Partitioning of PCBs from air to clothing materials in a Danish apartment.

Polychlorinated biphenyl (PCB) contamination of buildings continues to pose an exposure threat, even decades after their application in the form of calks and other building materials. In this research, we investigate the ability of clothing to sorb PCBs from contaminated air and thereby influence exposure. The equilibrium concentration of PCB-28 and PCB-52 was quantified for nine used clothing fabrics exposed for 56 days to air in a Danish apartment contaminated with PCBs. Fabric materials included pure materials such as cotton and polyester, or blends of polyester, cotton, viscose/rayon, and/or elastane. Air concentrations were fairly stable over the experimental period, with PCB-28 ranging from 350 to 430 ng/m3 and PCB-52 ranging from 460 to 550 ng/m3 . Mass accumulated in fabric ranged from below detection limits to 4.5 mg/g of fabric. Cotton or materials containing elastane sorbed more than polyester materials on a mass basis. Mass-normalized partition coefficients above detection limits ranged from 105.7 to 107.0  L/kg. Clothing acts as a reservoir for PCBs that extends dermal exposure, even when outside or in uncontaminated buildings.

Impact of surface ozone interactions on indoor air chemistry: A modeling study.

An INdoor air Detailed Chemical Model was developed to investigate the impact of ozone reactions with indoor surfaces (including occupants), on indoor air chemistry in simulated apartments subject to ambient air pollution. The results are consistent with experimental studies showing that approximately 80% of ozone indoors is lost through deposition to surfaces. The human body removes ozone most effectively from indoor air per square meter of surface, but the most significant surfaces for C6 -C10 aldehyde formation are soft furniture and painted walls owing to their large internal surfaces. Mixing ratios of between 8 and 11 ppb of C6 -C10 aldehydes are predicted to form in apartments in various locations in summer, the highest values are when ozone concentrations are enhanced outdoors. The most important aldehyde formed indoors is predicted to be nonanal (5-7 ppb), driven by oxidation-derived emissions from painted walls. In addition, ozone-derived emissions from human skin were estimated for a small bedroom at nighttime with concentrations of nonanal, decanal, and 4-oxopentanal predicted to be 0.5, 0.7, and 0.7 ppb, respectively. A detailed chemical analysis shows that ozone-derived surface aldehyde emissions from materials and people change chemical processing indoors, through enhanced formation of nitrated organic compounds and decreased levels of oxidants.

Dermal uptake of phthalates from clothing: Comparison of model to human participant results.

In this research, we extend a model of transdermal uptake of phthalates to include a layer of clothing. When compared with experimental results, this model better estimates dermal uptake of diethylphthalate and di-n-butylphthalate (DnBP) than a previous model. The model predictions are consistent with the observation that previously exposed clothing can increase dermal uptake over that observed in bare-skin participants for the same exposure air concentrations. The model predicts that dermal uptake from clothing of DnBP is a substantial fraction of total uptake from all sources of exposure. For compounds that have high dermal permeability coefficients, dermal uptake is increased for (i) thinner clothing, (ii) a narrower gap between clothing and skin, and (iii) longer time intervals between laundering and wearing. Enhanced dermal uptake is most pronounced for compounds with clothing-air partition coefficients between 104 and 107 . In the absence of direct measurements of cotton cloth-air partition coefficients, dermal exposure may be predicted using equilibrium data for compounds in equilibrium with cellulose and water, in combination with computational methods of predicting partition coefficients.

Dermal uptake directly from air under transient conditions: advances in modeling and comparisons with experimental results for human subjects.

To better understand the dermal exposure pathway, we enhance an existing mechanistic model of transdermal uptake by including skin surface lipids (SSL) and consider the impact of clothing. Addition of SSL increases the overall resistance to uptake of SVOCs from air but also allows for rapid transfer of SVOCs to sinks like clothing or clean air. We test the model by simulating di-ethyl phthalate (DEP) and di-n-butyl phthalate (DnBP) exposures of six bare-skinned (Weschler et al. 2015, Environ. Health Perspect., 123, 928) and one clothed participant (Morrison et al. 2016, J. Expo. Sci. Environ. Epidemiol., 26, 113). The model predicts total uptake values that are consistent with the measured values. For bare-skinned participants, the model predicts a normalized mass uptake of DEP of 3.1 (µg/m2 )/(µg/m3 ), whereas the experimental results range from 1.0 to 4.3 (µg/m2 )/(µg/m3 ); uptake of DnBP is somewhat overpredicted: 4.6 (µg/m2 )/(µg/m3 ) vs. the experimental range of 0.5-3.2 (µg/m2 )/(µg/m3 ). For the clothed participant, the model predicts higher than observed uptake for both species. Uncertainty in model inputs, including convective mass transfer coefficients, partition coefficients, and diffusion coefficients, could account for overpredictions. Simulations that include transfer of skin oil to clothing improve model predictions. A dynamic model that includes SSL is more sensitive to changes that impact external mass transfer such as putting on and removing clothes and bathing.

