1,3-bis(isocyanatomethyl)benzene

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 25 - November 19, 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

June 25- November 19, 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD (SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hino Breeding Center, Charles River Laboratories Japan, Inc.
- Age at study initiation: 10 weeks
- Weight at study initiation: males 355-394 g and females 240-285 g, females satellite groups 247-279 g
- Fasting period before study:
- Housing: During acclimatization animals were housed individually in stainless stgeel suspended ages. Animals were paired in males' cages. Dams were housed individually in plastic cages floored with an autoclaved substate of wood chips on Day 18 of pregnancy and thereafter. The dams were housed individually in stainless steel suspended cages on Day 4 of lactation and thereafter.
- Diet: ad libitum to feeders of solid diet (CRF-1, Oriental Yeast Co., Ltd.)
- Water: ad libitum tap water
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.9-24.3
- Humidity (%): 44-63
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The required amount of the test substance was measured out and dissolved in corn oil to a concentration of 40 mg/ml. Dosing preparations containing the test substance at concentrations of 10 and 2.5 mg/ml were prepared by serial dilution of the dosing preparation at 40 mg/ml with corn oil. Preparations were used within 4 hours and 54 minutes of preparation. Dosing volumes 5 ml/kg/day on the most recent body weight.

VEHICLE
- Justification for use and choice of vehicle (if other than water): corn oil
- Concentration in vehicle: same dosing volume.
- Lot/batch no.: V8F7016

Details on mating procedure:

- M/F ratio per cage: 1/1 one female was cohabitated with one male of the same treatment group, avoiding sibling mating
- Length of cohabitation: A maximum of 14 days was allowed for mating.
- Proof of pregnancy: Detection of mating was confirmed by evidence of sperm in the vaginal smear, or or by the appearance of an intravaginal copulatory plug. This day was designated Day 0 of preganancy. Once mating had occurred, the males and females were separated.
- After successful mating each pregnant female was caged individually and was allowed to deliver the litters spontaneously and observed for delivery conditions and completion of delivery daily from Day 21 of pregnancy to day 25 of pregnancy. The day when deliver was completed was defined as day 0 of lactation.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentrations of the substance in dosing preparations which were used for both sexes in the test groups on the first day of dosing and for the males in the test gorups on the last dosing day were measured by gas chromatography. Concentrations were between 92.9 and 95.1% of target concentration.

Duration of treatment / exposure:

Males treated for 14 days before mating and thereafter 28 days, total of 42 days. Half of the males per group were given a 14-day recovery period.
Females treated for 14 days before mating, during the mating period (max 4 days), and during pregnancy up to Day 6 of lactaction, a total of 44 - 48 days. Females of satellite groups, treated for 42 days, were given a 14-day recovery period.
Pups were not treated directly, but were potentially exposed to the test substance in utero and through lactational transfer.

Frequency of treatment:

Daily

Details on study schedule:

- Dose selection rationale: Dose levels based on a preliminary study in which death was noted at 500 mg/kg/day and higher. The dosing length in the present study was to be more than 3 times longes than in the preliminary study, the high dose was selected to be 200 mg/kg/day, at which toxicity was expected to occur and lower dose levels were calculated using a common ration of 4.
- Rationale for animal assignment (if not random): Random sampling method so that the mean body weight and variance were as equal as possible among the groups.
- Post-exposure recovery period in satellite groups: 14 days.

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

12 males including 6 with a recovery period.
12 females
6 females in satellite group with recovery period.

Control animals:

yes, concurrent vehicle

Positive control:

not applicable

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS:
- Time schedule: Animals were observed for mortality and clinical signs twice a day, once before and once after administration, once a day during the recovery period and once on the day of necropsy.

BODY WEIGHT: Yes
- Time schedule for examinations: twice a week and on the day of necropsy, with females during pregnancy on Days 0, 7, 14 and 21 and on Days 0, 4 and 6 of lactation.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
Time schedule: approx twice a week

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: approx twice a week

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: After last dosing day and after temination of recovery period.
- Anaesthetic used for blood collection: Yes, by ip injection of sodium pentobarbital
- Parameters examined: according to OECD 422 (1996)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: see haematology
- Parameters examined: according to OECD 422 (1996)

URINALYSIS: Yes
- Time schedule for collection of urine: Fresh urine and 24-hour urine was collected. For males on day 37 of administration and day 9 of recovery, for females on day 5 of lactation and day 9 of recovery.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: All animals were observed for FOB before start of administration and once a week during administration.
- Dose groups that were examined: all dose groups
- Battery of functions tested: FOB consisted of observations on: posture, palpebral closure, biting behavior and convulsions; ease of removal from cage, ease of handling, muscle tone, fur conditions, lacrimation, salivation, and respiration. In the open field, frequency of rearing and frequency of grooming for 2 minutes, gait, palpebral closure, consciousness, behavioral abnormalities, and righting reflex.
Sensory reactivity and grip strength in males before necropsy, in 6 females/group on Day 3 of lactation. Spontaneous Motor Activity in males on day 40 of administration and females on day 4 of lactation.

