ISSN:0271-3586    

DOI:10.1002/ajim.4700210102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0271-3586    

DOI:10.1002/ajim.4700210103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractExperimental animals are often used as surrogate models in estimating human cancer risk from environmental agents when adequate epidemiological data are not available. Studies in experimental animals have usually evaluated the effects of exposure to single substances; however, humans receive combinations of exposures, to both initiators and promoters of carcinogenesis. Exposure to several agents may modify the carcinogenic process of one of them. For many agents, the relationship between dose and carcinogenic response depends on both dose‐rate and cumulative dose. For a given total dose, dose‐rate may affect carcinogenic potency both qualitatively (target organ) and quantitatively. The effects of dose‐rate are a function of total dose, species, and, most importantly, the mechanism by which the agent exerts its carcinogenic effect. Prediction of the effects of different dose‐rates of potentially carcinogenic agents can be based on knowledge of its mechanism of

ISSN:0271-3586    

DOI:10.1002/ajim.4700210104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe nervous system differs from many other body organs by its central control of vital functions and its low regeneration capacity. Organic solvents have, as a group, been suspected to have neurotoxic effects. Because of their similar physical properties and the fact that in industrial uses, they are often present in various mixtures, organic solvents have also been regarded, unfortunately, to induce common neurotoxic effects.However, it is evident from experimental studies using specified exposure conditions that different organic solvents have very diverse neurotoxic effects and also that the toxic mechanism may differ between acute and chronic exposures. No specific method used to describe a neurotoxic effect or single toxic response can be used for the overall occupational risk assessment of all organic solvents. Each solvent has to be considered as having its own unique toxic effects.

ISSN:0271-3586    

DOI:10.1002/ajim.4700210105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractDose surrogates commonly used in occupational epidemiology are exposure intensity, exposure duration, and cumulative exposure. The appropriateness of any of these measures as dose indicators depends on the nature of the induction process for the disease under consideration. Peak exposure intensity is often associated with acute health outcomes, whereas cumulative exposure is generally more relevant for diseases with long induction times, i.e., “chronic” diseases. However, there may be situations where peak exposure is etiologically relevant in chronic disease induction, such as might occur with nonlinear rates of damage during brief intervals of very high exposure. An approach is described for evaluating the effect of peak exposures in which peaks may be defined on a relative basis for each worker, or with respect to an absolute value, such as the permissible occupational exposure limit. The analytic strategy is illustrated with data from a case‐control study of silicosis in relation to quantitative estimates of silica exposure. In this example, relative peak exposures and average non‐peak exposures appear to be better predictors of silicosis risk than cumulative e

ISSN:0271-3586    

DOI:10.1002/ajim.4700210106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractCumulative exposure (average intensity times duration) is one of the most common summary measures for exposure used in occupational epidemiology. Its utility for describing quantitative exposure‐effect relationships is based on several interlocking assumptions about the processes relating exposure to tissue dose, and tissue dose to adverse effects. The pharmacokinetic relationship between cumulative exposure and tissue dose was examined with models for two common exposures: inhalation of insoluble, respirable particles, and toxic metabolites of a nonpolar organic solvent. It was found that the assumption of a linear relationship between cumulative exposure and tissue dose was violated for typical exposure intensity for both substances. This caused strong nonlinear exposure‐tissue dose relationships and variability in the relationship. The findings provide a possible explanation for the common observation of a disproportionately high risk of pulmonary effects for workers with relatively short, intense dust exposures, and for the finding that workers exposed to metabolically activated organic agents have a risk that is related to years of exposure but not to intens

ISSN:0271-3586    

DOI:10.1002/ajim.4700210107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractQuantitative assessment of exposure intensity is a difficult process, particularly for jobs held long ago. Despite difficulties, the use of this approach is growing in occupational epidemiology because it is hoped that the estimates will more closely approximate delivered dose than more traditional measures such as duration of exposure. If this assumption is correct, development and use of quantitative exposure estimates should reduce nondifferential exposure misclassification, sharpen exposure‐response gradients, and enhance interpretation of study results. In this report, we used two methods to assess the value of quantitative exposure assessments in cancer epidemiology. In one, we surveyed the literature for investigations on occupational cancer that included assessments of both duration and intensity of exposure. The results of this survey indicated that exposure measures based on some measure of intensity of exposure yielded monotonically increasing exposure‐response gradients and larger relative risks more often than those based on duration of exposure. Duration of exposure, however, occasionally provided the larger relative risks. In another approach, we found that different measures of exposure to formaldehyde classified subjects quite differently. For example, duration of exposure was unrelated to average exposure and was only weakly associated with exposure intensity or peak exposure. Because different measures of exposure may classify subjects quite differently and because quantitative estimates usually, but not always, yield larger relative risks and sharper exposure‐response gradients than other measures of exposure, we believe that the prudent approach in epidemiologic investigations would be to develop quantitative estimates of exposure and to conduct analyses using several different measures of exposure, or combinations such as duration by intensity. Multiple comparisons would, however, increase chance findings. The value of such an approach is twofold. When a true association exists, use of several different measures decreases the chances of an unfortunate selection of an exposure measure that is poorly related to delivered dose, which would tend to produce negative results, and increases the chances of uncovering sharper exposure‐response gradients. Use of several exposure measures in investigations that fail to exhibit an association between exposure and disease would be of value because such an approach would provide greater confidence that negative findings were not simply due to exposure misclassif

ISSN:0271-3586    

DOI:10.1002/ajim.4700210108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractNew molecular methods have been developed to be used in assessing exposure to and effects of genotoxic and carcinogenic compounds. DNA and protein adducts are measures or surrogates of target dose. Molecular methods are available to probe mutations in oncogenes, antioncogenes, and other specific genes. Furthermore, concentrations of oncoproteins can be determined in biological fluids. If a close link is established between these markers and risk of cancer, they can be used as independent endpoints in the prevention of cancer.

ISSN:0271-3586    

DOI:10.1002/ajim.4700210109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThis report explores the importance of characterizing short‐term (peak) exposures for successful epidemiologic study of acute reversible effects. By selecting upper respiratory tract irritation, which is time‐limited, reversible, and not critically affected by host factor sensitivities, the illustrated approach (directed at an acute respiratory irritant) provides insights on issues important in the general study of acute effects. The fundamental concern in a study of acute irritant effects is that such events occur in response to abrupt increases in exposure. This calls for a closer examination of how to distinguish bursts, or peaks, of exposure from continuous exposures measured simply as time weighted averages. Three parameters of peak exposures are discussed: duration, magnitude, and frequency. The importance of duration is illustrated by contrasting exposure patterns relevant for the study of acute vs. chronic health effects. The minimum magnitude of a peak relevant to the study of a specific physiologic response requires knowledge of the threshold below which no detectable response occurs. For any identified threshold level, only exposures exceeding that level are defined as relevant peaks for an exposure‐response analysis. Finally, the issue of frequency, the minimum length of time between successive exposures necessary for the subject to return to baseline risk, is explored. A study of respiratory irritation associated with sodium borates is used to illustrate these i

ISSN:0271-3586    

DOI:10.1002/ajim.4700210110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe ergonomic field is rather new to epidemiology and ergonomists are usually without knowledge in epidemiology. This review presents exposure variables used in ergonomic epidemiology, especially those that concern mechanical trauma to the musculoskeletal system at the workplace and suggests how to approach exposure definition, exposure assessment, and exposure evaluation. The exposure variables that define the exposure can be divided into five main categories: posture, motion/repetition, material handling, work organization, and external factors. There is no consensus on how different exposure variables should be pooled and interpreted as single estimates of cumulative exposure. For future ergonomic epidemiology, it is suggested that exposure be described by different exposure variables giving an exposure profile and not by a single estimate of the exposure. The possibly short time‐response relationship for many work‐related musculoskeletal disorders provides a challenge in evaluating different cumulative exposure measures. These measures could easily turn into effective hazard surveillance tools. Large etiological fractions found for some musculoskeletal diseases indicate a great potential for ergonomic interventi

ISSN:0271-3586    

DOI:10.1002/ajim.4700210111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY