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Toxicological information

Repeated dose toxicity: dermal

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Administrative data

Endpoint:
sub-chronic toxicity: dermal
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1986-12-02 to 1987-03-06
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study is classified as reliable without restriction because it was carried out in a manner similar to OECD Guideline 411.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1990
Report Date:
1990

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)
GLP compliance:
no
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Read across to Distillate Aromatic Extract
- Name of test material (as cited in study report): 318 Isthmus Furfural Extract, CAS # 64742-05-8
- Substance type: light paraffinic distillate solvent extract (petroleum) - Distillate Aromatic Extract
- Physical state: liquid
- Analytical purity: not provided
- Impurities (identity and concentrations): not provided
- Composition of test material, percentage of components (wt. %): total non-aromatics- 22.3, total aromatics- 77.7%, less than 3 ring polynuclear aromatic hydrocarbons- 37.2%, 3 to 5 ring polynuclear aromatic hydrocarbons- 23.0%, N-polynuclear aromatic hydrocarbons- 2.3%, S-polynuclear aromatic hydrocarbons- 12.8%
- Isomers composition: not provided
- Purity test date: not provided
- Lot/batch No.: CRU no. 86187
- Expiration date of the lot/batch: April 30, 1991
- Stability under test conditions: 5 years
- Storage condition of test material: not provided

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Rat/Tac- N(SD) fBR/Taconic, Germantown, New York
- Age at study initiation: 49 days
- Weight at study initiation: not provided
- Fasting period before study: none
- Housing: animals were individually housed in suspended, stainless steel cages. Cages were 7 inches wide and 10 inches long and had wire mesh bottoms and fronts.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: minimum of 13 days in a quarantine room


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 21°C
- Humidity (%): 40 to 60%
- Air changes (per hr): not provided
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark cycle


IN-LIFE DATES: From: 1986-12-02 To: 1987-03-06

Administration / exposure

Type of coverage:
other: no coverage
Vehicle:
not specified
Details on exposure:
TEST SITE
- Area of exposure: hair was clipped from the dorsal trunk of each animal for test material application
- % coverage: not reported
- Type of wrap if used: no coverage
- Time intervals for shavings or clippings: hair was reclipped as necessary, but at least once a week.


REMOVAL OF TEST SUBSTANCE
- Washing (if done): every Saturday morning the application sites were wiped off with gauze pads to remove residual test material.
- Time after start of exposure: 6 days


TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0 30, 125, 500, 1250 mg/kg/day
- Constant volume or concentration used: no
- For solids, paste formed: not applicable


VEHICLE
No vehicle

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes, "Elizabethan" collars
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
thirteen weeks
Frequency of treatment:
five days per week
Doses / concentrations
Remarks:
Doses / Concentrations:
30, 125, 500, 1250 mg/kg/day
Basis:
no data
No. of animals per sex per dose:
10 animals per sex per dose
Control animals:
yes
Details on study design:
- Dose selection rationale: the dermal dose levels are based on data obtained in previous studies with similar materials and preliminary work done with furfural extract.
- Rationale for animal assignment (if not random): random
Positive control:
no data reported

Examinations

Observations and examinations performed and frequency:
Each animal was observed once daily during the pre-treatment and dosing phases for normal or abnormal clinical signs. The parameters observed included appearance, behaviour, excretory function, and discharges. Skin irritation was scored weekly for erythema, oedema, and chronic deterioration (flaking, thickening, stiffening, cracking, and sloughing) in animals from groups 1 through 5. On weekdays, animals were checked for moribundity and mortality twice daily, at least six hours apart. On weekends and holidays, they were checked once, as soon as practical each day.

All animals were weighed the day after receipt and approximately one week before the first dosing (the latter for allocation into experimental groups). Animals allocated into experimental groups were weighed immediately before the first dosing and approximately weekly thereafter. The body weight of each animal was recorded to the nearest tenth of a gram.

During weeks 5 and 13, blood samples were collected from all surviving animals for a haematological analysis.

