1,4-dichlorobenzene

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Reference 1

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study under GLP conditions.

Qualifier:

according to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

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
- Age at study initiation: (P) males 8 weeks; females 11 weeks
- Housing: one male and one female for mating, then individual
- Diet ad libitum
- Water ad libitum
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 60
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: From: To:

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on exposure:

P: males received the test substance for 77 days females for 14 days prior to mating, Then the animals received the tstsubstance upt and including the pups(F2) of the F1 generation

Details on mating procedure:

Start of mating procedure: Day 78 (p-generation); Day 204 (F1 generation).
End of mating procedure was 14 days (p-generation, respectively 30 days later (F1 generation).

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

After administration of the test substance for 77 days (male animals), 14 days (female animals) all animals were mated monogamic within the individual dosegroups and the administration of test substance was continued.
After the succeeded birth the dams were treated with the test material until the 21. day of life of the pups.
24 of these pups per sex and group remained in the experiment and were treated with the test substance until the elimination out of the experiment. After approx. 80 days the monogamic mating procedure was executed within this F1 generation to produce F2 generation.

Frequency of treatment:

daily

Details on study schedule:

see: table in ´Any other materials and methods´.

Remarks:

Doses / Concentrations:
0, 30, 90, 270 mg/kg/day, 7days/week
Basis:

No. of animals per sex per dose:

24 rats/dose/sex

Control animals:

yes

Details on study design:

After administration of the test substance for 77 days (male animals), 14 days (female animals) all animals were mated monogamic within the individual dosegroups and the administration of test substance was continued.
After the succeeded birth the dams were treated with the test material until the 21. day of life of the pups.
24 of these pups per sex and group remained in the experiment and were treated with the test substance until the elimination out of the experiment. After approx. 80 days the monogamic mating procedure was executed within this F1 generation to produce F2 generation.

Positive control:

no

Parental animals: Observations and examinations:

for clinical signs and mortality , behavior during mating and birth of the litter, body weight development, food consumption

Litter observations:

number of pups per litter, gender, body weight, survival, and changes during early development such as eyes, and ears. from day 21 e.g. reflexes , orientation

Postmortem examinations (parental animals):

sacrifice of all animals, investigationmacroscopically and microscopically of reproductive organs,liver, spleen, kidneys including organ weight determination, and macroscopically all organs with obvious changes

Postmortem examinations (offspring):

only macrospcopical investigation if found dead in cage
all offsprings all organs which demonstated macroscopically changes

Statistics:

arithmetic mean, variance analysis followed by Schffe-test, H-test of Kruskal and Wallis or U-test accorcing to Wilcoxon, Mann and Whitney,Chi-square test

Reproductive indices:

Fertility index, Gestation index

Offspring viability indices:

survival index (day 4), lactation index (day 21)

no mortality in P-generation, sacrifice of 4 moribund animals in F1 of 270 mg-group and 1 in 30 mg-group of F1
P-Generation body weight comparable to controls; F1 (high dose group reduced body weight development compared to controls
P-and F1-generation : no effects of test substance on Fertility Index and Gestation Index
Pathology:
P-generation:high dose and F1-generation high dose and mid dose:
males: increased relative and absolute weights of liver and kidneys, decreased spleen weights, histopathological changes in kidney but not in livers

Dose descriptor:

other: NOAEL (fertility)

Effect level:

270 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: The NOAEL for fertility was estimated to be 270 mg/kg/day;

Remarks on result:

other: Generation: P and F1 (migrated information)

Dose descriptor:

other: NOAEL (general toxicity)

Effect level:

90 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: the NOAEL of the P and F1 parents was found to be 90 mg/kg/day based on kidney changes at the highest test dose;

Remarks on result:

other: Generation: P and F1 (migrated information)

Dose descriptor:

other: NOAEL (offspring)

Effect level:

30 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: at 90 mg/kg/day toxicity in pups were seen associated with slight behavioral changes in pups from 90 mg/kg/day: the NOAL for these developmental effects is estimated at 30 mg/kg/day.

