Glossary

Accommodation The act or state of adjustment or adaptation.1

ACGIH (American Conference of Governmental Industrial Hygienists) ACGIH is a member-based organization and community of professionals that advances worker health and safety through education and the development and dissemination of scientific and technical knowledge. ACGIH publishes exposure guidance values called Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs). Exposures at or below TLVs or BEIs do not create an unreasonable risk of disease or injury. TLVs and BEIs are designed for use by industrial hygienists in making decisions regarding safe levels of exposure to various chemical substances and physical agents found in the workplace.2

Acute exposure An exposure lasting 1 day or less.3

Acute exposure guideline levels (AEGLs) AEGLs “represent threshold exposure limits for the general public and are applicable to emergency exposures ranging from 10 min to 8 h. Three levels—AEGL-1, AEGL-2, and AEGL-3—are developed for each of five exposure periods (10 min, 30 min, and 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. AEGL-1 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure. AEGL-2 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals,

1

Stedman, L.S. 1982. Stedman’s Medical Dictionary, 24th Ed. Baltimore, MD: Williams and Wilkins.

2

See http://www.acgih.org for more information.

3

Auletta, C.S. 1995. Acute, subchronic, and chronic toxicology. Pp. 69-127 in CRC Handbook of Toxicology, M.J. Derelanko and M.A. Hollinger, eds. Boca Raton: CRC Press.



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Glossary Accommodation The act or state of adjustment or adaptation.1 ACGIH (American Conference of Governmental Industrial Hygienists) ACGIH is a member-based organization and community of professionals that advances worker health and safety through education and the development and dissemination of scientific and technical knowledge. ACGIH publishes expo- sure guidance values called Threshold Limit Values (TLVs) and Biological Ex- posure Indices (BEIs). Exposures at or below TLVs or BEIs do not create an unreasonable risk of disease or injury. TLVs and BEIs are designed for use by industrial hygienists in making decisions regarding safe levels of exposure to various chemical substances and physical agents found in the workplace.2 Acute exposure An exposure lasting 1 day or less.3 Acute exposure guideline levels (AEGLs) AEGLs “represent threshold expo- sure limits for the general public and are applicable to emergency exposures ranging from 10 min to 8 h. Three levels—AEGL-1, AEGL-2, and AEGL-3— are developed for each of five exposure periods (10 min, 30 min, and 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. AEGL-1 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. How- ever, the effects are not disabling and are transient and reversible upon cessation of exposure. AEGL-2 is the airborne concentration of a substance above which it is predicted that the general population, including susceptible individuals, 1 Stedman, L.S. 1982. Stedman’s Medical Dictionary, 24th Ed. Baltimore, MD: Wil- liams and Wilkins. 2 See http://www.acgih.org for more information. 3 Auletta, C.S. 1995. Acute, subchronic, and chronic toxicology. Pp. 69-127 in CRC Handbook of Toxicology, M.J. Derelanko and M.A. Hollinger, eds. Boca Raton: CRC Press. 302

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Glossary 303 could experience irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape. AEGL-3 is the airborne concentration above which it is predicted that the general population, including susceptible individu- als, could experience life-threatening health effects or death.”4 Adaptation The ability of some sensory receptors to modify the response to repeated or continued stimuli.1 AEGL See acute exposure guideline levels. Aerosol A suspension of liquid or solid particles in a gas.5 Alveolar macrophage A mononuclear phagocytic cell arising from monocytic stem cells in bone marrow whose function is to ingest and digest foreign matter in the alveoli.1 Area under the curve (AUC) A measure of exposure that includes both dura- tion and concentration. It is calculated from the curve that results when the con- centrations of the test substance in some biologic tissue, typically blood, are plotted versus the exposure time. ATSDR (Agency for Toxic Substances and Disease Registry) The ATSDR is an agency of the Department of Health and Human Services that was created by Congress under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), commonly known as the Superfund Act. Its mission is to serve the public by using the best science, taking responsive public health actions, and providing trusted health information to prevent harm- ful exposures and disease related to toxic substances. ATSDR defines minimal risk levels (MRLs).6 AUC See area under the curve. CAMS See central atmosphere monitoring system. CEGL See continuous exposure guidance level. 4 NRC (National Research Council). 2001. Standing Operating Procedures for Devel- oping Acute Exposure Guideline Levels for Hazardous Chemicals. Washington, DC: National Academy Press. 5 Hawley, G.G. 1977. The Condensed Chemical Dictionary, 9th Ed. New York: Van Nostrand Reinhold Company. 6 See http://www.atsdr.cdc.gov/ for more information.

