Chemical asthma

It is important to remember that respiratory sensitization and asthma are related, but not identical, pathologies [31]. Asthma is a specific syndrome which appears to have genetic as well as environmental causes and there are numerous potential triggers which have been identified by immunotoxicologists [32], However, asthma is not the same disease as other respiratory hypersensitivity syndromes (sometimes referred to as chemical asthma, etc.) [33, 34], Various regulatory guidance documents have sought to deal with the latter disease entities to ensure that xenobiotics are assessed appropriately for their ability to induce immune-based pulmonary hypersensitivity reactions [35-37],... 

Breathing difficulties, i.e. bronchitis or asthma, arising from sensitization to bacterial contamination or additive chemicals, have been reported. 

Asthmagens. Critical assessments of the evidence for agents implicated m occupational asthma 1997. The technical basis for COSHH essentials. Easy steps to control chemicals... 

List the diseases prescnbed for the payment of disablement benefit, if related to specific occupations. Conditions due to chemical agents, e.g. poisoning by any of a range of chemicals and certain carcinomas, and miscellaneous conditions, e.g. pneumoconiosis, asthma, diffuse mesothelioma, non-mfective dermatitis are included. 

Dyspnea Dyspnea is shortness of breath or difficulty in breathing. The victim is usually quite aware of the unusual breathing pattern. Shortness of breath can be an indicator of many physical ailments including simple exertion, a panic attack, a blow to the chest, asthma, cardiac disease, as well as exposure to toxic chemicals. If a person is suffering from shortness of breath, evaluate them for additional symptoms and possible exposures. Keep the victim in a sitting position. Remove the victim to fresh air, if possible, and seek medical attention. 

In addition to the proteins discussed above, a large number of reactive chemicals used in industry can cause asthma and rhinitis. Hypersensitivity pneumonias have also been described. Isocyanates and acid anhydrides are industrial chemicals that cause occupational asthma. Acid anhydrides, such as phthalic anhydride, seem to cause mainly type I reactions, whereas the IgE-mediated mechanism explains only a part of the sensitizations to isocyanates. Several mechanisms have been suggested, but despite intensive research no models have been generally accepted. The situation is even more obscure for other sensitizing chemicals therefore, the term specific chemical hypersensitivity is often used for chemical allergies. This term should not be confused with multiple chemical sensitivity (MCS) syndrome, which is a controversial term referring to hypersusceptibility to very low levels of environmental chemicals. ... 

Many irritative chemicals may cause non-specific hyper-responsitivity of the airways and skin. The number of irritating chemicals is very large, several thousands. The symptoms caused by exposure to irritants may resemble allergic symptoms. In addition, exposure to irritating substances (such as sulfur dioxide or solvent vapors) often triggers the symptoms in individuals with allergic asthma. 

Respiratory acidosis results when decreased respiration raises the concentration of C02 in the blood. Asthma, pneumonia, emphysema, or inhaling smoke can all cause respiratory acidosis. So can any condition that reduces a person s ability to breathe. Respiratory acidosis is usually treated with a mechanical ventilator, to assist the victim s breathing. The improved exhalation increases the excretion of C02 and raises blood pH. In many cases of asthma, chemicals can facilitate respiration by opening constricted bronchial passages. 

A non-allergic mechanism imderlying precipitation of asthmatic attacks by aspirin in hypersensitive patients was proposed over 30 years ago [4]. It was founded on pharmacological inhibition of COX of arachidonic acid and explained a cross-reactivity between different NSAIDs varying in chemical structure. This COX theory was confirmed by several studies [11] and was further refined following discovery of the second COX isoenzyme - COX-2. At least two COX isoenzymes, COX-1 and COX-2, are coded by separate genes. Their role in inflammation, asthma and anaphylaxis has been reviewed previously [12]. 

Ephedrine and pseudoephediine are a vasodilator and decongestant respectively used widely in the treatment of asthma and the symptoms of colds and influenza. These pharmaceuticals were derived originally fi om the plant Ephedra sinica and used in traditional Chinese medicinal preparations. Although some are still produced fi om such sources, the major production is via a fermentation process followed by a chemical catalytic reaction. As shown in Figure 1, the intermediate / -phenylacetylcarbinol (PAC) is produced by decarboxylation of pyruvate followed by ligation to benzaldehyde. 

Respiratory Effects. One study suggested increased respiratory disorders (asthma, bronchitis, pneumonia) in children with chronic exposure to a solvent-contaminated water supply (Byers et al. 1988). Two municipal wells in eastern Woburn, Massachusetts, were found to contain several solvents including trichloroethylene (267 ppb) and tetrachloroethylene (21 ppb). The increased susceptibility to infection may be secondary to effects on the immune system. Accurate chemical-specific exposure levels for individuals could not be determined because the water distribution system was designed to use water from different wells at different rates and times. Other limitations of this study are described in Section 2.2.2.8. 

Major factors that may contribute to the severity of asthma include allergens typically associated with atopy chemical exposures in occupational environments and exposure to tobacco smoke, irritants, and indoor and outdoor pollution. Other factors include concurrent disease states or medications that may worsen asthma severity. 

T cells control these learned responses and decide which tools to use in the reaction. Sometimes they choose several different tools at once, and multiple reactions ensue, such as when a person becomes sensitized to penicillin and has not only anaphylaxis but hemolytic anemia and serum sickness. There are different types of T cells, and they communicate either directly with other cells or by chemical messages called cytokines. The pattern of cytokines released is one way T cells have of determining which kind of response will occur. They are broadly called Thl andTh2 responses, with Thl mostly responding to infections and Th2 often producing allergy or asthma. 

When realistic quantities of the natural prostaglandins became available, their extreme potency and wide-ranging biological activities were discovered and visions of therapeutic application in the regulation of fertility, control of ulcers, blood pressure, bronchial asthma, and many other conditions led to a torrent of chemical and biological studies which currently measures about four papers daily, and at least one a week dealing with synthesis alone. 

Bronchial asthma is defined as a chronic inflammatory disease of the lungs it affects an estimated 9 to 12 million individuals in the U.S. Furthermore, its prevalence has been increasing in recent years. Asthma is characterized by reversible airway obstruction (in particular, bronchospasm), airway inflammation, and increased airway responsiveness to a variety of bronchoactive stimuli. Many factors may induce an asthmatic attack, including allergens respiratory infections hyperventilation cold air exercise various drugs and chemicals emotional upset and airborne pollutants (smog, cigarette smoke). 

Kimber, I. and Dearman, R.J., What makes a chemical an allergen Ann. Allergy Asthma Immunol., 90 (Suppl.), 28, 2003. 

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