Foots oil (petroleum), clay-treated

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics in vivo

Type of information:

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

Adequacy of study:

key study

Study period:

Not reported

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable with restrictions because it an acceptable well-documented study report that followed sound scientific principles.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Materials and methods

Objective of study:

metabolism

Principles of method if other than guideline:

The method did not strictly follow the guideline but is deemed appropriate as utilized in this report.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Oleum-treated white oil, Hydrotreated white oil

IUPAC Name:

Oleum-treated white oil, Hydrotreated white oil

Details on test material:

Read Across to Highly Refined Base Oil (White Oil)
- Name of test material (as cited in study report): mineral hydrocarbons; oleum-treated white oil and hydrotreated white oil
- Substance type: Highly Refined Mineral hydrocarbons (white oils)
- C16 and C18 hydrocarbons
- Physical state: liquid

OTWO
-Specific gravity: 0.874 at 15°C
-Viscosity: 26 mm2/sec at 40°C

HTWO
-Specific gravity: 0.878 at 15°C
-Viscosity: 69 mm2/sec at 40°C

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Age at study initiation: six to eight weeks
- Housing: individually caged
- Diet (e.g. ad libitum): laboratory rat diet LAD2 (special diet services, Witham, Essex) was offered ad libitum
- Water (e.g. ad libitum): offered ad libitum

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: "DISTOL"-grade hexane

Details on exposure:

The test oils were separately incorporated into powdered laboratory rat diet, LAD2 at concentrations ranging from 10 to 20,000 ppm. Each oil was first dissolved in solvent ("DISTOL"-grade hexane) and a premix was used to achieve homogeneous dispersal in each batch of final test diet. An equivalent volume of solvent was also mixed with control diet.

Duration and frequency of treatment / exposure:

Animals were fed diet with test material for 13 weeks. Mean daily intake of food was calculated.

Doses / concentrations

Remarks:

Doses / Concentrations:
Experiment 1, Oleum-treated white oil (OTWO): 5000, 10000, 20000 ppm
Experiment 2, OTWO: 10, 100, 500, 1000, 10000, 20000 ppm
Experiment 1, Hydrotreated white oil (HTWO): 5000, 10000, 20000 ppm
Experiment 2, HTWO: 10, 100, 500, 5000, 10000, 20000 ppm

No. of animals per sex per dose / concentration:

Experiment 1 (OTWO and HTWO): three males and three females
Experiment 2 (OTWO and HTWO): six females

Control animals:

no

Details on dosing and sampling:

METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled : cardiac blood was collected at terminal necropsy and tail vein blood was taken 7 days prior to necropsy. Haematological variants were monitored and analyzed by autoanalyzer

Statistics:

Statistical analysis of data was accomplished by analysis of variance with a modified Student's t-test procedure for food intake, clinical chemistry, and haematological variants. The Wilcoxon two-sample rank sum test and Fisher's exact test were also used.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on distribution in tissues:

There were no mortalities and no adverse clinical signs associated with feeding either white oil. Treatment-related effects evidenced by haematological, clinical chemical, and pathological changes were generally dose-related and more marked in female than in male rats, and the OTWO caused a greater pathological response than the HTWO. Tissue residues of saturated hydrocarbons were up to 5.2 times higher in female rats than in males. Rats fed 5,000 ppm or more of either white oil showed dose-related alterations in several haematological and clinical chemistry variates associated mainly with hepatic damage or functional alteration. At necropsy, mesenteric lymph nodes were enlarged, and increases in weight of liver, kidney, and spleen were significant. Microscopic changes were characterized by multifocal lipogranulomata in mesenteric lymph node and liver. No changes were observed in rats fed OTWO or HTWO for 90 days at dietary concentrations of 10 or 100 ppm, equivalent to a minimum intake of 0.65 and 6.4 mg/kg/day, respectively. Differences in degree of pathological response associated with each oil may have been due to their differences in specification rather than processing method.

