Mono-, and di-(sec-hexadecyl)naphthalene

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report equivalent or similar to OECD guideline 411: GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

Deviations:

yes

Remarks:

test site not covered

GLP compliance:

yes

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Mono-, and di-(sec-hexadecyl)naphthalene

EC Number:

930-936-3

Molecular formula:

C26H40 + C42H72

IUPAC Name:

Mono-, and di-(sec-hexadecyl)naphthalene

Details on test material:

- Name of test material (as cited in study report): MCP 917
- Expiration date of the lot/batch: 04/01/94
- Storage condition of test material: room temperature

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic, Germantown New York
- Age at study initiation: ca. 42days
- Weight at study initiation: ca. 240g (males) ca. 172g (females)
- Fasting period before study:
- Housing: individually housed in suspended, stainless steel cages
- Diet (e.g. ad libitum): ad libitum except for periods of deprivation required for hematology/serum chemistry studies and necropsy
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 12 days


ENVIRONMENTAL CONDITIONS
- Temperature (°F): 68-72
- Humidity (%): 40-60
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Type of coverage:

open

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: dorsal trunk
- Type of wrap if used: none, animals wore "Elizabethan" collars to minimize ingestion
- Time intervals for shavings or clippings: 24h before the start of dosing, reclipped as necessary but at least once per week.


REMOVAL OF STUDY SUBSTANCE
- Washing (if done): each saturday collars were removed and backs of the rats wiped off with gauze to remove as much residual study substance as possible.
- Time after start of exposure: ca. 24h


STUDY SUBSTANCE
- Constant volume or concentration used: no (based on most recent body weight)


USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Daily, five days a week

Doses / concentrations

Remarks:

Doses / Concentrations:
125, 500, 2000 mg/kg/day
Basis:
nominal per unit body weight

No. of animals per sex per dose:

10 animals/sex/dose (total of 20 animals/dose)

Control animals:

yes, concurrent no treatment

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekdays


DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: weekly


BODY WEIGHT: Yes
- Time schedule for examinations: day after receipt and 1 week before first dosing, immediately before dosing and approximately weekly thereafter.


FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes / No / No data


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: No


WATER CONSUMPTION: Yes / No / No data
- Time schedule for examinations:


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood:Weeks 5 and 13
- Anaesthetic used for blood collection: Yes (diethyl ether)
- Animals fasted: Yes
- How many animals: all animals



CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Weeks 5 and 13
- Animals fasted: Yes
- How many animals: all animals



URINALYSIS: Yes
- Time schedule for collection of urine: Weeks 5 and 13
- Metabolism cages used for collection of urine: No
- Animals fasted: No data



NEUROBEHAVIOURAL EXAMINATION: No



OTHER:

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
adrenals, brain, epididymides, heart, kidneys, liver, ovaries, prostate, spleen, testes, thymus, uterus
HISTOPATHOLOGY: Yes
adrenals, eye, kidneys, lung, optic nerve, prostate, skin (treated), testis, thyroid, brain, heart, liver, ovaries, pancreas, seminal vesicles, spleen, thymus, urinary bladder, bone marrow, large intestine, small intestine, skeletal muscle, peripheral nerve (sciatic), salivary gland (submaxillary), stomach (squamous & glandular), uterus, gross lesions

Other examinations:

Spermatozoa and Spermatid Evaluations

Statistics:

Quantitative data were analyzed by parametric methods: analysis of variance (ANOVA) and associated F-test, followed by Dunnetts Test or Tukey’s multiple comparison test, respectively, provided that there was statistical significance in ANOVA.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

HAEMATOLOGY
The only statistically significant difference was for MCHC in females. A linear relationship was found between dose and blood MCHC level. When compared to historical hematology reference values, the dose response curve for female MCHC fell within the normal range as defined by the 10th and 90th percentiles of the historical data. Therefore, no biologically significant differences were observed in the hematology data following treatment.

