TOTAL PETROLEUM HYDROCARONS173. IDENTITY AND ANALYSIS OF TOTAL PETROLEUM HYDROCARBONS3.1INTRODUCTIONPetroleum hydrocarbons (PHCs) are common site contaminants, but they are not generally regulatedas hazardous wastes. Methods for sampling and analysis of environmental media for the family ofPHCs are generally thought of as TPH methods. For purposes of this profile, the term TPH refersnot only to analytical results, but also to environmental and health properties of PHCs. In part due tothe complexity of TPH components themselves, little is known about their potential for health orenvironmental impacts. As gross measures of petroleum contamination, TPH results simply showthat petroleum hydrocarbons are present in the sampled media. Measured TPH values suggest therelative 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 thanwhat is provided by a single TPH value. This chapter, Chapter 5, and the accompanying Appendix Eprovide more detailed physical and chemical properties and analytical information on TPH and itscomponents.The federal government has left much of the specific regulation and oversight of crude oil production/refining to the states. Leaking underground storage tanks (LUST) are the most frequent causes offederal and state governmental involvement in petroleum hydrocarbon problems. Soil contaminationhas been a growing concern, because it can be a source of groundwater (drinking water) contamination;contaminated soils can reduce the usability of land for development; and weathered petroleumresiduals may stay bound to soils for years. Positive TPH test results may require action on the partof land owners, local or state governments, and engineering firms called on to remove or reduce theTPH problem.ATSDR has the responsibility for health assessment at National Priorities List (NPL) hazardouswaste sites, many of which have petroleum hydrocarbon contamination. Specific contaminants thatare components of TPH, such as BTEX (benzene, toluene, ethylbenzene, and xylene), n-hexane, jetfuels, fuel oils, and mineral-based crankcase oil, have been studied by ATSDR and a number oftoxicological profiles have been developed on individual constituents and petroleum products. The
TOTAL PETROLEUM HYDROCARONS183. IDENTITY AND ANALYSIS OF TOTAL PETROLEUM HYDROCARBONSATSDR profiles relevant to petroleum products are listed in Table 3- 1. However, TPH itself has notbeen as extensively studied by ATSDR and no previous profile was developed. Although severaltoxicological profiles have been developed for petroleum products and for specific chemicals found inpetroleum, TPH test results have been too nonspecific to be of real value in the assessment of itspotential health effects.Several approaches are discussed in this document for interpreting TPH and related analytical results.The TPH approach taken by EPA and others, through the mid-1990s, followed general riskassessment approaches for chemical mixtures. In all approaches there is a need to reduce acomprehensive list of potential petroleum hydrocarbons to a manageable size. Depending on howconservative the approach is, methods that have been used select: (1) the most toxic among the TPHcompounds (indicator approach); (2) one or more representative compounds (surrogate approach, butindependent of relative mix of compounds); or (3) representative compounds for fractions of similarpetroleum hydrocarbons. ATSDR has taken, in part, the third approach in keeping with the TotalPetroleum Hydrocarbons Criteria Working Group (TPHCWG), but has developed its own set of TPHfraction representatives, many of which overlap those of the TPHCWG. In addition, this profileprovides information on petroleum products, where such information exists. TPH risk (screening)values for fractions presented in this profile are based on the ATSDR MRLs previously developed forindividual constituents and petroleum products. These MRLs are summarized in Appendix A. Thisfraction approach is the most demanding in information gathering and because of that would appearto be the most rigorous approach to date. Sections 6.1.2 and 6.1.3 contain a more comprehensivediscussion of the approaches. The identity, chemical-physical, and analytical information discussedand listed in this chapter, in Appendices D and E, and in Chapter 5 are integral to defining TPH.3.2CHEMICAL AND PHYSICAL INFORMATIONPetroleum products are complex mixtures of hundreds of hydrocarbon compounds, ranging from light,volatile, short-chained organic compounds to heavy, long-chained, branched compounds. The exactcomposition of petroleum products varies depending upon (1) the source of the crude oil (crude oil isderived from underground reservoirs which vary greatly in their chemical composition) and (2) therefining practices used to produce the product.
