Reproductive and Developmental Risks from Ethylene Oxide: A Probabilistic Characterization of Possible Regulatory Thresholds

Ethylene oxide is a gas produced in large quantities in the United States that is used primarily as a chemical intermediate in the production of ethylene glycol, propylene glycol, non-ionic surfactants, ethanolamines, glycol ethers, and other chemicals. It has been well established that ethylene oxide can induce cancer, genetic, reproductive and developmental, and acute health effects in animals. The U.S. Environmental Protection Agency is currently developing both a cancer potency factor and a reference concentration (RfC) for ethylene oxide. This study used the rich database on the reproductive and developmental effects of ethylene oxide to develop a probabilistic characterization of possible regulatory thresholds for ethylene oxide. This analysis was based on the standard regulatory approach for noncancer risk assessment, but involved several innovative elements, such as: (1) the use of advanced statistical methods to account for correlations in developmental outcomes among littermates and allow for simultaneous control of covariates (such as litter size); (2) the application of a probabilistic approach for characterizing the uncertainty in extrapolating the animal results to humans; and (3) the use of a quantitative approach to account for the variation in heterogeneity among the human population. This article presents several classes of results, including: (1) probabilistic characterizations of ED10s for two quantal reproductive outcomes-resorption and fetal death, (2) probabilistic characterizations of one developmental outcome-the dose expected to yield a 5% reduction in fetal (or pup) weight, (3) estimates of the RfCs that would result from using these values in the standard regulatory approach for noncancer risk assessment, and (4) a probabilistic characterization of the level of ethylene oxide exposure that would be expected to yield a 1/1,000 increase in the risk of reproductive or developmental outcomes in exposed human populations.     

Population Change and Changing Educational Attainment of Ethnic Groups in the United States, 1980–2000

This study assesses the effect of population change on decade changes in the educational attainments of country of origin populations in the United States. Our data are derived from decennial censuses, NLMS, the World Bank, and INS. We find that changes in the share of country of origin populations with one or more years of post-secondary schooling are associated with selected components of population change during the 1980–1990 and 1990–2000 decades. The specific components include survivors during the decade, in-migration, and emigration of the foreign-born. Likewise, intra-generational mobility is found to be an important determinant of changes in educational attainment. The discussion addresses limitations of the data and suggests directions for future research as well as policy implications.     

Alternative Medicine and Herbal Use Among University Students

Abstract

Objective: This study sought to (1) examine perceived stress and resources to cope with stress as predictors of emotional eating during the transition to college and (2) determine whether body mass index (BMI) moderated the emotional eating-stress relationship. Participants: Participants were 97 college freshmen (73% female; BMI: M = 25.3 kg/m², SD = 5.7 kg/m²). Research was conducted in September 2012. Methods: Participants completed the Perceived Stress Scale, Emotional Eating Scale, and Eating and Appraisal Due to Emotions and Stress Questionnaire during the first month of college. Height and weight were measured objectively. Results: BMI moderated the relationship between perceived stress and emotional eating. Higher stress predicted greater emotional eating for the lower BMI groups, but not the highest group. Greater resources to cope with stress predicted lower emotional eating. Conclusions: Greater perceived stress and poorer resources to cope with stress may contribute to emotional eating during the transition to college. The relationship between perceived stress and emotional eating may vary by BMI.     

The Good, the Bad, and the Regulator: An Experimental Test of Two Conditional Audit Schemes

Conditional audit rules are designed to achieve regulatory compliance with fewer inspections than required by random auditing. A regulator places individuals into audit pools that differ in probability of audit or severity of fine and specifies transition rules between pools. Future pool assignment is conditional on current audit results. We conduct an experiment to compare two specific schemes—Harrington's Past-Compliance Targeting and Friesen's Optimal Targeting—against random auditing. We find a production possibility frontier between compliance and minimizing inspections. Optimal targeting generates the lowest inspection rates as predicted, but random auditing the highest compliance. Past-compliance targeting is intermediate.     

Bayesian palaeoclimate reconstruction

Summary.  We consider the problem of reconstructing prehistoric climates by using fossil data that have been extracted from lake sediment cores. Such reconstructions promise to provide one of the few ways to validate modern models of climate change. A hierarchical Bayesian modelling approach is presented and its use, inversely, is demonstrated in a relatively small but statistically challenging exercise: the reconstruction of prehistoric climate at Glendalough in Ireland from fossil pollen. This computationally intensive method extends current approaches by explicitly modelling uncertainty and reconstructing entire climate histories. The statistical issues that are raised relate to the use of compositional data (pollen) with covariates (climate) which are available at many modern sites but are missing for the fossil data. The compositional data arise as mixtures and the missing covariates have a temporal structure. Novel aspects of the analysis include a spatial process model for compositional data, local modelling of lattice data, the use, as a prior, of a random walk with long-tailed increments, a two-stage implementation of the Markov chain Monte Carlo approach and a fast approximate procedure for cross-validation in inverse problems. We present some details, contrasting its reconstructions with those which have been generated by a method in use in the palaeoclimatology literature. We suggest that the method provides a basis for resolving important challenging issues in palaeoclimate research. We draw attention to several challenging statistical issues that need to be overcome.     

"PUBLIC' WORK AND SOCIAL PARTICIPATION:

The impact of labor force participation by women on their social activism is examined using data gathered in a study of 695 North Carolina farm families. The traditional gender division of labor into "instrumental' (male) and "expressive' (female) activism breaks down when women take off-farm jobs. Their rates of activism in instrumental organizations move closer to those of men. Labor force participation by women also reduces the impact of the husband on the wife's activism.     

Seat belt laws: why we should keep them

In the June 2007 issue of Significance , John Adams argued for the repeal of seat belt laws. They have never been demonstrated to save lives, he said; and they increase the number of pedestrians and cyclists killed on the roads. Richard Allsop, Oliver Carsten, Andrew Evans and Robert Gifford argue that Parliament should keep the seat belt laws on the statute book and that we should all keep wearing belts whenever we travel in a car, van or coach—and they contest John's statistics.     

Monitoring and evaluation in Malawi

When Ian Wilson and Carlos Barahona of the Statistical Services Centre at the University of Reading were asked to review an evaluation of the effectiveness of an aid package in Malawi, they expected a simple enough task. But few things in the developing world are simple. Where aid for the poorest is concerned, is evidence collected and analysed with enough rigour to enable well-informed decisions to be made?