Residues, steam cracked, thermally treated

Endpoint summary

Additional information

Genotoxicity information for specific streams identified for this category are variable with both positive and negative results in vitro and in vivo. Further information is included in the Category Summary for Fuel Oils Category (ACC, 2005).

Aromatic Pyrolysis Oil (CAS 64742 -90 -1): Positive mutagenic effects were reported in the in vitro CHO/HGPRT test for point mutations. A significant increase in mutation frequency was seen at concentrations of 500 µg/mL and above when tested with metabolic activation (Gulf Life Sciences, 1984b). In addition positive results were reported in further in vitro and in vivo studies and Aromatic Pyrolysis Oil was determined to be mutagenic and clastogenic (ACC, 2005).

Light Pyrolysis Fuel Oil (CAS 68527-18-4): Mixed results were seen in both in vitro and in vivo tests. In a cell transformation test using mouse embryo cells toxicity was seen after 2 days exposure beginning at 32 µg/mL and 100% toxic at >128 µg/mL. There was no increase in the frequency of transformation foci compared to control at any dose level (Gulf Life Sciences, 1984a). Light Pyrolysis Fuel Oil caused dose-related unscheduled DNA synthesis (43.3% at 8 μg/mL and 96% at 32 μg/mL compared with 2.7% in controls) at all nontoxic levels. (ACC, 2005). Following oral dosing at up to 1 mg/kg for 1-2 days mice did not show any significant change in micronucleus formation and there was no significant change in the ratio of polychromatic to normochromatic erythrocytes in bone marrow (Gulf Life Sciences, 1984c).

Rohnaphthalin-gemisch (CAS 85117-10-8): In an in vitro bacterial reverse mutation assay using Salmonella typhimurium tester strains TA98, TA100, TA1535 and TA1537 in the presence and absence or Aroclor-induced rat liver S9 toxicity was observed with some conditions at > 200 µg/plate. There was not a significant increase in revertant colonies in Salmonella strains with or without rat liver metabolic activation at any dose level and Rohnaphthalin-gemisch (CAS 85117-10-8) was considered not to be a mutagen in this test system (BASF, 1985).

The specific component benzene which has been identified as present in some streams at up to 30% has been shown to be mutagenic in vivo:

Benzene (Classification: EU –Toxic T Mutagen Cat 2 R46; GHS/CLP - Category 1B, H340): Benzene has been extensively examined for mutagenicity both in vitro and in vivo in a range of recognised core assay types. It has shown mixed results for mutagenicity in vitro although in mammalian cells there is overall evidence for potential mutagenic activity (EU, 2008a). Benzene has been shown to be mutagenic in vivo in both somatic cells and germ cells (Ciranni et al, 1991).

Short description of key information:
Genotoxicity data on streams within this category are limited and variable with both positive and negative in vivo and in vitro study results. However, there are substantial data on the genotoxicity of a number of specific components present in some streams. Of these, benzene has been shown to be mutagenic and when present in streams at concentrations equal or greater than 0.1% labelling for mutagenicity will be required.

Endpoint Conclusion: Adverse effect observed (positive)

Justification for classification or non-classification

Adequate data are available from in vitro and in vivo rodent studies to characterise the genotoxic potential of Fuel Oils streams. The results of a diverse array of mutagenicity, transformation and clastogenicity assays indicate positive responses in some assays and negative responses in others. However, Fuel Oils streams are also known to contain up to 30% benzene which is mutagenic in vivo and when present at ≥ 0.1% triggers labelling. Overall it is it is concluded that these streams are likely to be genotoxic.

It is proposed that Fuel Oils streams are classified as Mutagenic and labelled as follows: “May cause heritable genetic effects” Cat 2, R46 under Dir 1999/45/EC and “May cause genetic defects” Cat 1B, H340 under Reg (EC) 1272/2008.