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HANDBOOK OF ECOTOXICOLOGY

14.1 INTRODUCTION

Crude petroleum, refined petroleum products, and individual polyeycfic aromatic hydrocarbons (PAHs) eontained within petroleum are found throughout the World. Their presence has been detected in living and nonlwing eortiponents of ecosystems. Petroleum can be an environmental hazard for all organisms. Individual PAHs can be toxic to orgariisms, but they are most commonly associated with illnesses in humaj®. Because petroleum is a major environmental source of these PAHs, petroleum and PAHs are jointly presented in this chapter. Composition, sources, environ-mental fate, and toxic effects on all organisms of aąuatic and terrestrial environments are addressed.

Petroleum spills raised some environmental concem during the early twentieth century when ocean transport of large volumes of crude oil began.' World War I caused a large number of oil spills thćtl had a noticeably adverse effect on marinę birds. The subseąuent conversion of the ecbnorny of the world from cbal to oil, followed by World War II, greatly increased the petroleum threat to marinę life. Efforts to deal with a growing number of oil spills and intentional oil discharges at sea continued during the 1950s and 1960s.‘ The wreck of the Torrey Carfytm off the coast of Engłand in 1967 produced worldwide concem about the conseąuences of massive oil spills in the marinę environment. Research on the environmental fate and biological effects of spilled petroleum increased dramatically during the 1970s. The Exxon Valdez oil spili in Prince William Sound, Alaska, in 1989, and the massive releases of crude oil into the Arabian Gulf during the 1991 Gulf War again captured intemational attention and resulted in an increase in environmental research. Despite considerable progress in developing methods to clean up spills, the adoption of numerous National and intemational Controls an shipping practices, and high public concem (e.g., passage of the Oil Pollution Act of 1990 [33 USCA Sec. 2701-2761] in the United States), petroleum continues to be a widespread environmental hazard.

The associalron between skin cancer in chimney sweeps and exposure to contaminants in soot was madę in England during the late eighteenth century. By the early twentieth century, soot, coal tar, and piteh were all known to be carcinogenic to humans. In 1918 benzo(a)pyrene was identified ąs a major carcinogenic agent; other PAHs have sińce been identified as carcinogenic or tumorigenic. Many loxic and carcinogenic effects of PAHs on humans, laboratory animals, and wildlife have been described in numerous reviews.²

14.2 COMPOSITION AND CHARACTERISTICS

14.2.1 Petroleum

Petroleum cOnsists of cmde oils and a wide variety of refined oil products. Crude oils vary in chemical composition, polor,    specific gravity, and other physical properties. Color ranges

from light yellow-brown to black. Vfśebsity varies from free flowing to a substance that will barely pour. Specific gravity of most cmde oils varies between 0.73 and 0.95.³ Refined oil products most often spilled in large ąuantities are aviation fuel, gasoline, No. 2 fuel oil (diesel fuel), and No. 6 fuel oil (bunker C); Fuel oils 1 to 6) become increasittjglf. dense and viscous and contain increasingly-fewer volatile compounds as their numeric classification proceeds from one to six.

Cmde taHlfe a complex mixture of thousands of hydrocarbon and nonhydrocarbon compounds. Hydrocarbons comprise morę than 75% of most cmde and refined oils; heavy cmde oils can gipntain morę than jnonhydrocarbons.³’⁴ Hydrocarbons in petroleum are divided into four major classes: |!) straighbchain alkanes (n-alkanes or n-paraffins§; §2) branched alkanes (isoal-kanes or isoparaffinś), (3) cydoalkan# (cycloparaffins), and (4) aromalics (Figurę 14.1). Alkenes ®e®ur in (gsidiff ęiil, but they are rare. A variety of combinations of the different types of compounds t^urfjEaw-molecular-weight members of each class predominafE iii crude oils. Aliphatic hydro*