ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00750.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Legislative mandates have resulted in large‐scale conversion from groundwater to surface water sources of supply for Public Water Supply Systems in Harris and Galveston Counties, Texas. Geographically‐defined Regulatory Areas in the region are governed by the Harris Galveston Coastal Subsidence District. The district's mission, to end subsidence or loss of land elevation by allocating water usage by Area, has focused attention on potential health hazards and monetary issues related to substandard water quality and increased consumer utility rates. Study variables of: (1) Total Hardness (TH); (2) Total Trihalomethanes (TTHMs) concentrations; and (3) Water Utility Rates ($), were compared for each water source because of their suggested impacts on human health (TH:CVD; TTHMs:Cancer) and relative economic welfare (Utility Rates: $) as byproducts of current mandate requirements. Strong evidence of statistically significant differences in water quality parameters, and utility rates of groundwater and surface water source data, suggest that regulations dictating conversion need review and possible amending. This presentation describes the results of a 2‐year study of the issues regarding conversion of Public Water supplies from groundwater to surface

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00751.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

A Monte Carlo simulation is incorporated into a risk assessment for trichloroethylene (TCE) using physiologically‐based pharmacokinetic (PBPK) modeling coupled with the linearized multistage model to derive human carcinogenic risk extrapolations. The Monte Carlo technique incorporates physiological parameter variability to produce a statistically derived range of risk estimates which quantifies specific uncertainties associated with PBPK risk assessment approaches. Both inhalation and ingestion exposure routes are addressed. Simulated exposure scenarios were consistent with those used by the Environmental Protection Agency (EPA) in their TCE risk assessment. Mean values of physiological parameters were gathered from the literature for both mice (carcinogenic bioassay subjects) and for humans. Realistic physiological value distributions were assumed using existing data on variability. Mouse cancer bioassay data were correlated to total TCE metabolized and area‐under‐the‐curve (blood concentration) trichloroacetic acid (TCA) as determined by a mouse PBPK model. These internal dose metrics were used in a linearized multistage model analysis to determine dose metric values corresponding to 10‐6lifetime excess cancer risk. Using a human PBPK model, these metabolized doses were then extrapolated to equivalent human exposures (inhalation and ingestion). The Monte Carlo iterations with varying mouse and human physiological parameters produced a range of human exposure concentrations producing a

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00752.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Standard experimental designs for conducting developmental toxicity studies typically include three‐ or four‐dose levels in addition to a control group. Some researchers have suggested that designs with more exposure groups would improve dose‐response characterization and risk estimation. Such proposals have not, however, been supported by the results of simulation studies, which instead back the use of fewer dose levels. This discrepancy is partly due to using aknowndose–response pattern to generate data, making model choice obvious. While the carcinogenicity literature has explored implications of different study designs, little attention has been given to the role of design in developmental toxicity risk assessment (or noncancer toxicology in general). In this research, we explore the implications of various experimental designs for developmental toxicity by resampling data from a large study of 2,4,5‐trichlorophenoxyacetic acid in mice. We compare the properties of benchmark dose (BMD) estimation for different design strategies by randomly selecting animals within particular dose groups from the entire 2,4,5‐T database of over 77,000 birth outcomes to create smaller “pseudo‐studies” that are representative of standard bioassay sample sizes. Our results show that experimental designs which include more dose levels have advantages in terms of risk characterizati

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00753.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Relatively little attention has been paid to the role of human perception and judgment in ecological risk management. This paper attempts to characterize perceived ecological risk, using the psychometric paradigm developed in the domain of human health risk perception. The research began by eliciting a set of scale characteristics and risk items (e.g., technologies, actions, events, beliefs) from focus group participants. Participants in the main study were 68 university students who completed a survey instrument that elicited ratings for each of 65 items on 30 characteristic scales and one scale regarding general risk to natural environments. The results are presented in terms of mean responses over individuals for each scale and item combination. Factor analyses show that five factors characterize the judgment data. These have been termed: impact on species, human benefits, impact on humans, avoidability, and knowledge of impacts. The factor results correspond with initial expectations and provide a plausible characterization of judgments regarding ecological risk. Some comparisons of mean responses for selected individual items are also presented.

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00754.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

In this paper, we provide a framework for quantitative risk assessment in hazardous materials transport. We first outline a basic model where population centers are approximated by points on a plane with the assumption that in the case of an incident all residents in a population center will experience the same consequences. Different versions of this model have been used by other authors in the literature. This model may be valid if the hazardous materials route goes by small population centers. Then we extend this basic model to assess risks of shipping hazardous materials through large population centers that cannot be modeled as single points on a plane. In the extended model, large population centers are treated as two‐dimensional objects on the plane, which allows for a more accurate treatment of consequences than the basic model. To the extent of our knowledge the extended model is novel. We provide numerical examples for both the basic and the extended models, and finish by discussing limitations of the suggested risk assessment framewor

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00755.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Differences in the conceptual frameworks of scientists and nonscientists may create barriers to risk communication. This article examines two such conceptual problems. First, the logic of “direct inference” from group statistics to probabilities about specific individuals suggests that individuals might be acting rationally in refusing to apply to themselves the conclusions of regulatory risk assessments. Second, while regulators and risk assessment scientists often use an “objectivist” or “relative frequency” interpretation of probability statements, members of the public are more likely to adopt a “subjectivist” or “degree of confidence” interpretation when estimating their personal risks, and either misunderstand or significantly discount the relevance of risk assessment conclusions. If these analyses of inference and probability are correct, there may be a conceptual gulf at the center of risk communication that cannot be bridged by additional data about the magnitude of group risk. Suggestions are made for empirical studies that might help regulators deal with t

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00756.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Book Revies in this ArticleCommunity Risk Profiles Edited by Iddo K. WernickCauses of Death in the Workplace By J. Paul LeighIntroduction to Environmental Toxicology; Impacts of Chemicals Upon Ecological Systems By Wayne C. Landis and Ming‐Ho

ISSN:0272-4332    

DOI:10.1111/j.1539-6924.1995.tb00757.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY