Cost of Environmental-Related Health Effects A Plan for Continuing Study (1981) / Chapter Skim
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Chapter 3: Information Needed to Assess and Quantify Health Effects
Chapter 3: Information Needed to Assess and Quantify Health Effects
Pages 49-76
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From page 49... ...
. Although this committee suggests that the ongoing study focus on the health effects resulting from involuntary exposure to physical and chemical pollutants, it will often be necessary to consider additional factors such as life-style factors and socioeconomic status.
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From page 50... ...
They provide information on real people in a real environment and, therefore, are particularly useful for purposes of the ongoing study. The necessary use of observational investigation in most human epidemiologic studies means that such studies generally are not useful for predicting health effects before chemical or physical agents are introduced.
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From page 51... ...
Some difficulties can be overcome by study design and by collecting data on particular populations, such as workers or susceptible groups, and by taking advantage of accidental events that lead to high levels of exposure. RISK EXTRAPOLATION FROM NON-HUMAN DATA Most environmental hazards have been ;denti fled after they caused human illness or disease.
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From page 52... ...
~ harmful effects were detected in animal studies before such effects were recognized in human beings. Animal tests are widely used for detecting acute effects of substances .
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From page 53... ...
Much medical research is needed -- from fundamental molecular biology to more immediately applicable medical and public health practices -- in order to develop a theoretical basis for predicting possible human health effects from studies on non-human test systems. Improved understanding of the ways in which environmental agents affect different biological systems should provide a basis for developing less costly and more rapid tests to estimate human risk.
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From page 54... ...
Clinical documentation of human disease that disease permits more secure generalization EPIDEMIOLOGIC STUDIES The relevance of epidemiologic principles and methods to the ongoing study is evident from the common definition of epidemiology -- the study of the distribution and determinants of disease frequency in human populations. The unit of study -- human populations -- is emphasized.
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From page 55... ...
In the Community Health and Environmental Surveillance System (CHESS) and in the Six City Study, a group of communities was selected to represent an exposure gradient for designated pollutants so as to use the cross-sectional design as one of the study strategies.24-26 The surveys on health status of the U.S.
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From page 56... ...
One example of a cohort study is the Atomic Bomb Casualty Commission's study of the Japanese populations exposed to radiation in Hiroshima and Nagasaki, a study that has continued for more than 35 years.28 a less expensive technique that can be used to establish a cohort involves linking data that have already been collected on individuals for other purposes. For example, in England a 1 percent sample of the population is followed longitudinally by linking various records of individuals in order to study occupational health.29~30 Establishing Causal Relationships If~associations are demonstrated by rigorous unbiased epidemiologic studies, then the problem is to demonstrate a cause and effect relationship between a particular entity in the environment and a particular health effect.
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From page 57... ...
Almost all diseases of interest have multiple causes, and specific exposures generally are accompanied by a multiplicity of health consequences. ~ slightly different but similar approach to that above for establishing causality for environment-related health effects has been proposed by Hackney and Linn.31 They updated Koch's postulates to apply to modern problems of environmentally caused health effects.
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From page 58... ...
Such studies are often done by linking records of various kinds, such as birth records, death records, social security and health records, to obtain information from different sources. One very successful example of linking data on individuals to study occupational health is the 1 percent sample studies in Britain which define the cohort to be followed over time.29~30 In the United States, linking data on individuals in one data set with information on the same individual in another data set would be greatly facilitated by the use of a "person number" or a unique personal identifier.
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From page 59... ...
Complete Population and Integrated Environmental Surveillance The identification of all exposures and all disease episodes among all individuals would provide the totality of observational information available to identify environmental hazard-disease relationships. Although there are no instances of total surveillance, attempts have been made to implement portions of a general system through the use of population registries, disease registries, and environmental monitoring systems.
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From page 60... ...
As two examples, CHESS and the Six City Study have measured air quality of communities and selected respiratory symptoms in resident children and adults.24-26 In contrast to the specific environmental measurements, community orientation, and concurrent ascertainment of acute symptoms of these two studies, environmental epidemiologic studies often have to rely on estimations of exposures, sketchy work histories, and poorly documented subsequent disease that may not manifest itself for decades after exposure. Survey Samples There have been attempts to achieve more limited objectives than the goals of complete population and integrated environmental surveillance, by use of information derived from samples of environmental measurements and targeted surveys of subsets of the population.
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From page 61... ...
adequate workplace measurement of actual exposures, which includes generic names of chemicals and physical agents and data on exposure, duration, and severity c) lifetime exposure records for any worker exposed d)
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From page 62... ...
Despite many difficulties, occupational diseases and illnesses appear more amenable to surveillance than do health effects caused by non-occupational exposures to hazards in the general environment. The major methodologic advantages of conducting morbidity and death surveillance in occupationally exposed populations are the exposed populations can, on the basis of personnel, Social Security, and other record systems be identified, delimited, and to some extent followed.
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From page 63... ...
Limitations in the sample size and the present age of the data notwithstanding, the NOHS continues to be the main data resource used by government, labor, and medical care providers on the type, extent, and distribution of potential workplace hazards. Data from NOUS I are now at least six years old.
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From page 64... ...
hazards, as required for the ongoing study. Effects of Acute Environmental Exposures Such episodes as nuclear reactor accidents, chemical spills, and leaks of toxic wastes may cause the acute exposure of populations to environmental contaminants that affect health or result in chronic exposure that raises public concern acutely.
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From page 65... ...
It would be helpful if the responsible agency also coordinated health data collection among the many state and federal agencies with interest in the management of toxic environmental emergencies. The function of the response team would be to collect environmental, epidemiologic, and clinical data on acute environmental episodes to enable reliable estimates of the number of persons affected, and the establishment of further determination of dose/response and cause and effect relationships between exposures and subsequent health problems.
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From page 66... ...
Future follow-up of such registries, including follow-up through the National Death Index, would enable future estimation of the incidence of delayed disease resulting from acute environmental exposures. For both the acute and long-term phases of these evaluations, appropriate comparisons must be made to unexposed control groups.50 The results of too many acute environmental studies have been vitiated by failure to employ adequate epidemiologic methodology of this kind.
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From page 67... ...
However, the mechanisms responsible for differential susceptibility to toxic environmental agents are known for only a few predisposing conditions and substances. Moreover, attempts to estimate the costs of environment-related health effects for a population usually are based on data derived from studies that assume homogeneous populations.
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From page 68... ...
Furthermore, ingestion of the fava bean will damage red blood cells in males who carry the Mediterranean variant of C~5PD deficiency, but will generally have no detectable clinical effect on males who have the African variant. This mutation is quite common, with, for example, in the United States approximately 12 percent of black males of African descent having G6PD deficiency.
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From page 69... ...
Environmental agents may affect reproduction in males and females in many ways. They could affect fertility, diminish libido or sexual function, promote impotence, or otherwise impair reproductive ability by adversely affecting the reproductive cycle or contri but i ng to de fec t ive or i nsu fficient spermatogenesis or oogenesi s .
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From page 70... ...
In order for the ongoing study to be able to calculate the costs of reproductive effects of environmental agents, a great deal more information will be needed.60 High risk populations, including occupational cohorts, should be identified and monitored for point mutations, chromosome aberrations, abortions, stillbirths, birth weight, and congenital malformations. It would be useful to have sentinel indices and in vitro tests for assessing different levels of reproductive failure and for predicting the pathogenetic potential of environmental agents.
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From page 71... ...
Eco-genetics genetic variation in susceptibility to environmental agents. In Genetic Issues in Public Health and Medicine, pp.
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From page 72... ...
New York Plenum Publishing Corporation, 19 7 8 .
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From page 73... ...
Reflections on the work of the Atomic Bomb Casualty Commission in Japan. Epidemiologic Reviews 1~184-209, 1979.
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From page 74... ...
and Wegman, D.H. Exploring the use of death certificates as a component of an occupational health surveillance system.
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From page 75... ...
The effects of toxic agents on reproduction. Occupational Health and Safety 48:36-43, 1979.
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From page 76... ...
59. Herbst' A.L., Ulfelder, H., and Poskanzer, D.C.
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