Stressor

The subtle interaction of air pollutants with these other stressors to plants and vegetation is the subject of ongoing research. For some plant systems, exposure to air pollutants may induce biochemical modifications which interfere with the water balance in plants, thereby reducing their ability to tolerate drought conditions. 

This interaction between airborne acid components and the tree-soil system may alter the ability of the trees to tolerate other environmental stressors such as drought, insects, and other air pollutants like ozone. In Germany, considerable attention is focused the role of ozone and acid deposition as a cause of forest damage. Forest damage is a complex problem involving the interaction of acid deposition, other air pollutants, forestry practices, and naturally occurring soil conditions. 

One of the most serious stressors to personnel working in many chemical processes is the perception of danger by the workers arising from ineffective control and supervision of these systems. Despite the fact that modem plants are equipped with automated protection systems, there is always some perception of potential risk in their operation. Serious threats can be posed not only for those within the plant, but also for the neighboring public. An environment that is perceived as being highly dangerous will increase the stress experienced by the workers and may have a detrimental effect on their performance. 

Most of the research on the effects of these stressors on human performance has been done on simple laboratory tasks rather than actual work situations. As a result, the extent that such findings can carry over to tasks in the CPI is debatable. In addition, most of these studies have examined the effect of a single stressor (e.g., noise or heat) only, rather than the combined effect. Nevertheless, some useful guidelines about optimal levels of these stressors are available in the ergonomics literature (e.g., McCormick and Sanders, 1983 Salvendy, 1987). 

The extent to which a particular combination of such "operating environment" factors will be perceived by the workers as being stressful will depend on the available resources such as the quality of the control panel, procedures, training, organizational and social factors, and, finally, the individual characteristics of the workers. The outcome of this transaction between stress factors and coping resources will influence the onset of worker stress. Situations are not stressful merely because of the presence of a number of external stressors, but because they are perceived as such by workers. 

The definition of what constitutes a stressor is also an important issue. So far, we have considered only external stressors stemming from the demands of the operating environment. Deficiencies in the design of the control panel. 

Disadvantages may arise because the behavior observed may not be fully realistic. A static simulation, for instance, may not reveal the true nature of operators dynamic interaction with the system. There is also the possible disadvantage of behavior in a simulator not fully replicating that found in the real situation. This can happen because of the absence of real stressors found in the actual task, for example, risk to life, criticality of the process, and presence of other workers and supervisors. 

The aforementioned reviews and assessments were assimilated to characterize the effect of dielectric, rotational, and mechanical hazards on motor performance and operational readiness. Functional indicators were identified that can be monitored to assess motor component deterioration caused by aging or other accidental stressors. The study also includes a preliminary discussion of current standards and guides, maintenance programs, and research activities pertaining to nuclear power plant safety-related electric motors. Included are motor manufacturer recommendations, responses from repair facilities to a questionnaire, in-service inspection data, expert knowledge, USNRC-IE audit reports, and standards and guides published by the Institute of Electrical and Electronics Engineers (IEEE). 

Gubits, R.M. Fairhurst, J.L. (1988). c-fos mRNA levels are increased by the cellular stressors, heat shock and sodium arsenite. Oncogene 3, 163-168. 

Most medical students look askance at thermobiology. We think this is a mistake hence, we have included a section dealing with this subject. This brings us to the chapter on the heat shock response which at the very outset makes clear that many stressors besides heat are known to result in heat shock gene expression. Many of the heat shock proteins occur in unstressed cells and some of them behave as chaperones. These proteins also reach high levels in a wide range of diseases... 

Tockner K, Lorang MS, Borchardt D, et al (2009) Multiple stressors in coupled river-flood plain ecosystems. Freshw Biol (in press)... 

Only a small fraction of faecal contaminants contributed to the enviromnent through human and animal faeces reach new hosts to infect them. Many of the defecated microorganisms never reach the soil and/or water bodies, since faecal wastes are submitted to purification (water) and hygienization (solids) processes, which remove a fraction of the pathogens and indicators. An important fraction of those that reach either the soil or water are removed (adsorption to soil particles and suspended solids, followed by sedimentation) and/or inactivated by natural stressors (physical, chemical and biological) in soil and water bodies. 

Lugo, A.E. McCormick, J.F. (1981). Influence of environmental stressors upon energy flow in a natural terrestrial ecosystem. In Stress Effects on Natural Ecosystems, ed. G.W. Barrett R. Rosenberg, pp. 79-102. New York Wiley. 

Protein deficiency or other unidentified stressors may enhance the anemia-inducing effect of endosulfan. 

Ankley, G.T., Degitz, S.J., and Diamond, S.A. et al. (2004). Assessment of enviromnental stressors potentially responsible for malformations in North American annran amphibians. Ecotoxicology and Environmental Safety 58, 7-16. 

Atchison, G.J., Sandheinrich, M.B., and Bryan, M.D. (1996). Effects of environmental stressors on interspecific interactions of aquatic animals. In M.C. Newman and C.H. Jagoe (Eds.), Quantitative Ecotoxicology A Hierarchical Approach. Lewis, Chelsea, Ml. 

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