The Petroleum Hydrocarbon Gases Category includes 161 that are series of gases or highly volatile liquids, all of which are composed primarily of paraffinic, saturated hydrocarbons having one to five carbon atoms. Some of the gases may contain lower molecular weight hydrocarbons, ammonia, hydrogen, nitrogen, hydrogen sulfide, mercaptans, carbon monoxide, or carbon dioxide.  

The original category documents and Robust Summaries for the Petroleum Hydrocarbon Gases Category were submitted by the Petroleum HPV Testing Group to the United States Environmental Protection Agency (EPA) in 2000. In response to the EPA and public comments, the Testing Group divided the Petroleum Hydrocarbon Gases Category into a Hydrocarbon Gases Category (99 substances) and a Refinery Gases (62 substances) Category in 2010. The Testing Group subsequently submitted revised robust summaries for the Refinery Gases Category to the EPA.  

Both the petroleum gases and refinery gases are primarily produced in petroleum refineries as the light end fractions of numerous distillation and cracking processes or in gas plants that separate natural gas and natural gas liquids. Substances in both categories have high vapor pressure and moderate to high water solubility. They possess moderate to high mobility in soil and are expected possess low persistence and low bioaccumulation potential. Of the 99 substances within the petroleum gases, 10 substances are individual chemicals and 89 are mixtures. The mixtures are composed primarily of paraffinic and olefinic hydrocarbons, mostly containing one to six carbon atoms (C1 – C6). Some of the mixtures may contain varying amounts of other components, including benzene, C7 – C8 hydrocarbons, hydrogen, nitrogen and carbon dioxide. The refinery gas streams are composed primarily of paraffinic and olefinic C1 – C4 and C5 – C6 hydrocarbons. Some streams also contain varying amounts of other chemicals including, ammonia, hydrogen, nitrogen, hydrogen sulfide, mercaptans, carbon monoxide, carbon dioxide, 1,3-butadiene and/or benzene.  

To meet the HPV Challenge, the Testing Group has thoroughly evaluated the substances within this category and has made all of the reliable human health and ecological hazard data available to the public.

• The Category Assessment Document (CAD) for Petroleum Gases 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.
  • Appendix 5 of CAD


• The Robust Summary for Petroleum Gases 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 Petroleum Gases 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 Petroleum Gases.

• The Category Assessment Document (CAD) for Refinery Gases 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.
  • Appendix 5 of CAD


• The Robust Summary for Refinery Gases 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 Refinery Gases 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 Refinery Gases.