Slack wax (petroleum), clay-treated

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

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

Adequacy of study:

key study

Study period:

1985-01-14 to 1985-02-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restrictions because the study was conducted according to or similar to guideline study OECD TG 410.

Justification for type of information:

Concawe believes that dermal is the most relevant exposure route, and is sufficiently robust, to identify any potential hazards from repeated exposures to petroleum products to be able to adequately manage the potentially associated risks. However, the primary objective of the testing required for REACH is the identification of hazard, for which the default exposure route under the regulation is oral as this is considered to maximise systemic exposure. To address the regulatory exposure route issue, Concawe will review the current data base for evidence of systemic toxicity after dermal exposure and will also conduct a number of oral OECD 422 studies on prioritized substances in each relevant petroleum category. The document attached provides a concise overview of the information to further support the dermal route of exposure and proposed additional work, as part of a larger testing strategy (the strategy document can be found in Annex 13).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1986

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

64741-50-0

Cas Number:

64741-50-0

IUPAC Name:

64741-50-0

Constituent 2

Reference substance name:

Unrefined light paraffinic distillate

IUPAC Name:

Unrefined light paraffinic distillate

Test material form:

other: oily liquid

Details on test material:

- Name of test material (as cited in study report): Light Paraffinic Distillate
- Test substance: Unrefined light paraffinic distillate
- Molecular weight (if other than submission substance): 296
- Physical state: Liquid (light amber)
- CAS number: 64741-50-0
- Viscosity, cSt: 2.67 at 100°C
- API Gravity: 31.5
- Flash Point: (°F) 372
- Sulfur, Wt %: 0.2
- Nitrogen ppm: 256
- Distillation ASTM D 86 equivalent (°F) range: 601-803 (10-95%)
- Initial Boiling Point (°F): 579
- Composition of test material, Wt. %:
Olefins: 39.7
Naphthenes 21.7
- PONA % by MS: 37

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazelton Dutchland, Inc., Denver, Pennsylvania
- Age at study initiation: Only specified as young adult
- Weight at study initiation: Males:2.1 kilograms to 3.3 kilograms; females: 2.3 kilograms to 3.2 kilograms
- Housing: Individually in stainless steel cages
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: At least 17 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 26
- Humidity (%): 18 to 40%
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light

IN-LIFE DATES: From: 1985-01-14 To:1985-02-15

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: Dorsal trunk area
- % coverage: 10%
- Type of wrap if used: Gauze followed by a sheet of polyurethane
- Time intervals for shavings or clippings: 24 hours before first application and as needed throughout the study

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Gently wiped with a dry, clean, absorbent gauze pad
- Time after start of exposure: 6 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): Amount varied depending on weight
- Constant volume or concentration used: No

USE OF RESTRAINERS FOR PREVENTING INGESTION: No

Details on analytical verification of doses or concentrations:

Not applicable

Duration of treatment / exposure:

6 hours each day

Frequency of treatment:

3 times each week for a total of 12 applications

Doses / concentrations

Remarks:

Doses / Concentrations:
200, 1000 and 2000 mg/kg
Basis:
nominal per unit body weight

No. of animals per sex per dose:

Five animals per sex per dose; however, one of the animals in the 1000 mg/kg group was mis-sexed so there were 4 males and 6 females in this group.

Control animals:

yes

Details on study design:

- Dose selection rationale: A preliminary dose-range study was conducted
- Rationale for animal assignment (if not random): Not reported

Positive control:

Not applicable

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily
- Cage side observations checked included mortality, morbidity, and overt signs of toxicity.

DETAILED CLINICAL OBSERVATIONS: No data

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

BODY WEIGHT: Yes
- Time schedule for examinations: At study initiation and weekly throughout the study period

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

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At study termination
- Anaesthetic used for blood collection: No
- Animals fasted: No data
- How many animals: All animals
- Parameters checked in table 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At study termination
- Animals fasted: No data
- How many animals: All animals
- Parameters checked in table 2 were examined.

URINALYSIS: No, but samples were collected from the control and high-dose group for possible evaluation
- Time schedule for collection of urine: At study termination
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, specified as a complete necropsy
HISTOPATHOLOGY: Yes (see table 3)

Other examinations:

Heart, liver, kidneys, adrenals, thyroid with parathyroid, pituitary, testes, ovaries and brain were weighed.

Statistics:

Two-tailed Student's t-test with p<0.05

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

effects observed, treatment-related

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

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:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY: There were no treatment-related effects of clinical signs or mortality.


BODY WEIGHT AND WEIGHT GAIN: High-dose males and females had lower body weight and body weight gains compared to the control.


HAEMATOLOGY: There were no treatment-related effects on haematology.


CLINICAL CHEMISTRY: There were no treatment-related effects on clinical chemistry.



ORGAN WEIGHTS: Although there were several significant changes in the organ weights of high-dose animals, the changes are secondary to the reduced body weight in this group and not directly related to treatment.


GROSS PATHOLOGY: The only gross findings related to treatment were changes in the treated skin and included dry, scaly, rough, and/or reddened skin and thickened epidermis in all treatment groups.


