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Description of key information

Based on the results of the absorption, distribution, metabolism and excretion of components of the UVCB substance it is expected that the aromatic hydrocarbons and low olefin hydrocarbons will be well distributed in the body, but aromatic hydrocarbons do not tend to concentrate and might be expected to be readily metabolised and excreted through the urine; however, low olefin hydrocarbons might be expected to remain longer in the body due to their lipophilic nature, whilst being metabolised and excreted predominately through the urine. According to the information available, the substance might be expected to be well absorbed after oral, dermal, or inhalation exposure. 

Key value for chemical safety assessment

Additional information

The toxicokinetic behaviour of the substance was estimated based on the results of physicochemical and toxicological assessments and testing on the substance. Thermal cracking oil from blends of rubber, fuel oils and paraffin waxes, steam-stripped is a UVCB and, for the purpose of this toxicokinetics assessment, it has been treated as a complex mixture. The components of the oil have been considered and representatives from each of the different chemical groups that are deemed to have the greatest toxicological significance have been selected for investigation in the assessment process. Component Groups investigated:

- Aliphatic hydrocarbons in the range C8 to C30 (5%): this group will not be considered in the assessment due to their low concentration and limited hazardous properties.

- Aromatic hydrocarbons in the range C5 to C8 (5%)

- Aromatic hydrocarbons in the range C9 to C16 (64%)

- Low olefinic hydrocarbons (15%)

The absence of specific toxicokinetic data from animal testing means that it is not possible to make firm conclusions concerning the absorption, distribution, metabolism or excretion. However, an assessment of the toxicokinetic behaviour of selected components has been performed in conjunction with an assessment of available toxicological data on Thermal cracking oil from blends of rubber, fuel oils and paraffin waxes, steam-stripped and its parent oil, Gas oil (polymer-derived), thermal cracked, full range.

According to the information available, the substance might be expected to be well absorbed after oral, dermal, or inhalation exposure. The results of the acute oral toxicity study on Thermal cracking oil from blends of rubber, fuel oils and paraffin waxes, steam-stripped, showing no effect in rats after an ingestion of 2000 mg/kg could indicate either that the substance was not absorbed, or that the substance was absorbed but did not prove to be harmful to rats, which is consistent with the information from the Lower Olefins and Aromatics REACH Consortium (5) and The American Petroleum Institute (API) Petroleum HPV Testing Group (6). However, it should be noted that dermal absorption might be expected to be better than oral absorption.

Aromatic hydrocarbons and low olefin hydrocarbons might be expected to be well distributed in the body, but aromatic hydrocarbons do not tend to concentrate and might be expected to be readily metabolised and excreted through the urine; however, low olefin hydrocarbons might be expected to remain longer in the body due to their lipophilic nature, whilst being metabolised and excreted predominately through the urine. Results of the acute toxicity: oral study, showing no weight gain or loss could either mean that Thermal cracking oil from blends of rubber, fuel oils and paraffin waxes, steam-stripped was not absorbed, or that only a small fraction accumulated in the rats while the other fraction was rapidly excreted, which is consistent with this assessment

It is not considered appropriate to perform further animal studies on this substance.