CLINICAL CHEMISTRY
Statistically significant differences were observed at greater than 500mg/kg/day for 7 out of 20 serum chemistry parameters evaluated at Week 13. A linear relationship was found between dose and serum level for urea nitrogen, alanine aminotransferase (ALT), alkaline phosphatase and sodium in males and for ALT, alkaline phosphatase and cholesterol in females. When historical serum reference ranges were considered, the dose-response for male urea nitrogen and alkaline phosphatase at 2000mg/kg/day and for female ALT, alkaline phosphatase and cholesterol at 2000mg/kg/day fell outside the normal range as defined by the 10th and 90th percentiles.


ORGAN WEIGHTS
Significant increase was seen in the relative liver weights for females in all dose levels and in the absolute liver weight for females dosed at 2000mg/kg/day. Based on histopathology (enlarged liver cells), this response was believed to be adaptive and not toxicologically significant. A significant increase was also seen in the relative epididymides weight of the 2000 mg/kg/day males and in the relative kidney weight of the 500 mg/kg/day males.

GROSS PATHOLOGY
Pale and/or large livers were seen in 3/10 or 4/10 of the high-dose females, respectively.

HISTOPATHOLOGY: NON-NEOPLASTIC
Mild enlargement of liver cells at 2000mg/kg/day was observed in females. However, this is believed to be an adaptive response and not toxicologically significant.



OTHER FINDINGS
No treatment related effects were observed for sperm evaluation which included spermatozoa morphology and count, testicular spermatid count.

Minimal skin irritation was observed in the treated groups. A few animals exhibited barely perceptible to slight erythema with flaking and/or leathery feeling epidermis.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

>= 125 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: overall effects

2

Dose descriptor:

LOAEL

Effect level:

<= 500 mg/kg bw/day (actual dose received)

Sex:

male/female

Basis for effect level:

other: clinical chemistry (both sexes); organ weights (kidney, males)

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The NOAEL for rats dermally exposed to the study substance is 125 mg/kg/day. Statistically significant changes in serum chemistry parameters for males and females and changes in relative kidney weights in males were observed at the next highest dose of 500mg/kg/day. However, these effects are minimal and occur at doses above the guidance values for classification. These findings do not warrant classification of the study substance for target organ toxicity (repeated exposure) under the new Regulation (EC) 1272/2008 on classification, labeling, and packaging of substances and mixtures (CLP), under the Directive 67/518/EEC for dangerous substances and Directive 1999/45/EC for preparations, or under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS).

Executive summary:

A 90-day dermal toxicity study was conducted in rats at concentrations of 0, 125, 500, and 2000 mg/kg/day. Study substance was applied to the clipped backs of groups of 10 male and 10 female Sprague-Dawley rats five days a week for 13 weeks. Animals exhibited no signs indicative of systemic toxicity. Minimal skin irritation was exhibited by a few animals in all of the dose groups. The study substance had no effect on body weight gain. No biologically significant differences were observed between the hematology data from the control and treated animals. Statistically significant differences were observed between the data from the untreated group and the groups treated at greater than 500 mg/kg/day for 7 out of 20 serum chemistry parameters evaluated at Week 13. A linear relationship was found between dose and serum level for urea nitrogen, alanine aminotransferase (ALT), alkaline phosphatase and sodium in males and for ALT, alkaline phosphatase and cholesterol in females. When the historical serum reference values were taken into consideration, the dose-response curve for male urea nitrogen and alkaline phosphatase at 2000 mg/kg/day and for female ALT, alkaline phosphatase and cholesterol at 2000 mg/kg/day fell outside the normal range as defined by the 10th and 90^th percentile of the historical data. Sperm evaluation and urinalysis showed no treatment-related effects.

 

The only study substance-related finding at necropsy was pale and/or large liver seen in 3/10 or 4/10 of the high-dose females, respectively. A significant increase was seen in the relative liver weights for females in all dose levels and in the absolute liver weight for females dosed at 2000 mg/kg/day. A significant increase was also seen in the relative epididymus weight of the 2000 mg/kg/day males and in the relative kidney weight of the 500 mg/kg/day males. Microscopically, the only treatment-related finding was a mild enlargement of liver cells in females exposed to the study substance at 2000 mg/kg/day. The liver effect is deemed an adaptive response and is not believed to be toxicologically significant.

 

Based on the results of the study, a No-Observed-Adverse-Effect-Level (NOAEL) for the study substance was established to be 125 mg/kg/day.