Asphalt

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982-09-20 to 1982-10-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is classified as reliable without restrictions because it was an acceptable study that was well documented

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:

1983

Report date:

1983

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

Test compound was only applied three times a week instead of daily.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

64741-56-6

Cas Number:

64741-56-6

IUPAC Name:

64741-56-6

Constituent 2

Reference substance name:

Vacuum residue

IUPAC Name:

Vacuum residue

Test material form:

other: semi-solid

Details on test material:

- Name of test material (as cited in study report): Vacuum residuum (CAS number 64741-56-6)
- Substance type: Bitumen
- Physical state: semi-solid
- Composition of test material, percentage of components: Sample API 81-13: 4.46% sulphur, 0.51% nitrogen, 90+% carbon; 18 ppm nickel, <1 ppm copper, 33 ppm iron, 39 ppm vanadium; 6.5% asphaltenes.
- Lot/batch No.: API 81-13
- Expiration date of the lot/batch: not reported
- Stability under test conditions: not reported
- Storage condition of test material: Stored at room temperature in original containers
- Other:Sample 81-13 was selected because of its high sulphur and asphaltene contents
- Gravity API: 6.6
- Initial boiling point 650 °F (ASTM D-1160)

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Davidson's Mill Farm, Jamesburg, New Jersey
- Age at study initiation: Young adult
- Weight at study initiation: not reported
- Housing: Individually in stainless steel cages with grid bottoms
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum):Ad libitum
- Acclimation period: 15 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 26
- Humidity (%): 34% to 82%
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12 hours dark/12 hours light


IN-LIFE DATES: From:1982-09-20 To:1982-10-22

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: back
- % coverage: Not reported, but a 4 x 4 inch area was covered
- Type of wrap if used: Polyethelene sheet
- Time intervals for shavings or clipplings: As needed


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

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 200, 1000, or 2000 mg/kg was weighed onto the gauze pad
For solids, paste formed: No, sample is already the consistency of paste.


USE OF RESTRAINERS FOR PREVENTING INGESTION: No

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

Not applicable

Duration of treatment / exposure:

28 days

Frequency of treatment:

Three times a week for 6 hours each time

Doses / concentrations

Remarks:

Doses / Concentrations:
200, 1000, or 2000 mg/kg/day
Basis:
other: amount applied

No. of animals per sex per dose:

Five animals per sex per dose per sample

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Not reported, but a dose-range study was mentioned
- Rationale for animal assignment (if not random): Random

Positive control:

None reported

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice a day
- Cage side observations included mortality and toxic and pharmacologic signs.


DETAILED CLINICAL OBSERVATIONS: No


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


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


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
- How many animals: All animals
- Parameters checked in table 2 were examined.


URINALYSIS: No, but urine was collected for possible analysis
- 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
HISTOPATHOLOGY: Yes (see table 3), but was conducted in control and high-dose group only.

Other examinations:

Organs weighed were also provided in table 3.

Statistics:

Where appropriate a two-tailed Student's t-test was used.

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):

effects observed, treatment-related

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
Vacuum residuum sample 81-13: one male from the high-dose group and one female from the control group died on days 9 and 3, respectively. These deaths had no antemortem signs and hence were considered non-treatment related. One male from the control group and one female from the intermediate-dose group were found moribund and sacrificed on days 6 and 10, respectively. Both animals showed paralysis of the hind limbs the day prior to the sacrifice. These deaths were also not considered treatment-related, but rather as the result of trauma during dosing and wrapping. Treatment-related findings were decreased food-intake (qualitative observation), flaking skin and wheezing. Treatment related effects were observed in the skin: most males and females from the high-dose group showed very slight to slight oedema after the first treatment and it was a consistent finding in all animals as of day 16 until the last day (day 28). In the intermediate-dose groups some animals showed slight oedema until day 10; as of day 11 almost all animals showed very slight to slight oedema until the end of the study. In the low-dose group, most males showed oedema in the last two weeks and most females in the last week of treatment.


BODY WEIGHT AND WEIGHT GAIN
Sample 81-13: The decrease in body weight gain was statistically significant in the high-dose males (0.1 kg) as compared to the control group (0.6 kg).

HAEMATOLOGY
There were no treatment-related changes in haematology.