Any other information on results incl. tables

C16 and C18 hydrocarbons that are constituents of lubricant base oils are metabolised to corresponding fatty acids of the same carbon chain length as the parent hydrocarbons, suggesting a process of omega oxidation.

There were no deaths or any clinical signs caused by feeding either OTWO or HTWO at dietary concentrations up to the maximum of 20000 ppm. The only effect noted was a mild increase in food intake of males fed 20000 ppm OTWO during weeks 3 through 6 of the study. The only haematological changes attributes to treatment were slight leukocytosis and granulocytosis in rats of both sexes fed 20000 ppm of either white oil, with slight hypochromic microcytic anaemia in the 20000 ppm OTWO-fed females. Clinical chemistry findings in rats fed 5,000 ppm or more of either white oil indicated slight hepatic damage and functional disturbance. At necropsy, treatment-related organ weight changes occurred in mesenteric lymph node, spleen, liver, and kidney. Analysis of liver and mesenteric lymph node for total hydrocarbon residues showed higher tissue concentrations in females than in males. In both liver and mesenteric lymph node of treated rats, total hydrocarbon concentrations were greater in OTWO-fed rats than in HTWO-fed rats. There were no treatment-related histological changes in mesenteric lymph node or liver of rats fed 500 or 10,000 ppm of either white oil for 25 days. After 90 days lesions were found in mesenteric lymph node, liver, and spleen. Across all analyses (haematology, clinical chemistry, gross necropsy, tissue residue, and histopathology) findings were more marked in in female rats and male or female rats fed OTWO

Applicant's summary and conclusion

Conclusions:

In conclusion, the pathological findings in the test animals were quantitatively similar to those previously associated with the ingestion of mineral hydrocarbons by a range of species, but the effects occurred at much lower levels of dietary intake than previously reported. No pathological changes were observed after 25 days of feeding, but after 90 days there were very slight to moderate multifocal granulomatous changes in mesenteric lymph nodes and liver. Although rats fed the OTWO were more affected than those fed the HTWO differences in the specification of each oil rather than processing method were more likely to have accounted for the variation. The insufficiently refined hydrocarbons (oleum-treated white oil) are suggested to undergo a process of omega oxidation. The sufficiently refined hydrocarbons (hydrotreated white oil) are metabolized to the corresponding fatty acids of the same carbon chain length as the parent carbons, suggesting omega oxidation.

Executive summary:

Read across justification

The physical and chemical properties of foots oils are comparable to the other lubricant base oil intermediate streams from which they are derived. Hence their health effects are also similar to those of other lubricant base oils, and the conclusions of the hazard assessment for lubricant base oils also apply to foots oils. In this study, highly refined base oils (white oils) were tested but being similar in composition to other lubricant base oils, similar toxicokinetic properties would also be expected.

In a basic toxicokinetics study, a group of male and female rats were fed oleum-treated white oil (OTWO) and hydrotreated white oil (HTWO) in concentrations of 5000, 10000, 20000 ppm and a group of female rats were fed OTWO and HTWO in concentrations of 10, 100, 500, 1000, 10000, 20000 ppm for a period of 13 weeks. Animals were euthanized at the conclusions of the study, after which haematological, clinical chemistry, gross necropsy, tissue residue, and histopathological examination were preformed.

Pathological findings in the test animals were quantitatively similar to those previously associated with the ingestion of mineral hydrocarbons by a range of species, but the effects occurred at much lower levels of dietary intake than previously reported. No pathological changes were observed after 25 days of feeding, but after 90 days there were very slight to moderate multifocal granulomatous changes in mesenteric lymph nodes and liver. Although rats fed the OTWO were more affected than those fed the HTWO differences in the specification of each oil rather than processing method were more likely to have accounted for the variation. The insufficiently refined hydrocarbons (oleum-treated white oil) are suggested to undergo a process of omega oxidation. The sufficiently refined hydrocarbons (hydrotreated white oil) are metabolized to the corresponding fatty acids of the same carbon chain length as the parent carbons, suggesting omega oxidation.

This study received a Klimisch score of 2 and is classified as reliable with restrictions.