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304 Exposure Guidance Levels for Selected Submarine Contaminants Ceiling concentration A concentration that shall not be exceeded during any part of a working exposure.7 Central atmosphere monitoring system (CAMS) CAMS monitors the sub- marine atmosphere by using “an infrared spectrometer to measure carbon mon- oxide and a mass spectrometer to measure oxygen, nitrogen, carbon dioxide, hydrogen, water vapor, and fluorocarbons 11, 12, and 114.”8 Chronic exposure An exposure lasting 6-24 months.3 Chronic obstructive pulmonary disease (COPD) COPD is “a disease charac- terized by chronic bronchitis or emphysema and airflow obstruction that is gen- erally progressive, maybe accompanied by airway hyperreactivity, and may be partially reversible.”9 Continuous exposure guidance level (CEGL) A CEGL is defined as a ceiling concentration designed to prevent any immediate or delayed adverse health ef- fect or degradation in crew performance resulting from a continuous exposure lasting up to 90 days. COPD See chronic obstructive pulmonary disease. DBNP 2,6-Di-tert-Butyl-4-Nitrophenol. EEGL See emergency exposure guidance level. Electrostatic precipitator A system to clear particles and aerosols from air.10 Emergency exposure guidance level (EEGL) An EEGL is defined as a ceil- ing concentration that will not cause irreversible harm or prevent performance of essential tasks, such as closing a hatch or using a fire extinguisher, during a rare emergency situation lasting 1-24 hours. 7 NRC (National Research Council). 2002. Review of Submarine Escape Action Lev- els for Selected Chemicals. Washington, DC: National Academy Press. 8 NRC (National Research Council). 1988. Submarine Air Quality. Washington, DC: National Academy Press. 9 Beers, M.H., and R. Berkow, eds. 1999. The Merck Manual of Diagnosis and Ther- apy, 17th Ed. Whitehouse Station, NJ: Merck Research Laboratories. 10 Hagar, R. 2003. Submarine Atmosphere Control and Monitoring Brief for the COT Committee. Presentation at the First Meeting on Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants, January 23, 2003, Washington, DC.

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Glossary 305 EPA U.S. Environmental Protection Agency. Forced expiratory volume at one second (FEV1) FEV1 is a standard test of lung function. It is the volume of air that can be forcibly exhaled in 1 second following a maximal inspiration.1 Forced vital capacity (FVC) FVC is a standard test of lung function. It is the maximal volume of air that can be exhaled as forcibly and rapidly as possible after a maximal inspiration.1 Fumes Particulate, smoke-like emanations from the surface of heated metals.6 FVC See forced vital capacity. Gas One of the three states of matter, characterized by very low density and viscosity (relative to liquids and solids); comparatively great expansion and con- traction with changes in pressure and temperature; ability to diffuse readily into other gases; and ability to occupy with almost complete uniformity the whole of any container.6 H2 Hydrogen. HCFC Hydrochlorofluorocarbons. IARC (International Agency for Research on Cancer) IARC is an agency of the World Health Organization. IARC’s carcinogenicity classifications are as follows:11 Group 1. The agent (mixture) is carcinogenic to humans. The exposure circumstance entails exposures that are carcinogenic to humans. Group 2A. The agent (mixture) is probably carcinogenic to humans. The exposure circumstance entails exposures that are probably carcinogenic to humans. Group 2B. The agent (mixture) is possibly carcinogenic to humans. The exposure circumstance entails exposures that are possibly carcinogenic to humans. Group 3. The agent (mixture, or exposure circumstance) is not classifiable as to carcinogenicity in humans. Group 4. The agent (mixture, exposure circumstance) is probably not car- cinogenic to humans. 11 See http://www.iarc.fr/pageroot/GENERAL/indexgen.html for more information.

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306 Exposure Guidance Levels for Selected Submarine Contaminants Irritant A toxicant that exerts deleterious effects by causing inflammation of tissues on contact. Irritants can act on the respiratory system and cause pulmo- nary edema at high concentrations. At low concentrations, most effects are re- versible with cessation of exposure.12 Irreversible harm Permanent damage or injury to health. Emergency exposure guidance levels (EEGLs) are designed to avoid or prevent irreversible harm. LC01 Statistical determination of the lethal concentration for 1% of the sample population. LC50 Statistical determination of the lethal concentration for 50% of the sample population. LOAEL See lowest-observed-adverse-effect level. Lowest effect level The lowest dose or exposure level in a study at which a statistically or biologically significant effect is observed in the exposed popula- tion compared with an appropriate unexposed control group.13 Lowest-observed-adverse-effect level (LOAEL) A LOAEL is the “lowest exposure level at which there are statistically or biologically significant in- creases in frequency or severity of adverse effects between the exposed popula- tion and its appropriate control group.”14 Minimal risk level (MRL) ATSDR’s “estimate of daily human exposure to a hazardous substance at or below which that substance is unlikely to pose a measurable risk of harmful (adverse), noncancerous effects. MRLs are calcu- lated for a route of exposure (inhalation or oral) over a specified time period (acute, intermediate, or chronic).”15 MRL See minimal risk level. NAAQS See national ambient air quality standards. 12 Hodgson, E., R.B. Mailman, and J.E. Chambers, eds. 1988. Dictionary of Toxicol- ogy. New York: Van Nostrand Reinhold Company. 13 EPA (U.S. Environmental Protection Agency). Glossary of IRIS terms. Integrated Risk Information System, U.S. Environmental Protection Agency. [Online]. Available: http://www.epa.gov/iris/gloss8.htm. 14 NRC (National Research Council). 2000. Toxicological Effects of Methylmercury. Washington, DC: National Academy Press. 15 ATSDR (Agency for Toxic Substances and Disease Registry). 2003. ATSDR Glos- sary of Terms [Online]. Available: http:// www.atsdr.cdc.gov/glossary.htm.