OTHER:
Mating: After 14 days of treatment, males and females were paired continuously for a maximum period of 14 days until copulation was confirmed.
Nursing conditions: Dams were observed for nursing conditions once a day from days 0 to 4 of lactation.

Oestrous cyclicity (parental animals):

Estrous cycles: Females were observed once a day from the first dosing day to the day before confirmation of copulation.

Sperm parameters (parental animals):

Parameters examined in male parental generations:
testis weight, epididymis weight, microscopic examinations of testes, epididymides, seminal vesicles, prostate.

Litter observations:

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring: the number of pups born, their sexes, number of stillbirths, live pups born, and external abnormalities.
- Mortality: once a day
- Clinical signs: once a day
- Body weights: Live pups were weighed on Days 0 and 4 of lactation.

Postmortem examinations (parental animals):

GROSS PATHOLOGY: Yes
Organ weights in males: brain, pituitary, salivary glands, thyroids, thymus, heart, liver, spleen, kidneys, adrenals, testes and epididymides.
Females: number of corpora lutea and number of implantation sites were counted. After necropsy organ weights: same as males + ovaries and uterus.
HISTOPATHOLOGY: Yes
Organs and tissues from males and females of the high dose and control group were examined. When abnormalities were found, e.g. stomach, lower doses were also examined. Organs and tissues examined: heart, lungs, trachea, liver, pancreas, salivary glands, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, thymus, spleen, lymph nodes, kidneys, urinary bladder, testes, epididymides, seminal vesicles, prostate, pituitary, adrenals, thyroids, parathyroid glands, brain, spinal cord, sciatic nerves, eyeballs, Harderian glands, bone marrow and bones, testes, ovaries, uterus, vagina, and mammary glands.

Statistics:

Data were tested by Bartlett's test for homogeneity of variance, when variances were homogeneous, Dunnett's test was performed to compare the control group with each of the groups treated with substance. When variance was heterogeneous, Steel's test was performed.
FOB and reproduction/developmental parameters data were tested by Steel's test. Copulation index, fertility index and gestation index were tested by Fisher's exact test.
Effects in stomach: Steel's test was performed. When significant differences were seen, dose-responsiveness was tested by Cochran-Armitage exact test.

Reproductive indices:

For each group, the following calculations were performed:
- Copulation index: Number of animals which copulated/Number of animals paired x 100
- Fertility index: Number of pregnant females/Number of females paired x 100
- Gestation index: Number of dams with live pups/Number of pregnant females x 100

Offspring viability indices:

- Implantation index: number of implantation sites/number of corpora lutea x 100
- Delivery index: number of pups born/number of implantation sites x 100
- Birth index: Number of live pups born on Day 0 of lactation/Number of implantation sites x 100
- Live birth index: Number of live pups born on Day 0 of lactation/Number of pups born x 100
- Viability index: Number of live pups on Day 4 of lactation / Number of pups born alive x 100
- Incidence of external abnromalities: number of pups with external abnormalities/number of live pups born x 100
- Sex ratio: number of males/number of females

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Salivation was noted in 200 and 50 mg/kg bw/day group animals after administration. This was considered to be due to the irritancy of the substance and since no further neurological effects were found, not regarded as a systemic effect. During recovery no clinical signs in females and only one male with soiled perineal area was noted.

Mortality:

no mortality observed

Description (incidence):

No dead or moribund males/females were noted in any group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight was significantly lower in the males at 200 mg/kg bw/day throughout the administration period and in the females at the same dose level on Day 15 of administration, throughout pregnancy, and on Days 0 and 6 of lactation. Body weight was also lower in the males at 50 mg/kg bw/day on Days 29 and 36 of administration. However, these findings at 50 mg/kg bw/day are not considered attributable to the test substance, since (1) the differences from the control group were small, (2) these findings were transient changes, and (3) food consumption was not adversely affected by the test substance at this dose level. During the recovery period, body weight stayed lower in both sexes at 200 mg/kg/day but tended to revert to the normal body weight.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of food consumption, lower food consumption was noted in the males at 200 mg/kg bw/day at the beginning of the administration period, but no changes attributable to the test substance were noted in the females at this dose level. During the recovery period, food consumption was higher in the males at 200 mg/kg bw/day, but this finding is considered to be a recoverable change which occurred after termination of the administration period.

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of water consumption, higher water consumption was noted in the males at 200 mg/kg bw/day at the end of the administration period, in the females at this dose level before the start of mating, and in the females at 200 and 50 mg/kg bw/day during the lactation period. However, these findings were not regarded as having been caused by the toxicity of the test substance, since all of them were transient changes. During the recovery period, water consumption was higher in the males at 200 mg/kg bw/day, but no changes attributable to the test substance were noted in the females at this dose level.

Haematological findings:

no effects observed

Description (incidence and severity):

No changes attributable to test substance were noted in either sex on termination of the administration period or recovery period.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No changes attributable to test substance were noted in either sex on termination of the administration period or recovery period.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No changes attributable to test substance were noted in either sex on termination of the administration period or recovery period.

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of spontaneous motor activity in the females at 200 mg/kg bw/day, the ambulatory count and vertical count were lower 70 minutes after administration, and a lower total vertical count and a tendency for total ambulatory count to be lower were noted on termination of the administration period. In the males, no changes attributable to the test substance were noted in the spontaneous motor activity. Regarding FOB, sensory reactivity, and grip strength, no changes attributable to the test substance were noted in either sex at any dose level.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In the histopathological examinations, the following findings were noted in the males:
Slight or mild hyperplasia of squamous epithelium in the forestomach in all 6 males at 200 mg/kg bw/day and in 1 male at 50 mg/kg bw/day, slight or mild hyperkeratosis in the forestomach in all 6 males at 200 mg/kg bw/day, slight inflammatory cell infiltration in the forestomach in 1 male at 200 mg/kg bw/day, and cystic changes in the epithelial layer of the forestomach in 1 male at 200 mg/kg bw/day. In the females at 200 mg/kg bw/day, the following findings were noted: slight hyperplasia of squamous epithelium in the forestomach in 3 females, slight inflammatory cell infiltration in the forestomach in 1 female, and cystic changes in the epithelial layer of the forestomach in 1 female. From these findings in the stomach, it can be said that the above-mentioned higher water consumption in both sexes at 200 mg/kg bw/day was a change to alleviate the irritancy of m-xylylene diisocyanate given to the stomach; the higher water consumption noted in the present study is not judged to be a toxicological change. Since no histopathological changes in the stomach were noted in either sex on termination of the recovery period, higher water consumption occurring during administration will revert to normal water consumption after the discontinuation of administration.

Other effects:

no effects observed

Description (incidence and severity):

In the examinations for reproductive/developmental toxicity in parent animals, no changes attributable to the test substance were noted in the number of estrous cases during the administration period (for 14 days) before the start of mating, copulation index, number of conceiving days, number of pregnant females, fertility index, length of gestation, gestation index, number of corpora lutea, number of implantation sites, implantation index, delivery conditions, or nursing conditions.

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Decreased body weight in males and pregnant females.

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 examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

In the pups (F1), no changes attributable to the test substance were noted in the number of pups born, number of stillbirths, number of live pups born on Day 0 of lactation, delivery index, birth index, live birth index, sex ratio, number of live pups on Day 4 of lactation, viability index on Day 4 of lactation, clinical signs, body weight on Day 0 or 4 of lactation, appearance, or necropsy findings.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

>= 200 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest dose tested

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

Conclusions:

The reproductive/developmental NOAEL can be set at >= 200 mg/kg bw/day as no effects were noted in any parameter in either sex. At 200 mg/kg bw/day a decreased body weight was found in males and pregnant females and thus the parental NOAEL is set at 50 mg/kg bw/day.

Executive summary:

Rats were administered 0, 12.5, 50 or 200 mg/kg bw/d of test substance in a study performed according to OECD 422 (1996). Rats were dosed from 14 days before mating during mating and afterwards (total 42 days) for males and during mating period, pregnancy and up to lactation day 6 for females. No mortality occurred. Salivation was noted at 50 and 200 mg/kg bw/d in both sexes. Body weight was decreased in both sexes at 200 mg/kg bw/d. For food and water consumption only transient effects were noted which may be due to irritation of the stomach. No test substance-related effect was seen on haematological, clinical chemistry and urinalysis parameters or at gross pathology. Histopathology revealed an increased incidence of hyperplasia of squamous epithelium and hyperkeratosis in the forestomach in both sexes at 200 mg/kg bw/d. Inflammatory cell infiltration in the forestomach and mild cystic changes in the epithelial cell layer of the forestomach were noted in one male and one female at 200 mg/kg bw/d. In the pups (F1), no changes attributable to the test substance were noted in the number of pups born, number of stillbirths, number of live pups born on Day 0 of lactation, delivery index, birth index, live birth index, sex ratio, number of live pups on Day 4 of lactation, viability index on Day 4 of lactation, clinical signs, body weight on Day 0 or 4 of lactation, appearance, or necropsy findings. In addition, no effects on reproduction organs in parental animals were observed.

Cross-reference 2

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

developmental toxicity

Remarks:

Screening study

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

June 25-November 19, 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: Organisation of Economic Co-operation and Development (OECD) Guidelines for Testing of Chemicals, Guideline 422, Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test, March 1996

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD (SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hino Breeding Center, Charles River Laboratories Japan, Inc.
- Age at study initiation: 10 weeks
- Weight at study initiation: males 355-394 g and females 240-285 g, females satellite groups 247-279 g
- Fasting period before study:
- Housing: During acclimatization animals were housed individually in stainless stgeel suspended ages. Animals were paired in males' cages. Dams were housed individually in plastic cages floored with an autoclaved substate of wood chips on Day 18 of pregnancy and thereafter. The dams were housed individually in stainless steel suspended cages on Day 4 of lactation and thereafter.
- Diet: ad libitum to feeders of solid diet (CRF-1, Oriental Yeast Co., Ltd.)
- Water: ad libitum tap water
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.9-24.3
- Humidity (%): 44-63
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The required amount of the test substance was measured out and dissolved in corn oil to a concentration of 40 mg/ml. Dosing preparations containing the test substance at concentrations of 10 and 2.5 mg/ml were prepared by serial dilution of the dosing preparation at 40 mg/ml with corn oil. Preparations were used within 4 hours and 54 minutes of preparation. Dosing volumes 5 ml/kg/day on the most recent body weight.