TOTAL PETROLEUM HYDROCARONS203. IDENTITY AND ANALYSIS OF TOTAL PETROLEUM HYDROCARBONSDuring the refining process, crude oil is separated into fractions having similar boiling points. Thesefractions are then modified by cracking, condensation, polymerization, and alkylation processes, andare formulated into commercial products such as naphtha, gasoline, jet fuel, and fuel oils. Thecomposition of any one of these products can vary based on the refinery involved, time of year,variation in additives or modifiers, and other factors. The chemical composition of the product can befurther affected by weathering and/or biological modification upon release to the environment. Thefollowing subsections present overviews of petroleum products. Also, a master list of individualaliphatic and aromatic compounds found in TPH is provided in Appendix D. Further information onwhole petroleum products, their identity, major components, and physical/chemical properties isfound in Appendix E.Automotive Gasoline. Automotive gasoline is a mixture of low-boiling hydrocarbon compoundssuitable for use in spark-ignited internal combustion engines and having an octane rating of at least60. Additives that have been used in gasoline include alkyl tertiary butyl ethers (e.g. MTBE), ethanol(ethyl alcohol), methanol (methyl alcohol), tetramethyl-lead, tetraethyl-lead, ethylene dichloride, andethylene dibromide.Other categories of compounds that may be added to gasoline include anti-knock agents, antioxidants,metal deactivators, lead scavengers, anti-rust agents, anti-icing agents, upper-cylinderlubricants, detergents, and dyes (ATSDR 1995a).Automotive gasoline typically contains about 150 hydrocarbon compounds, though nearly 1,000 havebeen identified (ATSDR 1995a). The relative concentrations of the compounds vary considerablydepending on the source of crude oil, refinery process, and product specifications. Typical hydrocarbonchain lengths range from C4 through Cl2 with a general hydrocarbon distribution consisting of4-8% alkanes, 2-5% alkenes, 25-40% isoalkanes, 3-7% cycloalkanes, l-4% cycloalkenes, and20-50% aromatics (IARC 1989a). However, these proportions vary greatly. Unleaded gasolinesmay have higher proportions of aromatic hydrocarbons than leaded gasolines.Table E-1.b (Appendix E) presents ranges and weight percentage means for a representative subset ofthe hydrocarbon compounds identified in gasoline. In cases where data are not available, the rangeand mean are left blank.
TOTAL PETROLEUM HYDROCARONS213. IDENTITY AND ANALYSIS OF TOTAL PETROLEUM HYDROCARBONSStoddard Solvent. Stoddard solvent is a petroleum distillate widely used as a dry cleaning solventand as a general cleaner and degreaser. It may also be used as a paint thinner, as a solvent in some typesof photocopier toners, in some types of printing inks, and in some adhesives. Stoddard solvent isconsidered to be a form of mineral spirits, white spirits, and naphtha; however, not all forms of mineralspirits, white spirits, and naphtha are considered to be Stoddard solvent (ATSDR 1995b).Stoddard solvent consists of 30-50% linear and branched alkanes, 30-40% cycloalkanes, and lo-20%aromatic hydrocarbons. Its typical hydrocarbon chain ranges from C7 through C12 in length.Although a complete list of the individual compounds comprising Stoddard solvent is not available (AirForce 1989) some of the major components are presented in Table E-2.b (Appendix E). Alcohols,glycols, and ketones are not included in the composition, as few, if any, of these types of compoundswould be expected to be present in Stoddard solvent (ATSDR 1995b). Possible contaminants mayinclude lead ( 1 ppm) and sulfur (3.5 ppm).Jet Fuel. Jet fuels are light petroleum distillates that are available in several forms suitable for use invarious types ofjet engines. The exact compositions of jet fuels are established by the U.S. Air Force,using specifications that yield maximum performance by the aircraft. The major jet fuels used by themilitary are JP-4, JP-5, JP-6, JP-7, and JP-8. Briefly, JP-4 is a wide-cut fuel developed for broadavailability in times of need. JP-6 is a higher cut than JP-4 and is characterized by fewer impurities. JP-5is specially blended kerosene, and JP-7 is a high flash point special kerosene used in advanced supersonicaircraft. JP-8 is a kerosene modeled on Jet A-l fuel (used in civilian aircraft). For this profile, JP-4 willbe used as the prototype jet fuel due to its broad availability and extensive use.Typical hydrocarbon chain lengths characterizing JP-4 range from C4 to C16. Aviation fuels consistprimarily of straight and branched alkanes and cycloalkanes. Aromatic hydrocarbons are limited to20-25% of the total mixture because they produce smoke when burned. A maximum of5% alkenes areallowed in JP-4 (ATSDR 1995c). The approximate distribution by chemical class is: 32% straightalkanes, 31% branched alkanes, 16% cycloalkanes, and 21% aromatic hydrocarbons (ABBEnvironmental 1990). The typical hydrocarbon composition of JP-4 is presented in Table E-3.b(Appendix E).
