m-cresol

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1989

Report date:

1989

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: TSCA Health Effects Test Guideline for specific organ/tissue toxicity - Reproduction/Fertility effects (EPA, 1983)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

m-cresol

EC Number:

203-577-9

EC Name:

m-cresol

Cas Number:

108-39-4

Molecular formula:

C7H8O

IUPAC Name:

m-cresol

Details on test material:

Test substance: m-cresol, purity: 99.4 %

Test animals

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, Kingston, NY
- Age at study initiation: 6 wks (P) ;
- Weight at study initiation: (P) Males: 189.4-191.1 g; Females: 141.1-142.7 g;
- Housing: initially 2/same sex during acclimation period; and then singly except for the cohabitation and lactation periods
- Diet : ad libitum
- Water : ad libitum
- Acclimation period: 14 days


ENVIRONMENTAL CONDITIONS
- Temperature :68-74°F
- Humidity (%): 40-60
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Dosing formulations were prepared by weighing the amount of test chemical into a volumetric flask and diluting to volume with certified corn oil.
The resulting solutions were mixed by repeated inversions and stored at room temperature.

Details on mating procedure:

- M/F ratio per cage: 1/1
- Length of cohabitation: 21 days
- Proof of pregnancy: vaginal plug / sperm in vaginal smear referred to as day 0 of pregnancy
- After 7 days of unsuccessful pairing replacement of first male by another male with proven fertility.
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged singly
- Any other deviations from standard protocol: no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

A standard stock solution was prepared (1mg/ml propanol),which was used to prepare standards ranging fron 10 to 100 ng/µl. With these solutiower a standard curve was generated using HPLC. Dosing formulation concentrations were veryfied by preparing aliquots which were injected onto the HPLC column. The measured concentration of each dosing solution was then calculated from the equitation for the standard curve developed by linear regression.

Duration of treatment / exposure:

Exposure period: 27 w
Premating exposure period (males): 10 w
Premating exposure period (females): 10 w
Duration of test: 29 w

Frequency of treatment:

P- and F1-generation: once/day, 5 days/week
F1- generation producing F2: once/day , 7 days/week

Details on study schedule:

at day 28-40 post partum F1 animals selected to be parents of the F2 generation were gavaged with their respective formulations for at least
11 weeks 5 days/week.
the F1 animals ere approximately 15 to 17 weeks of age at the initiation of the mating period.
They were dosed from that time point 7 days/week. Mating procedure was performed as done with the P-generation

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 30, 175 or 450 mg/kg bw/d in corn oil (P and F1, m/f)
Basis:
actual ingested

No. of animals per sex per dose:

25 rat/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

no further data

Positive control:

no data

Examinations

Parental animals: Observations and examinations:

Mortality: twice daily
General conditon: daily throughout the course of the study including skin and fur, eyes and mucous membranes, respiratory symptoms, circulatory system, autonomic and central nervous system, somatomotor activity, behavior pattern
Body weight determination
male, female: initially and then weekly until mating
female during gestation : day 0, 7, 13, 20 post partum: day 0, 4, 7, 14, 21
Food consumption
measured weekly during pre-breed dosing period for P and F1 generation; all other phases of this sutdy determination was made visually

Oestrous cyclicity (parental animals):

vaginal smears were examined to determine pregnancy

Sperm parameters (parental animals):

no data

Litter observations:

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


PARAMETERS EXAMINED
The following parameters were examined in F1 / F2 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural 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 after the completion of the mating period
- Maternal animals: All surviving animals after the F1 and F2 litters have been weaned


GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera.
A complete gross necropsy was conducted for any parental animal dying on test.


HISTOPATHOLOGY
Male and female adult rats of the highest dose groups and the controls
The tissues as indicated below, were prepared for microscopic examination and weighed, respectively:
pituitary, vagina, uterus, ovaries, testes, epididymides, seminal vesicles, prostate and other tissues with gross lesions identified as being
potentially treatment-related.
A complete histopathological examination was conducted for any parental animal dying on test.

Postmortem examinations (offspring):

All pups dying during lactation are neccropsied to investigate the cause of death.

At weaning , postnatal day 21 , 1 female and 1 male from each F1 litter is selected on a random basis to become parents of the next
generation.
The remaining offspring is cexamined for gross external abnormalities , euthanized and discarded.