Remarks on result:

other: Generation: F1 and F2 (migrated information)

In the mid and the high dose groups :
reduced number of live pups at birth, increased number of pups deceased between days of lactation 1 to 4 and 5 to 21, reduced mean body weight of pups, retarded erection of ears and retarded of eye opening, reduced percentage of pups with positive draw-up test, dry and squamous skin and ring tails in pups followed by loss of the tail

Reproductive effects observed:

not specified

The NOAEL for fertility was estimated to be 270 mg/kg/day; the NOAEL of the F0 and F1 parents was found to be 90 mg/kg/day; at 90 mg/kg/day toxicity in pups were seen associated with slight behavioral changes in pups from 90 mg/kg/day: the NOAEL for these developmental effects is estimated at 30 mg/kg/day.

Executive summary:

p-Dichlorobenzene, dissolved in olive oil, was administered orally to two generations of rats to detect possible effects of the test substance on reproduction (OECD guideline 416 and GLP). The doses used for the three test substance groups were 30, 90 and 270 mg/kg bw/day. Olive oil was applied to one group of male and female rats that served as control group. Dose volume was 1 ml per kg body weight for all groups.

In both generations the test substance had no effects on: time between beginning of mating and evidence of copulation,

time of gestation, fertility index, gestation index, percentage of dams with only dead pups, total number of pups at birth,

percentage of pups with positive ear reflex, graspring reflex and orientation reaction, absolute and relative weights of

female kidneys, spleens and livers.

In the mid and/or high dose groups the test substance had an effect on number of live pups at birth (reduced), number of pups deceased between days of lactation 1 to 4 and 5 to 21 (increased), mean body weight of pups (reduced), erection of ears

and opening of eyes (retarded), percentage of pups with positive draw up test (reduced), alterations of the skin (dry,

squamous) and ring tails in pups, absolute and relative organ weights of adult males (livers and kidneys: increased;

spleens: reduced).damages to the kidneys in mild-and high-dose groups of both generations are also probably test

substance related.

At the low dose of 30 mg test substance per kg body weight no effects of the test substance were detected on fertility parameters of rats; the next higher dose of 90 mg/kg already caused massive damage in pups.

The NOAEL for fertility was estimated to be 270 mg/kg/day; the NOAEL of the F0 and F1 parents was found to be 90 mg/kg/day; at 90 mg/kg/day toxicity in pups were seen associated with slight behavioral changes in pups from 90 mg/kg/day: the NOAEL for these developmental effects is estimated at 30 mg/kg/day.

Overall, the NOAEL for fertility was estimated to be 270 mg/kg bw/day, the NOAEL(genral toxicity) for P and F1 parents was found to be 90 mg/kg bw/dayand the NOAELis estimated at 30 mg/kg bw.

Reference 2

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: OECD guideline not defined.

Principles of method if other than guideline:

Method: other: Two generation reproduction study
Weanling rats (P) were exposed to the test substance vapour at mean concentrations of 0, 66, 211 or 538 ppm, 28/sex/group for 3 weeks (with a switch for nonsuccessful females at 10 days and a satellite mating for nonsuccessful males). Selected F1 weanlings, 28/sex/group, were exposed for 11 weeks and mated, as described above. All nonselected F1 and F2 weanlings were necropsied.

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Route of administration:

inhalation

Type of inhalation exposure (if applicable):

not specified

Vehicle:

not specified

Details on exposure:

28/sex/group weanling rats (P) were exposed to p-dichlorobenzene vapor at mean concentrations of 0, 66, 211, 538 ppm 6 hr/day for 10 weeks and then mated for 3 weeks
28/sex/group selected F1 weanlings were exposed to 0, 66, 211, 538 ppm 6 hr/day for 11 weeks and then mated as described above to produce F2 generation.

Details on mating procedure:

no data

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

28/sex/groupweanling rats (P) were exposed to p-dichlorobenzene vapor 6 hr/day, daily for 10 weeks at mean concentrations of 0, 66, 211, 538 ppm and then mated for 3 weeks
28/sex/group selected F1 weanlings were exposed 6 hr/day, daily for 11 weeks and then mated as described above..

Frequency of treatment:

6 h/d, 7d/week.

