Exposure Assessment: Then, Now, and Quantum Leaps in the Future

Health risk assessments have become so widely accepted in the United States that their conclusions are a major factor in many environmental decisions. Although the risk assessment paradigm is 10 years old, the basic risk assessment process has been used by certain regulatory agencies for nearly 40 years. Each of the four components of the paradigm has undergone significant refinements, particularly during the last 5 years. A recent step in the development of the exposure assessment component can be found in the 1992 EPA Guidelines for Exposure Assessment. Rather than assuming worst-case or hypothetical maximum exposures, these guidelines are designed to lead to an accurate characterization, making use of a number of scientific advances. Many exposure parameters have become better defined, and more sensitive techniques now exist for measuring concentrations of contaminants in the environnment. Statistical procedures for characterizing variability, using Monte Carlo or similar approaches, eliminate the need to select point estimates for all individual exposure parameters. These probabilistic models can more accurately characterize the full range of exposures that may potentially be encountered by a given population at a particular site, reducing the need to select highly conservative values to account for this form of uncertainty in the exposure estimate. Lastly, our awareness of the uncertainties in the exposure assessment as well as our knowledge as to how best to characterize them will almost certainly provide evaluations that will be more credible and, therein, more useful to risk managers. If these refinements are incorporated into future exposure assessments, it is likely that our resources will be devoted to problems that, when resolved, will yield the largest improvement in public health.     

Labor markets and sunday closing laws

This paper puts forth arguments regarding the occurrence of state Sunday closing laws and reports statistical estimates that predict the occurrence of those laws in 1970 and 1984. Along with other socio-economic variables, two labor market activities are found to be significant determinants of Blue laws. Membership in labor unions is found to have a positive declining influence on the laws; female labor market participation is found to have a negative but growing influence.     

Determination of Less-Than-Lifetime Exposures to Point Source Emissions

This paper presents a method of estimating long-term exposures to point source emissions. The method consists of a Monte Carlo exposure model (PSEM or Point Source Exposure Model) that combines data on population mobility and mortality with information on daily activity patterns. The approach behind the model can be applied to a wide variety of exposure scenarios. In this paper, PSEM is used to characterize the range and distribution of lifetime equivalent doses received by inhalation of air contaminated by the emissions of a point source. The output of the model provides quantitative information on the dose, age, and gender of highly exposed individuals. The model is then used in an example risk assessment. Finally, future uses of the model's approach are discussed.     

The office of scientific integrity investigations: The importance of data analysis

Certified Public Accountants serve as independent auditors of financial statements. They perform information‐integrity testing for the economy and society, adding creditability to financial statements prepared by organizations’ management. Investors, creditors, and others rely on these financial statements and the audit report to make business decisions. Auditing work involves gathering evidence (research) and forming an opinion (reporting results) about the “fairness”; of financial statements according to regulatory, legal, and professional rules. As researchers, auditors are subject to a complex network of mechanisms to promote accountability in their work. These mechanisms exist at environmental, professional, and audit‐firm levels. They combine to influence the judgments of individual auditors.     

Probability computations for an extension of the geometric distribution

An extension of the stochastic process associated with the geometric distribution is presented. Combinatorial arguments are used to derive probabilities for various events of interest. Probabilities are approximated by evaluating truncated series. Bounds on the errors of approximation are developed. An example is presented and some additional applications are noted.     

Co-dependency and myth

Timmen Cernak’s use of Ovid’s mythological account of Narcissus and Echo as a classic case of co-dependence is critically analyzed against other interpretations. Simultaneous consideration is given to whether and to what extent the clinical concept of co-dependency has been confounded with the psychology of women in a male-oriented society. The complex and ambiguous symbolism of myth demands separation of myth from reality in describing the symptoms, etiology, and treatment of clinical co-dependence.