Modeling for Risk Assessment of Neurotoxic Effects

The regulation of noncancer toxicants, including neurotoxicants, has usually been based upon a reference dose (allowable daily intake). A reference dose is obtained by dividing a no-observed-effect level by uncertainty (safety) factors to account for intraspecies and interspecies sensitivities to a chemical. It is assumed that the risk at the reference dose is negligible, but no attempt generally is made to estimate the risk at the reference dose. A procedure is outlined that provides estimates of risk as a function of dose. The first step is to establish a mathematical relationship between a biological effect and the dose of a chemical. Knowledge of biological mechanisms and/or pharmacokinetics can assist in the choice of plausible mathematical models. The mathematical model provides estimates of average responses as a function of dose. Secondly, estimates of risk require selection of a distribution of individual responses about the average response given by the mathematical model. In the case of a normal or lognormal distribution, only an estimate of the standard deviation is needed. The third step is to define an adverse level for a response so that the probability (risk) of exceeding that level can be estimated as a function of dose. Because a firm response level often cannot be established at which adverse biological effects occur, it may be necessary to at least establish an abnormal response level that only a small proportion of individuals would exceed in an unexposed group. That is, if a normal range of responses can be established, then the probability (risk) of abnormal responses can be estimated. In order to illustrate this process, measures of the neurotransmitter serotonin and its metabolite 5-hydroxyindoleacetic acid in specific areas of the brain of rats and monkeys are analyzed after exposure to the neurotoxicant methylene-dioxymethamphetamine. These risk estimates are compared with risk estimates from the quantal approach in which animals are classified as either abnormal or not depending upon abnormal serotonin levels.     

Female Labor Force Participation in Urban and Rural China1

Abstract The objective of this study is to examine female labor force participation and its determinants in rural and urban China. The sociological literature has demonstrated that participation tends to increase in urban and industrialized places where women have higher levels of education and fewer children, where more workers are engaged in service pursuits, and where family structure is less traditional. With the use of data on counties and cities (N = 2,377) from the I-percent sample of the 1982 census of the People's Republic of China, it was found that female labor force participation is likely to rise in areas with increased agricultural employment, educational levels, proportion of female-headed households, and higher male-to-female sex ratios. Both the size of the service sector and the fertility rate had negligible effects on female labor force participation. Although, on average, rural places have slightly higher levels of female labor force participation, when other variables are controlled, urban places have a higher rate of female participation. In addition, the findings suggest that market factors (i.e., education) are more likely to determine the rate of female labor force participation in urban areas; whereas demographic and social factors (i.e., sex ratio and household structure) play a more important role in explaining the female labor force participation in rural counties.     

The twenty-percent majority: Pro-union bias in prevailing rate determinations

Each individual wage rate set by Davis-Bacon or by any similar state or local prevailing wage determination petrifies the outcome of competing views of how construction work should be staffed and paid on public works projects. Although presented with great precision (to tenths of a cent for both wages and fringe benefits), the level of wages themselves are of surprisingly little consequence: Those set at union levels soon rise, being automatically updated to new contracts and conditions; the rest fast become obsolete in any rising market, because surveys to update them are rare. But in addition to setting wage levels, determinations also delineate which jobs get to have rates set for them, and perhaps most critically, whether those delineated are identified as union or notunion. Whatever pattern is found may remain in effect for years or even decades, influencing which journeymen and laborers own what job tasks and who may perform what. Also, if a particular job happens to be set as union, it may bring with it dozens or even hundreds of related special job categories, grades of sub-groups, fine distinctions of fringe benefits, and complex divisions of geographic applicability based on local union jurisdictional areas. This study uses determinations recently made in Pennsylvania as an example to examine the mechanics of the wage-setting process. I find that, in addition to the endemic problems one might expect associated with a complex and partly judgmental process, every step of finding and setting prevailing rates includes overwhelming deference on the part of government towards union views and methods. It shows why unions representing less than 20 percent of the private construction work force consistently set the parameters controlling most of public construction. It ends with some suggestions on how better surveys and determinations could be made.     

Childhood parental loss and adult depression

Previous research demonstrates convincingly that childhood parental deaths and parental divorces have implications for adult well-being as defined by levels of depression, educational attainment, early age at marriage, and risk of divorce. What this research has failed to examine are the interconnections among these outcomes. Specifically, are the socioeconomic and marital outcomes of parental loss implicated in the observed higher levels of depression? This analysis takes a first step in answering this question. Using data from a sample of 1,755 married men and women, I estimated regression models which examine the extent to which adult socioeconomic status and current marital quality mediate and/or modify the loss-depression relationship. Parental divorce was strongly related to socioeconomic and marital outcomes. Furthermore, current marital quality contributed importantly to understanding the higher levels of depressed mood observed among persons from divorced homes. Parental death was much more weakly related to socioeconomic and marital outcomes, and these outcomes played little role in explaining its relationship to depression. Finally, all of these relationships were stronger among women than men. These findings support the utility of life-course approaches to understanding adult mental health.     

