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Effects on fertility

Description of key information
no data
Link to relevant study records
Reference
Endpoint:
two-generation reproductive toxicity
Remarks:
based on test type (migrated information)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Deviations:
yes
Remarks:
F1 generation was exposed to test substance 1 week after weaning instead of being exposed at weaning. Sperm parameters oestrus cycle not examined,. only brain, liver and kidney were weighed,reproductive organs (m+f), liver, kidneys microscopically
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Portage, MI
- Age at study initiation: (P) 6 wks; (F1) 6 wks
- Weight at study initiation: Males: 129-233 g; Females: 131-162 g
- Housing: all animals were individually housed in suspended stainless stell cages with wire mesh floors except during lactation.
- Diet (e.g. ad libitum): Rodent Laboratory Chow/5002 (registered trademark of Ralston Purina Company, St. Louis, MO) ad libitum.
- Water (e.g. ad libitum) :ad libitum during non-exposure period.
- Acclimation period: 13 days prior to initiation of exposure during non-exposure period.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 65-77°F
- Humidity (%): 40-70%
- Photoperiod (hrs dark / hrs light): 12hrs dark/12hrs light cycle.


Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
other: preconditioned air
Details on exposure:
For generating an atmosphere of MCB vapor the test material was fed into an atomizing nozzle via an FMI fluid metering pump. The vaporized test material was diluted with preconditioned air prior to entry into the exposure chamber
Details on mating procedure:
- M/F ratio per cage: 1:1
- Length of cohabitation: 10 days.
- Proof of pregnancy: vaginal plug / sperm in vaginal smear referred to as day 0 of pregnancy.
- After 10 days of unsuccessful pairing replacement of first male by another male with proven fertility of the same treatment group (random selection)
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged (how): Once the female had mated, she was housed individually for the remainder of the gestation period.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
MIRAN 1 A organic vapour analyzer was used. At least 4 samples were drawn daily at hourly intervals from each exposure chamber.
Duration of treatment / exposure:
Premating exposure period (males): F0 males: 10 weeks; F1 males: 11 w eeks
Premating exposure period (females): F0 females: 10 weeks; F1 females: 11 w eeks
Exposure period: F0 and F1 generation: during mating period, d0 - 20 of gestation and d4 - 21 of lactation
Duration of test: until weaning (day 21 of lactation) of F2 pups
Frequency of treatment:
6 hour per day, 7 days per week
Details on study schedule:
Groups of 30 males and 30 females CD rats, designed as P generation, were exposed to vapor of monochlorobenzene (MCB) at target concentrations of 0 , 50 , 150, or 450 ppm (0, 234, 702 or 2106 mg/m³) for 10 weeks prior to mating and during mating, gestation, and lactation. The progeny of the P generation was designed as the F1 generation and groups of 30 male and 30 female F1 animals were exposed to the same concentration of MCB as the F0 parents. Exposure of F1 animals was initiated 1 week postweaning and lasted 11 weeks prior to the mating and through mating, gestation, and lactation. All F2 pups were observed through weaning at which time they were killed.
Observations made during the study included body weights, food consumption, mating and fertility indices, pup and litter survival indices, and histopathology of selected tissues.
Remarks:
Doses / Concentrations:
F0 and F1 generation: 0, 50, 150 or 450 ppm (0, 234, 702 or 2106 mg/m³)
Basis:

No. of animals per sex per dose:
30
Control animals:
yes, concurrent vehicle
Positive control:
no data
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All adult and weanling animals were observed for mortality and clinical signs twice daily.


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Detailed physical examinations were performed weekly.


BODY WEIGHT: Yes
- Time schedule for examinations: Male body weights were recorded weekly; female body weights were recorded weekly prior to mating, on days 0, 4, 14, and 20 of gestation, on days 0, 4, 7, 14 and 21 of lactation, and weekly again following lactation.




Oestrous cyclicity (parental animals):
no data
Sperm parameters (parental animals):
not tested
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).


PARAMETERS EXAMINED
The following parameters were examined in [F0 / F1/ F2] offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical abnormalities.


GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; possible cause of death was not determined for pups born or found dead.
Postmortem examinations (parental animals):
SACRIFICE
- Male animals: All surviving animals were sacrificed after weaning of the F1 generation.
- Maternal animals: All surviving animals were sacrificed after weaning of the F1 generation.




HISTOPATHOLOGY / ORGAN WEIGHTS
The tissues indicated in Table 1 were prepared for microscopic examination and weighed, respectively.
Postmortem examinations (offspring):
SACRIFICE
- The F1 offspring not selected as parental animals and all F2 offspring were sacrificed at 21 days of age (weaning).






Statistics:
Mean body weights, food consumption, organ weights, organ to body weight ratios, gestation lengths, and numbers of offspring were evaluated statistically using the following methods: Bartlett´s test, parametric methods (one-way analysis of variance which was followed by a Dunnett test) , Kruskal- Wallis test, and Dunn´s summed rank test.
Incidence data, which included pregnancy rates, fertility indices, mating indices, and litter survival indices, were analyzed using contingency tables.
First, a standard chi-square analysis was performed to determine of the proportion of indices differed between the groups tested. Next, each treatment group was compared to the control group using 2X2 Fisher exact test , and the significance level was corrected using the Bonferroni inequality. Also, an Armitage test for linear trend was performed.
Reproductive indices:
The mating index for males (ratio of number of males for which mating was confirmed in at least one female to total number of males) and
the mating index for females (ratio of number of females showing evidence of mating to total number of females),
pregnancy rate (ratio of number pregnant to number mated), and
fertlity index for males (ratio of number of males impregnating a female to number mating) were calculated for each of the two matings.
Offspring viability indices:
Pup viability index at birth (total number of live pups at day 0 / total number of pups observed (live plus dead pups at day 0 for individual females
Pup survival index at day 4: total number of live pups at day 4 (precull) / total number of live pups at day 0 for individual females
Pup survival index at day 21: total no of live pups at day 21 / total number of live pups at day 4 (postcull) for individual females
Litter survival index: total number of litters with live pups at weaning (day 21) / total number of litters with live pups at birth
Clinical signs:
no effects observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Other effects:
not specified
Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed
REPRODUCTIVE PERFORMANCE
TEST DATA
Mating and fertility indices for males and females for both generations appeared unaffected by treatment
--Mean number of days to mate (control, 50, 150, 450 ppm)
P: 4.2, 3.1, 2.8, 3.1 F1: 4.9, 3.2, 3.1, 4.6
--Mating indices (%, females): control, 50, 150, 450 ppm
P: 100, 100, 96.7, 100 F1: 100, 96.7, 96.7, 93.3
--Mating indices (%, males): control, 50, 150, 450 ppm
P: 86.7, 93.3, 96.7, 96.7 F1: 90, 96.7, 96.7, 83.3
--Fertility indices , (%, males): control, 50, 150, 450 ppm
P: 92.3, 100, 93.1, 89.7 F1: 77.8, 100, 79.3, 88
--Pregnancy indices (%, females), control 50, 150, 450 ppm)
P: 90, 100, 93.1, 86.7 F1: 80, 100, 79.3, 89.3

HISTORICAL CONTROL DATA - CD rat (Bio/dynamics, Inc., 1978-1984)
represents reproduction indices for a total of 16 studies containing a total of 62 litter intervals:
------mean and range [....] of study values
--male mating index: mean = 92.6 % [66.7 % to 100.0 %]
--female mating index: mean = 88.3 % [70.0 % to 100.0 %]
--pregnancy rate:..........mean = 85.0 % [67.9 % to 100.0 %]
--male fertility index:....mean = 94.8 % [80.0 % to 100.0 %]

