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Administrative data

Description of key information

The repeated daily oral administration of 1-naphthol to rats for 13 weeks at 65, 130, or 400 mg/kg bw/day resulted in a number of altered urine and clinical chemistry parameters. However none of these findings were considered adverse. Microscopic, treatment-related changes were restricted to the stomach and spleen. In gastric tissues, squamous hyperplasia and hyperkeratosis of the nonglandular stomach were present in all males and most females given 400 mg/kg bw/day; and in both sexes at 130 mg/kg bw/day. At the high-dose level, gastric changes were moderate to severe and in both sexes given 130 mg/kg bw/day were minimal to mild. Treatment-related stomach or changes in spleen were not observed in rats at the 65 mg/kg bw/day group. The NOAEL was set at 130 mg/kg bw.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 1998 - July 2001
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
no
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: RE1141.03 - Lot n°03
- Expiration date of the lot/batch: March 9, 1999
- Purity test date: No data
- Purity : 99.7%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: Yes
- Solubility and stability of the test substance in the solvent/vehicle: Yes

TREATMENT OF TEST MATERIAL PRIOR TO TESTING : No

FORM AS APPLIED IN THE TEST Solution

Species:
rat
Strain:
Sprague-Dawley
Details on species / strain selection:
Crl:CD/(SD)BR VAF/Plus
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Portage, Michigan, facility of Charles River Laboratories, Inc.
- Females nulliparous and non-pregnant: Yes
- Age at study initiation: 5 weeks old
- Weight at study initiation: 161 - 202 g for the males and 142 - 181 g for the females
- Fasting period before study: No data
- Housing: individually
- Diet :ad libitum (Certified rodent diet - #8728C, Harlan Teklad)
- Water :ad libitum
- Acclimation period: 11 days

DETAILS OF FOOD AND WATER QUALITY: Diet and water is routinely analysed.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 to 25°C
- Humidity (%): 30 to 70%
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12h light / 12h dark
Route of administration:
oral: gavage
Vehicle:
CMC (carboxymethyl cellulose)
Remarks:
0.5%
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
The control material was 0.5% CMC in RO water.Concentrations were based on CMC as supplied. A specified amount of CMC was weighed and RO was added to achieve the required concentration. The preparation was mixed thoroughly and dispensed into labeled containers.Dose concentrations were based on the test material as supplied. Dose preparations were prepared approximately weekly.

Dose preparations were held at room temperature for at least 1 hour before dose administration. For at least 1 hour before dosing and throughout dose administration, homogeneous test material mixtures were maintained using a magnetic stir plate and stir
bar.

VEHICLE
- Justification for use and choice of vehicle (if other than water):
- Concentration in vehicle: 0.5% in reverse osmosis water
- Amount of vehicle (if gavage): 10 ml/kg
- Lot/batch no. (if required): MA0049 (CMC)
- Purity: No data
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analyses for homogeneity and concentration of the test material in the dose preparations were done by Covance-Vienna using an analytical method.
Eighteen samples were collected before initiation and during Week 8 from the 65- and 400- mg/kg/day dose preparations.

These results indicate that the mixing procedure produced a homogeneous distribution of the test material in the dose preparations.
The mean concentrations of the dose preparation analyses for all levels ranged from 86.2 to 110% of the theoretical concentrations. These data indicate that the levels of naphthol in the dose preparations were acceptable.
Duration of treatment / exposure:
90 days
7 days for groups used for the blood collection
Frequency of treatment:
Daily
Dose / conc.:
65 mg/kg bw/day (nominal)
Remarks:
one group exposed 90 days and another 7 days
Dose / conc.:
130 mg/kg bw/day (nominal)
Remarks:
one group exposed 90 days and another 7 days
Dose / conc.:
400 mg/kg bw/day (nominal)
Remarks:
one group exposed 90 days and another 7 days
No. of animals per sex per dose:
15 per sex per dose
5 per sex per dose of groups used for the blood collection
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: The goal of dose selection was a gradient of toxic effects based on a preliminary range finding study

Positive control:
No
Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: during week 1 through 4, four times/ day and once time by week
- Cage side observations checked.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: during week 5 to 14, each animal was observed in its cage then removed from its cage and examined for changes in skin, fur, eyes, and mucous membranes; respiratory, circulatory, autonomical, and central nervous systems; somatomotor activity; and behavior patterns; and abnormalities and signs of toxicity. Once during Week 13, each animal iwas observed upon removal from its cage, for approximately 2 minutes in an open field, and in response to battery of elicited behaviors.

