Extracts (petroleum), solvent-refined heavy paraffinic distillate solvent

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

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

Adequacy of study:

key study

Study period:

No data reported.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it was carried out according to OECD Test Guideline 471.

Justification for type of information:

The standard OECD 471 test is not suitable to test petroleum UVCBs, because it has a tendency to produce false negatives for these substances. Therefore, the petroleum industry has developed a Modified Ames assay, optimized to accurately identify positive results for this endpoint. This deviation from the prescribed testing procedure requires some further explanation which is given in the attached document. The document gives a brief history of the development of the Modified Ames test and outlines Concawe’s proposed work (as part of a wider testing strategy, see Annex 13) to further support the use of this test for PS.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1986

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Principles of method if other than guideline:

Modified Ames (1975) procedure to include preliminary solubilisation of the oil in cyclohexane followed by single extraction of dimethylsulphoxide. Additionally, S9 fraction from hamster liver was used instead of rat S9, and the concentration of NADP was increased from 4 to 8 millimolar.

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

64742-54-7; 64742-52-5

IUPAC Name:

64742-54-7; 64742-52-5

Constituent 2

Reference substance name:

Solvent-refined hydrotreated paraffinic distillate, Solvent-refined hydrotreated heavy naphthenic distillate, sufficiently refined, IP346<3%

IUPAC Name:

Solvent-refined hydrotreated paraffinic distillate, Solvent-refined hydrotreated heavy naphthenic distillate, sufficiently refined, IP346<3%

Test material form:

other: Oily liquid

Details on test material:

This substance is most similar where treatment was sufficient to reduce the 3-7 ring PACs (<3 wt% DMSO extractables as measured by IP-346).

Twenty two different oil samples were tested, but the two sufficiently refined lubricant base oils tested were:
Solvent-refined hydrotreated heavy paraffinic distillate (CAS # 64741-88-4/64742-54-7), referred to as Sample 18 in study report
Solvent-refined hydrotreated heavy naphthenic distillate (CAS # 64741-96-4/64742-52-5), referred to as Sample 20 in study report

The boiling ranges for both samples were between 700 and 900 degrees Fahrenheit.

Two millilitres of oil was dissolved in three millilitres of cyclohexane, mixed to homogeneity, and extracted with ten millilitres DMSO. The suspension was mixed every five minutes for thirty minutes. The lower DMSO layer was harvested and assayed.

Method

Target gene:

No data reported.

Species / strain

Species / strain / cell type:

S. typhimurium TA 98

Details on mammalian cell type (if applicable):

Not applicable

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with

Metabolic activation system:

Aroclor 1254-induced hamster liver S9

Test concentrations with justification for top dose:

ranges from 1 to 50 microlitres

Vehicle / solvent:

dimethyl sulphoxide

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

yes

Positive control substance:

not specified

Details on test system and experimental conditions:

Modified Ames (1975) procedure to include preliminary solubilisation of the oil in cyclohexane followed by single extraction of dimethylsulphoxide. Additionally, S9 fraction from hamster liver was used instead of rat S9, and the concentration of NADP was increased from 4 to 8 millimolar.

The extracted oil, tester bacteria (TA98), and metabolic activation system (hamster S9) or no S9 were combined in suspension, incubated for 20 minutes at 37°C were poured into a petri dish, incubated for 48 hours overnight at 37°C, and subsequently counted for revertant colonies.

Evaluation criteria:

No data reported.

Statistics:

No data reported.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

other:

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 2

Species / strain:

S. typhimurium TA 1535

Remarks:

not applicable, modified Ames protocol

Test results 3

Species / strain:

S. typhimurium TA 1537

Remarks:

not applicable, modified Ames protocol

Test results 4

Species / strain:

S. typhimurium TA 100

Remarks:

not applicable, modified Ames protocol

Test results 5

Species / strain:

S. typhimurium TA 102

Remarks:

not applicable, modified Ames protocol

Additional information on results:

No data reported.

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

The mutagenicity indices of both test substances were 0.0.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

The mutagenicity indices for both test substances were 0.0 and therefore not mutagenic.

Executive summary:

Justification for Read Across

Treated distillate aromatic extracts (TDAEs) are a further processing of untreated distillate aromatic extracts (UDAEs) in an attempt to reduce the amount of 3-7 ring PAC that is present. Since the treatment is mostly a selective reduction of PACs, the data from UDAEs can serve as read across where treatment was insufficient and a significant amount of PACs still remain (≥ 3 wt% DMSO extractables as measured by IP-346). Where treatment was sufficient to reduce the 3-7 ring PACs (<3 wt% DMSO extractables as measured by IP-346), the material is most similar to a lubricating base oil and it is this data that should be used for read across. 

In a modified Ames assay, S. typhimurium strain TA 98 was exposed to various petroleum products, of which two were sufficiently refined (proven non-carcinogenic) lubricating base oils, at concentrations ranging from 1 to 50 microlitres with metabolic activation by Aroclor 1254-induced hamster liver S9. The mutagenicity indices for the two test substances were 0.0 with metabolic activation indicating that the materials were non-mutagenic under the assay conditions.

This study received a Klimisch score of 1 and is classified as reliable without restriction because it was carried out in a manner consistent with OECD Test Guideline 471.