ORGAN WEIGHTS (PARENTAL ANIMALS)
Significant increases in mean absolute and/or relative liver weight were observed in the both P+F1 generation in the 150 and 450 ppm groups.
In the low-concentration group, only the relative liver weights of the F1 male rats were elevated.
males
absolute liver weights(g): control, 50, 150, 450 ppm
P: 19.25, 19.03, 21.48(p<=0.01), 21.84(p<=0.01) F1: 18.31, 19.46, 21.71(p<=0.01), 23.35(p<=0.01)
relative liver weights
P: 3.61, 3.60, 4.06(p<=0.01), 4.12(p<=0.01) F1: 3.47, 3.73(p<=0.05), 4.15(p<=0.01), 4.44(p<=0.01)
females
absolute liver weights(g): control, 50, 150, 450 ppm
P 11.45, 12, 12.08, 13.27(p<=0.01) F1: 12.36,12.7, 13.13, 13.95(p<=0.01)
relative liver weights
P: 3.77, 3.89, 3.95(p<=0.05), 4.41(p<=0.01) F1: 4.16, 4.17, 4.36, 4.59 (p<=0.01)

GROSS PATHOLOGY (PARENTAL ANIMALS)
--male, Increase in the incidence of small flaccid testes (50, 150, 450 ppm):
P: 0/30, 1/30, 3/30 F1: 0/30, 1/30, 5/30
--increase in incidence of dilated renal pelvis (control, 50, 150, 450 ppm)
male
P: 1/30, 1/30, 2/30, 4/30 F1: 1/30, 4/30, 6/30, 4/30
female:
P: 5/30, 4/30, 6/30, 5/30 F1: 0/30, 1/30, 2/30, 2/30

HISTOPATHOLOGY (PARENTAL ANIMALS)
Microscopic changes related to treatment were observed in the liver and kidney.

--Hepatocellular hypertrophy- incidence (0, 50, 150, 450 ppm)
male
P: 0/30, 0/30, 5/30, 14/30 F1: 2/30, 0/30, 3/30, 7/30.
All affected male rats showed only minimal to mild hepatocellular hypertrophy.
female
Only one high-concentration level female rat in the P generation showed hepatocellular hypertrophy (data not shown).

--Renal degeneration and inflammatory lesions were limited to the male rats.
The incidence and severity of renal changes were elevated in the mid-and high-concentration groups.
P. 30 males examined from each group: (0, 50, 150, 450 ppm)
bilateral tubular dilation/eosinophilic material : 0, 1, 4, 15
bilateral chronic interstitial nephritis : 1, 2, 7, 9
bilateral foci if regenerative epithelium : 0, 1, 5, 8
P: 30 females were examined of the control and 450 ppm group:
bilateral chronic interstitiial nephritis 0/30; 2/30
F1. 30 males examined from each group: (0, 50, 150, 450 ppm)
bilateral tubular dilation/eosinophilic material : 4, 3, 8, 16
bilateral chronic interstitial nephritis : 0, 1, 6, 11
bilateral foci if regenerative epithelium : 1, 0, 4, 10
F1: 30 females were examined of the control and the 450 ppm group
Unilateral tubular dilatation /eosinophilic material: 0/30; 3/30

Key result
Dose descriptor:
NOAEC
Remarks:
fertility
Effect level:
ca. 450 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Monochlorobenzene did not have any adverse effects on reproductive performance or fertility through 2 consecutive generations
Remarks on result:
other: Generation: P, F1 (migrated information)
Key result
Dose descriptor:
LOAEC
Remarks:
(systemic toxicity)
Effect level:
ca. 50 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Remarks on result:
other: Generation: P, F1 (migrated information)
Key result
Critical effects observed:
no
Key result
Dose descriptor:
NOAEC
Effect level:
450 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Pub survival indices were considered comparable for control and treated animals in both generations
Key result
Critical effects observed:
no
Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Sexual maturation:
no effects observed
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Histopathological findings:
not specified
VIABILITY (OFFSPRING)
No mortality was observed in the treated and control groups of the F1 generation.
In F2 litters, a slight decrease in pup survival index (days 0-4) was observed in the higest concentration level only.
The majority of the decrease in pup survival index(day 0-4) at the highest concentration level was attributed to two dams; one dam lost 12 of 15 pups during lactation days 0-4, and the other dam lost all 10 pups during the same time period. The authors stated that excluding pup survival data for these 2 litters the day 0-4 pup survival index for the high-concentration group was94.5 % which is similar to control value. they concluded that if this had been a compound-related response, more affected litters would have been expected.
Therefore, pup survival indices for control and treated animals for both litters were considered comparable.

