ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00664.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00665.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Recent trends indicate that vehicle miles traveled for large trucks is increasing at a higher rate than for other vehicles. The resulting competition between large trucks and other vehicles for highway space can be expected to result in more multivehicle collisions involving large trucks. This paper presents the result of an investigation of the causes and the mechanism related to large vehicle accidents. A fault‐tree analysis of large vehicle accidents identifies the individual roles played by driver, vehicle, and environmental factors, as well as their interactions in the accident mechanism. Using accident data for 1984‐1986, the probabilities for different basic events in the fault tree were assessed. The most likely events leading to a large vehicle accident, as well as the most effective counter measures, were then identified. The result indicate that the most prevalent form of accidents due to driver‐related failures is when a normal driver makes an error in judgment and is unsuccessful in his or her evasive action. For vehicle‐related failures, the predominant type of failure is equipment failure, and for environmental‐related failures, excessive demand on driver and vehicle performance created by the environmental or roadwa

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00666.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

There has been an increasing interest in physiologically based pharmacokinetic (PBPK)models in the area of risk assessment. The use of these models raises two important issues: (1)How good are PBPK models for predicting experimental kinetic data? (2)How is the variability in the model output affected by the number of parameters and the structure of the model? To examine these issues, we compared a five‐compartment PBPK model, a three‐compartment PBPK model, and nonphysiological compartmental models of benzene pharmacokinetics. Monte Carlo simulations were used to take into account the variability of the parameters. The models were fitted to three sets of experimental data and a hypothetical experiment was simulated with each model to provide a uniform basis for comparison. Two main results are presented: (1)the difference is larger between the predictions of the same model fitted to different data se1ts than between the predictions of different models fitted to the dame data; and (2)the type of data used to fit the model has a larger effect on the variability of the predictions than the type of model and the number of paramet

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00667.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A common strategy in estimation is to decompose the quantity being estimated into several factors, estimate a value for each factor, and then reaggregate these values to obtain an overall estimate. Until now, the extent of decomposition to use has been considered largely a matter of judgment. However, both the extent of decomposition and the manner in which the results are reaggregated can have a significant effect on the resulting estimate. This paper discusses factors affecting the optimum level of decomposition, and presents examples showing that the use of nonoptimal decomposition strategies can lead to significant inaccuracies.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00668.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Human beings have always been intuitive toxicologists, relying on their senses of sight, taste, and smell to detect harmful or unsafe food, water, and air. As we have come to recognize that our senses are not adequate to assess the dangers inherent in exposure to a chemical substance, we have created the sciences of toxicology and risk assessment to perform this function. Yet despite this great effort to overcome the limitations of intuitive toxicology, it has become evident that even our best scientific methods still depend heavily on extrapolations and judgments in order to infer human health risks from animal data. Many observers have acknowledged the inherent subjectivity in the assessment of chemical risks and have indicated a need to examine the subjective or intuitive elements of expert and lay risk judgments. We have begun such an examination by surveying members of the Society of Toxicology and the lay public about basic toxicological concepts, assumptions, and interpretations. Our results demonstrate large differences between toxicologists and laypeople, as well as differences between toxicologists working in industry, academia, and government. In addition, we find that toxicologists are sharply divided in their opinions about the ability to predict a chemical's effect on human health on the basis of animal studies. We argue that these results place the problems of risk communication in a new light. Although the survey identifies misconceptions that experts should clarify for the public, it also suggests that controversies over chemical risks may be fueled as much by limitations of the science of risk assessment and disagreements among experts as by public misconceptions.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00669.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A strategy for sampling of animal tissues and a statistical approach for analyzing data on body burdens of a parent chemical and its metabolites is presented such that the data may be evaluated in relation to the detection limit(s)of the analytical techniques used and the criterion levels established for acceptable tissue concentrations.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00670.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

This paper presents the results of a study that identified how often a probabilistic risk assessment (PRA)should be updated to accommodate the changes that take place at nuclear power plants. Based on a 7‐year analysis of design and procedural changes at one plant, we consider 5 years to be the maximum interval for updating PRAs. This conclusion is preliminary because it is based on the review of changes that occurred at a single plant, and it addresses only PRAs that involve a Level 1 analysis (i.e., a PRA including calculation of core damage frequency only). Nevertheless, this conclusion indicates that maintaining a useful PRA requires periodic updating efforts. However, the need for this periodic update stems only partly from the number of changes that can be expected to take place at nuclear power plants–changes that individually have only a moderate to minor impact on the PRA, but whose combined impact is substantial and necessitates a PRA update. Additionally, a comparison of two generations of PRAs performed about 5 years apart indicates that PRAs must be periodically updated to reflect the evolution of PRA methods. The most desirable updating interval depends on these two technical considerations as well as the cost of updating the PRA. (Cost considerations, however, were beyond the scope of this stu

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00671.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

When a buyer needs to purchase commercial or industrial property, the decision of what real estate to purchase should be based on an assessment of the total costs of acquisition. In addition to the direct purchase cost, other possible costs include hazardous waste site assessment studies and clean up costs if the purchased site proves to be contaminated. This paper presents a decision analysis model for determining when and which type of hazardous waste assessment tests should be conducted and how the test output affects the choice of site. The model assumes there are two types of hazardous waste assessment, an historical use review (phase 1 test)and soil and water sampling (phase 2 test). Model inputs include the cost, sensitivity and specificity for each type of test, a site's purchase price, anda prioriprobability of contamination, along with the clean‐up cost for a contaminated site. The analysis uses the results of a data survey of 17 environmental engineering firms in setting values on the model input requirements. The paper also reports on sensitivity analysis with the model for the purpose of providing decision‐makers with explicit protocols for test utilizat

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00672.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The extent of carcinogen regulation under existing U.S. environmental statutes is assessed by developing measures of the scope and stringency of regulation. While concern about cancer risk has played an important political role in obtaining support for pollution control programs, it has not provided the predominant rationale for most regulatory actions taken to date. Less than 20% of all standards established to limit concentrations of chemicals in various media address carcinogens. Restrictions on chemical use are more frequently based on concerns about noncancer human health or ecological effects. Of the chemicals in commercial use which have been identified as potential human carcinogens on the basis of rodent bioassays, only a small proportion are regulated. There is an inverse relationship between the scope of regulatory coverage and the stringency of regulatory requirements: the largest percentages of identified carcinogens are affected by the least stringent requirements, such as information disclosure. Standards based onde minimiscancer risk levels have been established for only 10% of identified carcinogens and are restricted to one medium: water. Complete bans on use have affected very few chemicals. The general role that carcinogenicity now plays in the regulatory process is not dramatically different from that of other adverse human health effects: if a substance is identified as a hazard, it may eventually be subject to economically achievable and technically feasible restrictions.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1992.tb00673.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY