A consistent and transparent approach for calculation of Derived No-Effect Levels (DNELs) for petroleum substances

The REACH legislation introduced Derived No-Effect Levels (DNELs) which are defined as ‘the levels of exposure above which humans should not be exposed’. DNELs were required for several categories of petroleum substances and CONCAWE developed a consistent approach for their derivation. First, the No-Observed Effect Level from a relevant study was corrected for pattern and route of exposure to obtain a modified Point-of-Departure (PODmodified). Subsequently, the DNEL was calculated by dividing the PODmodified by Assessment Factors (AFs) to adjust for inter- and intraspecies differences. If substance-specific information allowed, Informed Assessment Factors (IAFs), developed by CONCAWE were utilised. When little or no substance-specific information on those differences was known, default AFs from the guidance provided by ECHA were used. Some hazard endpoints did not lend themselves to calculation of DNELs (e.g. aspiration, dermal irritation, mutagenicity). DNEL calculation was considered not appropriate if adverse effects were not observed in tests conducted at a limit dose or if meaningful dose–response curves could not be developed. However, DNELs were calculated when hazards were identified, regardless of whether or not risk characterisation was required under REACH. Examples for gasoline, Lubricating Base Oils, gas oils and bitumen are provided to illustrate CONCAWE’s approach.