During weeks 5 and 13, blood samples were collected from surviving animals to perform a serum chemistry analysis. At least 1 ml of whole blood from each rat was collected in two Microtainer tubes, allowed to clot for approximately thirty minutes, and centrifuged to obtain the serum. Globulin and albumin to globulin ratio were calculated.

From all animals sacrificed as scheduled, the following organs were weighed to the nearest milligram: adrenals, brain, epididymides, heart, kidneys, liver, ovaries, prostate, spleen, testes, thymus, and uterus. Table 4 lists organs collected for study where (X) indicates organs collected from dose levels of 0, 125, and 500 mg/kg and (XX) indicates organs collected from dose levels of 0 and 500 mg/kg.

A urinalysis and sperm morphology analysis were also performed.
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Statistics:
Body weight, haematology and organ weight data were analyzed by parametric methods: analysis of variance (ANOVA) and associated F-test, followed by Student-Newman-Keuls Test, provided that there was statistical significance in ANOVA. Differences between control and treated animals were considered statistically significant only if the probability of the differences being due to chance was less than 5% (p<0.05).

Results and discussion

Results of examinations

Clinical signs:
effects observed, treatment-related
Dermal irritation:
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 examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
effects observed, treatment-related
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:
effects observed, treatment-related
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY: clinical signs, including pallor and decreased body temperature, indicative of system toxicity were observed in the 500 and 1250 mg/kg/day animals. At the 1250 mg/kg/day dose 10 of the female rats died during the study, one due to a laboratory accident, and 10 of the of the male rats died during the study. At the 500 mg/kg/day dose all of the males and three of the females died during the study. There were no mortalities in those animals applied with the remaining doses. Minimal skin irritation was observed.

BODY WEIGHT AND WEIGHT GAIN: Male rats exposed to 500 mg/kg/day or greater and female rats exposed to 30 mg/kg/day or greater gained significantly less weight than the controls.

HAEMATOLOGY: A significant decrease in red blood cell parameters (including red blood cell count, haemoglobin, and hematocrit) and platelet count was seen in males and females dosed at 125 mg/kg/day or greater. At week 13, white blood cell counts were significantly increased in females dosed at 30 and 125 mg/kg/day and were significantly decreased in the 200 mg/kg/day groups.

SERUM CHEMISTRY: A majority of serum chemistry parameters evaluated were adversely affected by exposure to the test material including, uric acid, glucose, urea nitrogen, asartate amino transferase, alanine amino transferase, alkaline phosphatase, creatinine, cholesterol, triglycerides, total protein, total bilirubin, albumin, inorganic phosphorus, sodium, potassium, chloride, and sorbitol dehydrogenase. Affects were seen as early as week five. A greater number of serum chemistry parameters were affected in male rats than in female rats.

URINALYSIS: no differences among the groups were evident for the parameters evaluated.

ORGAN WEIGHTS: A significant increase in absolute and/or relative liver weights and a significant decrease in absolute and/or relative thymus weights was seen in males and females dosed at as low as 30 mg/kg/day.

GROSS PATHOLOGY: red foci, areas of discolouration, streaks, scabs, sores, or raised areas were observed at necropsy in the treated skin of a few male and female rats dosed as low as 30 mg/kg/day. Focal areas of red discolouration and or generalized reddening were also observed in the brain, spinal cord, stomach, and testes of many of the rats dosed at 500 mg/kg/day. Both subcutaneous and internal lymph nodes had a wide-spread treatment-related incidence of gross reddening and enlargement. The thymus was small for most rats dosed at 125 mg/kg/day or greater. The epididymides, prostate, seminal vesicles and testes of most of the males dosed at 500 or 1250 mg/kg/day were also small.