Statistics:

Levine's test, ANOVA, t-test corrected by Bonferroni method, Kruskal-Wallis test, Mann Whitney U-test, Fishers exact test

Reproductive indices:

calculated for P and F1 animals:
Mating Index (%):
---for males: number of males impregnating females devided through the total number of males paired multiplied by 100
---for females: number of females with copulation plugs devided through the mumger of females cohabited multiplied by 100

Fertility Index(%):
---for males: number of males producing pregnant females devided through number of males impregnating females multiplied by 100
---for females. number of pregnant females devided through number of plug-positive females multiplied by 100

Gestational Index (%)
number of females with live litters devided through number of females pregnant multiplied by 100

Offspring viability indices:

calculated for F1 and for F2 animals
live birth index
number of live pups at birth devided through the toal number of pups born
4-Day Survival Index (%):
number of pups surviving 4 days devided through total number of live pups at birth multiplied by 100
7-Day Survival Index(%):
number of pups surviving 7 days devided through total number of live pups at 4 days multiplied by 100
14- Day Survival Index (%):
number of pups surviving 14 days devided through total number of live pups at 7 days multiplied by 100
21-day survival index (%):
number of pups surviving 21 days devided through total number of live pups at 14 days multiplied by 100
Lactation index (%):
number of pups surviving 21 days devided through total number of live pups at 4 days multiplied by 100

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

effects observed, treatment-related

Reproductive function: sperm measures:

effects observed, treatment-related

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
P, pre-breed period:
450 mg/kg bw
clinical signs: hypoactivity, ataxia, twitches, tremors, prostration, unkempt appearance(males), urine stains, audible respiration, perinasal encrustration, perioral wetness
mortality 7/25 males; 5/25 females
175 mg/kg bw/day
sacrifice due to trauma of 1/25 male
F1, pre-breed period
450 mg/kg bw/day:clinical signs: hypoactivity, ataxia, twitches, tremors, prostration, unkempt appearance(males), urine stains, audible respiration, perinasal encrustration, perioral wetness (also at 175 mg/kg bw/day)
mortality: 450mg/kg bw/day: 3 males and 4 females
F1 breed period,
mortality during gestation: 1 female in control and 30 and 175 mg/kg bw/day groups and 3 females in the 450 mg/kg bw/day group
mortality during lactation : 3 females at 450 mg/kg bw/day group

BODY WEIGHT (PARENTAL ANIMALS)
P, pre-breed period:
450 mg/kg bw/day, male, female: reduced body weight gain
P, breed period
mortality. 450 mg/kg bw 2/20 females; 175 mg/kg bw:: 1/24 female
F1, pre-breed period:
slightly reduced body weight in males (450, and 175, 30 mg/kg bw) and in females (450 and 30 mg/kg bw/day)
F1-breed period
450, 175, 30 mg/kg bw/day: reduced bw in males
450 mg/kg bw/day females: reduced maternal gestational and lactational body weights

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
P-generation:
reproductive parameters including gestational length were unaffected by treatment
F1-generation:
reproductive parameters including gestational length were unaffected by treatment
ORGAN WEIGHTS, GROSS PATHOLOGY, HISTOPATHOLOGY (PARENTAL ANIMALS).
all groups:
there were no treatment related gross or histological lesions in P, F1 andF2 rats which survivied to sheduled sacrifice
animals that died prior sheduled:
P and F1 males: lesions in brain, lungsm thymic regions, decrease in number of sperm in epididymides, atrophied seminal vesicles and coagulation glands, epididymitis
P and F1 females: lesions in brain and lungs

OTHER FINDINGS (PARENTAL ANIMALS)

Effect levels (P0)

1

Dose descriptor:

other: NOAEL (offspring)

Effect level:

ca. 175 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: In F1 the female pups had reduced body weights in the highest dose tested, but pup survival was not affected. In F2 pup body weight , pup body weight gain and pup lacational index were reduced and pup mortality was increased at the highest dose.

Remarks on result:

other: Generation: F1 and F2

2

Dose descriptor:

other: NOAEL (fertility)

Effect level:

ca. 450 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Effects on reproduction function or on morphology of reproductive tissues were not detected.

Remarks on result:

other: Generation: P and F1

3

Dose descriptor:

other: NOAEL (general toxicity)

Effect level:

ca. 30 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: >= 175 mg/kg bw/d: signs of overt toxicity : hypoactivity, ataxia, twitches, tremors, prostration, urine staining, audible respiration and perioral wetness

Remarks on result:

other: Generation: P and F1

Results: F1 generation

General toxicity (F1)

Clinical signs:

effects observed, treatment-related

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Sexual maturation:

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings:

effects observed, treatment-related

Details on results (F1)

F1 offspring:
litter size, sex ratio, litter viability and pup survival were unaffected by treatment
450 mg/kg bw/day, femle: reduced female pup body weight
F2-generation:
litter size andsex ratio were unaffected by treatment
450 mg7kg bw/day lactational index was reduced, pups body weight and body weight gain was reduced and pup deaths increased
Pathology:
all groups:
there were no treatment related gross or histological lesions in F1 and F2 rats which survivied to sheduled
sacrifice.

Effect levels (F1)

Dose descriptor:

NOAEL

Remarks:

offspring

Generation:

F1

Effect level:

175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: In F1 the female pups had reduced body weights in the highest dose tested, but pup survival was not affected. In F2 pup body weight , pup body weight gain and pup lactational index were reduced and pup mortality was increased at the highest dose.

