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  • Jacobs, James F. et al Glossary of technical terms and acronyms used in this book MTBE: Effects on Soil and Groundwater ResourcesEd. James Jacobs et al. Boca Raton: CRC Press LLC, 2001

  • Appendix A

    Glossary of technical terms andacronyms used in this book

    Acute Exposure A short-term exposure to a chemical, usually consistingof a single exposure or dose administered for a period of less than 24 hours(acute : chronic as short-term : long-term).Adsorb To gather (a gas, liquid, or dissolved substance) on a surface in acondensed layer, as when charcoal adsorbs gases.Advection The usually horizontal movement of a mass of fluid (air, forexample); transport by such movement.Animal Cancer Bioassay A long-term experimental study in which ani-mals are given high doses of a chemical in order to obtain information on thecarcinogenicity of the chemical in test animals. The likelihood that a chemicalwill cause cancer in humans at the low doses typical of human exposures isestimated from information obtained from animal cancer bioassays.Annular Space/Annulus The space in a soil boring or monitoring wellbetween the casing and the borehole wall.Benzene A volatile toxic liquid aromatic hydrocarbon used as a solventand in gasoline. Benzene has been determined to cause cancer in humansexposed to high concentrations.CPF Cancer potency factor (also called slope factor) in units of (mg/[kg body mass]/d)-1.Cal EPA California Environmental Protection AgencyCarbon Monoxide (CO) A colorless, very toxic gas that is formed as aproduct of the incomplete combustion of carbon and carbon-based fuels suchas gasoline.Carcinogen A substance or agent producing or inciting cancer.Carcinogenicity The ability of a chemical to induce cancer by reactingwith genetic material or by interfering with other normal biological processesof the bodys cells.Chronic Exposure A long-term exposure to a chemical for a period of 1year or more in animals, and more than 7 years in humans.Clean Air Act Legislation originally passed by the U.S. Congress in 1976,and amended in 1990. Among other provisions, the 1990 Amendments man-date the use of oxygenated fuels and reformulated gasoline in nonattainmentareas (areas with poor air quality). The Clean Air Act led to the establishment


  • 2001 CRC Press LLC

    of air quality standards, including air quality criteria that are based on whatis known about the effects of air pollutants on animals, humans, plants, andmaterials.Co-Elute Refers to substances whose retention times in a chromatographiccolumn are the same. The substances exit the column at the same time;therefore, they co-elute, and the detection of one substance through chro-matographic analysis may be masked by another.Diffusion The gradual mixing of the molecules of two or more substancesowing to random molecular motion, as in the dispersion of a vapor in air.Dose The quantity of a substance administered to the body over a speci-fied time period units: mg/(kg body mass)/d or mg/[(kg body mass)d].Dose-response Assessment A step in the assessment of risks to humansfrom potentially toxic agents, in which the relationship between the doselevels to which animals or humans are exposed and the health-effect re-sponses at each dose level are characterized in a quantitative manner.Elute To remove (adsorbed material) from an adsorbent by means of asolvent.Epidemiology A branch of medical science that deals with the incidence,distribution, and control of disease in a population; the sum of the factorscontrolling the presence or absence of a disease or pathogen.Exposure Contact of an organism with one or more substances.Exposure route Mode of substance bodily intake: inhalation, dermalsorption, ingestion.Exposure pathway Mode of substance transport from source to receptorthrough air, soil, water, and the food chain.Formaldehyde A reaction product in the photooxidation of hydrocarbonsand a primary metabolite, or breakdown product, of MTBE. Formaldehydeis classified as a primary irritant at high-dose environmental exposures.Gavage Introduction of material into the stomach by a tube.Incremental Risk Risk from a specific cause over and above the total riskfrom all causes.Inhalation Exposure Intake of a chemical or substance (e.g., dust) into thebody and the lungs through breathing.Intake rate Quantity of a substance taken into the body per unit time units: mg/(kg body mass)/d or mg/[(kg body mass)d].LC50 Lethal concentration that is estimated to kill 50% of control laboratoryanimals from a specified inhalation exposure duration (usually 96 hours).LD50 Lethal dose that is estimated to kill 50% of control laboratory animalsfrom a specified ingestion exposure duration (usually 96 hours).LOAEL Lowest observed adverse effect level.MCL Maximum contaminant level (for contaminant in water).MRL Minimal risk level.MTBE Methyl tertiary-butyl ether is an organic liquid containing oxygenthat is added to reformulated gasoline and fuel in order to reduce theemissions of toxics into the air. MTBE is the most widely used oxygenate inthe U.S.

