Petroleum hydrocarbons (PHCs) are common site contaminants, but they are not generally regulated as hazardous wastes. Methods for sampling and analysis of environmental media for the family of PHCs are generally thought of as TPH methods. For purposes of this profile, the term TPH refers not only to analytical results, but also to environmental and health properties of PHCs. In part due to the complexity of TPH components themselves, little is known about their potential for health or environmental impacts. As gross measures of petroleum contamination, TPH results simply show that petroleum hydrocarbons are present in the sampled media. Measured TPH values suggest the relative potential for human exposure and, therefore, the relative potential for human health effects. The assessment of health effects due to TPH exposure requires much more detailed information than what is provided by a single TPH value. This chapter, Chapter 5, and the accompanying Appendix E provide more detailed physical and chemical properties and analytical information on TPH and its components.