Details on study schedule:

no data

Remarks:

Doses / Concentrations:
0, 66, 211 or 538 ppm (actual) (0, 396.7, 1268.1 or 3233.4 mg/m³)
Basis:

No. of animals per sex per dose:

28/animals/sex/group

Control animals:

yes, concurrent no treatment

Positive control:

no

Oestrous cyclicity (parental animals):

no data

Sperm parameters (parental animals):

no data

Litter observations:

Postnatal toxicity in F1 and F2 litters was observed only at 538 ppm ( no further data in the published abstract)

Offspring viability indices:

Postnatal toxicity in F1 and F2 litters was observed only at 538 ppm ( no further data in the published abstract)

----There were no P and F1 reproductive effects (no details in the published abstract)
----No treatment-related adult death
----538 ppm:
-P and F1 males and females exhibited reduced body weights and weight gain, reduced food consumption and clinical signs of toxicity (no details)
-P and F1 females reduced gestational weight
-in F1 but not in P females reduced lactational body weight
-in P but not in F1 in females increased kidney weights
-in P and F1 males tubular cell hyperplasia
-in P and F1 males and females hepatocellular hypertrophy
----at 211 and 538 ppm
-P and F1 male and female: increased liver weights
-----66, 211, 538 ppm
all exposed P and F1 males
increased kidney weights and alpha 1µglobulin accumulation, hyaline dropletnephropathytubular proteinosis, interstitial nephritis

Dose descriptor:

other: NOAEC (general toxicity)

Effect level:

<= 66 ppm

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Remarks on result:

other: Generation: P and F1 (migrated information)

Dose descriptor:

other: NOAEC (fertility)

Effect level:

538 ppm

Sex:

male/female

Basis for effect level:

other: There were no reproductive effects

Remarks on result:

other: Generation: P and F1 (migrated information)

Dose descriptor:

other: NOAEC (development)

Effect level:

211 ppm

Sex:

male/female

Basis for effect level:

other: at 538 ppm F1 and F2 litters exhibited reduced body weight and increased perinatal deaths with no gross lesions

Remarks on result:

other: Generation: F1 and F2 (migrated information)

Postnatal toxicity in F1 and F2 litters was observed only at 538 ppm ( no further data in the published abstract)
F1 and F2 litters exhibited reduced body weight and increased perinatal deaths with no gross lesions

Reproductive effects observed:

not specified

Migrated dataset from IUCLID4

RS-Freetext:
Decrease in body weight, weight gain and food consumption
and clinical signs of toxicity for F0 and F1 males and
females at 538 ppm; decreased gestational body weights for
F0 and F1 females at 538 ppm; decreased lactational body
weights for F1 females at 538 ppm; no F0 or F1 reproductive
effects; decreased body weights for F1 and F2 litters and
increased perinatal deaths at 538 ppm with no gross lesions;
increased kidney weights, alpha-2u-globulin accumulation,
hyaline droplet nephropathy, tubular proteinosis,
hydronephrosis and interstitial nephritis in F0 and F1 males
at all exposure levels; increased kidney weights in F0
females at 538 ppm; renal tubular cell hyperplasia in F0 and
F1 males at 538 ppm; increased liver weights in F0 and F1
males and females at 211 and 538 ppm; hepatocellular hyper-
trophy in F0 and F1 males and females at 538 ppm; no
treatment-related adult deaths; F0 and F1 adult toxicity
with no effects on reproduction; postnatal toxicity in F1
and F2 litters only at 538 ppm; 
the NOEL for all adult animals would be 66 ppm if kidney
sections had not been examined for alpha-2u-globulin.

Executive summary:

Weanling rats (P) were exposed to the test substance vapour at mean concentrations of 0, 66, 211 or 538 ppm, 28/sex/group for 3 weeks (with a switch for nonsuccessful females at 10 days and a satellite mating for nonsuccessful males). Selected F1 weanlings, 28/sex/group, were exposed for 11 weeks and mated, as described above. All nonselected F1 and F2 weanlings were necropsied.