HISTOPATHOLOGY: NON-NEOPLASTIC: Slight to moderate proliferative changes of the skin occurred in all high-dose animals.


HISTOPATHOLOGY: NEOPLASTIC: There were no noted neoplastic changes.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: body weight

2

Dose descriptor:

LOAEL

Effect level:

200 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: dermal irritation

3

Dose descriptor:

LOAEL

Effect level:

ca. 12.5 mg/cm² per day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Mild dermal irritation

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Three animals died during the study but these were not dose-related and were, therefore, considered unrelated to treatment. Sporadic clinical signs were also unrelated to treatment. In the high dose group, body weight gains were affected by treatment. In the females, there was a group net loss in weight whereas in the males the gains were significantly less than controls. These effects were largely due to effects on growth rate during the first week of the study. A mean irritation index was calculated for each group each day and also for each treatment group overall. The value was determined from Draize scores for erythema and oedema for each animal. The mean irritation scores for each group were:   

Group	Irritation score
Control (male)	0
Control (female)	0
200 mg/kg (male)	0.5
200 mg/kg (female)	0.4
1000 mg/kg (male)	1.7
1000 mg/kg (female)	2.0
2000 mg/kg (male)	3.1
2000 mg/kg (female)	3.2

There were no statistical differences between treated and control groups for any of the haematological determinations. The clinical chemical data for the treated and control males was similar. In the females, there was a reduced BUN and an increased SGPT for the low-dose females. Since no other differences were noted and that values were within normal limits the effects were not considered to be toxicologically significant. The following absolute and relative organ weight differences (compared to controls) were recorded.

	Males	Females
2000 mg/kg
Relative liver wt.	Increased	Increased
Relative kidney wt.	Increased	Increased
Relative pituitary wt	Increased
Relative left testis	Decreased
Relative brain wt		Increased
1000 mg/kg
Abs. Rt. kidney wt	Decreased
Abs. Heart wt		Decreased

None of the organ weight differences were considered treatment-related. The higher than control relative organ weights were considered as a function of the reduced body weights in the affected animals.

The only findings at gross necropsy were confined to the treated skin. These consisted of dry, scaly, rough, and/or reddened skin and thickened dermis. These findings were noted throughout the treatment groups. There were no treatment-related gross necropsy findings in the internal organs.

Microscopic pathology findings were also largely confined to the skin. Slight to moderate proliferative changes of the skin were present in all of the male and female rabbits in the highest dose group.

The testes of one of the five males in the high dose group had bilateral diffuse tubular hypoplasia accompanied by aspermatogenesis and hypoplasia of the epididymis. These changes were considered to represent immature testes. Similar changes were not seen in the other animals in this dose group.

 

Applicant's summary and conclusion

Conclusions:

The systemic LOAEL for this study is 2000 mg/kg/day, based on the reduced body weights and the systemic NOAEL in this study is 1000 mg/kg/day. The dermal LOAEL is 200 mg/kg/day and the dermal NOAEL is <200 mg/kg/day, based on the irritation at the treatment site.

Executive summary:

Read across justification

No dermal repeat dose toxicity studies have been reported for slack waxes (carcinogenic or unknown feed-stock), but a study has been reported for unrefined / acid treated lubricant base oils, materials similar to the oil entrained in slack waxes (carcinogenic or unknown feed-stock).

A 28-day dermal repeated-dose study was conducted in New Zealand white rabbits with API 84-01, an unrefined light paraffinic distillate (CAS No. 64741-50-0).  In this study, the undiluted test material was applied at doses of 200, 1000 and 2000 mg/kg, once a day, three times a week for 4 weeks to the shorn dorsal skin of groups of five male and five female rabbits. The applied material was covered with an occlusive dressing for 6 hours and was then removed. At that time, the skin was wiped with dry gauze to remove any residual material. A group of five rabbits of each sex served as sham controls. The test skin site of each animal was examined and scored for irritation prior to each application of test material. Mortality and morbidity checks were performed twice daily, and body weights were recorded weekly.  At termination, blood samples were taken for a range of haematological and clinical chemical measurements. Urine samples were also collected and frozen for possible future examination.  A complete gross necropsy was performed on all animals. Major organs were weighed, and tissues were processed for subsequent histopathological examination.

Treatment-related findings included erythema and oedema in the 1000 and 2000 mg/kg groups with increasing frequency and severity with increasing dose,i.e.,the 2000 mg/kg group displayed moderate irritation and proliferative changes in the skin. Only minimal irritation was observed in the 200 mg/kg dose group. Bodyweight losses were observed in 1 male and 3 females at 2000 mg/kg, and the group mean bodyweights were significantly less than the controls. There was no other evidence of systemic toxicity.  No treatment-related trends were evident based on the haematology, clinical chemistry or organ weight data. The deaths of a low dose female, a high dose male and a sham-treated control male were not considered to be treatment-related.  The systemic NOAEL in this study was 1000 mg/kg/day. The dermal NOAEL was <200 mg/kg/day based on the irritation at the treatment site.

This study received a Klimisch score of 1 and is classified as reliable without restrictions because it was conducted according to or similar to guideline study OECD TG 410.