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At least 19 recordsLinked to original sources
PubMed1995

A comparison of some of the characteristics of patients with occupational and non-occupational asthma.

Occupational asthma is the most frequently diagnosed occupational lung disease reported to the SWORD (Surveillance of Work-related and Occupational Respiratory Disease) scheme. However, diagnosing occupational asthma is not straightforward, and establishing a link with work may be difficult. This study was undertaken to determine the differences between patients with occupational asthma and those with non-occupational asthma which might help in their diagnosis. Information was collected using a self-completed questionnaire. Questionnaires were distributed to 30 subjects aged 18-65 years at each of two clinics--one for patients with occupational asthma and one for those with cryptogenic and environmental asthma. Replies were received from 26 patients with occupational asthma (87%) and 29 patients with non-occupational asthma (97%). The age of onset was significantly higher for those with occupational asthma (42.6 vs 20.7 years). Significantly more subjects with occupational asthma reported improvement on holiday, whereas no significant difference was found in the numbers reporting worsening of symptoms on work days. Those with occupational asthma were less likely to report seasonal variation in symptoms, exacerbation by allergies, pets and stress, or a family history of asthma. Subjects with occupational asthma were more likely to become unemployed (50% vs 3%). Recognition of some of these features in a patient's history may help in the difficult task of differentiating occupational from non-occupational asthma, potentially avoiding the need for exhaustive investigations in some patients. The high prevalence of holiday improvement among subjects with non-occupational asthma suggested that domestic or environmental allergies arising outside the workplace may have been making an important contribution to ongoing symptoms in these subjects.

Adolescent↗
PubMed1995

Occupational asthma.

Occupational asthma is an important occupational respiratory disorder, both in terms of morbidity, disability and in the total number of cases. The two types of occupational asthma are classified on the basis of their temporal relationship to onset. Occupational asthma with latency reflects allergic occupational asthma and is a condition characterized by a preceding latent period of workplace exposure during which allergic sensitization to a material present at the work site occurs. It is characterized biochemically by immunologic alterations and physiologically by variable and work-related airflow limitation with the presence of both specific and nonspecific airway hyperresponsiveness. In contrast, occupational asthma without latency is an asthmatic condition that develops suddenly and without a preceding latent period, as epitomized by the reactive airways dysfunction syndrome (RADS). RADS is distinguished physiologically by chronic, persistent nonspecific airway hyperresponsiveness and usually occurs after a single brief high-level exposure to an irritant gas, vapor of fume; new information suggests that a more prolonged irritant exposure, in certain susceptible persons with a pre-existing allergic predisposition, can also lead to the initiation of new-onset asthma. The factors that may be influential in the pathogenesis of occupational asthma include: exposure characteristics, industrial factors, job attributes, geographic and climatic conditions, economic considerations and personal or host conditions, such as atopy and cigarette smoking. Preventive measures and opportunities for intervention are essential and must address plans for reducing or eliminating accidents and spills, as well as plans for engineering control methods and proper and effective local exhaust ventilation. Medical surveillance programs are the keystone for prevention and should identify persons who are at an increased risk for developing occupational asthma, as well as detecting asthma at an early stage when intervention options are likely to be successful. For sensitized workers, the best preventive option is completed removal from the work environment.

Asthma↗
PubMedDate not supplied

Occupational asthma.

Occupational asthma is the most common occupational lung disease in the world. Occupational asthma comprises approximately 25-50% of occupational lung diseases and is responsible for up to 15% of all asthma cases. Either immunologic or nonimmunologic causes may be responsible for occupational asthma. There are approximately 250 compounds known to cause occupational asthma. Common examples include flour, animal dander, isocyanates, and latex. The diagnosis of occupational asthma depends on an accurate history of asthma and documentation that the asthma is caused by workplace exposure. Peak flow measurements are commonly used to provide data to define this relationship. Spirometry and bronchial provocation testing are also helpful. The key management tool in occupational asthma is avoidance of the causative agent. Avoidance is more important than treatment with medications. Occupational asthma can have major socioeconomic impacts on an individual, and the diagnostic work-up and management needs to be performed with this in mind.

Asthma↗
PubMed1998

[Occupational asthma].

Occupational asthma is specifically induced by repeated exposure to substances in the work place. Diagnosis requires using the results of numerous tests, and a challenge test is the most appropriate to establish the diagnosis of occupational asthma due to chemical agents. Agents responsible for occupational asthma may be of animal or vegetable origin, or may be chemical agents. The pathophysiological mechanisms of occupational asthma are not well known. It is probable that immunologic mechanisms play an important role, in particular in occupational asthma due to glycoproteins. An important feature of occupational asthma is the relationship to chemical substances, for which the mechanisms are often still hypothetical. From the legal viewpoint, a recent law holds the promise of better compensation for those who are afflicted.

Asthma↗
PubMed2001

Clinical update on occupational asthma.