VEHICLE
- Justification for use and choice of vehicle (if other than water): corn oil
- Concentration in vehicle: same dosing volume.
- Lot/batch no.: V8F7016

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentrations of the substance in dosing preparations which were used for both sexes in the test groups on the first day of dosing and for the males in the test gorups on the last dosing day were measured by gas chromatography. Concentrations were between 92.9 and 95.1% of target concentration.

Details on mating procedure:

- M/F ratio per cage: 1/1 one female was cohabitated with one male of the same treatment group, avoiding sibling mating
- Length of cohabitation: A maximum of 14 days was allowed for mating.
- Proof of pregnancy: Detection of mating was confirmed by evidence of sperm in the vaginal smear, or or by the appearance of an intravaginal copulatory plug. This day was designated Day 0 of preganancy. Once mating had occurred, the males and females were separated.
- After successful mating each pregnant female was caged individually and was allowed to deliver the litters spontaneously and observed for delivery conditions and completion of delivery daily from Day 21 of pregnancy to day 25 of pregnancy. The day when deliver was completed was defined as day 0 of lactation.

Duration of treatment / exposure:

Males treated for 14 days before mating and thereafter 28 days, total of 42 days. Half of the males per group were given a 14-day recovery period.
Females treated for 14 days before mating, during the mating period (max 4 days), and during pregnancy up to Day 6 of lactaction, a total of 44 - 48 days. Females of satellite groups, treated for 42 days, were given a 14-day recovery period.
Pups were not treated directly, but were potentially exposed to the test substance in utero and through lactational transfer.

Frequency of treatment:

Daily

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

12 males including 6 with a recovery period.
12 females
6 females in satellite group with recovery period.

Control animals:

yes, concurrent vehicle

Maternal examinations:

DETAILED CLINICAL OBSERVATIONS:
- Time schedule: Animals were observed for mortality and clinical signs twice a day, once before and once after administration, once a day during the recovery period and once on the day of necropsy.

BODY WEIGHT: Yes
- Time schedule for examinations: twice a week and on the day of necropsy, with females during pregnancy on Days 0, 7, 14 and 21 and on Days 0, 4 and 6 of lactation.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
Time schedule: approx twice a week

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: approx twice a week

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: After last dosing day and after temination of recovery period.
- Anaesthetic used for blood collection: Yes, by ip injection of sodium pentobarbital
- Parameters examined: according to OECD 422 (1996)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: see haematology
- Parameters examined: according to OECD 422 (1996)

URINALYSIS: Yes
- Time schedule for collection of urine: Fresh urine and 24-hour urine was collected. For males on day 37 of administration and day 9 of recovery, for females on day 5 of lactation and day 9 of recovery.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: All animals were observed for FOB before start of administration and once a week during administration.
- Dose groups that were examined: all dose groups
- Battery of functions tested: FOB consisted of observations on: posture, palpebral closure, biting behavior and convulsions; ease of removal from cage, ease of handling, muscle tone, fur conditions, lacrimation, salivation, and respiration. In the open field, frequency of rearing and frequency of grooming for 2 minutes, gait, palpebral closure, consciousness, behavioral abnormalities, and righting reflex.
Sensory reactivity and grip strength in males before necropsy, in 6 females/group on Day 3 of lactation. Spontaneous Motor Activity in males on day 40 of administration and females on day 4 of lactation.

OTHER:
Mating: After 14 days of treatment, males and females were paired continuously for a maximum period of 14 days until copulation was confirmed.
Nursing conditions: Dams were observed for nursing conditions once a day from days 0 to 4 of lactation.

GROSS PATHOLOGY: Yes
Organ weights in males: brain, pituitary, salivary glands, thyroids, thymus, heart, liver, spleen, kidneys, adrenals, testes and epididymides.
Females: number of corpora lutea and number of implantation sites were counted. After necropsy organ weights: same as males + ovaries and uterus.
HISTOPATHOLOGY: Yes
Organs and tissues from males and females of the high dose and control group were examined. When abnormalities were found, e.g. stomach, lower doses were also examined. Organs and tissues examined: heart, lungs, trachea, liver, pancreas, salivary glands, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, thymus, spleen, lymph nodes, kidneys, urinary bladder, testes, epididymides, seminal vesicles, prostate, pituitary, adrenals, thyroids, parathyroid glands, brain, spinal cord, sciatic nerves, eyeballs, Harderian glands, bone marrow and bones, testes, ovaries, uterus, vagina, and mammary glands.

Ovaries and uterine content:

The ovaries, uterus, vagina and mammary glands were examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: No
- Number of late resorptions: No
- Number of stillbirths: Yes

Fetal examinations:

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring: the number of pups born, their sexes, number of stillbirths, live pups born, and external abnormalities.
- Mortality: once a day
- Clinical signs: once a day
- Body weights: Live pups were weighed on Days 0 and 4 of lactation.

