PROCEEDINGS OF THE EXPERT PANEL WORKSHOP
TO EVALUATE THE PUBLIC HEALTH IMPLICATIONS
FOR THE TREATMENT AND DISPOSAL OF POLYCHLORINATED BIPHENYLS-
CONTAMINATED WASTE
Chapter 2 - Expert Panel Report
Health Effects Panel (Cont'd)
These recommendations are presented for consideration by ATSDR, other public health agencies, and research organizations. Unless specifically noted, they are not intended for any particular organization.
Follow up existing cohorts for more complete evaluation of causes of mortality. Add morbidity evaluations when feasible.
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Appendix A. Health Effects Panel Biosketches
The following persons were members of the Health Effects Panel. Although their participation included reviews of the individual draft reports pertaining to their panel, this does not imply their endorsement of the final written panel report or support for the conclusions derived in the report.
CHAIR: James M. Melius, M.D., Dr.P.H.
Director, Division of Occupational Health
and Environmental Epidemiology
New York State Department of Health
Graduated from University of Illinois, School of Medicine, 1974. Received board certification in family practice and occupational medicine. Received Doctorate of Public Health in Epidemiology from the University of Illinois, School of Public Health, 1984.
Worked for the National Institute for Occupational Safety and Health (NIOSH) in Cincinnati, Ohio, from January 1980 to June 1987. Directed the Division of Surveillance, Hazard Evaluations and Field Studies, a large research group that conducted occupational medical and epidemiologic studies, the last 2 years at NIOSH.
Worked as a medical consultant in the Division of Environmental Health Assessment, New York
State Department of Health, June 1987. Appointed Director of the Division of Occupational
Health and Environmental Epidemiology, January 1988. Appointed Professor of Environmental
Health and Toxicology, School of Public Health of the State University of New York at Albany,
May 1990. Currently serves on the Study Section for Occupational Health for the National
Institutes of Health and has recently been a member of three National Academy of Sciences
committees.
RAPPORTEUR: Greg Steele, Dr.P.H., M.P.H.
Environmental Epidemiologist
Indiana State Department of Health
Doctor of Public Health, University of Alabama-Birmingham, School of Public Health,
Epidemiology, 1991. Environmental Epidemiologist, Epidemiology Resource Center, Indiana
State Department of Health, Indianapolis, Indiana, 1983 to present. Association of State and
Territorial Health Officials, Consultant to the Environmental Committee, 1987-1992.
Henry A. Anderson, M.D.
Chief Medical Officer, Occupational & Environmental Health
Wisconsin Division of Health
Chief Medical Officer from October 1991 to present. State Epidemiologist for Occupational and
Environmental Disease, Wisconsin Division of Health, Madison, June 1980 to present. M.D.,
University of Wisconsin Medical School, Madison, 1972. American Board of Preventive
Medicine, Subspecialty: occupational and environmental medicine, 1977. Chairperson, Council
of State and Territorial Epidemiologists (CSTE)-Section of Occupational, Environmental Health,
1982-1988. President, Wisconsin Preventive Medicine Society, 1986 to present. Associate
Editor, American Journal of Industrial Medicine.
Jean D. Brender, R.N., Ph.D.
Director, Noncommunicable Disease Epidemiology and Toxicology Division
Texas Department of Health
University of Washington School of Public Health, Ph.D., Epidemiology (Noninfectious disease epidemiology), 1983. Director, Environmental Epidemiology Program, Texas Department of Health, Austin, Texas, 1987-1993. Presently Director, Noncommunicable Disease Epidemiology and Toxicology Division, Texas Department of Health, and State Environmental Epidemiologist.
Dorothy A. Canter, Ph.D.
Science Advisor, Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency
George Washington University, Ph.D., Biophysics, May 1974. Assistant to the Director,
National Toxicology Program, 1980-1990. Science Advisor, Office of Solid Waste and
Emergency Response, Environmental Protection Agency, March 1990 to present.
Theodora Emily Colborn, Ph.D.
Senior Fellow, World Wildlife Fund, Inc.
Senior Fellow, World Wildlife Fund, 1989-1993. Senior Fellow, The Conservation Foundation,
Washington, D.C., 1987-1988. Congressional Fellow, Office of Technology Assessment,
1985-1987. University of Wisconsin-Madison, Ph.D. Zoology (distributed minor in
epidemiology, toxicology, and water chemistry), 1985.
Joe G.N. Garcia, M.D.
Professor of Medicine, Physiology, Biophysics
Director, Indiana University Occupational Lung Center
Indiana University School of Medicine
Graduated University of Texas Southwestern Medical School, M.D., Dallas, Texas. Residency
in Internal Medicine, University of Iowa. Board Certification in Internal Medicine, Pulmonary
Medicine, and Critical Care Medicine. Director of Occupational Medicine, University of Texas
at Tyler, 1985-1988. Director of the Occupational Lung Center, Indiana School of Medicine,
1988-1993. Calvin H. English Investigator in Medicine, 1989 to present. Presently at Wishard
Memorial Hospital, Division of Pulmonary and Critical Care Medicine.
Stephen B. Hamilton, Jr., Ph.D.
Manager, Environmental Science and Technology
General Electric Corporation
Doctor of Philosophy (Ph.D.) degree-Organic Chemistry, Northwestern University, 1959. Manager of Environmental Science and Technology, GE Corporate Environmental Programs, 1981 to present. Honors, Fulbright Fellow, 1959-1960. Special interests and competence: synthesis of organic compounds and intermediates, organic chemistry mechanisms, human health effects and toxicology of PCBs, especially individual PCB congeners, environmental fate of PCBs, PCB destruction research.
George W. Lucier, Ph.D.
Chief, Laboratory of Biochemical Risk Analysis
National Institute of Environmental Health Sciences
Ph.D. (Entomology), University of Maryland, June 1970. National Institute of Environmental
Health Sciences, Research Triangle Park, North Carolina, 1970 to present. Chief, Laboratory of
Biochemical Risk Analysis, Division of Biometry and Risk Assessment, 1984 to present.
Co-Editor, Environmental Health Perspectives, National Institute of Environmental Health
Sciences, 1973 to present.
Mitchell Singal, M.D., M.P.H.
Medical Officer
National Institute for Occupational Safety and Health
M.D., Wayne State University, Detroit, Michigan, May 1969. M.P.H. (major in Environmental
Health Sciences), University of California, Berkeley, June 1974. Medical Officer, Hazard
Evaluations and Technical Assistance Branch, National Institute for Occupational Safety and
Health, Cincinnati, Ohio, July 1977 to present. Senior Medial Officer, April 1991 to present.
Specialty Board Certification (American Board of Preventive Medicine), General Preventive
Medicine, 1976. Occupational Medicine, 1980.
CO-CHAIR: Lee M. Sanderson, Ph.D.
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Currently Senior Epidemiologist, Division of Health Assessment and Consultation, Agency for
Toxic Substances and Disease Registry. Epidemiology, Ph.D., University of Texas School of
Public Health, Houston, Texas, 1981.
CO-CHAIR: Obaid M. Faroon, Ph.D., D.V.M.
Division of Toxicology
Agency for Toxic Substances and Disease Registry
Environmental Health Scientist, Agency for Toxic Substances and Disease Registry, 1991 to
present. Ph.D., Histology and Pathology, College of Veterinary Medicine, The University of
Tennessee, Knoxville, Tennessee. D.V.M., School of Veterinary Medicine, The University of
Baghdad, 1976.
I. Introduction
The Agency for Toxic Substances and Disease Registry will convene three expert panels at a workshop to address PCB-related health issues. As one of the three, the Health Effects Panel will discuss the current knowledge of health effects associated with exposures to PCBs and make recommendations to better determine the public health implications associated with the remediation of PCB-contaminated soils and other waste materials. The Health Effects Panel is a multidisciplinary group of scientists who have expertise in toxicology, medicine, epidemiology, and environmental science.
The purpose of this document is to identify current issues and questions that will serve as an outline for the discussions of the Health Effects Panel and as a catalyst for formulating appropriate recommendations. These questions and issues were identified by the Chair, Rapporteur, and Co-chairs of the Health Effects Panel. The background and foundation for these specific questions and issues are included in a separate draft document entitled "Background Discussion Paper for the PCB Health Effects Panel: Summary of Health Effects associated with PCBs."
II. General Overview
III. Cancer Outcomes
IV. Reproductive/Developmental Effects
V. Neurologic Effects
VI. Other Effects
VII. Conclusions, Data Gaps, and Recommendations
Acute Exposure -- Exposure to a chemical for a duration of 14 days or less, as specified in the Toxicological Profiles.
Adjustment -- A summarizing procedure for rates or measures of association in which the effects of differences in composition for variable(s) among populations being compared have been removed by mathematical procedures. Age is the variable for which adjustment is most often carried out.
Adsorption Coefficient (Koc) -- The ratio of the amount of a chemical adsorbed per unit weight of organic carbon in the soil or sediment to the concentration of the chemical in solution at equilibrium.
