Tar acids, xylenol fraction

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

Summary of available data used for the endpoint assessment of the target substance

Adequacy of study:

key study

Justification for type of information:

refer to analogue justification provided in IUCLID section 13

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: TSCA Health Effects Test Guideline for Specific Organ/Tissue Toxicity - Reproduction/Fertility Effects (EPA 1983)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston NY
- Age at study initiation: 6 weeks (P)
- Weight at study initiation: (P) Males: 189-191 g; Females: 141-142 g;

- Housing:
initially 2 /same sex during acclimatisation period; and then singly except for the cohabitation and lactation periods
- Diet ad libitum
- Water ad libitum
- Acclimation period: 2 weeks


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

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 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 (1 mg/mL propanol), which was used to prepare standards ranging form 10 to 100 ng/µL. With these solutions standard curve was generated using HPLC. Dosing formulation concentrations were veryfied by preparing aliquots which were injectd on HPLC column. The measured concentration of each dosing solution was then calculated from the equitation for the standared curve developed by linear regression.

Duration of treatment / exposure:

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

Frequency of treatment:

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

Details on study schedule:

At day 28-40 post partum F1 animals were selected to be parents of the F2-generation and were gavaged with their respective formulations for at least 11 weeks on 5 days per week.
The F1 animals were approximately 15-17 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.

Dose / conc.:

30 mg/kg bw/day

Dose / conc.:

175 mg/kg bw/day

Dose / conc.:

450 mg/kg bw/day

No. of animals per sex per dose:

25 rats/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

no further data

Positive control:

no data

Parental animals: Observations and examinations:

Mortality: twice daily
General condition: 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 dertermination:
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 concumption:
measured weekly during pre-breed dosing period for P and F 1 generation;
all other phases of this study determination was made visually

Oestrous cyclicity (parental animals):

no data

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 weanded

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

HISTOPATHOLOGY
Male and female adult rats of the highest doses groups and the controls.
The tissues as indicated below were prepared for microscopic examination and weighted, 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 necropsied 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 examined for gross external abnormalities, euthanized and discarded

Statistics:

Levene's test, ANOVA, t-test corredted by bonferroni method, Kruskal-Wallis test, Mann-Whitney U-test, Fisher's exact test

Reproductive indices:

calculated for P and F1 animals:
Mating index (%):
---for males: number of males impregnation females divided through the total number of males paired multiplied by 100
---for females: number of females with copulation plugs divided through the number of females cohabited multiplied by 100

Fertility index(%):
---for males: number of males producing pregnant females divided through number of males impregnating females multiplied by 100
---for females: number of females with copulation plugs divided through the number of females cohabited multiplied by 100

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

Offspring viability indices:

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

Lactation index (%):
number of pups surviving 21 days through total number of live pups at 4 days multiplied by 100

Clinical signs:

effects observed, treatment-related

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

Mortality: 
8/28 males and 5/25 females at 450 mg/kg bw; 
1/25 females at 30 mg/kg bw

Clinical signs of toxicity occurred in F0 and F1 males and females at 450 mg/kg bw/day and included hypoactivity, ataxia, twitches, tremors, prostration, urine stains, audible respiration, perinasal encrustation (not in F0 males), and perioral wetness occurred at >= 175 mg/kg bw.

Body weight:
F0 adult males, sign. reduced (p<0.01) week 1 to week 13 in the 450 mg/kg bw group; 
F0 adult females: sign. reduced week 1 (p<0.05) in the 450 mg/kg bw-group, gestational weight gain not significantly different from control group, lactational body weight sign. reduced (p<0.05) at d4 at 450 mg/kg bw group

Gross lesions of parental males and females which died prior to scheduled  sacrifice included diffuse, focal or multifocal color changes in the lung and stained skin for males and lung congestion and congestion in the nasal turbinates and erythrocytes on the skin surface for females. There were no treatment related histologic lesions observed in the examination of organs from parental F0 and F1 adults which survived to scheduled sacrifice.

F0 or F1: No reproductive parameters were affected in either of the two generations (mating index of male and females, fertility index of males and females, gestational index).

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: >= 175 mg/kg bw/d: clinical signs of toxicity including hypoactivity, ataxia, twitches, tremors, prostration, urine stains, audible respiration, and perioral wetness; 450 mg/kg bw/d: increased mortality, and reduced body weight gain

Key result

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No reproductive parameters were affected in either of the two generations.

Critical effects observed:

not specified

Clinical signs:

effects observed, treatment-related

Dermal irritation (if dermal study):

not examined

Mortality:

not specified

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

Clinical signs of toxicity occurred in F0 and F1 males and females at 450 mg/kg bw/day and included hypoactivity, ataxia, twitches, tremors, prostration, urine stains, audible respiration, perinasal encrustation (not in F0 males), and perioral wetness occurred at >= 175 mg/kg bw.

Gross lesions of parental males and females which died prior to scheduled  sacrifice included diffuse, focal or multifocal color changes in the lung and stained skin for males and lung congestion and congestion in the nasal turbinates and erythrocytes on the skin surface for females. There were no treatment related histologic lesions observed in the examination of organs from parental F0 and F1 adults which survived to scheduled sacrifice.

F0 or F1: No reproductive parameters were affected in either of the two generations (mating index of male and females, fertility index of males and females, gestational index).

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: >= 175 mg/kg bw/d: clinical signs of toxicity including hypoactivity, ataxia, twitches, tremors, prostration, urine stains, audible respiration, and perioral wetness 450 mg/kg bw/d: increased mortality, and reduced body weight gain

Key result

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No reproductive parameters were affected in either of the two generations.

Critical effects observed:

not specified

Clinical signs:

not specified

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

not specified

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Histopathological findings:

not specified

Other effects:

not specified

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Still births in the F1 and F2 generations:
in F1 pups increased at 175  mg/kg/day (7/13 of one dam), but not at 450 mg/kg bw/day (low, mid, high dose versus control: 4/290 born pups, 13/312 born pups with 7/13 on one dam, 6/193 born pups)  
in F2 pups increased at 30 and 450 mg/kg bw, but not at 175 mg/kg/bw (low, mid, high dose versus control: 7/307 born pups, 4/265 born pups,9/163 born pups versus 0/318 born pups)

There was some variability in the number of stillborn in control groups  in F1 and F2 generation (2 versus 0). There was no clear dose-dependent effect in both generations (control/low/mid/high dose: F1 pups: 2/4/13/6; F2 pups: 0/7/4/9). 

F1, F2: Pup survival indices in both generations were not affected by treatment (4-day survival index, 7-day survival index, 14-day  surval index 21-day survival index and lactation index), except live birth indices in F2 (but not F1) which were reduced at 30 and 450 mg/kg  bw, but not at 175 mg/kg/day. Without any other effects especially in the 30 mg/kg bw-group it is unclear whether the effects on live birth indices were substance related. 

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: based on toxic effects in the F2 litters of the high dose group animals and no clear evidence of toxic effects in F1 pups.

Critical effects observed:

not specified

Clinical signs:

not specified

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

Pup survival indices in both generations were not affected by treatment (4-day survival index, 7-day survival index, 14-day  surval index 21-day survival index and lactation index), except live birth indices in F2 (but not F1) which were reduced at 30 and 450 mg/kg  bw, but not at 175 mg/kg/day. Without any other effects especially in the 30 mg/kg bw-group it is unclear whether the effects on live birth indices were substance related. 