BODY WEIGHT: Yes
- Time schedule for examinations: weekly (individual)

FOOD CONSUMPTION : Yes
- Time schedule for examinations: weekly
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / Not specified

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes / No / Not specified
- Time schedule for examinations:

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: initiation of exposure and during the week 13
- Dose groups that were examined: all groups exposed 90 days

HAEMATOLOGY: Yes
- Time schedule for collection of blood: On day 7 for groups exposed only 7 days and once during weeks 4 and 14 for groups exposed 90 days
- Anaesthetic used for blood collection: Not specified
- Animals fasted: Yes
- How many animals: all
- Parameters checked : red blood cell (erythrocyte) count, hemoglobin, hematocrit, mean corpuscular, volume mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet count, white blood cell (leukocyte) count, blood cell morphology, differential blood cell count, nucleated red blood cell count, corrected white blood cell count, segmented neutrophil count, band neutrophil count, lymphocyte count, monocyte count, eosinophil count, basophil count, prothrombin time activated partial thromboplastin time

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: On day 7 (animals in groups 5 through 8) and once during weeks 4 and 14 (animals in groups 1 through 4)
- Animals fasted: Yes
- How many animals: all
- Parameters checked :glucose, irea nitrogen, creatinine, total protein, albumin, globulin, albumin/globulin ratio, cholesterol, triglycerides, total bilirubin, alanine aminotransferase, alkaline phosphatase, gamma glutamyltransferase aspartate aminotransferase
calcium , inorganic phosphorus, sodium, potassium, chloride, serum protein electrophoresis.

URINALYSIS: Yes
- Time schedule for collection of urine: On day 7 (animals in groups 5 through 8) and once during weeks 4 and 14 (animals in groups 1 through 4)
- Metabolism cages used for collection of urine: No
- Animals fasted: Yes
- Parameters checked : specific gravity, pH protein, glucose, ketones, bilirubin, blood, urobilinogen, volume, microscopic examination of, sediment, appearance, sodium, potassium, chloride, excretion of sodium-potassium-chloride

NEUROBEHAVIOURAL EXAMINATION: No

IMMUNOLOGY: No.

OTHER: Vaginal smears were done daily for the females to evaluate the stage of the estrous cycle starting at Week 10 and continuing through treatment.
Sacrifice and pathology:
On day 7, animals exposed 7 days were sacrificed and during week 14, animals exposed 90 days were anesthetized, weighed, exsanguinated, and necropsied

GROSS PATHOLOGY: Yes -
- Macroscopic observations were recorded, selected organs were weighed for all rats
- Lungs, liver, kidneys, stomach, spleen, and macroscopic lesions were examined microscopically from each animal given 65 or 130 mg/kg bw/day
- The following organs were weighed adrenal, brain, epididymis, heart, kidney, liver ovary, pituitary (postfixation), prostate, spleen, testis, thymus, thyroid with parathyroid,

HISTOPATHOLOGY: Yes for from each animal in the control and 400 mg/kg bw/day exposed group
- Tissues preserved in 10% neutralbuffered formalin - adrenal, aorta,brain (cerebrum, cerebellum, and medulla), cecum, cervix, colon, duodenum, epididymis, esophagus, eye, femur with bone marrow (articular surface
of the distal end), harderian gland, heart, ileum, jejunum, kidney, lacrimal gland, liver, lung with mainstem bronchi, lymph node (mandibular and mesenteric), mammary gland (females only), ovary, pancreas, pituitary, prostate, rectum, salivary gland, sciatic nerve, seminal vesicle, skeletal muscle, skin, spinal cord (cervical, thoracic, and lumbar), spleen, sternum with bone marrow, stomach, testis [preserved in Bouin’s fixative], thymus,tissues with macroscopic changes or alterations,(i.e., gross lesions)
thyroid with parathyroid, tongue, trachea, urinary bladder, uterus with uterine horns, vagina)
Other examinations:
Sperm collected from each male was evaluated for motility, morphology, and concentration
Statistics:
One-way analysis of variance was used to analyze body weights; body weight changes; food consumption; continuous clinical pathology; sperm motility; organ weights; organ-to-body weight percentages; and organ-to-brain weight ratios.

Levene’s test (Levene, 1960) was done to test for variance homogeneity. In the case of heterogeneity of variance at p < 0.05, transformations were used to stabilize the variance. ANOVA was done on the homogeneous or transformed data. If the ANOVA was significant, Dunnett’s multiple comparison t-test (Dunnett, 1964) was used for pairwise comparisons between treated and control groups.

Expanded clinical observations were analyzed by contingency table methods appropriate for the type of response measured (e.g., binary, such as present or absent piloerection; ordinal, such as ease of handling; nominal with more than two levels, such as gait description). Exact permutation p- values were obtained.

Open field observations (posture, gait abnormalities, and other unusual behaviors) was treated as categorical observations (attribute either present or absent). Each individual attribute received a separate statistical analysis. In addition, a summary categorical response was formed for statistical analysis in each of these three classes of open field observations.
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Discoloured fur (brown perineal or general yellow hair coat) was noted in females given 400 mg/kg bw/day.

During Week 13, a number of findings were noted during the expanded clinical observations. The finding considered to be related to the administration of test material was the stained, brown haircoat in the anal- genital area of the females given 400 mg/kg/day. This finding was also consistent with the discolored pelage noted during the weekly clinical examinations of the high-dose females. Three high-dose males had no or low locomotor activity in the open field; whereas this finding was associated exclusively with the high-dose males, there were no other findings for these individual animals either during the weekly clinical observations or during the Week 13 expanded clinical observations that correlated with the decreased activity of these animals.
See table 1.
Mortality:
no mortality observed
Body weight and weight changes:
not examined
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
With the exception of the Week 1 mean food consumption for males given 65 or 400 mg/kg/day, there were no outstanding differences between the mean food consumption values of the males and females and their control counterparts.
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
A number of clinical chemistry parameters were altered, however none of these findings were considered adverse
Urinalysis findings:
no effects observed
Description (incidence and severity):
A number of urine parameters were altered, however none of these findings were considered adverse
Behaviour (functional findings):
not specified
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Neuropathological findings:
not specified
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Microscopically, treatment-related changes were restricted to the stomach and spleen of animals given higher doses of the test material. In gastric tissues, squamous hyperplasia and hyperkeratosis of the nonglandular stomach were present in all males and most females given 400 mg/kg bw/day; and in both sexes at130 mg/kg bw/day. At the high-dose level, gastric changes were moderate to severe and in both sexes given 130 mg/kg bw/day were minimal to mild. In the spleen sections, increased pigment deposits (hemosiderin) were minimally to slightly increased in the 400 mg/kg bw/day group. See table 2.
Histopathological findings: neoplastic:
not specified
Other effects:
no effects observed
Description (incidence and severity):
The sperm motility, morphology, and count were not affected

There was a tendency toward an increase in the duration of the estrous cycle with the increase in the dose level, but the variation in the data make the relation of this to the test material uncertain
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 130 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Remarks on result:
not determinable due to absence of adverse toxic effects
Key result
Dose descriptor:
LOAEL
Effect level:
ca. 400 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
histopathology: non-neoplastic
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
400 mg/kg bw/day (nominal)
System:
gastrointestinal tract
Organ:
stomach
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified

See data tables of results in attached background material.

Conclusions:
The study authors set the NOAEL for 1-naphthol at 130 mg/kg bw/day, based on the microscopical changes in stomach and in spleen.
Executive summary:

The dosages were based on a dose finding study (2 weeks)

Male and female Crl:CD/(SD)BR VAF/Plus rats were assigned to eight groups (15 animals/sex/group in control and exposure groups/90 days and five animals/sex/group in control and exposure groups/ 7 days). Each group was dosed to 65, 130, or 400 mg/kg bw/day or vehicle only. Food and water was provided ad libitum. The animals were observed twice daily for mortality/morbidity. Body weights were recorded for each animal and food consumption data were collected weekly. Ophthalmic examinations were done before initiation of exposure and during the week 13 for animals exposed 90 days. On day 7 (animals in groups 5 through 8) and once during weeks 4 and 14 (animals in groups 1 through 4), blood and urine samples were collected for haematology, clinical chemistry and urine chemistry tests. On day 7, animals in groups 5 through 8 were sacrificed and during week 14, animals in groups 1 through 4 were anesthetized, weighed, exsanguinated, and necropsied. Microscopic examinations were done on tissues from each animal in the control and 400 mg/kg bw/day exposed group, respectively. The lungs, liver, kidneys, stomach, spleen, and macroscopic lesions were examined microscopically from each animal given 65 or 130 mg/kg bw/day. Sperm collected from each male was evaluated for motility, morphology, and concentration.

Results

No mortality occurred during the study. Discoloured fur (brown perineal or general yellow hair coat) was noted in females given 400 mg/kg bw/day. Food consumption for males and females was similar in exposed and control groups. No differences in body weight or body weight gain or differences in ophthalmic observations were reported. The sperm motility, morphology, and count were not affected. A number of urine and clinical chemistry parameters were altered, however none of these findings were considered adverse. Microscopically, treatment-related changes were restricted to the stomach and spleen of

animals given higher doses of the test material. In gastric tissues, squamous hyperplasia and hyperkeratosis of the nonglandular stomach were present in all males and most females given 400 mg/kg bw/day; and in both sexes at130 mg/kg bw/day. At the high-dose level, gastric changes were moderate to severe and in both sexes given 130 mg/kg bw/day were minimal to mild. In the spleen sections, increased pigment deposits (hemosiderin) were minimally to slightly increased in the 400 mg/kg bw/day group. Treatment-related stomach or changes in spleen were not observed in rats at the 65 mg/kg bw/day group.

Conclusion

The study authors set the NOAEL for 1-naphthol at 130 mg/kg bw/day, based on the microscopical changes in stomach and in spleen.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
130 mg/kg bw/day
Study duration:
subchronic
Species:
rat
Quality of whole database:
Klimisch 1

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

Justification for classification or non-classification

On the basis of the data, the 1-naphthol is not classified