--Pup viability index [%] (0, 50, 150, 450 ppm)
F1: 96.9, 96.1, 99, 96.4 F2: 98.1, 97.2, 97.9, 97.4

--Pup survival index [%] day 0-4 (0, 50, 150, 450 ppm)
F1 92.4, 96.7, 94.1, 90.5 F2: 94.4, 93.2, 97.6, 87.7

--Pup survival index [%] day4-21 (0, 50, 150, 450 ppm)
F1: 96.7, 95, 97.1., 93.5 F2: 88.4, 99.1, 89.1, 89.6
--Litter survival index [%] (0, 50, 150, 450 ppm)
F1: 100, 96.7, 96.3, 92.3 F2: 91.7, 96.6, 91.3, 88
Key result
Dose descriptor:
NOAEC
Generation:
F1
Effect level:
450 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Pub survival indices were considered comparable for control and treated animals in both generations
Key result
Critical effects observed:
no
Key result
Dose descriptor:
NOAEC
Generation:
F2
Effect level:
450 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Pub survival indices were considered comparable for control and treated animals in both generations
Key result
Critical effects observed:
no
Key result
Reproductive effects observed:
no

F0 mating (for F1 litters)

Group (ppm)              Pregnancy, female (percentage)       Fertility, males

0                        90.0                                   92.3

50                       100.0                                  100.0

150                      93.1                                   93.1

450                      86.7                                   89.7

F1 mating (for F2 litters)

Group (ppm)              Pregnancy, female (percentage)       Fertility, males

0                        90.0                                   77.8

50                       96.7                                  100.0

150                      96.7                                   79.3

450                      83.3                                   88.0

Executive summary:

Groups of 30 males and 30 females CD rats, designed as P generation, were exposed to vapor of monochlorobenzene (MCB) at target concentrations of 0 , 50 , 150, or 450 ppm (0, 234, 702 or 2106 mg/m³) for 10 weeks prior to mating and during mating, gestation, and lactation. The progeny of the P generation was designed as the F1 generation and groups of 30 male and 30 female F1 animals were exposed to the same concentration of MCB as the F0 parents. Exposure of F1 animals was initiated 1 week postweaning and lasted 11 weeks prior to the mating and through mating, gestation, and lactation. All F2 pups were observed through weaning at which time they were killed.

Observations made during the study included body weights, food consumption, mating and fertility indices, pup and litter survival indices, and histopathology of selected tissues.

No mortality was observed during the course of this study. No adverse effect of treatment was evident on body weight, food consumption, and physical observation. Mating and fertility indices for males and females for both generations appeared unaffected by treatment.The slightly reduced pregnancy indices mainly at the highest concentration level (0, 50, 150, 450 ppm: P: 90, 100, 93.1, 86.7 F1: 80, 100, 79.3, 89.3) were within the historical control data of the testing facility in the respective time interval (CD rat at Bio/dynamics, Inc., 1978 -1984, representing pregnancy rates for a total of 16 studies containing a total of 62 litter intervals:

mean = 85.0 % [67.9 % to 100.0 %]. Body weights and food consumption for all treated groups were comparable to controls during the growth period. Maternal body weight data during gestation and lactation were also comparable between the control and treated groups

Overall, reproductive performance, fertility and development of pups were not affected by treatment with monochlorobenzene yielding a NOAEC of 450 ppm (corresponding to 2106 mg/m³) for reproduction and development.

However, post mortem examinations revealed significantly elevated absolute and relative liver weights in F0 and F1 male and female rats at 150 and 450 ppm and at 50 ppm in F1 males accompanied by hepatocellular hypertrophy in F0 and F1 males exposed to 150 and 450 ppm. In addition, renal changes (tubular dilation with eosinophilic material, interstitial nephritis, and foci of regenerative epithelium) were observed mainly in F0 and F1 male rats exposed to 150 and 450 ppm. The significance of reported degeneration of the testicular germinal epithelium in male rats at 450 ppm is unclear because no histopathological correlate is reported. Thus, the LOAEC (systemic toxicity) is considered to be 50 ppm (corresponding to 234 mg/m³).

