Gas oils (petroleum), straight-run, high-boiling

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:

1984-09-24 to 1984-10-26

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

This study is classified as reliable with restrictions because even though it was GLP compliant and generally followed OECD 410 guidelines, the study did not perform histopathology on the low- or mid-dose groups to determine the toxicological significance of the increased granulopoiesis of bone marrow.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1985

Report date:

1985

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:

Compound was only administered 3 days a week instead of the recommended 5 or 7 days a week.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Straight run middle distillate (CAS number 64741-44-2)

IUPAC Name:

Straight run middle distillate (CAS number 64741-44-2)

Details on test material:

- Name of test material (as cited in study report): Straight run middle distillate (API 83-11)
- Substance type: Straight run gas oil primarily C11 to C20 hydrocarbons
- Physical state: Liquid
- Analytical purity: Not reported
- Composition of test material, percentage of components: 77% saturates, 21% aromatics, 2% paraffins, 80 parts per million nitrogen, and 0.30% sulphur
- Lot/batch No.: API 83-11
- Stability under test conditions: Not reported
- Storage condition of test material: Refrigerated in original container

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazleton Dutchland, Denver, Pennsylvania
- Age at study initiation: Young adult
- Weight at study initiation: Males: 2.7 kilograms to 3.1 kilograms; females: 2.6 kilograms to 3.1 kilograms
- Housing: Individually in stainless steel cages
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 26
- Humidity (%): 51% to 79%
- Air changes (per hr): 10 to 15
- Photoperiod (hrs dark / hrs light): 12 hours datk/12 hours light

IN-LIFE DATES: From: 1984-09-24 To: 1984-10-26

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: Sheet of polyethylene
- Time intervals for shavings or clippings: As necessary

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

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

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:

4 weeks

Frequency of treatment:

Three times a week

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 200, 1000, or 2000 mg/kg/day
Basis:
nominal per unit body weight

No. of animals per sex per dose:

Five

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Based on a pilot 5-day study

Positive control:

Not applicable

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice a day
- Cage side observations included checks for mortality and morbidity.

DETAILED CLINICAL OBSERVATIONS: No data

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

BODY WEIGHT: Yes
- Time schedule for examinations: Study initiation, weekly, and at study termination

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

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 urine was collected pretest and at study termination for possible analysis

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes (see table 3), in control and high-dose animals

Other examinations:

The following organs were weighed: heart, liver, spleen, kidneys, adrenals, thyroid with parathyroid, testes, ovaries, and brain.

Statistics:

Two-tailed Student's t-test

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:

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: One low dose male rabbit died on day 12 (death considered incidental). The only reported clinical signs were soiling of the anal area and soft faeces in one low-dose male (days 22 and 23) and thin appearance for one high-dose female (days 12, 13, and 18-20). Dose-dependent skin irritation developed gradually over the course of the study, with mean irritation scores (Draize scale) of 0.55, 2.2 and 2.95 for the combined low-, mid- and high-dose groups at study termination. Treatment related skin changes were present in all treated rabbits and included erythema and oedema as well as cracked, flaky, and/or leathery appearance of skin at the test site.


BODY WEIGHT AND WEIGHT GAIN: Animals from the high- dose group failed to gain weight during the study, whereas, mean body weight gains for the low- and mid-dose animals of both sexes were comparable to the controls.


HAEMATOLOGY: Haematological parameters were relatively unaffected by treatment and limited to a statistically significant increase in haemoglobin concentration in the 1000 mg/kg body weight/day males only. In the absence of comparable effects in females or in high-dose males, these findings are not regarded as treatment-related.


CLINICAL CHEMISTRY: An isolated (10%) increase in blood urea nitrogen in the high-dose male group was considered a chance event (all other clinical chemical parameters were comparable to control values).


ORGAN WEIGHTS: Absolute and relative right kidney weight, and the relative left kidney weight, were decreased (approx 20%) in high-dose males, but in the absence of supporting changes in clinical chemistry or microscopic pathology, these findings are judged not to be treatment related. Other minor organ weight differences were not dose-related and, in the absence of any other related changes, were not attributable to the test substance.


GROSS PATHOLOGY: Treatment related pathological findings in moribund- and terminally sacrificed animals were confined to the treatment site and consisted of dry, scaly, fissured, crusted, and/or thickened skin.


HISTOPATHOLOGY: Microscopically, slight to moderate proliferative changes were present in treated skin from all high-dose rabbits, with minimal inflammatory changes also present. These were accompanied in four high-dose males and five high-dose females by increased granulopoiesis of the bone marrow (lower dose groups not examined). This is in contrast to the controls in which there were no findings. There were no changes in any other tissues.

