A probabilistic model for the carry-over of PCDD/Fs from feed to growing pigs

When food producing animals are contaminated with PCDD/F congeners, information on the contaminant’s concentration in the bodies of the animals at time of slaughter is needed for risk management purposes. We have developed a mathematical model for the kinetics of PCDD/Fs in growing pigs in case of contaminated feed fed for a limited duration of time. This model allows the prediction of concentrations in body fat. It considers absorption fractions of PCDD/Fs, clearance by metabolism, dilution by growth and excretion through fecal fat. The model parameters were calibrated by fitting the model to experimental data. On the basis of this toxicokinetic model a probabilistic model has been constructed. The probabilistic model handles the parameters with appropriate probability distributions and Monte-Carlo simulation technique, providing for realistic situations with many animals and a range of contaminations and feeding intervals. We applied the new model to describe the German dioxin incident of winter 2010/2011 and discuss its viability as decision tool. The approach demonstrated here is a showcase how a risk assessment in the case of contaminated feeding can be performed.     

Models to Estimate Volatile Organic Hazardous Air Pollutant Emissions from Municipal Sewer Systems

Abstract

Emissions from municipal sewers are usually omitted from hazardous air pollutant (HAP) emission inventories. This omission may result from a lack of appreciation for the potential emission impact and/or from inadequate emission estimation procedures. This paper presents an analysis and comparison of the models available to estimate volatile organic HAP (VOHAP) emissions from sewers. Comparisons were made between the different theoretical foundations of the models, as well as between the emissions predicted by the models for a single sewer component. Sewer gas concentrations predicted by the models were also compared to measured sewer gas concentrations reported in the literature. Two of the models were compared in their ability to estimate sewer VOHAP emissions for a large U. S. city using National Pollution Discharge Effluent System data for the influent wastewater to the city's municipal wastewater treatment facilities. This estimate showed that, regardless of the model used, sewer emissions are a potentially significant source of VOHAP emissions in the urban environment. The choice of model, however, is thought to be less critical to sewer emission estimates than the source of sewer wastewater VOHAP concentration data.     

PCBs in the eggs of Eurasian kestrels indicate exposure to local pollution

Fail-to-hatch kestrel (Falco tinnunculus) eggs collected at the end of the 1999 and 2005 breeding seasons from nest boxes in and around the city of Rome, Italy, were analyzed by gas chromatography with electron capture detection for their PCB content and for the presence of DDT derivatives and other organochlorines. Among the various PCBs, congeners 153 and 180 were detected in all the eggs and showed the highest concentrations. Eggs collected from the same nest from a polluted location in Rome during 2 different years showed similar type and number of PCB congeners. These data and the fact that eggs from another nest near a sulphate mine had, atypically, low-chlorinated congeners support the conclusion that eggs of this species, whose adults in the Mediterranean and continental Europe perform only short or no migration movements, might be indicative of local pollution. When multiple eggs in the same clutch were analyzed, the PCBs were similar in type but their concentration decreased within clutch, likely in parallel to the laying order.     

Interrole conflict and marital functioning amongst employed fathers

While the influence of maternal interrole conflict on marital functioning has been investigated, the issue of fathers' interrole conflict has been neglected. Consequently, 67 fathers' (M age = 38.51 years) interrole conflict and marital adjustment are investigated. In addition, the moderating role of personality hardiness is assessed. Using multiple moderator regression and sub-group analyses, hardiness was shown to moderate negative effects of interrole conflict on marital adjustment. Conceptual and practical implications of these findings are discussed.     

Snowblower injuries in Vermont, 1981–1984

The Vermont Department of Health carried out two studies of snowblower injuries in Vermont during the winters of 1982–1983 and 1983–1984. The first was a case-control study in which we assessed risk factors that predisposed operators to injury during snowblower use. We found 20 persons who had been injured by snowblowers and matched 28 controls to these by neighborhood. In this study, owning a snowblower for 1 year or less and having operated a snowblower for 10 days or less in one's lifetime were significantly associated with injury. The second study was population-based. We estimated that approximately 1.5% of Vermont residents owned snowblowers during the winter of 1982–1983 and that, among snowblower owners, injuries occurred at a rate of 1.3/1,000 person-years of ownership (0.1% chance of injury).     

The role of electricity in sustainable development

Current projections estimating world population growth read in conjunction with corresponding projections of increased world energy consumption, point to electricity as the cleaner fuel of the future, especially because of its high efficiency and low levels of pollution. Due mostly to the fact that the electrical end-use devices are considerably more efficient than those using other forms of energy, most developed countries show decreasing curves of energy intensity as technologies become more sophisticated and shift over to increased reliance on electricity. It is therefore argued in this article that a gradual shift away from fossil fuels to electricity is a promising possibility to bring down global air pollution and emissions of greenhouse gases to acceptable levels. Examples are given of greater efficiency achieved by electrification. Overall gains in energy efficiency from the change over from fossil fuels to electricity, are possible even in situations where the electricity is generated by fossil fuel combustion, despite the loss of primary energy in the conversion process. The article also presents electricity generating projects designed for developing countries and countries with economies in transition. The generation of electricity from the combustion of renewable sources (biomass waste), fossil fuels, and other innovative methods are outlined.     

Burrow environment and coelomic fluid characteristics of the echiuran worm Urechis caupo from populations at three sites in northern California

The burrow microhabitat and physiology of the echiuran worm Urechis caupo at a high-density site (Elkhorn Slough, California, USA), were investigated from 1987 to 1990 to determine physical and chemical conditions, worm density and distribution, and coelomic fluid characteristics such as heme composition, pO₂, pH, and coelomocyte volume. During tidal exposure, worm burrows at this site exhibited, on average, 52% air-saturated water, 11M burrow-water sulfide, 85 g/mg wet weight sediment sulfide, and salinity and osmolalities similar to those of seawater. These conditions are compared to those of another California site, Bodega Bay, which had slightly lower oxygen concentrations, but higher water and sediment-sulfide levels. A more limited comparison to a third site, Princeton Harbor, California, is included. Worms from Bodega Bay, the higher sulfide site, had greater concentrations of hematin, a non-globin heme compound contained in the coelomocytes, and exhibited a greater tolerance to sulfide in the laboratory. These data are consistent with the hypothesis that hematin is a sulfide-detoxifying agent that may enhance survival of U. caupo in the sulfide-rich mudflat environment.     

Designing Optimal Strategies to Attain the New U.S. Particulate Matter Standards: Some Initial Concepts

ABSTRACT

This paper proposes that a fundamental principle for designing optimal strategies to attain new U.S. particulate matter (PM) standards be minimization of community and susceptible group exposure to, and inhaled dosage of, ambient PM. Properly done, such minimization maximizes human health risk reduction. To illustrate implementation of such a principle, an initial prototype model, PM Exposure (PMEX), is described that calculates PM exposure and inhaled dosage as figures-of-merit for control strategy optimization. The model accounts for age-occupation and susceptible group activity patterns, indoor-outdoor concentration differences, and geographical location. Modeling results are presented for a hypothetical example, apportioning inhaled dosage among different classes of sources, under alternative assumptions about the relative potency of different PM species categories. The results, while preliminary, demonstrate that conclusions about source class contribution based on inhaled dosage can be appreciably different than those based on ambient air measurements or emission inventories.