At 538 ppm, P and F1 males and females exhibited reduced body weights and weight gain, reduced food consumption and clinical signs of toxicity. Gestational body weights were decreased for P and F1 females at 538 ppm; lactational body weights were reduced for F1 (but not P) females at 538 ppm.

There were no P or F1 reproductive effects.

F1 and F2 litters exhibited reduced Body weights and increased perinatal deaths at 538 ppm with no gross lesions observed. Increased kidney weights and alpha2µ globulin accumulation, hyaline droplet nephropathy, tubular proteinosis, hydronephrosis, and interstitial nephritis were seen in Pand F1 males at all test substance concentrations. Kidney weights were also increased in P (but not in F1) females at 538 ppm. renal tubular cell hyperplasia was seen in P and F1 males at 538 ppm. P and F1 male and female liver weights were increased at 211 and 538 ppm; hepatocellular hypertrophy was observed in F0 and F1 males and females at 538 ppm. There were no treatment-related adult deaths.

Therefore, exposure to the test substance vapour for two generations, one litter/generation, resulted in P and F1 adult toxicity (NOAEC <= 66 ppm) with no effects on reproduction (NOAEC: 538 ppm); postnatal toxicity in F1 and F2 litters was observed only at 538 ppm (NOAEC 211 ppm).

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

270 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

This is the only available study using oral exposure route
This study is performed according to OECD Guideline under GLP conditions and therefore evaluated with Klimisch score=1

Effect on fertility: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

3 228 mg/m³

Study duration:

chronic

Species:

rat

Quality of whole database:

This is the only reliable study using inhalaltion exposure route which is very well performed also guidline was not mentioned . therefore the study is evaluated with Klimisch score 2

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Oral exposure

p-Dichlorobenzene, dissolved in olive oil, was administered orally to two generations of rats (OECD guideline 416 and GLP) at doses of 30, 90 and 270 mg/kg bw/day. Olive oil was applied to one group of male and female rats that served as control group.

Considering this two-generation study in rats via gavage, in both generations, 1,4 -dichlorobenzene had no effects on time between beginning of mating and evidence of copulation. time of gestation, fertility index, gestational index, total number of pups (NOAEL fertility 270 mg/kg bw/day). Developmental toxicity in pups appears from 90 mg/kg/day associated with slight behavioral anomalies (reduced percentage of pups with positive draw up test in F1/F2 generation) (1 out of 4 tests including positive ear erection reflex, positive draw up reflex, opening eyes reflex, grasping reflex and orientation reaction). The NOAEL for these developmental effects is estimated at 30 mg/kg/day. Toxic effects were seen in parents at 270 mg/kg/day, but histological examinations were not systematically done in control and high dose groups (NOAEL: 90 mg/kg bw/day; Bornatowicz 1994).

INHALATION EXPOSURE

Weanling rats (P) were exposed to the test substance vapour at mean concentrations of 0, 66, 211 or 538 ppm, 28/sex/group for 3 weeks (with a switch for nonsuccessful females at 10 days and a satellite mating for nonsuccessful males). Selected F1 weanlings, 28/sex/group, were exposed for 11 weeks and mated, as described above. All nonselected F1 and F2 weanlings were necropsied.

Exposure to the test substance vapour for two generations, one litter/generation, resulted in P and F1 adult toxicity (NOAEC <= 66 ppm) with no effects on reproduction (NOAEC: 538 ppm); postnatal toxicity in F1 and F2 litters was observed only at 538 ppm (NOAEC 211 ppm).

In the two-generation study in rats via inhalation, similar signs of toxicity (weight loss, increased perinatal mortality, reduced litter size, reduction in number of live foetuses per litter) as those observed at the high dose tested via oral route (270 mg/kg/day) were observed in the offspring at 538 ppm where parenteral toxicity was noted. A NOAEC of 211 ppm for the two-generation study through inhalation in rats is established.

