Transport and anaerobic biodegradation of propylene glycol in gravel-rich soil materials

Continued input of airplane de-icing/anti-icing fluids (ADAF) to runway adjacent soils may result in the depletion of soil-borne terminal electron acceptors. We studied the transport and transformation of propylene glycol (PG), the major constituent of many ADAF, in topsoil and subsoil samples using saturated column experiments at 4 degrees C and 20 degrees C. The export of soil-borne DOC was generally high, non-exhaustive and rate limited. Retardation of added PG was negligible. Rapid PG degradation was observed only in topsoil materials high in organic matter at 20 degrees C. At 4 degrees C, no significant degradation was observed. Thus, under unfavorable, i.e., wet and cold conditions typical for winter de-icing operations, PG and its metabolites will be relocated to deeper soil horizons or even to the groundwater. In subsoil materials, PG degradation was very slow and incomplete. We found that subsoil degradation depended on the import of active microorganisms originating from the organic-rich topsoil material. The degradation efficiency is strongly influenced by the flow velocity, i.e., the residence time of PG in the soil column. Poorly crystalline iron(III) and manganese(IV) (hydr)oxides are used during microbial respiration acting as terminal electron acceptors. This results in the formation and effective relocation of reduced and mobile Fe and Mn species. Long-term application of ADAF to runway adjacent soil as well as the lasting consumption of Fe and Mn will tend to decrease the soil redox potential. Without proper counteractive measures, this will eventually favor the development of methanogenic conditions.     

Options for broadening and deepening the LCA approaches

Life Cycle Assessment (LCA) has matured over the past decades and become part of the broader field of sustainability assessment. To strengthen LCA as a tool and eventually increase its usefulness for sustainability decision-making, it is argued that there is a need to expand the ISO LCA framework by integration and connection with other concepts and methods. This paper explores the potential options for deepening and broadening the LCA methodologies beyond the current ISO framework for improved sustainability analysis. By investigating several environmental, economic and social assessment methods, the paper suggests some options for incorporating (parts of) other methods or combining with other methods for broadening and deepening the LCA.     

Updating federal standards for toxicants: n-Hexane as the model

Regulatory agencies commonly set standards for a myriad of chemical and physical hazards, with a special focus on carcinogens. This focus can obscure the need to update previously set standards for non-carcinogenic hazards in response to new scientific data. This paper considers n-hexane as a representative chemical hazard: the occupational standard of 500 ppm over an 8 hr time weighted average for a 40 hr week as set in 1948. In the last 12 yr, n-hexane has been shown to cause adverse effects on the peripheral and central nervous systems, the eye, and the respiratory tract. Yet, these new data have not, as yet, been incorporated into a revised standard for n-hexane. The lack of scientific data on the carcinogenicity of n-hexane may be an underlying reason explaining the failure of regulatory agencies to revise their standards. Perhaps, the most troubling problem to regulatory agencies is the sheer magnitude of the chemical regulatory burden. Research should proceed on developing meaningful categories or groupings both for the initial setting of standards and for revising existing standards.     

The older driver with dementia: an updated literature review

INTRODUCTION: At some point during their illness, drivers with dementia pose a public safety risk. METHOD: To address the issue of determining driving competence in drivers with dementia, the authors reviewed 11 studies. RESULTS: When comparing different driving assessments, the authors found that while road tests, simulators, and neuropsychological tests are important, each has limitations. CONCLUSION: Neuropsychological tests that highlighted visual spatial skills, attention, and reaction time provided the most meaningful correlations with driving performance. Furthermore, the authors recommend that patients with MMSE scores of 24 or less have a driving evaluation, and that driving evaluations be repeated at six month intervals or more frequently if a noticeable decline is observed. IMPACT: Because many older adults with dementia continue to drive, competence must be addressed.     

Two Concepts of Dignity for Humans and Non-Human Organisms in the Context of Genetic Engineering

The 1992 incorporation of an article by referendum in the SwissConstitution mandating that the federal government issue regulations onthe use of genetic material that take into account the dignity ofnonhuman organism raises philosophical questions about how we shouldunderstand what is meant by ``the dignity of nonhuman animals,' andabout what sort of moral demands arise from recognizing this dignitywith respect to their genetic engineering. The first step in determiningwhat is meant is to clarify the difference between dignity when appliedto humans and when applied to nonhumans. Several conceptions of humandignity should be rejected in favor of a fourth conception: the rightnot to be degraded. This right implies that those who have it have thecognitive capacities that are prerequisite for self-respect. In the caseof nonhuman organisms that lack this capacity, respecting their dignityrequires the recognition that their inherent value, which is tied totheir abilities to pursue their own good, be respected. This value isnot absolute, as it is in the case of humans, so it does not prohibitbreeding manipulations that make organisms more useful to humans. But itdoes restrict morally how sentient animals can be used. In regard togenetic engineering, this conception requires that animals be allowedthe uninhibited development of species specific functions, a positionshared by Holland and Attfield, as opposed to the Original Purposeconception proposed by Fox and the Integrity of the Genetic Make-upposition proposed by Rolston. The inherent value conception of dignity,as here defended, is what is meant in the Swiss Constitution article.