Statistics:

Data were tested by Bartlett's test for homogeneity of variance, when variances were homogeneous, Dunnett's test was performed to compare the control group with each of the groups treated with substance. When variance was heterogeneous, Steel's test was performed.
FOB and reproduction/developmental parameters data were tested by Steel's test. Copulation index, fertility index and gestation index were tested by Fisher's exact test.
Effects in stomach: Steel's test was performed. When significant differences were seen, dose-responsiveness was tested by Cochran-Armitage exact test.

Indices:

- Implantation index: number of implantation sites/number of corpora lutea x 100
- Delivery index: number of pups born/number of implantation sites x 100
- Birth index: Number of live pups born on Day 0 of lactation/Number of implantation sites x 100
- Live birth index: Number of live pups born on Day 0 of lactation/Number of pups born x 100
- Viability index: Number of live pups on Day 4 of lactation / Number of pups born alive x 100
- Incidence of external abnromalities: number of pups with external abnormalities/number of live pups born x 100
- Sex ratio: number of males/number of females

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Salivation was noted in 200 and 50 mg/kg bw/day group animals after administration. This was considered to be due to the irritancy of the substance and since no further neurological effects were found, not regarded as a systemic effect. During recovery no clinical signs in females and only one male with soiled perineal area was noted.

Mortality:

no mortality observed

Description (incidence):

No dead or moribund males/females were noted in any group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight was significantly lower in the males at 200 mg/kg bw/day throughout the administration period and in the females at the same dose level on Day 15 of administration, throughout pregnancy, and on Days 0 and 6 of lactation. Body weight was also lower in the males at 50 mg/kg bw/day on Days 29 and 36 of administration. However, these findings at 50 mg/kg bw/day are not considered attributable to the test substance, since (1) the differences from the control group were small, (2) these findings were transient changes, and (3) food consumption was not adversely affected by the test substance at this dose level. During the recovery period, body weight stayed lower in both sexes at 200 mg/kg/day but tended to revert to the normal body weight.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of food consumption, lower food consumption was noted in the males at 200 mg/kg bw/day at the beginning of the administration period, but no changes attributable to the test substance were noted in the females at this dose level. During the recovery period, food consumption was higher in the males at 200 mg/kg bw/day, but this finding is considered to be a recoverable change which occurred after termination of the administration period.

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of water consumption, higher water consumption was noted in the males at 200 mg/kg bw/day at the end of the administration period, in the females at this dose level before the start of mating, and in the females at 200 and 50 mg/kg bw/day during the lactation period. However, these findings were not regarded as having been caused by the toxicity of the test substance, since all of them were transient changes. During the recovery period, water consumption was higher in the males at 200 mg/kg bw/day, but no changes attributable to the test substance were noted in the females at this dose level.

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of spontaneous motor activity in the females at 200 mg/kg bw/day, the ambulatory count and vertical count were lower 70 minutes after administration, and a lower total vertical count and a tendency for total ambulatory count to be lower were noted on termination of the administration period. In the males, no changes attributable to the test substance were noted in the spontaneous motor activity. Regarding FOB, sensory reactivity, and grip strength, no changes attributable to the test substance were noted in either sex at any dose level.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Test substance-like residuals were noted in the stomach of animals of both sexes at 200 mg/kg bw/ day.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In the females at 200 mg/kg bw/day, the following findings were noted: slight hyperplasia of squamous epithelium in the forestomach in 3 females, slight inflammatory cell infiltration in the forestomach in 1 female, and cystic changes in the epithelial layer of the forestomach in 1 female. From these findings in the stomach, it can be said that the above-mentioned higher water consumption in both sexes at 200 mg/kg bw/day was a change to alleviate the irritancy of m-xylylene diisocyanate given to the stomach; the higher water consumption noted in the present study is not judged to be a toxicological change. Since no histopathological changes in the stomach were noted in either sex on termination of the recovery period, higher water consumption occurring during administration will revert to normal water consumption after the discontinuation of administration.

Other effects:

no effects observed

Description (incidence and severity):

In the examinations for reproductive/developmental toxicity in parent animals, no changes attributable to the test substance were noted in the number of estrous cases during the administration period (for 14 days) before the start of mating, copulation index, number of conceiving days, number of pregnant females, fertility index, length of gestation, gestation index, number of corpora lutea, number of implantation sites, implantation index, delivery conditions, or nursing conditions.

Dose descriptor:

NOAEL

Effect level:

>= 200 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: no developmental toxicity at the highest dose tested

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: decreased body weight of pregnant females at 200 mg/kg bw/day

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects. Remark: Only early postnatal pup development parameters were examined including body weight, post-natal loss, sex ratio, clinical signs, body weight and external macroscopy.

Details on embryotoxic / teratogenic effects:
In the pups (F1), no changes attributable to the test substance were noted in the number of pups born, number of stillbirths, number of live pups born on Day 0 of lactation, delivery index, birth index, live birth index, sex ratio, number of live pups on Day 4 of lactation, viability index on Day 4 of lactation, clinical signs, body weight on Day 0 or 4 of lactation, appearance, or necropsy findings.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No developmental effects including highest dose tested

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

no

Conclusions:

The reproductive/developmental NOAEL can be set at >= 200 mg/kg bw/day as no effects were noted in any parameter in either sex. At 200 mg/kg bw/day a decreased body weight was found in pregnant females and thus the maternal NOAEL is set at 50 mg/kg bw/day.