For comparison, calculation for the two concentrations (538 ppm and 270 mg/kg/day), shows that the concentration levels reaching the blood are the same range. At the mid dose (90 mg/kg/day and 211 ppm) differences were noted, with slight toxicity in pups by gavage study (and not by inhalation study) without parental toxicity. To evaluate these differences (slight toxicity, reversible for reduction body weight and not observed in the two generations consistently), routes of exposure have to be taken into account: oral application by gavage results in higher peak concentration than in inhalation studies with continuous exposure (6 hours/day) and could give more toxic effects in pups (Tyl 1989).

The other data (one two-generation study in rats via inhalation route and several teratogenicity studies on rats and rabbits via oral and inhalation exposure) did not reveal any evidence of reproductive or teratogenic effects in the absence of parenteral toxicity (Hodge 1977; Giavini 1986; Hayes 1982/1985; Makita 2004/2005/2006; Ruddick 1983).

Short description of key information:
Reliable two-generation reproductive toxicitystudies are available with p-dichlorobenzene following oral and inhalation exposure indicating that the tp-dichlorobenzene is not toxic to fertility.

Justification for selection of Effect on fertility via oral route:
This is the only available study using oral exposure route
This study is performed according to OECD Guideline under GLP conditions and therefore evaluated with Klimisch score=1 . With respect ot fertility there is no evidende that oral application of p-dichlorobenzene reveals effects on fertility in rats

Justification for selection of Effect on fertility via inhalation route:
This is the only reliable study using inhalaltion exposure route which is very well performed also guidline was not mentioned . therefore the study is evaluated with Klimisch score 2

Effects on developmental toxicity

Description of key information

based on the available data  in the concentration range used p-dichlorobenzene causes no developmental toxicity in the absence of maternal tocicity.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

3 055.5 mg/m³

Study duration:

subacute

Species:

rat

Quality of whole database:

No endpoint selections was chosen because there are 2 reliable studies on developmental toxicity available which are chosen as key studies : one study in rabbit (NOAEC: 800 ppm) and an older one in rats (NOAEC: 508 ppm) and were evaluated with Klimisch score 2. Both studies did not show any developmental effects without slight maternal toxicity

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

p-Dichlorobenzene was evaluated for teratogenic potential in New Zealand White rabbits. Groups of inseminated female rabbits were exposed to 0, 100, 300 or 800 ppm (approx. 590, 1770 or 4720 mg/m³) p-dichlorobenzene, 6 h/day on gestation day 6 -18. Slight maternal toxicity was observed in groups of rabbits exposed to 800 ppm of the test substance as evidenced by significantly decreased body weight gain during the first 3 days of exposure. The maternal NOAEC was found to be 300 ppm; the NOAEC for teratogenicity is 800 ppm because p-dichlorobenzene vapor was not enbryotoxic or teratogenic in rabbits at any of the exposure levels used in this study.

In another teratogenic study on groups of 20 pregnant female Alderley-Park rats per group by inhalation exposure (vapour) from the 6th to the 15th day of gestation at target concentrations 0, 75, 200, 508 ppm. Exposure to p-dichlorobenzene did not cause any signs of toxicity in the mothers (other than a reduction in the gestation period in 5% of the mothers) and yielded negative results. No signs of embryotoxicity (number of corpora lutea, implantation, resorption, number of live foetuses, litter and foetus weight, and sex ratio not significantly different from control group), and no skeletal or soft tissue abnormalities (only one localised eventration of the abdominal wall was observed in 212 foetuses at 75 ppm, 1/203 at 200 ppm) were noted. In all, there were no embryotoxic, nor foetotoxic effects at non-toxic doses in the mothers. The maternal NOAEC is 508 ppm; the NOAEC for teratogenicity is 508 ppm (Hodge, 1977).

Overall, in none of the available studies using the inhalation exposure route p-dichlorobenzene revealed developmental toxiciy at non-toxic doses in the mothers. Consequently, p-dichlorobenzene is not regarded as a development al toxicant-

Justification for selection of Effect on developmental toxicity: via inhalation route:
No endpoint selections was chosen because there are 2 reliable studies on developmental toxicity available which are chosen as key studies : one study in rabbit and an older one in rats and were evaluated with Klimisch score 2. Both studies did not show any developmental effects without slight maternal toxicity

Justification for classification or non-classification

Based on the available data no classification or labelling is required.