Effect on fertility: via oral route
Endpoint conclusion:
no study available
Effect on fertility: via inhalation route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
2 106 mg/m³
Study duration:
subchronic
Species:
rat
Quality of whole database:
GLP study similar to guideline
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

Groups of 30 males and 30 females CD rats, designed as P generation, were exposed to vapor of monochlorobenzene (MCB) at target concentrations of 0 , 50, 150, or 450 ppm (0, 234, 702 or 2106 mg/m³) for 10 weeks prior to mating and during mating, gestation, and lactation. The progeny of the P generation was designed as the F1 generation and groups of 30 male and 30 female F1 animals were exposed to the same concentration of MCB as the F0 parents. Exposure of F1 animals was initiated prior to the mating and through mating, gestation, and lactation. All F2 pups were observed through weaning at which time they were killed.

Observations made during the study included body weights, food consumption, mating and fertility indices, pup and litter survival indices, and histopathology of selected tissues.

No mortality was observed during the course of this study. No adverse effect of treatment was evident on body weight, food consumption, and physical observation. Mating and fertility indices for males and females for both generations appeared unaffected by treatment.The slightly reduced pregnancy indices mainly at the highest concentration level (0, 50, 150, 450 ppm: P: 90, 100, 93.1, 86.7 F1: 80, 100, 79.3, 89.3) were within the historical control data of the testing facility in the respective time interval (CD rat at Bio/dynamics, Inc., 1978 -1984, representing pregnancy rates for a total of 16 studies containing a total of 62 litter intervals:

mean = 85.0 % [67.9 % to 100.0 %]. Body weights and food consumption for all treated groups were comparable to controls during the growth period. Maternal body weight data during gestation and lactation were also comparable between the control and treated groups

Overall, reproductive performance, fertility and development of pups were not affected by treatment with monochlorobenzene yielding a NOAEC of 450 ppm (corresponding to 2106 mg/m³) for reproduction and development.

However, post mortem examinations revealed significantly elevated absolute and relative liver weights in P and F1 male and female rats at 150 and 450 ppm and at 50 ppm in F1 males accompanied by hepatocellular hypertrophy. In addition, renal changes (tubular dilation with eosinophilic material, interstitial nephritis, and foci of regenerative epithelium) were observed mainly in F0 and F1 male rats. The significance of reported degeneration of the testicular germinal epithelium in male rats at 450 ppm is unclear because no histopathological correlate is reported. Thus, the LOAEC (systemic toxicity) is considered to be 50 ppm (corresponding to 234 mg/m³).


Short description of key information:
In a two generation reproductive toxicity study in accordance to OECD TG 416 male and female CD rats were exposed to 0, 50, 150 and 450 ppm ( corresponding to 0, 234, 702, 2106 mg/m³) monochlorobenzene. The exposure to monochlorobenzene has no adverse effect s on reproductive performance or fertility of male and female rests despite the availabliity of systemic toxicity:
NOAEC ( male, female, reproduction and fertility): 450 ppm (2106 mg/m³); LOAEC male, female, systemic): 50 ppm (234 mg/m³)

Justification for selection of Effect on fertility via inhalation route:
key study is used (only available 2-generation study)

Effects on developmental toxicity

Description of key information
The embryotoxic and teratogenic potential of inhaled chlorobenzene was evaluated in rats and rabbits  
Fischer 344 rats and New Zealand White rabbits were exposed to 0, 351, 983, or 2761 mg/m³ chlorobenzene via inhalation for 6 hr/day during the period of major organogenesis. In a second study with rabbit, additional groups were exposed to 0, 47, 140, 351, or 2761 mg/m³ using the same experimental conditions. Overall, based on the available results in rats and rabbits the NOAEC (development) is considered to be 450 ppm ( corresponding to 2761 mg/m³ ).
Link to relevant study records
Reference
Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions
Reason / purpose for cross-reference:
reference to same study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
Rats exposure was too short.Gravid uterus weight not dtermined. Food consumption data and results were not reported. Recording of body weights started too late.
GLP compliance:
not specified
Limit test:
no
Species:
rat
Strain:
Fischer 344
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Portage, Michigan, USA.
- Age at study initiation: adult.
- Weight at study initiation: 175-220 g at breeding.
- Housing: Animals were housed in wire-bottom cages.
- Diet (e.g. ad libitum): Feed (Certified Laboratory Animal Chow, Ralston Purin Co., St. Louis, Mo.) were available ad libitum.
- Water (e.g. ad libitum): tap water was available ad libitum.
- Acclimation period: at least 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): approx. 22°C
- Humidity (%): approx. 50%
- Photoperiod (hrs dark / hrs light):12hrs dark / 12hrs light

Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
other: compressed air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation exposures were conducted in 4.3 m³ Rochester-type stainless-steel and glass chambers under dynamic airflow conditions.
- Source and rate of air: dynamic airflow conditions (circa 800 liters air/min).
- System of generating particulates/aerosols: exposure concentrations of monochlorobenzene were generated by metering the liquid test material at controlled rates into vaporization tubes (described in Miller et al. 1980. Amer. Ind. Hyg. Assoc. J. 4, 844-846). Vapors from the tubes were swept into the chamber inlet ducts with compressed air where they were mixed and diluted with incoming air by turbulence. The compressed air supply to the vaporization tubes was preheated (120 to 135°C) to facilitate complete vaporization of the liquid test material.
- Temperature, humidity, pressure in air chamber: temperature was approximately of 21°C, and the humidity of approximately 50%.



Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Monochlorobenzene concentrations in the chambers were analyzed one to two times per hour throughout the exposure periods by infrared spectrophotometry using a Miran IA-CVF analyzer equipped with a variable pathlength gas cell.
Details on mating procedure:
- Impregnation procedure: cohoused
- If co-housed:
- M/F ratio per cage: 1:1
- Further matings after two unsuccessful attempts: no
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy.


Duration of treatment / exposure:
6 h/d
Frequency of treatment:
daily from day 6 to day 15 of gestation
Duration of test:
On day 21 of gestation test animals were sacrificed
No. of animals per sex per dose:
32 /33 bred rats
Control animals:
yes
Details on study design:
Sex: female
Duration of test: Section on d 21 of gestation
Control animals were exposede to filtered air
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily


DETAILED CLINICAL OBSERVATIONS: Yes
--Time schedule: daily


BODY WEIGHT: Yes
- Time schedule for examinations: body weights of rats were recorded on gestation days 6, 9, 12, 16, and 21.


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: uterine horns.


Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: number and position of fetuses in utero, number of live and dead fetuses
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: all per litter
-body weight : Yes: all per litter
-sex: Yes: all per litter
Statistics:
Statistical evaluation of the frequency of alterations and of resorptions among litters and the fetal population was conducted by the Wilcoxon test as modified by Haseman & Hoel, 1974. Statistical analysis of the percentage of pregnancy and other incidence data were conducted by the Fisher exact probability test (Siegel, 1956. Nonparametric statistics for the behavioral Sciences. MCGraw-Hill, New York). Analyses of the other data were made by parametric or non parametric analysis of variance followed by either Dunnett test or the Wilcoxon test as appropriate (Steel and Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill, New York). The reported level of statistical significance was alpha=0.05. For feed and water consuption data, statistical outliers were identified by a sequential outlier test, alpha=0.02 (Grubbs FE, 1969. Technometrics 11, 1-21), and were deleted from the calculation of mean values.
Indices:
no data
Historical control data:
Yes
Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
No maternal deaths occurred during the period of the study, and no significant effects on general appearance were observed among bred rats exposed to 0, 75, 210, or 590 ppm of monochlorobenzene on days 6 through 15 of gestation. Some evidence of maternal toxicity was observed in the 590 ppm exposure group. Monochlorobenzene exposed pregnant rats gained significantly less weight than controls on Days 6 through 8 of gestation and the absolute and relative weights of the liver on Day 21 of gestation were significantly increased but histopathological correlates were not reported. No effects on body weight gain or liver weights were observed in the 75 or 210 ppm groups.
Key result
Dose descriptor:
NOAEC
Effect level:
590 ppm
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The pregnancy rate in rats was not altered by exposure to 75, 210, 590 ppm of monochlorobenzene.No adverse effects were observed on the mean litter size or incidence of implantations which were undergoing resorption. Fetal body measurements for the monochlorobenzene exposed groups were comparable to the control values. The incidence of malformations, when considered individually or collectively, was not significantly increased for any of the exposed groups compared to the control groups.
Skeletal examinations of the fetuses reveled increased incidences of some minor variants, but all of them were not considered to be indicative of a teratogenic response.
Key result
Dose descriptor:
NOAEC
Effect level:
590 ppm
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Inhalation of monochlorobenzene was not embryotoxic or teratogenic in rats
Key result
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no

