ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518869

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518870

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

The recent review of the National Ambient Air Quality Standard for particuslate matter and the resultant new health-based PM2.5standard was in part motivated by findings from epidemiological studies. These studies reported significant associations between adverse health effects and concentrations of ambient particulate matter at levels below the previously existing PM10standard. Interpretation of these results has been hindered by our relatively poor understanding of the relationship between personal exposures and concentrations in the indoor and outdoor environments. Individuals spend the majority of their time in indoor environments. Therefore, it is important to understand where and how they may be exposed to the contaminants which may be causing the health effects, and which activities place them at a higher risk of exposure to these agents. In addition, since particulate matter is a complex mixture of contaminants, further research is required to examine its formation process, sources, composition, and health effects. Without an improved scientific understanding of these issues, it is difficult to assess whether the new PM2.5standard will be implemented, and if so, whether it can be adequately protective of public health.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518871

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

Large quantities of African dust are carried into the southeastern United States each summer with concentrations typically in the range of 10 to 100 µg m−3. Because approximately one-third to one-half of the dust mass is in the size range under 2.5 µm diameter, the advection of African dust has implications for the EPA's newly implemented standard for PM2.5particulate matter and for the assessment of human health effects. It will be difficult to assess the impact of African dust events on air quality because they occur during the summer (maximum in July) when photochemical pollution events are frequent and intense in the eastern United States. Indeed, the presence of dust could affect the evolution of photochemical dust events. In order to assess the role of African dust in air quality in the United States, it will be necessary to develop a set of diagnostic indicators; it appears that dust mineralogy and elemental composition might be useful for this purpose. Various satellite products can be used to characterize the spatial coverage of dust events and, when coupled with meteorological tools, to predict impact regions.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518872

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

Epidemiologic studies have shown significant and consistent associations between ambient particulate matter (PM) and a variety of adverse cardiopulmonary health consequences. These associations are strongest in elderly sub-populations identified with preexistent cardiopulmonary diseases. While the consistency of the findings appears to warrant serious public health concern, the lack of clear mechanistic underpinnings (“biological plausibility”) has prompted skepticism of the epidemiology. Toxicologists have embraced the challenge to address the issue of biologic plausibility in the context of the PM epidemiology and are vigorously investigating both causality and mechanisms by which effects might be mediated at the molecular, cellular, and organismic levels. Among the several hypotheses being touted, that involving constituent bioavailable transition metals appears most coherent with the epidemiologic observations. It provides a conceptual pathway that could have clinical implications. To date, the toxicology has involved relatively high doses of PM-metal to the lung of animal models and certainly more remains to be determined as to metal-specific biological roles at low environmental doses, especially in the context of host susceptibility. Nevertheless, the cumulative evidence is sufficiently cohesive to support our contention that metals are likely one important causal factor in the pathophysiological cascade leading to PM health effects. However, it would be premature at this point to consider metals in any risk management strategy for PM.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518873

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

The new annual PM2.5standard will be the most difficult particulate matter (PM) standard to satisfy. At issue is whether the extant health evidence supports the rationale for this standard being the controlling standard. Indeed the key issue is whether this standard will result in the most cost-effective way to protect public health. This paper examines the health literature and concludes that the evidence for the annual PM2.5standard is weak. The bulk of the health evidence is related to daily exposures to PM10and larger particle sizes, and there is no rational way to decide upon the correct level for this standard. It is unclear whether the most restrictive PM2.5standard will be protective of public health. Clearly research is needed to determine the correct PM metric, averaging time, and level for a standard. To date such research has been limited.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518874

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

Simulation software programs continue to evolve and to meet the needs of risk analysts. In the past several years, two spreadsheet add-in programs added the capability of fitting distributions to data to their tool kits using classical statistical (i.e.,non-Bayesian) methods. Crystal Ball version 4.0 now contains this capability in its standard program (and in Crystal Ball Pro version 4.0), while the BestFit software program is a component of the @RISK Decision Tools Suite that can also be purchased as a stand-alone program. Both programs will automatically fit distributions using maximum likelihood estimators to continuous data and provide goodness-of-fit statistics based on chi-squared, Kolmogorov-Smirnov, and Anderson-Darling tests. BestFit will also fit discrete distributions, and for all distributions it offers the option of optimizing the fit based on the goodness-of-fit parameters. Analysts should be wary of placing too much emphasis on the goodness-of-fit statistics given their limitations, and the fact that only some of the statistics are appropriately corrected to account for the fact that the distribution parameters are also fit using the data. These programs dramatically simplify efforts to use maximum likelihood estimation to fit distributions. However, the fact that a program is used to fit distributions should not be viewed as validation that the data have been fitted and interpreted correctly. Both programs rely heavily on the analyst's judgment and will allow analysts to fit inappropriate distributions. Currently, both programs could be improved by adding the ability to perform extensive basic exploratory data analysis and to give regression diagnostics that are needed to satisfy critical analysts or reviewers. Given that Bayesian methods are central to risk analysis, adding the capability of fitting distributions by combining data with prior information would greatly increase the utility of these programs.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518875

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

Much attention has focused on people's concerns about technological and environmental risks, but it is important to acknowledge that these are not the only risks that individuals have to face. In this article we present the results of a national survey ranking levels of worry across a broader spectrum of risk issues, including ‘lifestyle’, social welfare, financial and personal safety risks. A total of 1742 interviews were conducted, at home, among a nationally representative quota sample of adults age 15+ in Great Britain. Field work took place between January 24 to 27, 1997. Respondents' spontaneous mentions of worry centered on issues to do with health, education, and money. When prompted, respondents expressed most concern about a number of social issues, while certain ‘lifestyle’ factors identified as significant risks to health were accorded only low levels of worry. The survey demonstrates that risk issues that engage some expert attention do not always have the same immediacy for the general public. Thus, while technological and environmental risks certainly deserve attention, they should not overshadow consideration of other risks that have equal if not greater implications for people's lives.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518876

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

Recent efforts to improve risk assessment methodologies have sought to provide a fuller representation of the variability and uncertainty in risk estimates in order to provide risk managers with a more complete description of risks. Recently, we and others (Swartoutet al., 1998; Priceet al., 1997; Slob and Pieters, 1997; Bairdet al., 1996) have proposed approaches to characterize the uncertainty in the reference dose, (RfD) a key component of the non-carcinogenic risk estimation process. The operational definition of the RfD as the “lower-bound” estimate of the NOAEL in a sensitive human subpopulation (NOAELHS) is used along with information on the inter-chemical variation in ratios associated with the uncertainty factors used in setting the RfD to characterize the uncertainty in the NOAELHS(Swartoutet al., 1998). This paper presents a description of how information on the uncertainty in the NOAELHScan be used to characterize the uncertainty and variability in estimates of non-carcinogenic risks for individuals and populations. The paper also explores the impact of using alternative estimates of the inter-chemical variation in the ratios. The analysis suggests the following findings. First, the current method of estimating risks from mixtures of chemicals may overestimate the risks when two or more compounds contribute significantly to the estimate of the hazard index. Second, the uncertainty in the NOAELHSof a mixture is affected by the number and size of the uncertainty factors used in setting the RfDs of the mixture's components. Third, jointly assessing both the uncertainty and variability in exposure and the uncertainty in the estimate of the NOAELHScan have a significant impact on the characterization of noncarcinogenic risks for individuals and populations. Finally, these findings are independent of the choice of distributions for interchemical variation in ratios.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518877

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor

摘要:

This investigation assessed the effect of soil particle size on soil ingestion estimates of children residing at a superfund site. Earlier research indicated that wide intertracer variability in soil ingestion estimates are based on soil concentrations with a soil particle size of 0 to 2 µm was markedly reduced when the estimates were based on soil tracer concentrations for a soil particle size of 0-250 µm. The reduced intertracer variation was principally attributed to changes in soil concentrations of only three of the soil tracers (i.e., Ce, La, Nd) which became concentrated in the finer particle size by approximately 2.5 to 4.0-fold. It was hypothesized that the intertracer agreement in soil ingestion estimates may continue to improve if the estimates are based on concentrations of tracers at finer particle sizes assuming that children ingest finer particles and that the above three tracers would continue to be further concentrated in the finer sized soil particles. The principal findings indicate: 1. The soil concentrations of Al, Si, and Ti do not increase at the two finer particle size ranges measured. 2. The soil concentrations of Ce, La, and Nd increased by a factor 2.5 to 4.0 in the 100 to 250 µm particle size range when compared with the 0 to 2 µm particle size range. No further substantial increase in concentration was observed in the 53 to 100 |jm particle size range. 3. The soil ingestion estimates are consistently and markedly changed only between the estimates based in 0 to 2 µm and 100 to 250 µm for Ce, La, and Nd. These changes reduced the intertracer variability in estimating soil ingestion, suggesting that the children eat finer soil particle sizes. 4. Because the particle sizes for all tracers (except Zr) were only modestly affected at the 53 to 100 µm range, it was not possible to confidently resolve the particle size of soil ingested by the children. 5. Residual intertracer variability in soil ingestion estimates based on Ce, La, Nd are likely to be significantly affected by non-food, non-soil sources of these tracers (i.e., source error). 6. Soil ingestion estimates of this study will be more reliable when derived from the finer-sized particles.

ISSN:1080-7039    

DOI:10.1080/10807039.1999.10518878

出版商:TAYLOR & FRANCIS    

年代:1999

数据来源: Taylor