Effect levels

1

Dose descriptor:

LOEL

Effect level:

200 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: dermal irritation

2

Dose descriptor:

NOAEL

Remarks:

Systemic effects

Effect level:

>= 2 000 mg/kg bw/day

Sex:

male/female

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Based on these findings, the skin was the primary site of toxicity for straight run middle distillate with dose-dependent increases in irritation and inflammation apparent both macroscopically and microscopically. Local irritation was minimal in animals treated with 200 mg/kg body weight/day. Increased granulopoiesis of bone marrow was present in high-dose animals, and was apparently considered by the study authors to be linked to skin damage at the treatment site; however, since lower dose groups were not examined no NOAEL can be established for this finding. Therefore, a LOAEL of 200 mg/kg/day is established based on local irritation. This LOAEL is conservative because occlusion would have enhanced skin irritation and penetration. No NOAEL was determined for local irritation. However, there were no systemic findings that were considered treatment related. Accordingly, the systemic NOAEL is greater than or equal to 2000 mg/kg/day.

Executive summary:

In a 28-day dermal toxicity study, straight run middle distillate (API 83 -11) was applied to rabbit (5 per sex per dose) skin at doses of 200, 1000 or 2000 mg/kg/day, three times/week for a total of 12 applications (API, 1985). The sample was applied under occlusion for 24 hours to clipped backs. Each animal was observed twice daily during the treatment period for clinical signs of toxicity. An assessment of dermal reaction to the test material was made daily and body weights were recorded weekly. At the end of the 28-day treatment period all surviving animals were sacrificed and a gross necropsy was performed. Blood samples were collected and analysed for a range of clinical chemistry and haematological parameters. Major organs were weighed, and a range of tissues from control and high-dose animals subjected to microscopic examination.

 

One low dose male rabbit died on day 12 (death considered incidental). The only reported clinical signs were soiling of the anal area and soft faeces in one low-dose male (days 22 and 23) and thin appearance for one high-dose female (days 12, 13, and 18-20). Animals from the high- dose group failed to gain weight during the study, whereas, mean body weight gains for the low- and mid-dose animals of both sexes were comparable to the controls.

 

Dose-dependent skin irritation developed gradually over the course of the study, with mean irritation scores (Draize scale) of 0.55, 2.2 and 2.95 for the combined low-, mid- and high-dose groups at study termination. Treatment related skin changes were present in all treated rabbits and included erythema and oedema as well as cracked, flaky, and/or leathery appearance of skin at the test site. Haematological parameters were relatively unaffected by treatment and limited to a statistically significant increase in haemoglobin concentration in the 1000 mg/kg body weight/day males only. In the absence of comparable effects in females or in high-dose males, these findings are not regarded as treatment-related. Similarly, an isolated (10%) increase in blood urea nitrogen in the high-dose male group was considered a chance event (all other clinical chemical parameters were comparable to control values). Absolute and relative right kidney weights, and the relative left kidney weight, were decreased (approx 20%) in high-dose males, but in the absence of supporting changes in clinical chemistry or microscopic pathology, these findings are judged not to be treatment related. Other minor organ weight differences were not dose-related and, in the absence of any other related changes, were not attributable to the test substance.

 

Treatment related macroscopic findings in moribund- and terminally sacrificed animals were confined to the treatment site and consisted of dry, scaly, fissured, crusted, and/or thickened skin. Microscopically, slight to moderate proliferative changes were present in treated skin from all high-dose rabbits, with minimal inflammatory changes also present. These were accompanied in four high-dose males and five high-dose females by increased granulopoiesis of the bone marrow (lower dose groups not examined). This is in contrast to the controls in which there were no findings. There were no changes in any other tissues.

No treatment-related effects were noted in examination of the weights of ovaries and testes, nor in the histopathology of ovaries and testes at 2000 mg/kg.

 

Based on these findings, the skin was the primary site of effects for straight run middle distillate with dose-dependent increases in irritation and inflammation apparent both macroscopically and microscopically. Local irritation was minimal in animals treated with 200 mg/kg body weight/day. Increased granulopoiesis of bone marrow was present in high-dose animals, and was apparently considered by the study authors to be linked to skin damage at the treatment site; however, since lower dose groups were not examined no NOAEL can be established for this finding. Therefore, a LOAEL of 200 mg/kg/day is established based on local irritation. However, there were no systemic findings that were considered treatment related.  Accordingly, the systemic NOAEL is greater than or equal to the high dose (2000 mg/kg/day).

This study received a Klimisch score of 2 and is classified as reliable with restrictions because even though it was GLP compliant and generally followed OECD 410 guidelines, the study did not perform histopathology on the low- or mid-dose groups to determine the toxicological significance of the increased granulopoiesis of bone marrow.