Target system / organ toxicity (F1)

Critical effects observed:

yes

Lowest effective dose / conc.:

450 mg/kg bw/day (nominal)

Organ:

other: In F1 the female pups had reduced body weights in the highest dose tested, but pup survival was not affected. In F2 pup body weight , pup body weight gain and pup lactational index were reduced and pup mortality was increased at the highest dose.

Treatment related:

yes

Dose response relationship:

yes

Results: F2 generation

Effect levels (F2)

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: In F1 the female pups had reduced body weights in the highest dose tested, but pup survival was not affected. In F2 pup body weight , pup body weight gain and pup lactational index were reduced and pup mortality was increased at the highest dose.

Target system / organ toxicity (F2)

Critical effects observed:

yes

Lowest effective dose / conc.:

450 mg/kg bw/day (nominal)

System:

other: In F1 the female pups had reduced body weights in the highest dose tested, but pup survival was not affected. In F2 pup body weight , pup body weight gain and pup lactational index were reduced and pup mortality was increased at the highest dose.

Treatment related:

yes

Dose response relationship:

yes

Overall reproductive toxicity

Reproductive effects observed:

no

Any other information on results incl. tables

F0: pre-breed dosing period:
450 mg/kg: f,m: significant reduced body weight, signs of toxicity: hypoactivity, ataxia, twitches, tremors, prostration, unkempt appearance(males), urine stains, audible respiration perinasal encrustration and perioral wetness; mortality: 7/25 m, 5/25 f;
175 mg/kg: sacrifice due to trauma 1/25 m.

F0: breed period:
450 mg/kg: maternal gestat. and lactat. bw sign. reduced,

Mortality: 450 mg/kg: 2/20 f; 175 mg/kg: 1/25 f;
Reproductive parameters including gestational length were unaffected by treatment.

F1:
Litter size, sex ratio, litter viability, pup survival were unaffected by treatment;

450 mg/kg: reduced female pup bw.

F1 pre-breed period:
Slightly reduced bw in m (450, 175,30 mg/kg) and in f (450,30 mg/kg); signs of toxicity: 450 mg/kg bw: hypoactivity, ataxia twitches, tremors prostration urine stains, audible respiration and perioral wetness (also at 175 mg/kg females);

Mortality: 450 mg/kg 3 m and 4 f.

F1 breed period:
450, 175, 30 mg/kg: reduced bw in m; maternal gestational and lactational bw reduced in 450 mg/kg f;

Mortality during gestation: 1 f each at control, 30, 175 mg/kg and 3 f at 450 mg/kg, mortality during lactation: 3 f at 450 mg/kg.
Reproductive parameters including gestational parameters were unaffected by treatment.

F2:
litter size and sex ratio unaffected; F2 pup lactational index was reduced at 450 mg/kg
450 mg/kg: pup bw and pup bw gain was reduced and pup deaths increased.

Pathology:
All groups: there were no treatment related gross lesions or histologic lesions in F0, F1 and F2 rats which survived to scheduled sacrifice.
Dead prior to schedule: F0,F1 m: lesions in brain , thymic regions, lungs, decrease in number of sperm in epididymides, atrophied seminal vesicles and coagulation glands, epididymitis;

F0,F1 f: lesions in the brain, lungs.

NOAEL (fertility): 450 mg/kg bw

The exact A/D ratio cannot be calculated. But it can be assumed that the A/D ratio would be less than 1 (<30.0 mg/kg bw/day/175.0 mg/kg bw) indicating no increased risk to
offspring in the absence of parental toxicity.

A/D ratio: exposure level at which there were no observable effects in adults/the exposure level at which there were no observable effects in offspring

Applicant's summary and conclusion

Executive summary:

Two-generation study according to TSCA Health Effects Test Guideline for specific organ/tissue toxicity - Reproduction/Fertility effects (EPA, 1983):

Sprague-Dawley rats were given daily 0, 30, 175, 450 mg/kg bw/daym-cresol in corn oil by gavage. Effects on reproductive function or on morphology of reproductive tissues were not detected even at doses producing overt toxicity in adult rats (hypoactivity, ataxia, twitches, tremors, prostration,urine stains, audible respiration, and perioral wetness). The NOAEL (fertility) was 450 mg/kg bw/day. The NOAEL (toxicity) was 30 mg/kg bw/d. In F1 and F2 , litter size, sex ratio, and litter viablity was unaffected by treatment. In F1 the female pups had reduced body weights in the highest dose tested, but pup survival was not affected. In F2, pup body weight, pup body weight gain and pup lactational index were reduced and pup mortality was increased at the highest dose. Thus the NOAEL (offspring) was 175 mg/kg bw/d