| Abstract
| - The 1 billion gal of used oil generated in the U.S. eachyear are managed in three primary ways: rerefined intobase oil for reuse, distilled into marine diesel oil fuel, andmarketed as untreated fuel oil. Management of used oilhas local, regional and global impacts. Because of the globallydistributed nature of fuel markets, used oil as fuel haslocalized and regional impacts in many areas. In this paper,the human health and environmental tradeoffs of themanagement options are quantified and characterized.The goal of this study was to assess and compare theenvironmental impacts and benefits of each managementmethod in a product end-of-life scenario using a life-cycle assessment (LCA) approach. A life-cycle inventoryshowed that 800 mg of zinc and 30 mg of lead air emissionsmay result from the combustion of 1 L of used oil as fuel (50−100 times that of crude-derived fuel oils). As an example,up to 136 Mg of zinc and 5 Mg of lead air emissions maybe generated from combustion of over 50 M gal of California-generated used oil each year. While occurring elsewhere,these levels are significant (of the same magnitude asreported total stationary source emissions in California).An impact assessment showed that heavy metals-relatedtoxicity dominates the comparison of managementmethods. Zinc and lead emissions were the primarycontributors to the terrestrial and human toxicity impactpotentials that were calculated to be 150 and 5 times higher,respectively, for used oil combusted as fuel than forrerefining or distillation. Low profits and weak marketsincreasingly drive the used oil management method selectiontoward the untreated fuel oil market. Instead, both thererefining and distillation methods and associated productmarkets should be strongly supported because they areenvironmentally preferable to the combustion of unprocessedused oil as fuel.
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