The Crude Oil Category includes a single substance, Petroleum (CAS # 8002-05-9). Petroleum is defined as a complex combination of hydrocarbons consisting predominantly of aliphatic, alicyclic and aromatic hydrocarbons. It may also contain small amounts of nitrogen, oxygen and sulfur compounds. This category encompasses light, medium, and heavy petroleum, as well as the oils extracted from tar sands.  

Crude oil is a naturally occurring substance derived from the decomposition over thousands of years of plant and animal organic matter under elevated temperature and pressure. In appearance, crude oils range from mobile, volatile, light colored liquids to dark, viscous tar-like materials with low vapor pressure. Although, crude oils are assigned a single CAS #, they are generally classified by their density, predominant type of hydrocarbon (paraffinic or naphthenic) present, and whether their sulfur content is high (sour) or low (sweet). The hydrocarbons in crude oil have carbon numbers that range from four (C 4 or butanes), to large molecules containing more than sixty carbons. Sulfur, oxygen, and nitrogen compounds, organometallic complexes notably of nickel and vanadium, and dissolved gases, such as hydrogen sulfide, are also found in crude oil. Analytical studies indicate that similar hydrocarbons, heterocyclics, metals and other constituents, e.g. hydrogen sulfide, are present in all crude oils but their proportions vary depending on the crude source. The composition of crude oils from different producing regions, and even from within a particular geological formation, can vary widely. 

To meet the HPV Challenge, the Testing Group has thoroughly evaluated crude oil and has made all of the reliable human health and ecological hazard data available to the public. Key parameters when analyzing crude oil for hazards are the widely varying physical and chemical properties, the chemical and physical transformations that occur when crude oil is dispersed in the environment, and the specific polycyclic aromatic compound (PAC) profile when evaluating mammalian toxicity.

• The Category Assessment Document (CAD) for Crude Oil 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.

• The Robust Summary for Crude Oil  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 summary document for data on human health toxicity from gasoline blending streams created by the Petroleum HPV Testing Group. 

• The EPA Screening-Level Hazard Characterization for Crude Oil 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 Crude Oil.