Long-term performance of passive materials for removal of ozone from indoor air.

The health effects associated with exposure to ozone range from respiratory irritation to increased mortality. In this paper, we explore the use of three green building materials and an activated carbon (AC) mat that remove ozone from indoor air. We studied the effects of long-term exposure of these materials to real environments on ozone removal capability and pre- and post-ozonation emissions. A field study was completed over a 6-month period, and laboratory testing was intermittently conducted on material samples retrieved from the field. The results show sustained ozone removal for all materials except recycled carpet, with greatest ozone deposition velocity for AC mat (2.5-3.8 m/h) and perlite-based ceiling tile (2.2-3.2 m/h). Carbonyl emission rates were low for AC across all field sites. Painted gypsum wallboard and perlite-based ceiling tile had similar overall emission rates over the 6-month period, while carpet had large initial emission rates of undesirable by-products that decayed rapidly but remained high compared with other materials. This study confirms that AC mats and perlite-based ceiling tile are viable surfaces for inclusion in buildings to remove ozone without generating undesirable by-products. PRACTICAL IMPLICATIONS The use of passive removal materials for ozone control could decrease the need for, or even render unnecessary, active but energy consuming control solutions. In buildings where ozone should be controlled (high outdoor ozone concentrations, sensitive populations), materials specifically designed or selected for removing ozone could be implemented, as long as ozone removal is not associated with large emissions of harmful by-products. We find that activated carbon mats and perlite-based ceiling tiles can provide substantial, long-lasting, ozone control.

Reaction rates of ozone and terpenes adsorbed to model indoor surfaces.

UNLABELLED: Reaction rates and reaction probabilities have been quantified on model indoor surfaces for the reaction of ozone with two monoterpenes (Δ(3) -carene and d-limonene). Molar surface loadings were obtained by performing breakthrough experiments in a plug-flow reactor (PFR) packed with beads of glass, polyvinylchloride or zirconium silicate. Reaction rates and probabilities were determined by equilibrating the PFR with both the terpene and the ozone and measuring the ozone consumption rate. To mimic typical indoor conditions, temperatures of 20, 25, and 30°C were used in both types of experiments along with a relative humidity ranging from 10% to 80%. The molar surface loading decreased with increased relative humidity, especially on glass, suggesting that water competed with the terpenes for adsorption sites. The ozone reactivity experiments indicate that higher surface loadings correspond with higher ozone uptake. The reaction probability for Δ(3) -carene with ozone ranged from 2.9 × 10(-6) to 3.0 × 10(-5) while reaction probabilities for d-limonene ranged from 2.8 × 10(-5) to 3.0 × 10(-4) . These surface reaction probabilities are roughly 10-100 times greater than the corresponding gas-phase values. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially for lower volatility terpenoids. PRACTICAL IMPLICATIONS: At present, it is unclear how important heterogeneous reactions will be in influencing indoor concentrations of terpenes, ozone and their reaction products. We observe that surface reaction probabilities were 10 to 100 times greater than their corresponding gas-phase values. Thus indoor surfaces do enhance effective reaction rates and adsorption of terpenes will increase ozone flux to otherwise low-reactivity surfaces. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially for lower volatility terpenoids.

Insulin infusion via an intraosseous needle in diabetic ketoacidosis.

We report the successful management of a five-year-old child with severe diabetic ketoacidosis with dehydration, who received his initial resuscitative fluids and a continuous infusion of insulin via an intraosseous needle. The patient had presented to a remote community hospital and intravenous access could not be gained. The correction of hyperglycaemia and metabolic acidaemia was achieved at a rate comparable to intravenous therapy. No complications were observed. Although intraosseous access is well described in paediatric resuscitation guidelines, it is not mentioned in International Diabetes Society guidelines for the management of diabetic ketoacidosis. Alternatives to intravenous administration of insulin delivery recommended in such guidelines, such as the subcutaneous or intramuscular routes, may be less appropriate than the intraosseous route. This route can also allow resuscitation fluids and other drugs to be reliably administered in children with diabetic ketoacidosis and severe dehydration where intravenous access can not be attained. We suggest that the potential role of intraosseous access, when intravenous access can not be obtained, should be considered when management guidelines for paediatric diabetic ketoacidosis with dehydration are reviewed.