Table 1

Body weights and organ weights of pregnant rats

              MCB
   Gestation day  0  75  210  590
 Number of dams    27  29  27  28
 Body weight  6  196±7a  196 ±28  195±6  196±5
 Body weight gain  6-8  3±2  4±3  2±3  -2±5b
   9-11  10±4  9±3  9±4  10±4
   12 -15  13±4  14±4  15±4  15±5
   16 -20  37±8  36±11  40±7  40 ±11
 Total  6 -20  63±11  63±14  67±9  64±17
 Maternal liver weight  21        
 Absolute    9.82±1.13  9.97±0.81  10.12±0.54  10.99±0.83b
 Relative    3.79±0.28  3.85±0.28  3,86±0.21  4.25±0.42b

a Grams, average ± SD

b Different from the control value by Dunnett´s test,alfa=0.05

c Grams liver/weight/100 grams body weight, average

± SD

Table 2

Incidence of fetal alterations among litters of rats

            MCB (ppm)
   0  75  210  590
            No. fetuses (No.litters) examinated
 External and skeletal examination  241 (27)  256 (29)  267 (27)  258 (28)
 Soft tissue examination  128 (27)  138 (29)  141 (27)  139 (28)
             No. fetuses (No.litters) affected
 External alterations      
 Omphalocele a  1 (1)  0
 Cleft palate a  0 1 (1) 
 Soft tissue alterations           
 Liver, focal necrosis  30 (21)  25 (18)  22 (14)b  19 (14) b
 Renal agenesis a  1 (1) c  0 0
 Dilated renal pelvis a  0  1 (1)  2 (2)
 Right-sidedaortic arch a  1 (1) c  0
 Microphthalmia a  2 (2) c  0 1(1) 
 Anophthalmia a  1 (1)  0   1 (1)  0
 Skeletal alteration           
 Vertebrae           
 Delayed ossification of centra  59 (23)  91 (27) b  73 (23)  103 (27)b
 Bilobed centra  8 (5)  8 (7)  3 (2)  12 (11) b
 Cervical spur(s)  25 (17)  35 (18)  22 (14)  13 (11) b
 Sternebrae delayed ossification  75 (24)  94 (27)  86 (24)  75 (25)
             
 Total malformed d  4 (4)  1 (1)  2 (2)  3 (3)

a Considered to be a malformation.

b Different from control incidence by a modified Wilcoxon test, alpha=0.05

c One fetus exhibited renal agenesis (unilateral), right-sided aortic arch, and microphthalmia.

d Total number of fetuses (litters) exhibiting one or more malformations.

Executive summary:

The embryotoxic and teratogenic potential of inhaled chlorobenzene was evaluated in rats. This study was conducted according to OECD guideline 414 with deviations (Rats exposure was too short. Gravid uterus weight was not determined. Food consumption data and results were not reported .Recording of body weights started too late).

Pregnant female Fischer 344 rats were exposed to 0, 75, 210, or 590 ppm (0, 351, 983 or 2761 mg/m³) of chlorobenzene via inhalation for 6 hour/day during the period of major organogenesis (days 6 through 15 of gestation). No maternal deaths occurred during the period of the study, and no significant effects on general appearance were observed among rats. Some evidence of maternal toxicity was observed in the 590 ppm (2761 mg/m³) exposure group. Chlorobenzene exposed pregnant rats gained significantly less weight than controls on Days 6-8 of gestation and the absolute and relative weights of the liver were significantly increased but a histopathological correlate was not reported.

