Using Probabilistic Modeling to Evaluate Human Exposure to Organotin in Drinking Water Transported by Polyvinyl Chloride Pipe

The leaching of organotin (OT) heat stabilizers from polyvinyl chloride (PVC) pipes used in residential drinking water systems may affect the quality of drinking water. These OTs, principally mono- and di-substituted species of butyltins and methyltins, are a potential health concern because they belong to a broad class of compounds that may be immune, nervous, and reproductive system toxicants. In this article, we develop probability distributions of U.S. population exposures to mixtures of OTs encountered in drinking water transported by PVC pipes. We employed a family of mathematical models to estimate OT leaching rates from PVC pipe as a function of both surface area and time. We then integrated the distribution of estimated leaching rates into an exposure model that estimated the probability distribution of OT concentrations in tap waters and the resulting potential human OT exposures via tap water consumption. Our study results suggest that human OT exposures through tap water consumption are likely to be considerably lower than the World Health Organization (WHO) "safe" long-term concentration in drinking water (150 μg/L) for dibutyltin (DBT)—the most toxic of the OT considered in this article. The 90th percentile average daily dose (ADD) estimate of 0.034 ± 2.92 × 10⁻⁴μg/kg day is approximately 120 times lower than the WHO-based ADD for DBT (4.2 μg/kg day).     

Reliability of isokinetic and isometric knee-extensor force in older women

Because of the need for efficient, consistent strength measurements, the test-retest reliability of concentric, isometric, and eccentric strength; concentric work; and concentric power was determined in older women without a familiarization session. The reliability of measures derived from a single peak score were compared with those derived from an averaged score. On 2 occasions 25 older women with a mean age of 72 +/- 6 years performed 3 submaximal knee extensions and 5 maximal contractions on an isokinetic dynamometer at 90 degrees/s (CON), 0 degrees/s, and -90 degrees/s on both lower limbs. Statistical analyses for peak and averaged values (best 3 contractions of 5) exhibited good relative reliability (ICCs > .88), except for CON power. Typical error as a coefficient of variation and ratio limits of agreement for peak and averaged score values were larger than desired, with CON power scores demonstrating unacceptable error ranges. Although relative reliability of this 1-session assessment protocol was acceptable, further research is needed to determine whether additional practice trials could enhance absolute reliability.     

Tools for Comparative Analysis of Alternatives: Competing or Complementary Perspectives?

A third generation of environmental policy making and risk management will increasingly impose environmental measures, which may give rise to analyzing countervailing risks. Therefore, a comprehensive analysis of all risks associated with the decision alternatives will aid decision-makers in prioritizing alternatives that effectively reduce both target and countervailing risks. Starting with the metaphor of the ripples caused by a stone that is thrown into a pond, we identify 10 types of ripples that symbolize, in our case, risks that deserve closer examination: direct, upstream, downstream, accidental risks, occupational risks, risks due to offsetting behavior, change in disposable income, macro-economic changes, depletion of natural resources, and risks to the manmade environment. Tools to analyze these risks were developed independently and recently have been applied to overlapping fields of application. This suggests that either the tools should be linked in a unified framework for comparative analysis or that the appropriate field of application for single tools should be better understood. The goals of this article are to create a better foundation for the understanding of the nature and coverage of available tools and to identify the remaining gaps. None of the tools is designed to deal with all 10 types of risk. Provided data suggest that, of the 10 types of identified risks, those associated with changes in disposable income may be particularly significant when decision alternatives differ with respect to their effects on disposable income. Finally, the present analysis was limited to analytical questions and did not capture the important role of the decision-making process itself.     

Career story: Official Statistician

It was a desire to travel which first attracted Melissa Rice to a career in the Civil Service. And, even though she hasn't yet done as much travelling as she would like, she already has several job changes under her belt and, as she tells Helen Joyce, opportunities to broaden her horizons in other ways.     

Poverty, Welfare, and Patriarchy: How Macro-Level Changes in Social Policy Can Help Low-Income Women

A critical review of the current status of low-income women reveals how patriarchy, violence, and discrimination mitigates against their employment and contributes to their poverty. Myths that fuel prejudice against the poor have led to public policy and welfare legislation based on individualistic rather than structural assumptions about the causes of poverty. Research on the effects of welfare reform reinforces the conclusion that changes in social welfare and policy are necessary for income parity and improvement in the employment opportunities, access, and status of low-income women. A human-capital model and recommendations for macro-level changes in public policy and programming that address the systemic causes of women's poverty are presented.     

Family-Centered,Community-Based Asset Building: A Strategic Use of Individual Development Accounts

This research examines individual development account (IDA) programs as part of a broader community development strategy for low-income/low-wealth communities, particularly communities of color. Through a review of multiple literatures and detailed case studies, we explore the potential of explicitly creating a community-based, family-centered development account program as a step toward a comprehensive community asset building approach in low-income urban neighborhoods. From the perspective of IDA practitioners, such an approach provides program participants with local support networks and access to additional services. From the perspective of grassroots community organizers, such an approach provides tangible benefits to low-income residents of their neighborhoods. The likelihood of success may depend on the availability of local resources to build areas of strength and reduce vulnerabilities, but there are examples where a family-centered, community-based asset building approach seems to thrive.     

Temporal Aspects of Life Satisfaction

Time pressure is a familiar phenomenon. The quantity of spare time people have clearly effects their satisfaction with their leisure and with their life as a whole. But so too, we show, does how much control people have over how much spare time they have. We measure this through an indicator of ‘discretionary time’, which proves to be equally or more important than spare time itself in these connections.