (during the two consecutive matings) within the parental (P0/F0) generation suggested a treatment-related effect. In F1 generation 100% mortality was observed among female rats at 150 mg/kg bw/day. Therefore, the high dose group was terminated and 55 mg/kg bw/day was the highest dose tested in the F1 generation and therefore F2 generation pups. No adverse effects on fertility were observed. Based on these observations the NOAEL (fertility) was derived at 55 mg/kg bw/d (highest dose tested under the conditions of this study).

Executive summary:

In a multigeneration generation reproduction study (similar to OECD Guideline 416) maleic anhydride (purity 99%) was administered to 10 male and 20 female rats/dose in by gavage at dose levels of 0, 20, 55 or 150 mg/kg bw/day). The rats were mated to produce two generations, each with two litters. Groups of the same size from the second litter were used for subsequent generations and were given the same dose of maleic anhydride as were their parents.Since 100% mortality was observed among parental F1 female rats at 150 mg/kg bw/day. The high dose group was terminated in the F1 and 55 mg/kg bw/day was the highest dose tested in the F1 generation and therefore F2 generation pups. The study was reduced from a three generation to a two generation study..

Renal cortical necrosis occurred in high-dose P/F0 males and females. Increased kidney weights were observed in low- and mid-dose adult F1 females. Therefore, no NOAEL could be determined and the LOAEL (systemic) was regarded as 20 mg/kg bw/day. With reference to fertility, neither a dose-related reduction nor a pattern (during the two consecutive matings) within the parental (P0) generation suggested a treatment-related effect. In F1 generation 100% mortality was observed among female rats at 150 mg/kg bw/day. Therefore, the high dose group was terminated and 55 mg/kg bw/day was the highest dose tested in the F1 generation. No adverse effects on fertility was observed. Based on these observations the NOAEL(fertility) was derived at 55 mg/kg bw/d (highest dose tested under the conditions of this study).

This study is acceptable and satisfies the guideline requirement for a 2-generation reproductive study OECD 416 in rats.

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