Executive summary:

Rats were administered 0, 12.5, 50 or 200 mg/kg bw/d of test substance in a study performed according to OECD 422 (1996). Rats were dosed from 14 days before mating during mating and afterwards (total 42 days) for males and during mating period, pregnancy and up to lactation day 6 for females. No mortality occurred. Salivation was noted at 50 and 200 mg/kg bw/d in both sexes. Body weight was decreased in both sexes at 200 mg/kg bw/d. For food and water consumption only transient effects were noted which may be due to irritation of the stomach. No test substance-related effect was seen on haematological, clinical chemistry and urinalysis parameters or at gross pathology. Histopathology revealed an increased incidence of hyperplasia of squamous epithelium and hyperkeratosis in the forestomach in both sexes at 200 mg/kg bw/d. Inflammatory cell infiltration in the forestomach and mild cystic changes in the epithelial cell layer of the forestomach were noted in one male and one female at 200 mg/kg bw/d. In the pups (F1), no changes attributable to the test substance were noted in the number of pups born, number of stillbirths, number of live pups born on Day 0 of lactation, delivery index, birth index, live birth index, sex ratio, number of live pups on Day 4 of lactation, viability index on Day 4 of lactation, clinical signs, body weight on Day 0 or 4 of lactation, appearance, or necropsy findings. In addition, no effects on reproduction organs in parental animals were observed. The NOAEL for systemic parental effects is 50 mg/kg bw/d based on decreased body weight and salivation and the NOAEL for developmental toxicity is >= 200 mg/kg bw/d.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,3-bis(isocyanatomethyl)benzene

EC Number:

222-852-4

EC Name:

1,3-bis(isocyanatomethyl)benzene

Cas Number:

3634-83-1

Molecular formula:

C10H8N2O2

IUPAC Name:

1,3-bis(isocyanatomethyl)benzene

Details on test material:

- Name of test material (as cited in study report): m-xylylene diisocyanate, XDI, CAS no. 3634-83-1
- Physical state: colorless clear liquid

Test animals

Species:

rat

Strain:

other: Crl:CD (SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hino Breeding Center, Charles River Laboratories Japan, Inc.
- Age at study initiation: 10 weeks
- Weight at study initiation: males 355-394 g and females 240-285 g, females satellite groups 247-279 g
- Fasting period before study: not indicated
- Housing: During acclimatization animals were housed individually in stainless stgeel suspended ages. Animals were paired in males' cages. Dams were housed individually in plastic cages floored with an autoclaved substate of wood chips on Day 18 of pregnancy and thereafter. The dams were housed individually in stainless steel suspended cages on Day 4 of lactation and thereafter.
- Diet: ad libitum to feeders of solid diet (CRF-1, Oriental Yeast Co., Ltd.)
- Water: ad libitum tap water
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.9-24.3
- Humidity (%): 44-63
- Air changes (per hr): 12
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The required amount of the test substance was measured out and dissolved in corn oil to a concentration of 40 mg/ml. Dosing preparations containing the test substance at concentrations of 10 and 2.5 mg/ml were prepared by serial dilution of the dosing preparation at 40 mg/ml with corn oil. Preparations were used within 4 hours and 54 minutes of preparation. Dosing volumes 5 ml/kg/day on the most recent body weight.

VEHICLE
- Justification for use and choice of vehicle (if other than water): corn oil
- Concentration in vehicle: same dosing volume.
- Lot/batch no.: V8F7016

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentrations of the substance in dosing preparations which were used for both sexes in the test groups on the first day of dosing and for the males in the test groups on the last dosing day were measured by gas chromatography. Concentrations were between 92.9 and 95.1% of target concentration. All results of the examination of specificity, linearity, precision, and intr-assay precision, which were obtained from the present study were within the acceptable criteria. The standard solution was confirmed to be stable in an autosampler for 24 hours. See report study no. 093527, validation of an analytical method for determination of m-xylylene diisocyanate concentration in dosing preparations, June 11, 2008.

Duration of treatment / exposure:

Males treated for 14 days before mating and thereafter 28 days, total of 42 days. Half of the males per group were given a 14-day recovery period.
Females treated for 14 days before mating, during the mating period (max 4 days), and during pregnancy up to Day 6 of lactaction, a total of 44 - 48 days. Females of satellite groups, treated for 42 days, were given a 14-day recovery period.

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

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

Doses / concentrations 3

Dose / conc.:

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

No. of animals per sex per dose:

12 males including 6 with a recovery period.
12 females
6 females in satellite group with recovery period.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels based on a preliminary study in which death was noted at 500 mg/kg/day and higher. The dosing length in the present study was to be more than 3 times longer than in the preliminary study, the high dose was selected to be 200 mg/kg/day, at which toxicity was expected to occur and lower dose levels were calculated using a common ration of 4.
- Rationale for animal assignment (if not random): Random sampling method so that the mean body weight and variance were as equal as possible among the groups.
- Post-exposure recovery period in satellite groups: 14 days.