TOTAL PETROLEUM HYDROCARONS223. IDENTITY AND ANALYSIS OF TOTAL PETROLEUM HYDROCARBONSFuel Oil #1. Fuel oil #l is a petroleum distillate that is one of the most widely used of the fuel oiltypes. It is used in atomizing burners that spray fuel into a combustion chamber where the tiny dropletsbum while in suspension. It is also used as a carrier for pesticides, as a weed killer, as a mold releaseagent in the ceramic and pottery industry, and in the cleaning industry. It is found in asphalt coatings,enamels, paints, thinners, and varnishes.Fuel oil #1 is a light petroleum distillate (straight-run kerosene) consisting primarily of hydrocarbons in therange C9-C16 (ATSDR 19958). Fuel oil #l is very similar in composition to diesel fuel oil #l; the primarydifference is in the additives. The typical hydrocarbon composition of fuel oil #l is presented inTable E-4.b (Appendix E).Fuel Oil #2. Fuel oil #2 is a petroleum distillate that may be referred to as domestic or industrial. Thedomestic fuel oil #2 is usually lighter and straight-run refined; it is used primarily for home heating and toproduce diesel fuel #2. Industrial distillate is the cracked type, or a blend of both. It is used in smeltingfurnaces, ceramic kilns, and packaged boilers (ABB Environmental 1990).Fuel oil #2 is characterized by hydrocarbon chain lengths in the C11-C20 range, whereas diesel fuelspredominantly contain a mixture of C10-C19 hydrocarbons (ATSDR 1995g). The composition consists ofapproximately 64% aliphatic hydrocarbons (straight chain alkanes and cycloalkanes), l-2% unsaturatedhydrocarbons (alkenes), and 35% aromatic hydrocarbons (including alkylbenzenes and 2-, 3-ringaromatics) (Air Force 1989). Fuel oil #2 contains less than 5% polycyclic aromatic hydrocarbons (IARC1989b). The typical hydrocarbon composition of fuel oil #2 is presented in Table E-4.b (Appendix E).Fuel Oil #6. Fuel oil #6 is also called Bunker C or residual. It is the residual from crude oil after thelight oils, gasoline, naphtha, fuel oil #l, and fuel oil #2 have been fractioned off. Fuel oil #6 can beblended directly to heavy fuel oil or made into asphalt. It is limited to commercial and industrial useswhere sufficient heat is available to fluidize the oil for pumping and combustion (ABB Environmental1990).Residual fuel oils are generally more complex in composition and impurities than distillate fuels. Limiteddata are available on the composition of fuel oil #6 (ATSDR 1995g). Clark et al. (1990) indicate that fueloil #6 includes about 25% aromatics, 15% paraffins, 45% naphthenes, and 15% non-hydrocarbon
TOTAL PETROLEUM HYDROCARONS233. IDENTITY AND ANALYSIS OF TOTAL PETROLEUM HYDROCARBONScompounds. Polycyclic aromatic hydrocarbons (PAHs) and alkyl PAHs and metals are importanthazardous and persistent components of fuel oil #6. Table E-4.b (Appendix E) presents the results of ananalysis of one sample (Pancirov and Brown 1975).Mineral Oils, Including Mineral-based Crankcase Oil. Mineral oils are often lubricating oils,but they also have medicinal and food uses. A major type of hydraulic fluid is the mineral oil class ofhydraulic fluids (ATSDR 1997b). The mineral-based oils are produced from heavy-end crude oildistillates. Distillate streams may be treated in several ways, such as vacuum-, solvent-, acid-, or hydro- treated, toproduce oils with commercial properties. Hydrocarbon numbers ranging from C15 to C50 arefound in the various types of mineral oils, with the heavier distillates having higher percentages of thehigher carbon number compounds (IARC 1984).Crankcase oil or motor oil may be either mineral-based or synthetic. The mineral-based oils are morewidely used than the synthetic oils and may be used in automotive engines, railroad and truck dieselengines, marine equipment, jet and other aircraft engines, and most small 2- and 4-stroke engines.The mineral-based oils contain hundreds to thousands of hydrocarbon compounds, including a substanti