Adsorption Ratio (Kd) -- The amount of a chemical adsorbed by a sediment or soil (i.e., the solid phase) divided by the amount of chemical in the solution phase, which is in equilibrium with the solid phase, at a fixed solid/solution ratio. It is generally expressed in micrograms of chemical absorbed per gram of soil or sediment.
Age-Specific Rate -- A rate for a specified age group. The numerator (number of cases or persons with disease) and denominator (number of persons) refer to the same age group.
Association -- The degree of statistical dependence between two or more events or variables. Events are said to be associated when they occur more frequently together than one would expect by chance. Association does not necessarily imply a causal relationship. Statistical significance testing enables us to determine how unlikely it would be to observe the sample relationship by chance if in fact no association exists in the population that was sampled.
Bias -- Any effect at any stage of investigation or inference tending to produce results that depart systematically from the true values (to be distinguished from "random error").
Bioconcentration Factor (BCF) -- The quotient of the concentration of a chemical in aquatic organisms at a specific time or during a discrete time period of exposure divided by the concentration in the surrounding water at the same time or during the same period.
Birth Certificate -- Official, legal document recording details of a live birth, usually comprising name, date, place, identity of parents, and sometimes additional information such as birth weight. It provides the basis for vital statistics of birth and birth rates in a political or administrative jurisdiction, and is the denominator for infant mortality and certain other vital rates.
Cancer Effect Level -- The lowest dose of chemical in a study, or group of studies, that produces significant increases in the incidence of cancer (or tumors) between the exposed population and its appropriate control.
Carcinogen -- A chemical capable of inducing cancer.
Case -- In epidemiology, a person in the population or study group identified as having the particular disease, health disorder, or condition under investigation. A variety of criteria may be used to identify cases, e.g., individual physician diagnoses, registries and notifications, abstracts of clinical records, surveys of the general population, population screening, and reporting of defects such as in a dental record. The epidemiological definition of a case is not necessarily the same as the ordinary clinical definition.
Case-control Study -- Persons with a specific disease (cases) are compared to persons without that disease (controls or comparisons) to evaluate differences in potential risk factors or determinants of disease. When a case-control study demonstrates that cases have been exposed to a presumed risk factor significantly more often than controls, it is possible to estimate the approximate relative risk associated with exposure.
Cause-specific Rate -- A rate that specifies events, such as deaths, according to their cause.
Ceiling Value -- A concentration of a substance that should not be exceeded, even instantaneously.
Chronic Exposure -- Exposure to a chemical for 365 days or more, as specified in the Toxicological Profiles.
Cohort study -- A defined group of peoples with varying levels of exposure are followed over a period of time sufficient to allow health outcomes of interest to occur. Numbers or rates of cause-specific disease or death are calculated for members of the cohort and compared to what would be expected based upon a pre-determined "standard" population.
Confounding [from the Latin "confundere," to mix together] -- A situation in which the effects? of two processes are not separated. In other words, it is the distortion of an apparent effect of an exposure on risk brought about by the association with other factors that can influence the outcome.
Confounding variable (or confounder ) -- A factor that distorts the apparent magnitude of the effect of a study factor on risk. Such a factor is a determinant of the outcome of interest and is unequally distributed among the exposed and the unexposed.
Congener -- A chemical compound closely related to another in composition and exerting similar or antagonistic effects, or something derived from the same source or stock.
Death Certificate -- A vital record signed by a licensed physician or, in some nations, by another designated health worker, that includes cause of death, decedent's name, sex, birth date and place of residence and of death. Occupation, birthplace, and other information may be included. Immediate cause of death is recorded on the first line, followed by conditions giving rise to the immediate cause; the underlying cause is entered last.
Denominator -- The population (or population experience, as in person-years, passenger-miles, etc.) at risk in the calculation of a rate or ratio. The lower portion of a fraction used to calculate a rate or ratio.
Developmental Toxicity -- The occurrence of adverse effects on the developing organism that may result from exposure to a chemical before conception (either parent), during prenatal development, or postnatally to the time of sexual maturation. Adverse developmental effects may be detected at any point in the life span of the organism.
Embryotoxicity and Fetotoxicity -- Any toxic effect on the conceptus as a result of prenatal exposure to a chemical; the distinguishing feature between the two terms is the stage of development during which the insult occurred. The terms, as used here, include malformations and variations, altered growth, and in utero death.
EPA Health Advisory -- An estimate of acceptable drinking water levels for a chemical substance based on health effects information. A health advisory is not a legally enforceable federal standard, but serves as technical guidance to assist federal, state, and local officials.
Epidemiology -- The study of the distribution and determinants of health-related states and events in populations, and the application of this study to control of health problems.
Immediately Dangerous to Life or Health (IDLH) -- The maximum environmental concentration of a contaminant from which one could escape within 30 minutes without any escape-impairing symptoms or irreversible health effects.
Immunologic Toxicity -- The occurrence of adverse effects on the immune system that may result from exposure to environmental agents such as chemicals.
Incidence -- The number of instances of illness commencing, or of persons falling ill, during a given period in a specified population. More generally, the number of new events, e.g., new cases of a disease in a defined population, within a specified period of time. The term incidence is sometimes used to denote INCIDENCE RATE.
Incidence Rate -- A measure of the rate at which new events occur in the population. The number of new events, e.g., new cases of a specified disease diagnosed or reported during a defined period of time, is the numerator, and the number of persons in the stated population in which cases occurred is the denominator.
Intermediate Exposure -- Exposure to a chemical for a duration of 15-364 days, as specified in the Toxicological Profiles.
International Classification of Diseases (ICD) -- The classification of specific conditions and groups of conditions determined by an internationally representative group of experts who advise the World Health Organization, which publishes the complete list in a periodically revised book, the Manual of the International Statistical Classification of Diseases, Injuries and Causes of Death. Every disease entity is assigned a number. There are 17 major divisions (chapters) and a hierarchical arrangement of subdivisions (rubrics) within each. The Ninth Revision of the Manual (ICD-9) was published by WHO in 1977, after ratification in 1976.
In Vitro -- Isolated from the living organism and artificially maintained, as in a test tube.
In Vivo -- Occurring within the living organism.
Isomerism -- The relationship that exists between two or more different chemical compounds that have the same molecular formula; the compounds are isomers of each other.
Latent Period (or latency) -- Delay between exposure to a disease-causing agent and the appearance of manifestations of the disease. After exposure to ionizing radiation, for instance, there is a latent period of 5 years, on average, before development of leukemia, and a latent period of more than 20 years before development of certain malignant conditions. The term "latent period" is often used synonymously with "induction period," that is, the period between exposure to a disease-causing agent and the appearance of manifestations of the disease. It has also been defined as the period from disease initiation to disease detection.
Lethal Concentration(LO) (LCLO) -- The lowest concentration of a chemical in air that has been reported to have caused death in humans or animals.
Lethal Concentration(50) (LC50) -- A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.
Lethal Dose(LO) (LDLO) -- The lowest dose of a chemical introduced by a route other than inhalation that is expected to have caused death in humans or animals.
Lethal Dose(50) (LD50) -- The dose of a chemical that has been calculated to cause death in 50% of a defined experimental animal population.
Lethal Time(50) (LT50) -- A calculated period of time within which a specific concentration of a chemical is expected to cause death in 50% of a defined experimental animal population.
Lowest-Observed-Adverse-Effect Level (LOAEL) -- The lowest dose of chemical in a study, or group of studies, that produces statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control.
Malformations -- Permanent structural changes that may adversely affect survival, development, or function.
Minimal Risk Level -- An estimate of daily human exposure to a dose of a chemical that is likely to be without an appreciable risk of adverse non-cancer effects over a specified duration of exposure.
Morbidity -- Any departure, subjective or objective, from a state of physiological or psychological well-being. In this sense, sickness, illness, and morbid condition are similarly defined and synonymous.
Morbidity Rate -- A term used indiscriminately to refer to incidence or prevalence rates of disease.
Mortality Rate -- A rate expressing the proportion of a population who die of disease, or of all causes. The numerator is the number of persons dying; the denominator is the total population (usually mid-year population) in which the deaths occurred. The unit of time is usually a calendar year. To produce a rate that is a manageable whole number, the fraction is usually multiplied by 1,000 to produce a rate per 1,000. The rate is also called the "crude death rate."
Mortality Statistics -- Statistical tables compiled from the information contained in DEATH CERTIFICATES. Most administrative jurisdictions in all nations produce tables of mortality statistics. These may be published at regular intervals; they usually show numbers of deaths or rates of death, or both, by age, sex, cause, and sometimes other variables.
Mutagen -- A substance that causes mutations. A mutation is a change in the genetic material in a body cell. Mutations can lead to birth defects, miscarriages, or cancer.
Neurotoxicity -- The occurrence of adverse effects on the nervous system following exposure to a chemical.
No-Observed-Adverse-Effect Level (NOAEL) -- The dose of chemical at which there were no statistically or biologically significant increases in frequency or severity of adverse effects seen between the exposed population and its appropriate control. Effects may be produced at this dose, but they are not considered adverse.
Octanol-Water Partition Coefficient (Kow) -- The equilibrium ratio of the concentrations of a chemical in n-octanol and water, in dilute solution.
Permissible Exposure Limit (PEL) -- An allowable exposure level in workplace air averaged over an 8-hour workday.
Prevalence -- The number of instances of a given disease or other condition in a given population at a designated time; sometimes used to mean PREVALENCE RATE. When used without qualification, the term usually refers to the situation at a specified point in time (point prevalence).
Prevalence Rate (Ratio) -- The total number of all individuals who have an attribute or disease at a particular time (or during a particular period) divided by the population at risk of having the attribute or disease at this point in time or midway through the period. A problem may arise with calculating period prevalence rates because of the difficulty of defining the most appropriate denominator.
q1* -- The upper-bound estimate of the low-dose slope of the dose-response curve as determined by the multistage procedure. The q1* can be used to calculate an estimate of carcinogenic potency, the incremental excess cancer risk per unit of exposure (usually µg/L for water, mg/kg/day for food, and µg/m3 for air).
Reference Dose (RfD) -- An estimate (with uncertainty spanning perhaps an order of magnitude) of the daily exposure of the human population to a potential hazard that is likely to be without risk of deleterious effects during a lifetime. The RfD is operationally derived from the NOAEL (from animal and human studies) by a consistent application of uncertainty factors that reflect various types of data used to estimate RfDs and an additional modifying factor, which is based on a professional judgment of the entire database on the chemical. The RfDs are not applicable to non-threshold effects such as cancer.
Reportable Quantity (RQ) -- The quantity of a hazardous substance that is considered reportable under CERCLA. Reportable quantities are (1) 1 pound or greater or (2) for selected substances, an amount established by regulation either under CERCLA or under Section 311 of the Clean Water Act. Quantities are measured over a 24-hour period.
Reproductive Toxicity -- The occurrence of adverse effects on the reproductive system that may result from exposure to a chemical. The toxicity may be directed to the reproductive organs or the related endocrine system or both. The manifestation of such toxicity may be noted as alterations in sexual behavior, fertility, pregnancy outcomes, or modifications in other functions that depend on the integrity of this system.
Risk -- A probability that an event will occur, e.g., that an individual will become ill or die within a stated period of time or at a particular age. Also, a nontechnical term encompassing a variety of measures of the probability of a (generally) unfavorable outcome.
Short-Term Exposure Limit (STEL) -- The maximum concentration to which workers can be exposed for up to 15 minutes continually. No more than four excursions are allowed per day, and there must be at least 60 minutes between exposure periods. The daily TLV-TWA may not be exceeded.
Standardized Mortality Ratio (SMR) -- The ratio of the number of deaths observed in the study population to the number of deaths expected if it had the same rate structure as the standard population.
Statistical Significance -- Statistical methods allow an estimate to be made of the probability of the observed or greater degree of association between independent and dependent variables under the null hypothesis. From this estimate, in a sample of given size, the statistical "significance" of a result can be stated. Usually the level of statistical significance is stated in the P value.
Stratification -- The process of or result of separating a sample into several subsamples according to specified criteria such as age groups, socioeconomic status, etc. The effect of confounding variables may be controlled by stratifying the analysis of results. For example, lung cancer is known to be associated with smoking. To examine the possible association between urban atmospheric pollution and lung cancer, controlling for smoking, the population may be divided into strata according to smoking status.
Target Organ Toxicity -- This term covers a broad range of adverse effects on target organs or physiologic systems (e.g., renal, cardiovascular) extending from those arising through a single limited exposure to those assumed over a lifetime of exposure to a chemical.
Teratogen -- A chemical that causes structural defects that affect the development of an organism.
Threshold Limit Value (TLV) -- A concentration of a substance to which most workers can be exposed without adverse effect. The TLV may be expressed as a TWA, as an STEL, or as a CL.
Time-Weighted Average (TWA) -- An allowable exposure concentration averaged over a normal 8-hour workday or 40-hour workweek.
Toxic Dose (TD50) -- A calculated dose of a chemical, introduced by a route other than inhalation, which is expected to cause a specific toxic effect in 50% of a defined experimental animal population.
Uncertainty Factor (UF) -- A factor used in operationally deriving the RfD from experimental data. UFs are intended to account for (1) the variation in sensitivity among the members of the human population, (2) the uncertainty in extrapolating animal data to the case of humans, (3) the uncertainty in extrapolating from data obtained in a study that is of less than lifetime exposure, and (4) the uncertainty in using LOAEL data rather than NOAEL data. Usually each of these factors is set equal to 10.
Sources
ATSDR. 1993. Toxicological Profile for Selected PCBs (update). Atlanta: ATSDR/TP-92/16.
Last J, ed. 1983. A Dictionary of Epidemiology. New York: Oxford University Press.
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