Acute concern

Another evaluation of metal transfer rates was made by Sposito (1986) on the basis of the data compiled by Buat-Menard (1985). Despite many uncertainties, the conclusion emerges from Sposito s review (1986) that the trace metals Cu, Zn, Ag, Sb, Sn, Hg, and Pb are the most potentially hazardous on a global or regional scale. Lead is of acute concern on the global scale, because of its prominent showing in all the enrichment factors and transfer rates considered. These conclusions are in accordance with those of Andreae et al. (1986a) in a Dahlem report. 

It was shown in Chapter 6 that the contrasts among molecules are most acute concerning mutual information and energy dispersion. Following the same approach, reduced descriptors for the states can be constructed using ethane data for a baseline, for example ... 

It seems that in the early 1970s, while recognising a Soviet threat, the United States was not acutely concerned about it. Colonel William E. Dismore Jr, Chief of the Chemical Branch in the Chemical and Nuclear Systems Directorate of the Department of the Army, told a symposium of the American Chemical Society,... 

As a class of compounds, the two main toxicity concerns for nitriles are acute lethality and osteolathyrsm. A comprehensive review of the toxicity of nitriles, including detailed discussion of biochemical mechanisms of toxicity and stmcture-activity relationships, is available (12). Nitriles vary broadly in their abiUty to cause acute lethaUty and subde differences in stmcture can greatly affect toxic potency. The biochemical basis of their acute toxicity is related to their metaboHsm in the body. Following exposure and absorption, nitriles are metabolized by cytochrome p450 enzymes in the Hver. The metaboHsm involves initial hydrogen abstraction resulting in the formation of a carbon radical, followed by hydroxylation of the carbon radical. MetaboHsm at the carbon atom adjacent (alpha) to the cyano group would yield a cyanohydrin metaboHte, which decomposes readily in the body to produce cyanide. Hydroxylation at other carbon positions in the nitrile does not result in cyanide release. 

The short-term or acute effects of the P-agonists may be different from chronic effects. Acute Hpolysis and glycogenolysis are not observed beyond the first day or two of treatment. Exact mechanisms of action on Hpid metaboHsm may differ among species. Chronic effects of the P-agonists reduce circulating insulin concentrations ST treatment causes an opposite change. Whereas residue levels may be of concern with adrninistration of several of the P-agonists, such is not the case for ST or GRE. 

Unfortunately steroids merely suppress the inflammation while the underlying cause of the disease remains. Another serious concern about steroids is that of toxicity. The abmpt withdrawal of glucocorticoid steroids results in acute adrenal insufficiency. Long term use may induce osteoporosis, peptidic ulcers, the retention of fluid, or an increased susceptibiUty to infections. Because of these problems, steroids are rarely the first line of treatment for any inflammatory condition, and their use in rheumatoid arthritis begins after more conservative therapies have failed. 

Public concern about the abundance of algae, and of the toxic cyanobacteria in particular, was raised by events in the UK in the summer of 1989 which involved the deaths of dogs and sheep at Rutland Water, Leicestershire, and the acute... 

In the first environment, we are concerned with the potential health risks that chemicals pose to the public, as well as possible impacts on the ecology. In the latter case, we are concerned with indoor air quality and its possible adverse impacts on the health and safety of the workforce. In both cases the health dangers may be either acute, or long-term chronic health risks. We will first discuss general concepts of air pollution and table our discussions on... 

Chronic. Continuous exposure occurs over long periods of time, generally several mondis to years. Concentradons of inlialed (toxic) contaminants are usually reladvely low. This subject area falls in die general domain of healdi risk assessment (HRA) and it is diis subject tliat is addressed in die next five chapters. Thus, in contrast to the acute (short-term) exposures dial predominate in hazard risk assessments, cliroiiic (loiig-temi) exposures are the major concern in health risk assessments. 

Humans experience a wide range of acute adverse health effects, including irritation, narcosis, asphyxiation, sensitization, blindness, organ system damage, and death. In addition, the severity of many of these effects varies with intensity and duration of e.xposure. For example, exposure to a substance at an intensity that is sufficient to cause only mild throat irritation is of less concern than one that causes severe eye irritation, lacrimation, or dizziness, since the latter effects arc likely to impede escape from the area of contamination. 

The difficulty of assigning a formal oxidation state is more acutely seen in the case of 5-coordinate NO adducts of the type [Co(NO)(salen)]. These are effectively diamagnetic and so have no unpaired electrons. They may therefore be formulated either as Co -NO or Co -NO+. The infrared absorptions ascribed to the N-O stretch lie in the range 1624-1724 cm which is at the lower end of the range said to be characteristic of NO+. But, as in all such cases which are really concerned with the differing polarities of covalent bonds, such formalism should not be taken literally. 

As the science of indoor air quality has matured, indoor air professionals have realized that many indoor air contaminants and the associated health effects are linked to specific types of buildings and their characteristics. For example, radon is primarily an indoor air concern in homes because of the ease with which it can be transported inside residential construction from the soil beneath. On the other hand. Sick Building Syndrome (SBS) primarily afflicts office building occupants who experience acute health and comfort effects that appear to be linked to time spent in a specific building. 

On occasion, it may be necessary to postpone the regular immunization schedule, particularly for children. This is of special concern to parents. The decision to delay immunization because of illness or for other reasons must be discussed with the primary health care provider. However, the decision to administer or delay vaccination because of febrile illness (illness causing an elevated temperature) depends on the severity of the symptoms and the specific disorder. In general, all vaccines can be administered to those with minor illness, such as a cold virus and to those with a low-grade fever. However, moderate or severe febrile illness is a contraindication. hi instances of moderate or severe febrile illness, vaccination is done as soon as the acute phase of... 

When spills and releases of hazardous gases or liquids occur, the concentration of the hazardous material in the vicinity of the release is often the greatest concern, since potential health effects on those nearby will be determined by the concentration of the substance at the time of the acute exposure. There are many models of routine continuous discharges (e.g., discharges arising from leaky valves in chemical plants), but these carmot be applied to single episodic events. Research on the ambient behavior of short-term environmental releases and the development of models for concentration profiles in episodic releases are cmcial if we are to plan appropriate safety and abatement measures. 

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