Positive control:

not applicable

Examinations

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS:
- Time schedule: Animals were observed for mortality and clinical signs twice a day, once before and once after administration, once a day during the recovery period and once on the day of necropsy.

BODY WEIGHT: Yes
- Time schedule for examinations: twice a week and on the day of necropsy, with females during pregnancy on Days 0, 7, 14 and 21 and on Days 0, 4 and 6 of lactation.

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
Time schedule: approx twice a week

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: approx twice a week

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: After last dosing day and after temination of recovery period.
- Anaesthetic used for blood collection: Yes, by ip injection of sodium pentobarbital
- Parameters examined: according to OECD 422 (1996)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: see haematology
- Parameters examined: according to OECD 422 (1996)

URINALYSIS: Yes
- Time schedule for collection of urine: Fresh urine and 24-hour urine was collected. For males on day 37 of administration and day 9 of recovery, for females on day 5 of lactation and day 9 of recovery.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: All animals were observed for FOB before start of administration and once a week during administration.
- Dose groups that were examined: all dose groups
- Battery of functions tested: FOB consisted of observations on: posture, palpebral closure, biting behavior and convulsions; ease of removal from cage, ease of handling, muscle tone, fur conditions, lacrimation, salivation, and respiration. In the open field, frequency of rearing and frequency of grooming for 2 minutes, gait, palpebral closure, consciousness, behavioral abnormalities, and righting reflex.
Sensory reactivity and grip strength in males before necropsy, in 6 females/group on Day 3 of lactation. Spontaneous Motor Activity in males on day 40 of administration and females on day 4 of lactation.

OTHER:
Estrous cycles: Females were observed once a day from the first dosing day to the day before confirmation of copulation.
Mating: After 14 days of treatment, males and females were paired continuously for a maximum period of 14 days until copulation was confirmed.
Nursing conditions: Dams were observed for nursing conditions once a day from days 0 to 4 of lactation.

Pups - F1:
At delivery dams were examined for the number of pups born, their sexes, number of stillbirths, live pups born, and external abnormalities.
Pups were observed for clinical signs and mortality once a day.
Pups were weighed on Day 0 and Day 4 of lactation.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Organ weights in males: brain, pituitary, salivary glands, thyroids, thymus, heart, liver, spleen, kidneys, adrenals, testes and epididymides.
Females: number of corpora lutea and number of implantation sites were counted. After necropsy organ weights: same as males + ovaries and uterus.
HISTOPATHOLOGY: Yes
Organs and tissues from males and females of the high dose and control group were examined. When abnormalities were found, e.g. stomach, lower doses were also examined. Organs and tissues examined: heart, lungs, trachea, liver, pancreas, salivary glands, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, thymus, spleen, lymph nodes, kidneys, urinary bladder, testes, epididymides, seminal vesicles, prostate, pituitary, adrenals, thyroids, parathyroid glands, brain, spinal cord, sciatic nerves, eyeballs, Harderian glands, bone marrow and bones, testes, ovaries, uterus, vagina, and mammary glands.

Statistics:

Data were tested by Bartlett's test for homogeneity of variance, when variances were homogeneous, Dunnett's test was performed to compare the control group with each of the groups treated with substance. When variance was heterogeneous, Steel's test was performed.
FOB and reproduction/developmental parameters data were tested by Steel's test. Copulation index, fertility index and gestation index were tested by Fisher's exact test.
Effects in stomach: Steel's test was performed. When significant differences were seen, dose-responsiveness was tested by Cochran-Armitage exact test.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Salivation was noted in 200 and 50 mg/kg bw/day group animals after administration. This was considered to be due to the irritancy of the substance and since no further neurological effects were found, not regarded as a systemic effect. During recovery no clinical signs in females and only one male with soiled perineal area was noted.

Mortality:

no mortality observed

Description (incidence):

No dead or moribund males/females were noted in any group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight was significantly lower in the males at 200 mg/kg bw/day throughout the administration period and in the females at the same dose level on Day 15 of administration, throughout pregnancy, and on Days 0 and 6 of lactation. Body weight was also lower in the males at 50 mg/kg bw/day on Days 29 and 36 of administration. However, these findings at 50 mg/kg bw/day are not considered attributable to the test substance, since (1) the differences from the control group were small, (2) these findings were transient changes, and (3) food consumption was not adversely affected by the test substance at this dose level. During the recovery period, body weight stayed lower in both sexes at 200 mg/kg bw/day but tended to revert to the normal body weight.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

In the measurement of food consumption, lower food consumption was noted in the males at 200 mg/kg bw/day at the beginning of the administration period, but no changes attributable to the test substance were noted in the females at this dose level. During the recovery period, food consumption was higher in the males at 200 mg/kg bw/day, but this finding is considered to be a recoverable change which occurred after termination of the administration period.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of water consumption, higher water consumption was noted in the males at 200 mg/kg bw/day at the end of the administration period, in the females at this dose level before the start of mating, and in the females at 200 and 50 mg/kg bw/day during the lactation period. However, these findings were not regarded as having been caused by the toxicity of the test substance, since all of them were transient changes. During the recovery period, water consumption was higher in the males at 200 mg/kg bw/day, but no changes attributable to the test substance were noted in the females at this dose level.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No changes attributable to test substance were noted in either sex on termination of the administration period or recovery period.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No changes attributable to test substance were noted in either sex on termination of the administration period or recovery period.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No changes attributable to test substance were noted in either sex on termination of the administration period or recovery period.

