The Gasoline Blending Streams Category includes 81 volatile liquids at standard temperature and pressure referred to as naphthas. Gasoline-blending naphthas are complex petroleum substances consisting of paraffinic hydrocarbons (normal and branched chain), olefinic hydrocarbons, naphthenic hydrocarbons (cycloparaffins), and aromatic hydrocarbons (mainly alkylbenzenes). These four basic chemical classes generally present in all naphthas - Paraffins, Olefins, Naphthenes and Aromatics- are identified by the acronym PONA.  

Given the wide range of chemicals that make up Gasoline/Gasoline Blending Streams, a basic strategy was developed for characterizing the human health, physical chemistry characteristics, environmental fate and ecotoxicity hazards that are defensible and applicable to a broad range of chemical combinations.  Data from naphthas that have a higher carbon number in one of these four chemical classes was used to estimate the boundaries of toxicity and to predict the potential hazards of untested substances. Data from gasoline are used as supplemental information to support the overall and endpoint specific hazard characterizations. Detailed analysis of the data from new and existing studies on these and similar streams were combined with results of studies on formulated gasoline.  These comparisons demonstrated similarities in the HPV hazard endpoint results and supports simplification of the category assessment to characterize the potential hazard for most human health and environmental endpoints without using the  PONA class distinctions. Consequently, prediction of values for untested category members consists of the range of the highest and lowest values obtained from key studies on all PONA substances and formulated gasoline. 

To meet the HPV Challenge, the Testing Group has thoroughly evaluated the substances within the Gasoline/Gasoline Blending Streams category and has made all of the reliable human health and ecological hazard data available to the public. The majority of the mammalian health data are derived from dermal and inhalation studies. Inhalation is the most relevant route of human exposure; however, most of the substances in this category are blended into formulated gasoline and are not found outside the refinery. Environmental toxicity studies were performed with water accommodated fractions of whole samples of representative streams.

• The Category Assessment Document (CAD) for Gasoline Blending Streams submitted to EPA by API which includes the final chemical hazard characterization and considers any new testing and analysis carried out for substances within the category. Also available are the Data Matrix (Appendix D) and the List of Read-Across Substances (Appendix D ) and an Analytical Data Summary for category members.

• The Robust Summary for Gasoline Blending Streams submitted to EPA by the American Petroleum Institute (API) which summarizes the available reliable data on physic-chemical properties, environmental fate and transport pathways, ecotoxicity, and human health toxicity.  

• The EPA Screening-Level Hazard Characterization  for Gasoline Blending Streams which summarizes EPA’s views on the available data for the category and on the need for additional studies to fill data gaps.

• The API Petroleum HPV Testing Group’s response  to the EPA Screening-Level Hazard Characterization for Gasoline  Blending Streams.