  • 2001 CRC Press LLC

    Metabolism The sum of the processes by which a particular substance ishandled in the living body.Metabolite A product of metabolism; the compound formed when aparent compound is metabolized as a result of biological processes in thebody.NOAEL No observed adverse effect level.Oxygenated Fuel Gasoline to which additives containing oxygen havebeen added. Oxygenated fuel differs from reformulated gasoline in the amountof oxygenate (2.7% by mass, 15% by volume) that it contains. (See Reformu-lated Gasoline.)Ozone (O3) A molecule consisting of three oxygen atoms that is a majorair pollutant in the lower atmosphere. Ozone is a primary component ofurban smog, resulting from the combustion of gasoline.Part per million A way of expressing low concentrations of a substancein a medium such as air or water; for example, 1 part per million MTBEmeans that there is 1 unit of MTBE in a million units of air, soil, or water.Part per billion A way of expressing very low concentrations of a sub-stance in a medium such as air or water; for example, 1 part per billion MTBEmeans that there is 1 unit MTBE in a billion units of air, soil, or water.Pharmacokinetics The study of the bodily absorption, distribution, me-tabolism, and excretion of a drug or chemical.Proposition 65 Safe Drinking Water & Toxic Enforcement Act of 1986(California).Reference dose (RfD)/Reference concentration (RfC) (inhalation) TheU.S. EPA-approved intake rate for a substance that is unlikely to result insignificant adverse noncancer (mostly acute but also chronic) effects.Reformulated gasoline Gasoline to which additives containing oxygenhave been added. The amended Clean Air Act requires the year-round useof reformulated gasoline in areas with unhealthful levels of ozone. Reformu-lated gasoline differs from oxygenated fuel in the amount of oxygenate (2.0%by mass, 11% by volume) that it contains. (See Oxygenated Fuel.)Risk The statistical probability that a particular adverse effect will occur,measured in dimensions of frequency or incidence (i.e., one in one million).Risk assessment The assessment of the likelihood and potential magni-tude of adverse health effects associated with human exposures to agentssuch as toxic chemicals or radiation. The four steps of risk assessment are:hazard identification, toxicity assessment, exposure assessment, and riskcharacterization.Tertiary-butyl alcohol Tertiary-butyl alcohol (TBA) is a primary metabo-lite of MTBE in the body. TBA may be associated with some adverse healtheffects observed in animals.Threshold dose The dose above which a chemical or other toxic agentproduces an adverse health effect and below which no adverse health effectsare seen or anticipated.Toxicity The ability of an agent, such as a chemical or drug, to causeharmful health effects to living organisms.

  • 2001 CRC Press LLC

    Toxicology A science that deals with poisons and their effects and with theproblems (clinical, industrial, or legal, for example) involved therein.Vadose Zone A term used in geology indicating a soil zone found orlocated above the water table. (The term unsaturated zone also fits thisdefinition.)

    SourcesMerriam-Websters Collegiate Dictionary,, 2000Jacques GuertinChristy Herron

  • Jacobs, James F. et al Conversions for international system (SI metric) and United States units MTBE: Effects on Soil and Groundwater ResourcesEd. James Jacobs et al. Boca Raton: CRC Press LLC, 2001

  • Appendix B

    Conversions for internationalsystem(SI metric) andUnited States units


    Square Millimeters Square centimeters (cm2) 0.01Square inches (in2) 1.55 103

    Square Centimeters Square millimeters (mm2) 100.0Square meters (m2) 1. 104

    Square inches 0.1550Square feet (ft2) 1.07639 103

    Square Inches Square millimeters 645.16Square centimeters 6.4516Square meters 6.4516 104

    Square feet 69.444 104

    Square feet Square meters 0.0929Hectares (ha) 9.2903 106

    Square inches 144.0Acres 2.29568 105

    Square yards Square meters 0.83613Hectares 8.3613 105

    Square feet 9.0Acres 2.0612 104

    Square meters Hectares 1.0 104

    Square feet 10.76391Acres 2.47 104

    Square yards (yd2) 1.19599

    Acres Square meters 4046.8564Hectares 0.40469Square feet 4.356 104

    Hectares Square meters 1.0 104

    Acres 2.471

    2001 CRC Press LLC

  • 2001 CRC Press LLC

    Square kilometers Square meters 1.0 106

    Hectares 100.0Square feet 107.6391 105

    Acres 247.10538Square miles (Mi2) 0.3861

    Square miles Meters 258.998Hectares 81 104

    Square kilometers (km2) 258.99881Square feet 2.58999Acres 2.78784 107

    Force per unit area, pressure-stress

    Pounds per square i