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Glossary 307 National ambient air quality standards (NAAQS) “The Clean Air Act, re- quires EPA to set National Ambient Air Quality Standards (NAAQS) for pollut- ants considered harmful to public health and the environment. The Clean Air Act established two types of national air quality standards. Primary standards set limits to protect public health, including the health of ‘sensitive’ populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings. NAAQS have been set for six prin- cipal pollutants, which are called ‘criteria’ pollutants: carbon monoxide, nitro- gen dioxide, ozone, lead, particulate matter, and sulfur dioxide.”16 NH3 Ammonia. NIOSH National Institute for Occupational Safety and Health. NOAEL See no-observed-adverse-effect level. NOEL See no-observed-effect level. No-observed-adverse-effect level (NOAEL) A NOAEL is “an exposure level at which there are no statistically or biologically significant increases in the fre- quency or severity of adverse effects between the exposed population and its appropriate control; some effects may be produced at this level, but they are not considered as adverse, nor precursors to specific adverse effects. In an experi- ment with several NOAELs, the regulatory focus is primarily on the highest one leading to the common usage of the term NOAEL as the highest exposure with- out adverse effect.”15 No-observed-effect level (NOEL) A NOEL is the “greatest concentration or amount of a substance, found by experiment or observation, that causes no al- terations of morphology, functional capacity, growth, development, or life span of target organisms distinguishable from those observed in normal (control) organisms of the same species and strain under the same defined conditions of exposure.”17 OR Odds ratio. 16 EPA (U.S. Environmental Protection Agency). 2003. National Ambient Air Quality Standards (NAAQS). Office of Air and Radiation, U.S. Environmental Protection Agency. [Online]. Available: http://www.epa.gov/air/criteria.html. 17 IUPAC (International Union of Pure and Applied Chemistry). 1993. Glossary for chemists of terms used in toxicology. Pure Appl. Chem. 65(9):2003-2122. [Online]. Available: http://www.sis.nlm.nih.gov/Glossary/main.htm.

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308 Exposure Guidance Levels for Selected Submarine Contaminants OSHA (Occupational Safety and Health Administration) OSHA is an agency of the U.S. Department of Labor. It is authorized to set workplace health and safety standards for a wide variety of physical and chemical hazards and occupational situations. OSHA establishes permissible exposure limits (PELs) for a typical 8-hour workday within a 40-hour workweek and short-term expo- sure limits (STELs) applicable to a 15-min period within a workday.18 Pb Lead. PEL See permissible exposure limit. PEL-TWA See permissible exposure limit. Permissible exposure limit (PEL) A PEL is the “maximum amount or concen- tration of a chemical that a worker may be exposed to under OSHA regula- tions.”19 According to OSHA regulations, the permissible exposure limit–time- weighted average (PEL-TWA) is a regulatory standard for a particular chemical expressed as “an average value of exposure over the course of an 8 hour work shift.”20 RD50 A statistically estimated concentration resulting in 50% reduction in res- piratory rate. Recommended exposure limit (REL) A REL is “an 8- or 10-h time-weighted average (TWA) or ceiling concentration recommended by NIOSH that is based on an evaluation of the health effects data.”21 Reference concentration (RfC) EPA’s estimate of “air exposure concentration to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime.”21 REL See recommended exposure limit. 18 See http://www.osha.gov/ for more information. 19 29 CFR 1910.1200. 20 NIOSH (National Institute for Occupational Safety and Health). 2003. NIOSH Pocket Guide to Chemical Hazards. [Online]. Available: http://www.cdc.gov/niosh/npg/ pgintrod/html. 21 EPA (U.S. Environmental Protection Agency). 1989. Glossary of Terms Related to Health, Exposure, and Risk Assessment. EPA/450/3-88/016. Air Risk Information Sup- port Center, U.S. Environmental Protection Agency, Washington, DC.

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Glossary 309 Relative risk (RR) RR is an epidemiologic measure of association between an exposure or risk factor and disease incidence. It is expressed as a ratio of the incidence rate for exposed persons to the incidence rate for the unexposed.22 Reversible effect An injury from which a target tissue or organ can recover or regenerate. RfC See reference concentration. RR See relative risk. SEAL See submarine escape action levels. Short-term exposure limit (STEL) As defined by ACGIH, a STEL is a “15- minute TWA exposure for a regulated chemical that should not be exceeded at any time during a workday, even if the 8-hour TWA is within the TLV-TWA or PEL-TWA.”20 Short-term public emergency guidance levels (SPEGLs) SPEGLs are “suit- able concentrations for single, short-term, emergency exposures, of the general public.”23 SMAC See spacecraft maximum allowable concentrations. Spacecraft maximum allowable concentrations (SMACs) SMACs are “con- centrations of airborne substances (such as gas, vapor, or aerosol) that will not compromise the performance of specific tasks during emergency conditions. Exposure to 24-h SMACs will not cause serious or permanent effects but may cause reversible effects that do not impair judgment or interfere with proper responses to emergencies such as fires or accidental releases. Long-term SMACs (e.g., 7 day) are intended to avoid adverse health effects (either imme- diate or delayed) and to avoid degradation in crew performance with continuous exposure in a closed space-station environment. SMACs were developed for astronauts (healthy individuals).”24 22 Mausner, J.S., S. Kramer, and A.K. Bahn. 1985. Epidemiology: An Introductory Text, 2nd Ed. Philadelphia: W.B. Saunders Company. 23 NRC (National Research Council). 1986. Criteria and Methods for Preparing Emer- gency Exposure Guidance Level (EEGL), Short-Term Public Emergency Guidance Level (SPEGL), and Continuous Exposure Guidance Level (CEGL) Documents. Washington, DC: National Academy Press. 24 NRC (National Research Council). 1994. Spacecraft Maximum Allowable Concen- trations for Selected Airborne Contaminants, Vol. 1. Washington, DC: National Acad- emy Press.

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310 Exposure Guidance Levels for Selected Submarine Contaminants SMR See standardized mortality ratio. SPEGL See short-term public emergency guidance levels. Standardized mortality ratio (SMR) SMR is a measure of population health. It is calculated by taking the ratio of the number of deaths observed in the popu- lation of interest to the number of deaths expected on the basis of the mortality rates of a reference population. STEL See short-term exposure limit. Subchronic exposure An exposure lasting 2-13 weeks or 10% of the test ani- mal’s lifespan.3 Submarine escape action levels (SEALs) At concentrations below a SEAL 1, respiratory and central nervous system function should not be impaired enough to significantly affect the ability to escape or to be rescued, and crew members can remain in the submarine without wearing eye and respiratory protection (EABs) for up to 10 days. At and above SEAL 1, but below SEAL 2, respiratory and central nervous system effects should not be severe enough to hamper abil- ity to escape, and crew members would not be required to wear EABs but would plan to escape so that the last man leaves the submarine within 24 h. At and above a SEAL 2, unprotected exposure to the gas can result in impairment to respiratory and central nervous system function to an extent that the ability to escape would be compromised, and crew members should be required to wear EABs.7 2190 TEP Turbine oil. Threshold Limit Value (TLV) A TLV is the “concentration in air of a sub- stance to which it is believed that most workers can be exposed daily without adverse effect (the threshold between safe and dangerous concentrations). These values are established (and revised annually) by the American Conference of Governmental Industrial Hygienists and are time-weighted concentrations for a 7- or 8-hour workday and a 40-hour workweek.”18 Time-weighted average (TWA) Under OSHA regulations, a TWA is the aver- age concentration of a regulated chemical to which a worker may be repeatedly exposed during a conventional 8-hour workday and a 40-hour workweek with- out adverse effect.18 TLV See Threshold Limit Value. TWA See time-weighted average.

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Glossary 311 UF See uncertainty factor. Uncertainty factor (UF) A UF (e.g., 1, 2, 3, or 10) can be used when deriving human health risk reference values from experimental data to account for inter- or intraspecies differences, database gaps, extrapolations from high to low dose, or other adjustments required. Multiple UFs can be used in a calculation. A UF of 10 is considered to be a health-protective default value to be employed when little is known about a particular source of variability or uncertainty, such as intraspecies differences or lack of information on a relevant health effect. As additional research becomes available, UFs change as indicated by the new in- formation. Vent fog precipitator A system used in the submarine engine room to clear the air of oil mists. VOC See volatile organic compounds. Volatile organic compounds (VOCs) VOCs are organic chemicals that have high vapor pressure and easily form vapors at normal temperature and pressure.

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