HISTOPATHOLOGY: NON-NEOPLASTIC: treatment related and dose-related histopathologic changes were most prominent in the adrenals, bone marrow, kidneys, liver, lymph nodes, skin, stomach and thymus. Adrenals in males dosed at 30 mg/kg/day or greater showed a slight to moderate diffuse cortical vacuolation and at a lower incidence and lesser severity, cortical necrosis. Bone marrow had a slight to moderate fibrosis and decreased cellularity at 125 mg/kg/day or greater. Small focal haemorrhages were seen by microscopic examination in several organs including the brain, spinal cord, heart, lung, testes, and bone marrow. Kidneys showed a low incidence of minimal to slight epithelial necrosis in the cortical tubules in rats exposed to 500 or 1250 mg/kg/day. Liver showed slight to moderate cell hypertrophy and centrilobular necrosis at dose levels of 500 mg/kg/day and above. Microscopically, the thymus exhibited minimal to marked atrophy. Treated skin showed slight to moderate hyperplasia and hyperkeratosis of the epidermis, minimal to slight hyperplasia of sebaceous glands and minimal dermal infiltration by mononuclear inflammatory cells. The stomach showed congestion of the glandular mucosa and hyperplasia and hyperkeratosis of the squamous mucosa near the limiting ridge. This may suggest that some dermally treated rats ingests the test material.


OTHER FINDINGS

Effect levels

Dose descriptor:
NOAEL
Effect level:
< 30 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: Based on large reddened lymph nodes and adrenal effects (microscopic findings of slight to moderate cortical vacuolation with some cortical necrosis.

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
In a 90 day subchronic dermal study, the administration of Light paraffinic distillate solvent extract had an adverse effect on survivability, body weights, organ weights (particularly the liver and thymus), and variety of haematology and serum chemistry parameters in exposed animals. Histopathological changes which were treatment-related were most prominent in the adrenals, bone marrow, kidneys, liver, lymph nodes, skin, stomach, and thymus. Based on the results of this study, the NOAEL for the test material is less than 30 mg/kg/day.
Executive summary:

Read Across Justification

Read-across from DAE is based on the fact that DAEs are a by-product from the extraction of aromatic components from the vacuum distillates used to produce LBO. In that sense, they can represent a fraction derived from unrefined/poorly refined LBO that potentially has a higher content of polycyclic aromatic compounds (PACs) compared to the LBO. Since systemic effects are related to the level and profile of PACs, DAE might represent a worst-case example of effects from the poorly refined LBO.

In a 90 day subchronic dermal study, Light paraffinic distillate solvent extract was applied to the clipped backs of male and female Sprague-Dawley rats (10 animals/gender/group) for five days per wek for thirteen weeks at dose levels of 30, 125, 500, and 1250 mg/kg/day. A group of 10 males and 10 females served as controls. Each animal was observed once daily during the pre-treatment and dosing phases for normal or abnormal clinical signs. On weekdays, animals were checked for moribundity and mortality twice daily, at least six hours apart. On weekends and holidays, they were checked once, as soon as practical each day. The parameters used to assess toxic response included clinical observations, skin irritation, body weights, haematology, serum chemistry, urinalysis, organ weights, histopathology, and sperm morphology.

Clinical signs, including pallor and decreased body temperature, indicative of system toxicity were observed in the 500 and 1250 mg/kg/day animals. At the 1250 mg/kg/day dose 10 of the female rats died during the study, one due to a laboratory accident, and 10 of the of the male rats died during the study. At the 500 mg/kg/day dose all of the males and three of the females died during the study. There were no mortalities in those animals applied with the remaining doses. Minimal skin irritation was observed. the administration of Light paraffinic distillate solvent extract had an adverse effect on survivability, body weights, organ weights (particularly the liver and thymus), and variety of haematology and serum chemistry parameters in exposed animals. Histopathological changes which were treatment-related were most prominent in the adrenals, bone marrow, kidneys, liver, lymph nodes, skin, stomach, and thymus. Based on the results of this study, the NOAEL for the test material is less than 30 mg/kg/day.

This study received a Klimisch score of 1 and is classified as reliable without restriction because it was carried out in a manner similar to OECD Guideline 411.