Inhalation of chlorobenzene vapors during gestation was not embryotoxic or teratogenic in rats. The pregnancy rate in rats was not altered by exposure to 75, 210, 590 ppm (351, 983 or 2761 mg/m³) of chlorobenzene. No adverse effects were observed on the mean litter size or incidence of implantations which were undergoing resorption. Fetal body measurements for the chlorobenzene exposed groups were comparable to the control values. The incidence of malformations, when considered individually or collectively, was not significantly increased for any of the exposed groups compared to the control groups. Skeletal examinations of the fetuses revealed increased incidences of some minor variants, but all of them were not considered to be indicative of a teratogenic response.

On the basis of these results the NOAEC for maternal and developmental toxicity was estimated to be 590 ppm (2761 mg/m³, John et al., 1984 ).

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
2 761 mg/m³
Study duration:
subacute
Species:
rat
Quality of whole database:
equivalent or similar to guideline study
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

The embryotoxic and teratogenic potential of inhaled chlorobenzene was evaluated in rats and rabbits (John et al, 1984). Fischer 344 rats and New Zealand White rabbits were exposed to 0, 351, 983, or 2761 mg/m³ chlorobenzene via inhalation for 6 hr/day during the period of major organogenesis. To further evaluate the effects of chlorobenzene in rabbits, additional groups were exposed to 0, 47, 140, 351, or 2761 mg/m³ under the same experimental conditions

With respect to the studies in rats monochlorobenzene vapor inhalation during gestation was not embryotoxic or teratogenic.

In the first study with rabbits, evidence of slight maternal toxicity was observed among rabbits exposed to 983 or 2761 mg/m³; the absolute and relative weights of the liver were significantly increased in these groups. No statistically identified or consistent effects on body weight or body weight gain were observed in any of the exposure groups of rabbits. The pregnancy rate in rabbits was not altered by exposure to chlorobenzene. At the same time any adverse effects on the mean litter size or the incidence of implementations which were undergoing resorption were observed.

In the second study in rabbits, exposure to 2761 mg/m³ produced an increase in the liver weight of maternal animals. A significant increase in the percentage of implantations undergoing resorption was observed in the 2761 mg/m³group. In this group, 61% of the litters (12% of fetuses) contained resorptions compared to 41% of the litters for the controls (6% of the fetuses). The resorption rate was not signifcantly altered at the lower exposure concentrations.

A significant increase in the mean fetal crown-rump lenght was observed in litters from the 983 mg/m³ group, but this increase was not considered to be of toxicological importance. Mean fetal body weights of litters from the exposed groups were not significantly altered. In the first study, exposure of rabbits to 0, 351, 983, or 2761 mg/m³ chlorobenzene resulted in a variety of malformations in all groups, at an incidence slightly higher than historical controls. Forelimb flexure, the malformation most often observed occurred more often among controls than among any of the treatment groups as malformations of the skeletal system. The latter induced hemivertebrae, missing or fused vertebrae, crooked long bones, and a variety of rib malformations. However, there were several cases of external and visceral malformations which were scattered among exposed groups. For instance spina bifica (single case) and low incidence of heart anomalies were observed in the 210 and 590 ppm (983 and 2761 mg/m³) groups, whereas these malformations were not observed among the concurrent control group. In the second study , fetal body measurements were not adversely affected by exposure by chlorobenzene. The incidence of malformations from the exposed groups, when cosidered individually or collectively, was not significantly increased compared to the control group. Fetuses with external soft tissue, and the skeletal malformations were observed among all groups including controls.

Overall, the NOAEC was deduced to more than 2761 mg/m3.


Justification for selection of Effect on developmental toxicity: via inhalation route:
Key study in rats is used (no developmental toxicity in rats and rabbits)

Toxicity to reproduction: other studies

Additional information

no data

Justification for classification or non-classification

No classification/labelling is required.

Additional information