The influence of ammonia and carbon dioxide on the sorption of a basic organic pollutant to a mineral surface.

UNLABELLED: Indoor surfaces have a sorptive capacity for organic pollutants which may be significantly influenced by other gases and the pH of the surface. In this research, we examine the influence of a common indoor gaseous acid, CO2, and base, NH3, on the adsorption of a volatile organic base, trimethylamine (TMA), to a mineral surface, zirconium silicate beads. Varying ammonia and CO2 within concentration ranges of indoor relevance substantially influences the sorptive capacity of this mineral surface. Increasing the CO2 mixing ratio to 1000 p.p.m. enhances surface capacity of TMA by 40-50%; increasing the NH3 mixing ratio to 10 p.p.m. decreases the TMA surface capacity by approximately 5-80% depending on relative humidity. The phenomena of dissolution of TMA into bulk surface water and acid-base chemistry in the surface water do not adequately describe equilibrium adsorption on this surface. Instead, adsorption to the dry solid or to adsorbed water layers appears to dominate. Reduction in the equilibrium partition coefficient, ke, in the presence of NH3 is due to a competition between TMA and ammonia molecules for adsorption sites. Site competition appears to follow the Langmuir competitive model and most ke values range from 0.003-0.045 m. PRACTICAL IMPLICATIONS: Sorptive interactions with indoor surfaces strongly influence indoor exposure to pollutants. For basic or acidic compounds, these interactions are themselves influenced by surface pH and competition with other acidic or basic gases such as CO2 and NH3. We show that CO2 tends to cause mineral surfaces to store more amines but NH3 tends to decrease this surface capacity. Given the typical range of indoor CO2 and NH3 concentrations, the indoor sorbtive capacity of amines on mineral surfaces may vary by greater than an order of magnitude.

Improving the sensitivity of the time trade-off method: results of an experiment using chained TTO questions.

We test a chained time trade-off (TTO) approach to estimating health gains from interventions by asking respondents to directly compare the "before" and "after" intervention health states in the TTO framework. Respondents with experience of both health states were used, thus minimising biases stemming from confusion surrounding health descriptions. We found that responses to these direct comparisons were much more likely to capture a perceived change in health status than the conventional approach to TTO estimation. This is an important finding because the TTO method is preferred by practitioners to many other direct generic methods of health status valuation both on empirical grounds and because it is based on the notion of opportunity cost, which is central to consumer theory, requiring respondents to express their preferences in terms of foregoing some of one good in exchange for more of another (unlike a rating scale).

Demand for health care in Denmark: results of a national sample survey using contingent valuation.

In this paper we use willingness to pay (WTP) to elicit values for private insurance covering treatment for four different health problems. By way of obtaining these values, we test the viability of the contingent valuation method (CVM) and econometric techniques, respectively, as means of eliciting and analysing values from the general public. WTP responses from a Danish national sample survey, which was designed in accordance with existing guidelines, are analysed in terms of consistency and validity checks. Large numbers of zero responses are common in WTP studies, and are found here; therefore, the Heckman selectivity model and log-transformed OLS are employed. The selectivity model is rejected, but test results indicate that the lognormal model yields efficient and unbiased estimates. The results give confidence in the WTP estimates obtained and, more generally, in CVM as a means of valuing publicly provided goods and in econometrics as a tool for analysing WTP results containing many zero responses.

Measuring the effects of seating on people with profound and multiple disabilities--a preliminary study.

This paper describes a preliminary study to investigate a range of approaches that might be used for measuring the effects of special seating on people with profound and multiple disabilities and their carers. A number of tools are proposed for measuring the effects on quality of life, function and carer satisfaction. The results of applying these tools to measure the effects of intervention with customized molded seating on nine people with multiple disabilities are described. The results suggest that these tools are sensitive to this intervention, showing a general beneficial effect with good carer satisfaction. The study points the way towards application of these tools to people with a wider range of disabilities and to different interventions.

Reducing the risk of accidental death due to vehicle-related carbon monoxide poisoning.