Native American drinking: a neglected subject of study and research

Although Native Americans are plagued by high rates of alcoholism, violence, suicide and early death, these social and clinical problems are usually given little more than cursory treatment in textbooks. A content analysis of twenty-six textbooks on alcoholism and substance misuse revealed that only four provided a detailed discussion of Native American drinking. Greater attention needs to be given to the cultural, psychological, and biological issues of drinking and drunkenness among this special population.     

A comparative approach to assessing the quality of life of intercollegiate athletes

Although concerns have frequently been raised recently regarding the quality of life of intercollegiate athletes, information is seldom available on which college and university administrators can base policy decisions. Particularly lacking are studies that provide administrators with assessments of their own athletics programs relative to athletics programs at other institutions. We describe here a method we used in conducting a comparative evaluation of the status of student-athletes at a large public university, involving comparisons of student-athletes at this university to student-athletes at a subset of the institutions that participated in the 1987–88 National Study of Intercollegiate Athletes. By utilizing existing data sets to construct comparison samples, relative assessments of the status of student-athletes at a given institution can be performed without the excessive costs of gathering data on student-athletes at comparison institutions. Techniques employed in data collection and analysis are discussed as well as the format of the report in which the findings of the study were presented.     

Characteristics of smokeless tobacco use among high school football players as related to type of smokeless tobacco and period of use.

The present study was conducted to assess differences in the behavioral and demographic characteristics of snuff (dip) users as compared to users of chewing tobacco. High School football players (1116) were surveyed concerning their use and perceptions of smokeless tobacco. Adolescent athletes who tried smokeless tobacco were more likely to be white, to use cigarettes, alcohol, and cigars and to have family users than those who never tried. Initial use was highest before the age of fourteen years and was influenced by friends, curiosity and family. Dippers tended to initiate use because of friends, while chewers started because of family users. Users of both dip and chew started primarily because of curiosity. Users of both were more likely to consume greater amounts to alcohol and cigarettes and to smoke cigars and pipes. It appears that the longer smokeless tobacco is consumed, the more likely both dip and chew will be used. Users of smokeless tobacco for more than two years tended to consume more of the product each week, used it for more hours/day, initiated use at an earlier age, and used it more often at school and work than those using it for less than two years. Use of cigars/pipes, consumption of alcohol, and quantity of cigarette consumption increased significantly with longer duration of smokeless tobacco use. Intervention and prevention programs would be helped by understanding differences between users of various smokeless tobacco products and differences related to the duration of use. In addition, further analyses of smokeless tobacco users should study chewers, dippers, and users of both separately.     

The impact of ideology on regulation: The case of board and care homes

Debates about regulatory efforts to monitor the delivery of health and long-term care have become commonplace in health policy. Efforts to examine the key assumptions underlying the current regulatory strategies have been limited, however. Using the board and care industry as an example, this article examines how ideology influences the regulatory strategy developed. Three ideological perspectives-a free-market approach, a market correction strategy, and a critical policy framework-are reviewed in the context of efforts to regulate board and care homes in the United States. Differences in approaches to regulating board and care are presented for each of the major perspectives.     

Summary of the Workshop on Issues in Risk Assessment: Quantitative Methods for Developmental Toxicology

This report summarizes the proceedings of a conference on quantitative methods for assessing the risks of developmental toxicants. The conference was planned by a subcommittee of the National Research Council's Committee on Risk Assessment Methodology ⁴ in conjunction with staff from several federal agencies, including the U.S. Environmental Protection Agency, U.S. Food and Drug Administration, U.S. Consumer Products Safety Commission, and Health and Welfare Canada. Issues discussed at the workshop included computerized techniques for hazard identification, use of human and animal data for defining risks in a clinical setting, relationships between end points in developmental toxicity testing, reference dose calculations for developmental toxicology, analysis of quantitative dose-response data, mechanisms of developmental toxicity, physiologically based pharmacokinetic models, and structure-activity relationships. Although a formal consensus was not sought, many participants favored the evolution of quantitative techniques for developmental toxicology risk assessment, including the replacement of lowest observed adverse effect levels (LOAELs) and no observed adverse effect levels (NOAELs) with the benchmark dose methodology.