Body weight and weight changes:

not specified

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Histopathological findings:

not specified

Other effects:

not examined

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Still births in the F1 and F2 generations:
in F1 pups increased at 175  mg/kg/day (7/13 of one dam), but not at 450 mg/kg bw/day (low, mid, high dose versus control: 4/290 born pups, 13/312 born pups with 7/13 on one dam, 6/193 born pups)  
in F2 pups increased at 30 and 450 mg/kg bw, but not at 175 mg/kg/bw (low, mid, high dose versus control: 7/307 born pups, 4/265 born pups,9/163 born pups versus 0/318 born pups)
There was some variability in the number of stillborn in control groups  in F1 and F2 generation (2 versus 0). There was no clear dose-dependent effect in both generations (control/low/mid/high dose: F1 pups: 2/4/13/6;  F2 pups: 0/7/4/9). 

F1, F2: Pup survival indices in both generations were not affected by treatment (4-day survival index, 7-day survival index, 14-day  surval index 21-day survival index and lactation index), except live birth indices in F2 (but not F1) which were reduced at 30 and 450 mg/kg  bw, but not at 175 mg/kg/day. Without any other effects especially in the 30 mg/kg bw-group it is unclear whether the effects on live birth indices were substance related. 

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: based on toxic effects in the F2 litters of the high dose group animals and no clear evidence of toxic effects in F1 pups.

Critical effects observed:

not specified

Key result

Reproductive effects observed:

no

Conclusions:

Reproductive toxicity was examined in a two-generation toxicity study according to TSCA Health Effects Test Guideline for specific organ/tissue toxicity - Reproduction/Fertility effects. Sprague-Dawley rats were given daily 0, 30, 175, or 450 mg/kg bw/day p-cresol in corn oil by gavage. No effects on fertility were detected despite overt general toxicity including increased mortality and reduced body weight gain at 450 mg/kg bw and at >= 175 mg/kg bw/day hypoactivity ataxia, twitches, tremors, prostration, urine stains, audible respiration and perioral wetness. Thus, the NOAEL(fertility) was 450 mg/kg bw/day and the NOAEL(general toxicity) was 30 mg/kg bw/day. The NOAEL(offspring) is 175 mg/kg bw/day due to toxic effects in the F2 litters of the high dose group animals and no clear evidence of toxic effects in F1 pups.

Cross-reference 2

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

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

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 solutions 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 were 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

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

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

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):

no data

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 necropsied 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 examined 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 divided through the total number of males paired multiplied by 100
---for females: number of females with copulation plugs divided through the number of females cohabited multiplied by 100

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

Gestational Index (%)
number of females with live litters divided 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 divided through the toal number of pups born
4-Day Survival Index (%):
number of pups surviving 4 days divided through total number of live pups at birth multiplied by 100
7-Day Survival Index(%):
number of pups surviving 7 days divided through total number of live pups at 4 days multiplied by 100
14- Day Survival Index (%):
number of pups surviving 14 days divided through total number of live pups at 7 days multiplied by 100
21-day survival index (%):
number of pups surviving 21 days divided through total number of live pups at 14 days multiplied by 100
Lactation index (%):
number of pups surviving 21 days divided through total number of live pups at 4 days multiplied by 100

Clinical signs:

effects observed, treatment-related

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

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 and F2 rats which survived to scheduled sacrifice animals that died prior scheduled:
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

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

30 mg/kg bw/day

Based on:

test mat.

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

Key result

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

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

Critical effects observed:

not specified

Clinical signs:

effects observed, treatment-related

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

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 and F2 rats which survived to scheduled sacrifice animals that died prior scheduled:
P and F1 males: lesions in brain, lungsm thymic regions, decrease in number of sperm in epididymides, atrophied seminal vesicles and coagulation glands, epididymidis
P and F1 females: lesions in brain and lungs

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

30 mg/kg bw/day

Based on:

test mat.

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

Key result

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

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

Critical effects observed:

not specified

Clinical signs:

effects observed, treatment-related

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Other effects:

not specified

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

F1 offspring:
litter size, sex ratio, litter viability and pup survival were unaffected by treatment
450 mg/kg bw/day, female: reduced female pup body weight
F2-generation:
litter size andsex ratio were unaffected by treatment
450 mg/kg 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 survived to scheduled sacrifice.

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

175 mg/kg bw/day

Based on:

test mat.

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 lactational index were reduced and pup mortality was increased at the highest dose.

Critical effects observed:

not specified

Clinical signs:

effects observed, treatment-related

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Other effects:

not specified

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

F1 offspring:
litter size, sex ratio, litter viability and pup survival were unaffected by treatment
450 mg/kg bw/day, female: reduced female pup body weight
F2-generation:
litter size andsex ratio were unaffected by treatment
450 mg/kg 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 survived to scheduled sacrifice.

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

175 mg/kg bw/day

Based on:

test mat.

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 lactational index were reduced and pup mortality was increased at the highest dose.

Critical effects observed:

not specified

Key result

Reproductive effects observed:

no

Conclusions:

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

Cross-reference 3

Reason / purpose for cross-reference:

read-across source

Reference

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

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: 193-194 g; Females: ca. 151 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

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 (1 mg/mL propanol),which was used to prepare standards ranging fron 10 to 100 ng/µL. With these solutions 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 weeks
Premating exposure period (females): 10 weeks

Frequency of treatment:

once per day , 5 d/w
F1 generation producing F2: once per day, 7 days per 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 were 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

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

25 animals/sex/group

Control animals:

yes, concurrent vehicle

Details on study design:

no further data

Positive control:

no data

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 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):

no data

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 necropsied 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 examined for gross external abnormalities, euthanized and discarded.

Statistics:

Levene's test for equal variances, analysis of variance (ANOVA), t-test, Kruskal-Wallis test, Mann-Whitney U test Fisher's exact test

Reproductive indices:

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

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

Gestational Index (%)
number of females with live litters divided 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 divided through the toal number of pups born multiplied by 100
4-Day Survival Index (%):
number of pups surviving 4 days divided through total number of live pups at birth multiplied by 100
7-Day Survival Index(%):
number of pups surviving 7 days divided through total number of live pups at 4 days multiplied by 100
14- Day Survival Index (%):
number of pups surviving 14 days divided through total number of live pups at 7 days multiplied by 100
21-day survival index (%):
number of pups surviving 21 days divided through total number of live pups at 14 days multiplied by 100
Lactation index (%):
number of pups surviving 21 days divided through total number of live pups at 4 days multiplied by 100

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

F0-generation:
Mortality during pre-breed period:
450 mg/kg bw/d males: 12/25 and females: 8/25
Signs of intoxication: 450 mg/kg bw/d, males and females: hypoactivity, ataxia, twitches, tremors, prostration, gasping, rapid respiration, lacrimation, amd perioral wetness occurred immediately after dosing but did not persist until the next day.
Mean weight gain in F0 males and F0 females were equivalent across the groups
Mean body weight, significantly reduced: males: 175 mg-gr., 450 mg-gr., week 13: 489.9 g,470.9 g versus 522 g of controls
 
Reproductive parameters for F0 parents:
Mating index (males and females), fertility index (males and females) and gestational index were not affected by treatment.
Body weight development during gestation and lactation was equivalent across the groups.

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 450 mg/kg bw: increased mortality; 450 and 175 mg/kg bw/d: signs of intoxication

Key result

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: There were no treatment related reproductive effects obseved in this study.

Critical effects observed:

not specified

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

F1-adult-generation
Signs of intoxication: 450 mg/kg bw/d, males and females: hypoactivity, ataxia, twitches, tremors, prostration, gasping, rapid respiration, lacrimation, and perioral wetness
175 mg/kg bw/d: males: perioral wetness females: hypoactivity, ataxia, perioral wetness
Mortality: 450 mg-group: pre-breed period: 8 males and 14 females additionally: 7 males and 9 females died prior to mating, 3 females which were found pregnant diedand another one died during gestation
body weight and weight development females: equivalent across the groups. Males: week 14, low, mid, high dose: 586.6 g, 564.1 g, 494.4 g vs.526.3 g of controls
 
Reproductive parameters for F1 parents: Mating index (males and females), fertility index (males and females) and gestational index were not affected by treatment.
Body weight development during gestation and lactation was equivalent across the groups.

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity

Effect level:

30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 450mg/kg bw: increased mortality; 450 and 175 mg/kg bw/d: signs of intoxication

Key result

Dose descriptor:

NOAEL

Remarks:

fertility

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: There were no treatment related reproductive effects obseved in this study.

Critical effects observed:

not specified

Clinical signs:

not specified

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Histopathological findings:

not specified

Other effects:

not specified

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

F1-pups: Live-birth index was comparable across the groups, sex ratio was not affected
Survival Indices: 4-day-, 7-day-, 14-day- and 21-day-survival indices and lactation index were equivalent across the groups.
450 mg/kg bw/d, males (pre-breed period): significantly reduced mean body weights: 139.6 g versus 162 g in controls

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

ca. 175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: F1 (males) significantly reduced body weights at 450 mg/kg bw group

Critical effects observed:

not specified

F2-pups:
- Live-birth index was comparable across the groups, sex ratio was not affected
- Survival Indices: 4-day-, 7-day-, 14-day- and 21-day-survival indices were equivalent across the groups.
- Lactation index: 450 mg-group: was significantly reduced (75.5 versus 99.4 in controls)
 

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Significantly reduced lactation index in the 450 mg/kg bw group

Critical effects observed:

not specified

Key result

Reproductive effects observed:

no

Conclusion:

The A/D ratio (the dose level at which there were no observable effects in offsprings) is less than 1: (30/175) indicating no increased risk to offspring from o-cresol in the absence of parental effects.

Conclusions:

Two-generation reproductive toxicity according to TSCA Health Effects Test Guideline for specific organ/tissue toxicity - Reproduction/Fertility effects (EPA, 1983)
Continued administration of o-cresol by gavage for two generations to Sprague-Dawley rats resulted in general toxicity including increased mortality at 450 mg/kg bw/d and in clinical signs of toxicity including hypoactivity, ataxia, twitches, tremors, prostration, gasping, rapid respiration and perioral wetness at >= 175 mg/kg bw/d (NOAEL (general toxicity) 30 mg/kg bw/d). No reproductive parameters were affected by treatment in either of the two generations (NOAEL (fertility) 450 mg/kg bw/d).
The NOAEL (offspring) is 175 mg/kg bw/d based on significantly reduced body weights in F1 males and in significantly reduced lactation index in F2 at 450 mg/kg bw.

Materials and methods

Test material

Test material information

Constituent 1

Reference substance name:

Tar acids, xylenol fraction

EC Number:

284-895-5

EC Name:

Tar acids, xylenol fraction

Cas Number:

84989-06-0

Molecular formula:

not applicable

IUPAC Name:

2,3-dimethylphenol; 2,4-dimethylphenol; 2,5-dimethylphenol; 2,6-dimethylphenol; 3,4-dimethylphenol; 3,5-dimethylphenol

Results and discussion

Results: P0 (first parental generation)

Effect levels (P0)

1

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity, rat

Effect level:

30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 450 mg/kg bw: increased mortality; 450 and 175 mg/kg bw/d: signs of intoxication

Remarks on result:

other: Source, CAS 95-48-7, o-cresol / CAS106-44-5, p-cresol / CAS 108-34-9, m-cresol; CMA, 1989

2

Key result

Dose descriptor:

NOAEL

Remarks:

fertility, rat

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: There were no treatment related reproductive effects obseved in this study.

Remarks on result:

other: Source, CAS 95-48-7, o-cresol / CAS106-44-5, p-cresol / CAS 108-34-9, m-cresol; CMA, 1989

Target system / organ toxicity (P0)

Critical effects observed:

not specified

Results: P1 (second parental generation)

Effect levels (P1)

1

Key result

Dose descriptor:

NOAEL

Remarks:

general toxicity, rat

Effect level:

30 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 450 mg/kg bw: increased mortality; 450 and 175 mg/kg bw/d: signs of intoxication

Remarks on result:

other: Source, CAS 95-48-7, o-cresol / CAS106-44-5, p-cresol / CAS 108-34-9, m-cresol; CMA, 1989

2

Key result

Dose descriptor:

NOAEL

Remarks:

fertility, rat

Effect level:

450 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: There were no treatment related reproductive effects obseved in this study.

Remarks on result:

other: Source, CAS 95-48-7, o-cresol / CAS106-44-5, p-cresol / CAS 108-34-9, m-cresol; CMA, 1989

Target system / organ toxicity (P1)

Critical effects observed:

not specified

Results: F1 generation

Effect levels (F1)

Key result

Dose descriptor:

NOAEL

Remarks:

rat

Generation:

F1

Effect level:

ca. 175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 450 mg/kg bw: o-cr.: F1 (males) reduced bw; p-cr.: toxic effects in the F2 litters / no clear evidence of toxic effects in F1 pups; m-cr.: F1 (females) reduced bw; F2 pups reduced bw, pup bw gain and pup lactational index, increased pup mortality

Remarks on result:

other: Source, CAS 95-48-7, o-cresol / CAS106-44-5, p-cresol / CAS 108-34-9, m-cresol; CMA, 1989

Target system / organ toxicity (F1)

Critical effects observed:

not specified

Results: F2 generation

Effect levels (F2)

Key result

Dose descriptor:

NOAEL

Remarks:

rat

Generation:

F2

Effect level:

175 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 450 mg/kg bw: o-cr.: reduced lactation index; p-cr.: toxic effects in F2 litters/no clear evidence of toxic effects in F1 pups; m-cr.: F1(females) reduced bw; F2 pups reduced bw, pup bw gain and pup lactational index, increased pup mortality

Remarks on result:

other: Source, CAS 95-48-7, o-cresol / CAS106-44-5, p-cresol / CAS 108-34-9, m-cresol; CMA, 1989

Target system / organ toxicity (F2)

Critical effects observed:

not specified

Overall reproductive toxicity

Key result

Reproductive effects observed:

no

Applicant's summary and conclusion

Conclusions:

Two-generation studies with each of the source substances o-, p- and m-cresol are available. Continued administration of the source substances by gavage for two generations to Sprague-Dawley rats resulted in general toxicity including increased mortality at 450 mg/kg bw/day and in clinical signs of toxicity resulting in a NOAEL (general toxicity) of 30 mg/kg bw/day. No reproductive parameters were affected by treatment in either of the two generations resulting in a NOAEL (fertility) of 450 mg/kg bw/day. The NOAEL (offspring) is 175 mg/kg bw/day based on significant toxic effects in F1 and F2 animals at 450 mg/kg bw/day. A read-across approach can be used with comparable NOAEL values expected to be obtained for the target substance.

Executive summary:

For the three cresol isomers two-generation studies in rats showed that the general toxicity was dominating over the reproductive toxicity as a NOAEL of 30 mg/kg bw/day for general toxicity was derived. No reproductive parameters were affected by the treatment in either of the two generations resulting in a NOAEL of 450 mg/kg bw/day for fertility. The offsprings (F1 and F2) showed toxic effects mainly regarding clinical signs, body weight and lacation index leading to a NOAEL of 175 mg/kg bw/day. Whilst no studies on toxicity to reproduction have been conducted with xylenols or ethylphenols, the experimental data available on cresols are considered to be suitable and meaningful to predict toxicity to reproduction (fertility) of the target substance.