Emissions of carbon monoxide (CO) from motor vehicles cause several hundred accidental fatal poisonings annually in the United States. The circumstances that could lead to fatal poisonings in residential settings with motor vehicles as the source of CO were explored. The risk of death in a garage (volume = 90 m3) and a single-family dwelling (400 m3) was evaluated using a Monte Carlo simulation with varying CO emission rates and ventilation rates. Information on emission rates was obtained from a survey of motor vehicle exhaust gas composition under warm idle conditions in California, and information on ventilation rates was obtained from a summary of published measurements in the U.S. housing stock. The risk of death ranged from 16 to 21% for a 3-hr exposure in a garage to 0% for a 1-hr exposure in a house. Older vehicles were associated with a disproportionately high risk of death. Removing all pre-1975 vehicles from the fleet would reduce the risk of death by one-fourth to two-thirds, depending on the exposure scenario. Significant efforts have been made to control CO emissions from motor vehicles with the goal of reducing CO concentrations in outdoor air. Substantial public health benefit could also be obtained if vehicle control measures were designed to take account of acute CO poisonings explicitly.

Indoor air quality impacts of ventilation ducts: ozone removal and emissions of volatile organic compounds.

The concentrations of contaminants in the supply air of mechanically ventilated buildings may be altered by pollutant emissions from and interactions with duct materials. We measured the emission rate of volatile organic compounds (VOCs) and aldehydes from materials typically found in ventilation ducts. The emission rate of VOCs per exposed surface area of materials was found to be low for some duct liners, but high for duct sealing caulk and a neoprene gasket. For a typical duct, the contribution to VOC concentrations is predicted to be only a few percent of common indoor levels. We exposed selected materials to approximately 100-ppb ozone and measured VOC emissions. Exposure to ozone increased the emission rates of aldehydes from a duct liner, duct sealing caulk, and neoprene gasket. The emission of aldehydes from these materials could increase indoor air concentrations by amounts that are as much as 20% of odor thresholds. We also measured the rate of ozone uptake on duct liners and galvanized sheet metal to predict how much ozone might be removed by a typical duct in ventilation systems. For exposure to a constant ozone mol fraction of 37 ppb, a lined duct would initially remove approximately 9% of the ozone, but over a period of 10 days of ozone removal efficiency would diminish to less than 4%. In an unlined duct, in which only galvanized sheet metal is exposed to the air-stream, the removal efficiency would be much lower, approximately 0.02%. Therefore, ducts in ventilation systems are unlikely to be a major sink for ozone.

HYE (healthy years equivalent) and TTO (time trade-off): what is the difference?

This paper demonstrates that the HYE (healthy-years-equivalent) procedure not only has nothing more to offer than the TTO (time trade-off) method, but that it introduces a systematic bias that is not present using TTO. Diagrams are used to illustrate that the HYE yields health status values, not utilities as its creators suggest, and to show that the HYE and TTO techniques are theoretically identical. Then, empirical evidence concerning the standard gamble/certainty equivalence disparity noted elsewhere in the literature is shown to indicate that HYE responses are likely to contain systematic biases that will lead to HYE estimates exceeding TTO values.

Appraising the use of contingent valuation.

The valuation of treatments and health states has been pursued in a number of ways. Most predominant are contingent valuation (CV), QALYs, and HYEs. CV--that is, willingness to pay and willingness to accept--is the only one of these methods that can be consistent with welfare economic theory, but, as discussed by Gafni (1990), in order to do so three criteria must be met. This article argues that the fulfilment of these criteria is not sufficient to obtain useful results, and some additional criteria are suggested. Several CV studies carried out in the area of health are reviewed, and their compliance or non-compliance, with both sets of criteria, is discussed. Finally, it is argued that, although CV is the more theoretically correct method, it is not a superior tool to QALYs and HYEs, and that the decision as to which is the appropriate valuation method depends on the policy issue at hand.

Cardiotonic agents. 6. Synthesis and inotropic activity of 2,4-dihydro-5-[4-(1H-imidazol-1-yl)phenyl]-3H-pyrazol-3-ones: ring-contracted analogues of imazodan (CI-914).

A series of 2,4-dihydro-5-[4-(1H-imidazol-1-yl)phenyl]-3H-pyrazol-3-ones was synthesized and evaluated for positive inotropic activity. Only compounds with two small alkyl groups at C-4 showed significant activity. The structure-activity relationships for optimal inotropic activity are presented and compared with those of the 4,5-dihydro-3(2H)-pyridazinone series. The phosphodiesterase inhibitory activity is also reported and correlated with the substitution pattern at C-4 in the pyrazolone ring.