Occupational asthma is the most common occupational respiratory disease in many developed countries as well as in Singapore. About 4% to 9% of adult asthmatics may have occupational asthma. The condition is still under-diagnosed and under-reported. Asking an adult asthma patient whether his or her symptoms improve when away from work and worsen during periods at work is important in detecting potential cases of occupational asthma. Serial peak expiratory flow rate (PEFR) monitoring during periods at work and away from work is useful for providing objective documentation of work-relatedness. Specific challenge testing is carried out to confirm a specific causative agent where a new agent is suspected, where there are multiple agents involved and it is important to establish the exact agent, and when it is not possible to carry out serial PEFR monitoring. Early diagnosis and removal from further exposure to the causative agent in the workplace will benefit the patient with occupational asthma. Preventive measures are important to protect other workers at risk.

Asthma↗
PubMed1986

Occupational asthma.

Occupational asthma accounts for a significant percentage of all asthma. Prevalence varies markedly, depending on host factors, the agent, and the manufacturing facility. The number of agents capable of inducing occupational asthma is large and will continue to increase as new agents are introduced into the workplace. Once an individual is sensitized, very low concentrations of the agent can initiate an asthmatic response. In many cases the mechanisms of the asthma are yet to be determined. The ultimate outcome of both the specific asthmatic response and the nonspecific bronchial hyperreactivity that usually occurs is variable, but in some cases it can continue for decades. Future needs are a better understanding of the prevalence of occupational asthma and the causative mechanisms involved in the disease and prophylactic or "desensitizing" measures. Environmental experts should explore methods to decrease the exposure of workers, and manufacturers should also begin to explore the possibility that chemical modification of their products may reduce their asthmatic potential (e.g., MDI, which has a vapor pressure 1000 times less than TDI, appears to be a significantly less potent inducer of occupational asthma). Finally, the physician, by identifying individuals with occupational asthma, will help improve our understanding of the disease, the mechanisms involved, and the development of therapeutic and preventive modalities.

Asthma↗
PubMed1999

[Occupational asthma].

Occupational asthma is an important disorder, both for the affected individual and for society. The diagnosis of this condition is not easy and it, therefore, often happens that the occupational origin of asthma is overlooked by physicians. In most instances occupational asthma is due to immunological sensitization to an agent present in the workplace. The numerous possible causes of occupational asthma can be classified in high molecular weight compounds of biologic origin and low molecular weight chemicals. Occupational asthma can also follow from airway irritation, either after an acute inhalational injury, or after chronic or repeated peak exposures to irritants. From a medicolegal point of view, occupational asthma presents problems with regard to establishing a causal relationship between work and asthma and in relation to the generally inadequate compensation of victims. To prevent occupational asthma the best policy is to avoid and minimize exposure to sensitizers at work. Occupational asthma offers interesting models for the study of asthma in general.

Asthma↗
PubMed1994

Aetiological agents in occupational asthma.

Occupational asthma has become the most prevalent occupational lung disease in developed countries. At present, about 200 agents have been implicated in causing occupational asthma in the workplace. These agents can be divided into two categories by their mechanism of action: immunological and nonimmunological. Immunological causes can be further divided into those that induce asthma through an immunoglobulin E (IgE)-dependent mechanism, and those that induce asthma through a non-IgE-dependent mechanism. In the latter category, specific IgE antibodies are found only in a small percentage of the patients with proven disease, even though the clinical picture is compatible with an allergic reaction. The immunological mechanism(s) responsible for these agents has yet to be identified. The best known example of nonimmunological asthma is Reactive Airways Dysfunction Syndrome (RADS) or irritant-induced asthma. In this review, examples of types of agents causing occupational asthma are discussed and a compendium table of aetiological agents is given.

Allergens↗
PubMed2001

A guide to the diagnosis and treatment of occupational asthma.

Occupational asthma is the most prevalent form of occupational lung disease in industrialized nations. As increasing numbers of new chemicals are produced and new manufacturing processes are introduced, the variety of environments in which individuals may become exposed to respiratory sensitizers and irritants makes diagnosing and treating this illness even more challenging. In addition to adverse pulmonary effects, the diagnosis of occupational asthma may bring with it negative social and financial implications that may ultimately affect the patient's quality of life. For this reason, it is important for clinicians to recognize work-related respiratory symptoms early on in their course, maintain a high clinical suspicion for an occupational cause in the diagnostic work-up of asthma, and have a high degree of certainty in the diagnosis. While a number of classification schemes have been proposed to simplify the diagnostic approach to occupational asthma, the inciting factors typically involve sensitization (often by an IgE mechanism), direct airway inflammation, various pharmacologic responses, or irritant reflex pathways. Clinicians must first document the presence of asthma, then establish a relationship between asthma and the work-place. The occupational history is the key diagnostic tool, and clinical suspicions may be evaluated further by serial peak expiratory flow measurements, nonspecific hypersensitivity challenges with histamine or methacholine, collaboration with industrial/occupational hygienists to obtain workplace exposure measurements, and specific challenge testing at tertiary referral centers providing specialized laboratories. Removal from the inciting exposure is the mainstay of therapy, and pharmacologic treatment of patients with occupational asthma is similar to the treatment of patients with other forms of asthma.

Asthma↗
PubMed1991

Occupational asthma.