Behaviour (functional findings):

effects observed, treatment-related

Description (incidence and severity):

In the measurement of spontaneous motor activity in the females at 200 mg/kg bw/day, the ambulatory count and vertical count were lower 70 minutes after administration, and a lower total vertical count and a tendency for total ambulatory count to be lower were noted on termination of the administration period. In the males, no changes attributable to the test substance were noted in the spontaneous motor activity. Regarding FOB, sensory reactivity, and grip strength, no changes attributable to the test substance were noted in either sex at any dose level.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

In the organ weight measurement on termination of the administration period, a higher relative spleen weight and a tendency for the absolute spleen weight to be higher were noted in the males at 200 mg/kg bw/day, and higher absolute and relative spleen weights were noted in the females at this dose level. On termination of the recovery period, no changes attributable to the test substance were noted in either sex at any dose level. However, the histopathological examinations on termination of the administration period (see below) shows that there were no changes attributable to the test substance in the spleen in either sex, and hematological examinations shows that the parameters related to the organ weight changes were not affected by the test substance. Therefore, the findings in the spleen weights at 200 mg/kg bw/day in the present study are considered to be minor changes.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Test substance-like residuals were noted in the stomach of animals of both sexes at 200 mg/kg bw/ day.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In the histopathological examinations, the following findings were noted in the males:
slight or mild hyperplasia of squamous epithelium in the forestomach in all 6 males at 200 mg/kg bw/day and in 1 male at 50 mg/kg bw/day, slight or mild hyperkeratosis in the forestomach in all 6 males at 200 mg/kg bw/day, slight inflammatory cell infiltration in the forestomach in 1 male at 200 mg/kg bw/day, and cystic changes in the epithelial layer of the forestomach in 1 male at 200 mg/kg bw/day. In the females at 200 mg/kg bw/day, the following findings were noted: slight hyperplasia of squamous epithelium in the forestomach in 3 females, slight inflammatory cell infiltration in the forestomach in 1 female, and cystic changes in the epithelial layer of the forestomach in 1 female. From these findings in the stomach, it can be said that the above-mentioned higher water consumption in both sexes at 200 mg/kg bw/day was a change to alleviate the irritancy of m-xylylene diisocyanate given to the stomach; the higher water consumption noted in the present study is not judged to be a toxicological change. Since no histopathological changes in the stomach were noted in either sex on termination of the recovery period, higher water consumption occurring during administration will revert to normal water consumption after the discontinuation of administration.

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Description (incidence and severity):

In the examinations for reproductive/developmental toxicity in parent animals, no changes attributable to the test substance were noted in the number of estrous cases during the administration period (for 14 days) before the start of mating, copulation index, number of conceiving days, number of pregnant females, fertility index, length of gestation, gestation index, number of corpora lutea, number of implantation sites, implantation index, delivery conditions, or nursing conditions.
In the pups (F1), no changes attributable to the test substance were noted in the number of pups born, number of stillbirths, number of live pups born on Day 0 of lactation, delivery index, birth index, live birth index, sex ratio, number of live pups on Day 4 of lactation, viability index on Day 4 of lactation, clinical signs, body weight on Day 0 or 4 of lactation, appearance, or necropsy findings.

Effect levels

1

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Significantly decreased bodyweight in males and pregnant females.

2

Dose descriptor:

NOAEL

Remarks:

local

Effect level:

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

Based on:

test mat.

Sex:

male

Basis for effect level:

other: Histopathological changes in forestomach and salivation

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The NOAEL for local effects is 12.5 mg/kg bw/d based on histopathological effects in the forestomach. The NOAEL for systemic effects is 50 mg/kg bw/d based on decreased body weight and salivation.

Executive summary:

Rats were administered 0, 12.5, 50 or 200 mg/kg bw/d of test substance in a study performed according to OECD 422 (1996). Rats were dosed from 14 days before mating during mating and afterwards (total 42 days) for males and during mating period, pregnancy and up to lactation day 6 for females. No mortality occurred. Salivation was noted at 50 and 200 mg/kg bw/d in both sexes. Body weight was decreased in both sexes at 200 mg/kg bw/d. For food and water consumption only transient effects were noted which may be due to irritation of the stomach. No test substance-related effect was seen on haematological, clinical chemistry and urinalysis parameters or at gross pathology. Histopathology revealed an increased incidence of hyperplasia of squamous epithelium and hyperkeratosis in the forestomach in both sexes at 200 mg/kg bw/d. Inflammatory cell infiltration in the forestomach and mild cystic changes in the epithelial cell layer of the forestomach were noted in one male and one female at 200 mg/kg bw/d.

The NOAEL for local effects is 12.5 mg/kg bw/d based on histopathological effects in the forestomach. The NOAEL for systemic effects is 50 mg/kg bw/d based on decreased body weight and salivation.