Science of odor as a potential health issue

Historically, unpleasant odors have been considered warning signs or indicators of potential risks to human health but not necessarily direct triggers of health effects. However, citizen complaints to public health agencies suggest that odors may not simply serve as a warning of potential risks but that odor sensations themselves may cause health symptoms. Mal-odors emitted from large animal production facilities and wastewater treatment plants, for example, elicit complaints of eye, nose, and throat irritation, headache, nausea, diarrhea, hoarseness, sore throat, cough, chest tightness, nasal congestion, palpitations, shortness of breath, stress, drowsiness, and alterations in mood. There are at least three mechanisms by which ambient odors may produce health symptoms. First, symptoms can be induced by exposure to odorants (compounds with odor properties) at levels that also cause irritation or other toxicological effects. That is, irritation--rather than the odor--is the cause of the health symptoms, and odor (the sensation) simply serves as an exposure marker. Second, health symptoms from odorants at non-irritant concentrations can be due to innate (genetically coded) or learned aversions. Third, symptoms may be due to a co-pollutant (such as endotoxin) that is part of an odorant mixture. Objective biomarkers of health symptoms must be obtained, however, to determine if health complaints constitute health effects. One industry that is receiving much attention, worldwide, related to this subject is concentrated animal production agriculture. Sustainability of this industry will likely necessitate the development of new technologies to mitigate odorous aerial emissions. Examples of such "environmentally superior technologies" (EST) developed under the initiative sponsored through agreements between the Attorney General of North Carolina and Smithfield Foods and Premium Standard Farms are described.     

Uptake and Metabolism of TNT and GTN by Plants Expressing Bacterial Pentaerythritol Tetranitrate Reductase

The manufacture and improper disposal of explosives has resulted in a significant amount of land requiring remediation. The compound 2,4,6-trinitrotoluene (TNT) is the most persistent and toxic of the explosive pollutants with current treatment methods being energy intensive and costly. Bacterial enzymes such as pentaerythritol tetranitrate reductase (PETNR) from Enterobacter cloacae PB2 have been found to have activity against TNT; however, microbes often lack the biomassnecessary for remediation applications. The PETNRgene (onr1) was transformed into tobacco plants in an attempt to combine the metabolic diversity of microbes with the sequestering properties of plants. The resulting transgenic plants were shown to have enhanced tolerance to TNT during germination and as seedlings. Phytoremediation applications with these plants may provide an alternative treatment of TNT contamination.     

Formula allocation as a policy tool: politics and measurement

Formula allocation is a major tool for the distribution of public funds in the United States of America. This paper explores several examples of formulae used in U.S. domestic programmes, looking at their construction, meaning and consequences. The authors argue that the design of formulae is both a political and technical task. The paper concludes with a series of recommendations to improve formulae as tools of distributional policy.     

Secondary organic aerosol formation from cyclohexene ozonolysis in the presence of water vapor and dissolved salts

A series of 90 experiments were conducted in the UC Riverside/CE-CERT environmental chamber to evaluate the impact of water vapor and dissolved salts on secondary organic aerosol formation for cyclohexene ozonolysis. Water vapor (low – 30 ± 2% RH, medium – 46 ± 2% RH, high – 63 ± 2% RH) was found to directly participate in the atmospheric chemistry altering the composition of the condensing species, thus increasing total organic aerosol formation by ～22% as compared to the system under dry (<0.1% RH) conditions. Hygroscopicity measurements also indicate that the organic aerosol composition is altered in the presence of gaseous water. These results are consistent with water vapor reacting with the crigee intermediate in the gas phase resulting in increased aldehyde formation. The addition of dissolved salts ((NH₄)₂SO₄, NH₄HSO₄, CaCl₂, NaCl) had minimal effect; only the (NH₄)₂SO₄ and NaCl were found to significantly impact the system with ～10% increase in total organic aerosol formation. These results indicate that the organics may be partitioning to an outer organic shell as opposed to into the aqueous salt. Hygroscopicity measurements indicate that the addition of salts does not alter the aerosol composition for the dry or water vapor system.     

A Markov random field spatio-temporal analysis of ocean temperature

The National Oceanic Data Center (NODC) contains historical records from approximately 144,000 hydrographic stations in the North Atlantic. This data has been used by oceanographers to construct maps of point estimates of pressure, temperature, salinity and oxygen in the North Atlantic (Levitus (1994); Lozier et al. (1995)). Because data from any particular year are scarce, the previous maps have been for time-averaged values only. In addition, the maps have been reported without uncertainty estimates. This paper presents a Markov random field (MRF) analysis that can generate maps for specific time periods along with associated uncertainties. To estimate changes in oceanic properties over time previous oceanographic work has focused on differences between a few time periods each having many observations. Due to data scarcity this poses a severe restriction for both spatial and temporal coverage of climatic change. The MRF analysis provides a means for temporal modeling that does not require high data density at each time period. To demonstrate the usefulness of a MRF analysis of oceanic data we investigate the temporal variability along 24.5°N in the North Atlantic. Our results are compared to an earlier analysis (Parrilla et al. (1994)) where data from only three time periods was used. We obtain a more thorough understanding of the temperature change found by this previous study.