Latex-induced occupational asthma: time trend in incidence and relationship with hospital glove policies

Respiratory symptoms of exposure to substances in the workplace among Bulgarian dentists

OBJECTIVES

Dentists are exposed to a variety of airborne chemicals that can act as irritants and sensitizers and may give rise to work-related respiratory symptoms. The aim of this study was to estimate the prevalence of respiratory symptoms of exposure to substances in the workplace and associated risk factors in Bulgarian dentists.

METHODS

A cross-sectional study was performed among Bulgarian dentists by using a self-report questionnaire. A direct acyclic graph (DAG) was elaborated to illustrate the direct and indirect causal pathways between exposure to irritants and/or allergens from dental environment and work-related respiratory symptoms among dentists. Multiple logistic regression analysis was conducted in order to investigate the relationship between sex, work experience, daily exposure to chemicals from dental environment, history of atopic disorder and work-related respiratory symptoms.

RESULTS

A total of 4675 dentists completed the questionnaire (response rate 48.1%). The prevalence of self-reported work-related respiratory symptoms was 20.7%. The most common repeated causes of respiratory reactions were disinfectants (65.7%) and materials based on acrylic resins (29.7%). Factors associated with work-related respiratory symptoms are personal history of asthma (odds ratio (OR) 2.50, 95% confidence interval [CI]: 1.71-3.64), work experience >20 years (OR 2.17, 95% CI: 1.74-2.70) and female gender (OR 2.14, 95% CI: 1.81-2.56).

CONCLUSION

Work-related respiratory symptoms are frequent among dentists and indicate a need for efforts to establish effective programmes and techniques of reducing or eliminating direct exposure to airborne chemicals in the dental environment.

Opportunities and obstacles in translating evidence to policy in occupational asthma

PURPOSE

Occupational asthma (OA), a common respiratory disorder in Western countries, is caused by exposures at the workplace. It is part of a broader definition of work-related asthma (WRA) that also includes pre-existing asthma aggravated by substances present in the workplace environment, and it is potentially preventable. The purpose of this paper is to illustrate preventive measures for occupational asthma by case studies.

METHODS

In three case studies we discuss preventive measures that have been associated with reductions in incidence of occupational asthma from natural rubber latex and from diisocyanates as supported by published literature. We also discuss challenges in relation to asthma from cleaning products in healthcare work.

RESULTS AND CONCLUSIONS

Several preventive measures have been associated with reduction in incidence of occupational asthma from natural rubber latex and from diisocyanates, and may provide lessons for prevention of other causes of occupational asthma. Cleaning products remain an unresolved problem at present with respect to asthma risks but potential measures include the use of safer products and safer applications such as avoidance of spray products, use of occupational hygiene methods such as improving local ventilation, and when appropriate, the use of personal protective devices.

Occupational Latex Allergy: the Current State of Affairs

PURPOSE OF REVIEW

Allergy to natural rubber latex (NRL) reached epidemic proportions during the nineties and led to intense preventive efforts. The aim of this review was to provide a comprehensive compilation of the current status of occupational NRL allergy.

RECENT FINDINGS

Recent advances led to the characterization of 15 NRL allergens and the development of assays for measuring the allergen content of NRL materials and specific IgE antibodies against NRL allergen components. Preventive measures aimed at reducing workplace exposure to NRL allergens were associated with decreasing incidence rates of NRL allergy. However, a pooled analysis of epidemiological surveys published during the last 10 years provided prevalence estimates of NRL sensitization and allergy similar to those derived from studies conducted before 2003. Substantial progress has been made in the understanding and prevention of NRL allergy, although the disease may still remain a worldwide cause of concern.

Worldwide trends in incidence in occupational allergy and asthma

PURPOSE OF REVIEW

Recent improvements in the methods for analyzing trends in occupational health surveillance and the prospect of future improvements in the collecting and sharing of electronic data alongside increasing availability of linked datasets make this a good time to review the existing literature on trends in occupational allergy and asthma (OAA).

RECENT FINDINGS

There is a notable lack of reports of recent trends in OAA in the academic literature and much of the published work comes from European countries. The incidence of OAA appears to be declining based on physician-reporting or recognized compensation claims for the countries with published data. However, we need to be cautious in interpreting this as a decline in the 'true' incidence of OAA. Few of the studies adjusted appropriately for changes in the population at risk and one of the most robust study designs showed no change in the incidence of allergic contact dermatitis in contrast to the other studies.

SUMMARY

Many existing datasets have the potential to be used to examine trends, and studies from Canada show the potential of using linked databases for surveillance. We hope that this review will encourage improvements in the analysis, and more dissemination, of trends.

The role of allergen components for the diagnosis of latex-induced occupational asthma

BACKGROUND

Recombinant Hevea brasiliensis (rHev b) natural rubber latex (NRL) allergen components have been developed to assess the patients' allergen sensitization profile and to improve the diagnosis of NRL allergy.

OBJECTIVE

To examine whether the determination of specific IgE (sIgE) reactivity to a panel of recombinant allergen components would be helpful for diagnosing NRL-induced occupational asthma (OA) in predicting the outcome of a specific inhalation test.

METHODS

sIgE levels to NRL extract and 12 recombinant NRL allergen components were assessed in 82 subjects with OA ascertained by a positive specific inhalation challenge (SIC) with NRL gloves and in 25 symptomatic subjects with a negative challenge.

RESULTS

The sensitivity, specificity, positive predictive value, and negative predictive value of a NRL-sIgE level ≥0.35 kUA /l as compared to the result of SICs were 94%, 48%, 86%, and 71%, respectively. The positive predictive value increased above 95% when increasing the cutoff value to 5.41 kUA /l. Subjects with a positive SIC showed a significantly higher rate of sIgE reactivity to rHev b 5, 6.01, 6.02, and 11 than those with a negative SIC. A sIgE sum score against rHev b 5 plus 6.01/6.02 ≥ 1.46 kUA /l provided a positive predictive value >95% with a higher sensitivity (79%) and diagnostic efficiency (Youden index: 0.67) as compared with a NRL-sIgE ≥5.41 kUA /l (49% and 0.41, respectively).

CONCLUSION

In suspected OA, high levels of sIgE against rHev b 5 combined with rHev b 6.01 or 6.02 are the most efficient predictors of a bronchial response to NRL.

Occupational Rhinitis

Occupational rhinitis (OR) involves nasal congestion, rhinorrhea, nasal itching, and/or sneezing resulting from workplace exposures. OR can have a significant negative effect on quality of life and productivity. OR can be divided into allergic or nonallergic subgroups based on the underlying pathogenesis. Certain occupational exposures place employees at greater risk for developing disease. Primary treatment is avoidance of implicated exposures. Antihistamines, saline rinses, and nasal steroids may be useful. OR can coexist with occupational asthma, and rhinitis symptoms have been reported to precede those of the lower respiratory tract. OR is has both medical and socioeconomic implications.

Latex hypersensitivity among allergic Egyptian children: relation to parental/self reports

BACKGROUND

Latex allergy is one of the major health concerns and allergic reactions to latex may be serious and fatal.

PURPOSE

In this study, we sought to determine the frequency of latex hypersensitivity in a group of allergic Egyptian infants and children and its relation to the history provided by the patients or caregivers.

METHODS

We consecutively enrolled 400 patients with physician diagnosed allergic diseases. The study measurements included clinical evaluation for the site and duration of allergy, history suggestive of latex allergy, family history of allergy, and skin prick testing (SPT) using a commercial latex extract.

RESULTS

The study revealed that 16/400 (4%) patients had positive SPT; 11 of them only had positive history of sensitivity to latex. Positive latex SPT was reported in 3.4% (11/326) of patients with bronchial asthma, 5.9% (7/118) of patients with skin allergy, and 4.5% (2/44) of patients with allergic rhinitis. SPT was positive in 7.4% (4/54) of patients with concomitant respiratory and skin allergy. Latex SPT was more specific than sensitive (97.69% and 77.77%, resp.) with a negative predictive value of 99.47%.

CONCLUSION

Although underrecognized, latex is an important allergen in the pediatric age group with a sensitization frequency of 4% among allergic children. It was observed to be especially associated with multiple allergic diseases coexisting in the same patient. Pediatric allergologists should educate their patients on latex allergy and encourage the use of latex-free products.

Occupational upper airway disease: how work affects the nose

Chronic inflammation of the upper airways is common and can arbitrarily be divided into rhinitis and rhinosinusitis. Infection and allergy represent two well-characterized and most frequently diagnosed etiologies of upper airway inflammation. Persistent upper airway inflammation caused by agents inhaled in the work environment represents a diagnostic challenge in clinical practice, and its pathophysiology has been little studied. Occupational rhinitis is a recognized medical condition with diagnostic and therapeutic guidelines. In contrast, only limited evidence is available about the relationship between work exposures and rhinosinusitis. This review aims at providing a comprehensive overview of the available literature on occupational upper airway disease with a focus on pathophysiological mechanisms and with an emphasis on the current unmet needs in work-related upper airway disease.

Asthma and rhinitis in cleaning workers: a systematic review of epidemiological studies

OBJECTIVE

This article presents a systematic review of epidemiological studies linking cleaning work and risk of asthma and rhinitis.

METHODS

Published reports were identified from PubMed covering the years from 1976 through June 30, 2012. In total, we identified 24 papers for inclusion in the review. The quality of studies was evaluated using the Strengthening of the Reporting of Observational Studies in Epidemiology (STROBE) statement checklist of 22 items for cross-sectional, cohort and case-control studies.