Occupational asthma is becoming an increasingly common problem worldwide. To date however, the impact of this disorder in Ireland has not been evaluated. In this present study we document 39 cases of occupational asthma presenting to St. Vincent's Hospital between 1978 and 1988 and evaluate the patient characteristics, the occupationals involved, the causative agents and clinical course and outcome. The characteristics of the occupational asthma group were striking when compared to traditional occupational lung diseases, such as the pneumoconioses. These features were (i) the relatively young age--30 patients (77%) developed their disease by the age of 35, (ii) the presence of a substantial group of women--31% of the study group, and (iii) the relatively rapid onset of asthma after taking up employment--56% had asthma within three years of exposure. In contrast the pneumoconioses affect older, preponderantly male workers who manifest clinically symptomatic disease after decades of exposure. Long standing traditional industries were well represented ranging from milling and the bakery trade to textiles and printing. However, there was an even larger contribution from the more modern, high technology sector particularily the chemical, electronic and plastic industries.

Adult↗
PubMed1994

Serial peak expiratory flow rate monitoring--a useful tool in epidemiological studies on occupational asthma.

Occupational asthma is the leading occupational respiratory disease. Epidemiological studies of occupational asthma have made use of the serial peak expiratory flow rate (PEFR) monitoring as a tool to identify cases, describe prevalence and to compare the mean diurnal variation (DV) in PEFR with an unexposed control group. Various indices of PEF variability can be used. The serial PEFR is a useful additional tool to the respiratory questionnaire and spirometry as it measures airway variability. It is also a practical alternative to histamine or methacholine inhalation testing. It has the advantage of providing multiple sequential readings of PEF and simple indices are available to express the airway variability of almost every subject studied. The validity of the serial PEFR recording should be further evaluated considering both the technical and human aspects. The monitoring protocol should be standardised and some criteria for validity should be pre-set. Factors that may affect DV in PEFR such as age, sex, smoking, race and the mean or maximum PEFR should be taken into account when comparing with controls.

Asthma↗
PubMed2005

[Occupational asthma].

Occupational asthma is an entity caused by conditions deriving from a certain work milieu and not from stimuli found outside the workplace. Nowadays, occupational asthma is the most frequent respiratory occupational disease in the majority of the industrialised countries and it is estimated that the proportion of new cases of asthma that can be attributed to exposure at work is around 10-15%. It can be developed due to an immunological mechanism or to a non-immunological mechanism. Influential in its development are the type of agent exposed to, the level and form of exposure and genetic factors of susceptibility. In the diagnostic process there is a concurrent confirmation that the patient has bronchial asthma and that this has been caused by occupational reasons. As shown by the natural history of the disease, an early diagnosis and the consequent posterior actions result in an improved prognosis.

Asbestos↗
PubMed1984

Occupational asthma.

Occupational asthma is a hypersensitivity syndrome, and must be distinguished from non-specific aggravation of existing asthma. Probably only a minority of the causal agents produce sensitization by allergic mechanisms. The important clinical features of occupational asthma are the latent period before the onset of symptoms, the characteristic periodicity of symptoms, and the progressive increase in the severity of symptoms with continuing exposure. The diagnosis can usually be made from the history; serial measurements of peak expiratory flow will provide objective confirmation of the diagnosis. Identification of the agent responsible is desirable but not essential to the diagnosis, and specific bronchial challenge with the causal agent should be reserved for atypical cases. Symptomatic or prophylactic drug treatment should never be more than a short-term measure. The most effective treatment is for the patient to change his job.

Asthma↗
PubMed1994

Animal models of occupational asthma.

Occupational asthma is characterized by variable airflow obstruction occurring in the workplace. The presence of airways inflammation and hyperreactivity provides further evidence for the disease. Since its pathogenic mechanism(s) are unknown, animal models have been developed to investigate the various disease processes, as well as to enable study of environmental and genetic factors which may contribute to disease development. Numerous parameters can be measured in animal systems, including specific and total immunoglobulin E (IgE), pulmonary eosinophilia, diaphragm contractions and airflow muscle hypertrophy. It is recognized that no single factor is sufficient to lead to a conclusion of occupational asthma, but rather that a selected combination of parameters is most fitting. Animal species selected for study have included: mice, rats, guinea-pigs, rabbits, sheep, horses and nonhuman primates. A guinea-pig system has been utilized for more than 90 yrs and has contributed to the basic understanding of physiological and immunological processes involved in allergic respiratory sensitization. The benefits as well as the disadvantages to be derived from each of the animal systems have been enumerated in this review. Certain caveats must be recognized in using animal systems. Attention must always be given to identifying differences which exist between animal and human systems, including morphological, physiological and immunological factors. The extent of bronchus-associated lymphoid tissue (BALT) differs greatly among animal species and probably plays a major role in development of allergic responsiveness in animals. In using animal systems, it must be appreciated that animals are only surrogates. Results from such studies must be compared with information obtained from clinical evaluation in order to avoid faulty extrapolations. Prudent employment of animal models is expected to advance the recognition, treatment and prevention of occupationally-based asthma.

Animals↗