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Human Health Risk Assessment <br /> o - <br /> Former Mobil Oil Bulk Plant 04 343 <br /> 500 East Grant Line Road <br /> Tracy, California <br /> GLOSSARY <br /> CUTE TOXICITY: The toxic effects which result from a single exposure to a substance. <br /> SORPTION FRACTION: The fraction of a substance which condenses or adheres on the surface of solids. <br /> BIOAVAILABILITY: The fraction of a chemical dose which crosses a physiologic barrier. <br /> IIODEGRADATION: The chemical decomposition of a substance by biological agents. <br /> CANCER SLOPE FACTOR: A plausible upper-bound estimate of the probability of a response per unit intake of a chemical over a lifetime. <br /> e slope factor is used to estimate the upper-bound probability of an individual developing cancer as a result of a lifetime of exposure to a <br />'• rticular concentration of a potential carcinogen. The cancer slope factor is specific to a particular route of exposure (e.g., inhalation, ingestion). <br /> 1APILLARY FRINGE ZONE: A "transition" zone between the saturated and vadose zones. Within this zone, ground water and free <br /> product are suspended within the soil as a result of the capillary forces of the two fluids. <br /> XPOSURE ASSESSMENT: The process of measuring or estimating the intensity,frequency,and duration of human exposures to an agent <br /> fXPenvironment. <br /> OSURE: The means by which a chemical or agent can reach appropriate receptors in the -jpulation or individual. <br /> OXPOSURE ROUTE: The means by which a chemical or physical agent comes in contact with an organism (e.g., ingestion, inhalation, or <br /> rmal contact). <br /> AZARD IDENTIFICATION: A qualitative assessment containing a review of biological and chemical information used to determine <br /> hether exposure to a chemical or agent may pose a hazard or result in an increase in the incidence of a health condition or effect (e.g., cancer). <br /> l R. <br /> NTEGATED RISK INFORMATION SYSTEM (IRIS): An EPA data base which contains verified reference doses and cancer <br /> ope factors for a number of chemicals. IRIS is EPA's preferred source for toxicity information for Superfund. <br /> IFET ME AVERAGE DAILY DOSE (LADD): The dose of a chemical ingested or absorbed on a daily basis and averaged over <br /> 75-year lifetime. <br /> OWEST OBSERVED ADVERSE EFFECT LEVEL (LOAEL): The lowest exposure level at which there are not statistically <br /> biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control group. <br /> 30-0136-11 <br />