CLINICAL CHEMISTRY
There were no treatment-related changes in clinical chemistry

ORGAN WEIGHTS
There were no treatment-related changes in organ weights.=

GROSS PATHOLOGY
Gross findings were confined to the skin and included redened and thickened skin in a few animals.

HISTOPATHOLOGY:
Histopathology confirmed the gross pathology findings in the skin.

Effect levels

1

Dose descriptor:

LOAEL

Remarks:

Topical effects

Effect level:

200 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Based on absence of significant histopathological findings. No treatment-related effects on reproductive organs were noted.

2

Dose descriptor:

NOAEL

Remarks:

systemic effects

Effect level:

>= 2 000 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: Based on body weight data in the absence of significant histopathological findings. No treatment-related effects on reproductive organs were noted.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The LOEL - Local effects for vacuum residuum was 200 mg/kg/day, based on mild skin irritation and on the absence of histopathological findings. The value of 200 mg/kg/d was taken forward to calculate the DNEL for dermal local effects. The NOEL for systemic effects was >1000 mg/kg, based on body weight effects. As there were no clinical or histopathological findings, the decreased body weight was considered to be secondary to the reduced food intake and the value of 2000 mg/kg/d was taken forward to calculate the DNEL for dermal systemic effects.

Executive summary:

The petroleum vacuum residue 81 -13 was tested in a 28-day dermal toxicity study in NZW rabbits. Four groups of 5 male and 5 female rabbits were exposed to sample 81 -13 of vacuum residue once per day, three days/week for 4 weeks (12 applications in total). Doses applied were 0 (sham-exposed), 200, 1000 or 2000 mg/kg body weight. The neat material was slightly heated just prior to application to decrease its viscosity, put on a 4 x 4 inch patch and subsequently applied to shaven dorsal skin and occluded. After 6 hours the patch was removed and any remaining test material was wiped off using gauze; however, the test material was not completely removed. Body weight was recorded prior to the first application and from then on weekly. Each day the application area on the skin was examined and scored for erythema and oedema (Draize scores). Scoring for erythema proved difficult due to residual material on the skin that prevented observance of the colour of the skin. At the end of the study, all animals were sacrificed for clinical chemistry, haematology and histopathology investigations.

With vacuum residue sample 81-13, one male from the high-dose group and one female from the control group died on days 9 and 3, respectively. These early decedents had no antemortem signs and hence these deaths were not considered treatment related. One male from the control group and one female from the intermediate-dose group were found moribund and sacrificed on days 6 and 10, respectively. Both animals showed paralysis of the hind limbs the day prior to the sacrifice. These deaths were also not considered treatment-related, but rather as the result of trauma during dosing and wrapping. Treatment-related findings were flaking skin, wheezing and a decreased food-intake (qualitative observation) resulting in less body weight gain in the exposed groups compared to controls. The lesser body weight gain was statistically significant in the high-dose males as compared to the control group. No treatment-related trends were observed in either clinical chemistry or haematology investigations. No treatment-related effect on reproductive organs were noted. Treatment related effects were observed in the skin of most high-dose males and females with very slight to slight oedema observed after the first treatment and consistent in all animals as of day 16 until the last day (day 28). In the intermediate-dose groups (1000 mg/kg) some animals showed slight oedema until day 10; as of day 11 almost all animals showed very slight to slight oedema until the end of the study. In the low-dose group (200 mg/kg) most males showed oedema in the last two weeks and most females in the last week of treatment. Gross pathology findings of reddened or thickened skin, were consistent with the microscopic observations of skin effects: minimal to moderate subacute acanthotic dermatitis and minimal to moderate hyperkeratosis.

The LOEL for vacuum residuum was 200 mg/kg/day, based on mild skin irritation and the absence of histopathological findings and the value of 200 mg/kg/d was taken forward to calculate the DNEL for dermal local effects. The NOEL for systemic effects was 1000 mg/kg, based on body weight effects. As there were no clinical or histopathological findings, the decreased body weight was considered to be secondary to the reduced food intake and the value of >2000 mg/kg/d was taken forward to calculate the DNEL for dermal systemic effects.

This study received a Klimisch score of one and is classified as reliable without restrictions because it was an acceptable study that was well documented.