RESULTS

Increased risk of asthma or rhinitis has been shown in 79% of included epidemiological studies. In four studies the increased risk of asthma in cleaning workers was confirmed by objective tests, such as bronchial hyper-reactivity or airflow obstruction. Level of exposure to cleaning products, cleaning sprays, bleach, ammonia, mixing products and specific job tasks has been identified as specific causes of asthma and rhinitis.

CONCLUSIONS

Possible preventive measures encompass the substitution of cleaning sprays, bleach and ammonia, avoidance of mixing products, the use of respiratory protective devices, worker education and medical surveillance.

Ten years incidence of natural rubber latex sensitization and symptoms in a prospective cohort of health care workers using non-powdered latex gloves 2000-2009

OBJECTIVES

To assess the incidence of sensitization and gloves-related symptoms in 10-year follow-up in a group of health care workers (9,660 person-years) using non-powdered latex gloves from 2000 to 2009 and to examine related factors.

MATERIALS AND METHODS

We studied 2,053 health care workers in Trieste Hospitals by means of skin prick test for latex extract, patch tests and medical examinations. We report the incidence of latex sensitization among workers using non-powdered latex gloves.

RESULTS

The incidence of latex sensitization, rhinitis, asthma, urticaria, irritant and allergic contact dermatitis were 1.0; 0.12; 0.21; 0.72; 2.39 and 2.50 cases per 1,000 person-years, respectively. Respiratory symptoms and urticaria were positively related with latex sensitization (OR = 8.0; 95 % CL 1.27-48.6), with common allergic respiratory symptoms (OR = 4.19; 95 % CL 1.04-16.8) and with familial atopy (OR = 4.47; 95 % CL 1.1-17.9).

CONCLUSION

The incidence of latex sensitization and latex-related symptoms were very low but subjects with allergic symptoms related to common allergens are at higher risk. The use of non-latex gloves is suggested for them.

Occupational asthma: new deleterious agents at the workplace

This article summarizes the main new categories of occupational agents responsible for causing occupational asthma, with and without a latency period reported in the last 10 years. It also reports examples of occupational agents for which the fabrication processing or use have influenced the outcome of occupational asthma.

Primary prevention of latex allergy in healthcare-spectrum of strategies including the European glove standardization

IgE-mediated allergy to natural rubber latex was first noted from rubber gloves in 1979. The initial reports in dermatological journals described contact urticarial reactions; later, severe generalized allergic reactions and asthma were documented. A considerable proportion of the people involved in medical and dental care were found to be sensitized to latex. This article describes and surveys a broad range of primary prevention measures at the local and national levels. Examples are given from paediatrics, dental education, and medical care. National strategies and position papers on latex allergy are presented in which medical professionals, manufacturers and public authorities have cooperated. Special reference is paid to the European work to standardize medical gloves, which led to document EN 455:3.

Old and new causes of occupational asthma

International reviews suggest that the median proportion of adult cases of asthma attributable to occupational exposure is between 10% and 15%. Therefore, it is essential that clinicians have a broad knowledge of the various causes associated with occupational asthma. Occupational asthmagens are categorized as low-molecular-weight (LMW, ≤1000 kd) and high-molecular-weight (HMW, ≥1000 kd) antigens. The purpose of this article is to review the most common representative LMW and HMW causes of occupational asthma over the past 70 years, with specific emphasis on newer causes reported over the past 5 years.

The epidemiology of work-related asthma

Much has been learned from epidemiologic studies conducted in the past 4 decades that can be directly applied to the management of workers affected with occupational asthma. Studies have provided information about host factors, environmental exposure, and occupational agents posing the highest risks for development of severe irreversible airway obstruction and asthma disability. Investigators have developed methods for screening workers at risk and novel interventions that may prevent new cases among exposed worker populations. Less is known about the natural history and chronic morbidity associated with work-aggravated asthma and irritant-induced asthma syndromes; more studies are needed in at-risk worker populations.

Occupational rhinitis

Work-related rhinitis, which includes work-exacerbated rhinitis and occupational rhinoconjunctivitis (OR), is two to three times more common than occupational asthma. High molecular weight proteins and low molecular weight chemicals have been implicated as causes of OR. The diagnosis of work-related rhinitis is established based on occupational history and documentation of immunoglobulin E (IgE) mediated sensitization to the causative agent if possible. Management of work-related rhinitis is similar to that of other causes of rhinitis and includes elimination or reduction of exposure to causative agents combined with pharmacotherapy. If allergens are commercially available, allergen immunotherapy can be considered.

Analysis of available diagnostic tests for latex sensitization in an at-risk population

BACKGROUND

Lack of a Food and Drug Administration (FDA)-approved skin testing reagent for latex allergy in the United States requires reliance on patient history and serologic assays for diagnosis.

OBJECTIVE

To determine the diagnostic sensitivity, specificity, and predictive values of an FDA-cleared antilatex IgE serology test and an enzyme-linked immunosorbent assay (ELISA) with various sources of latex protein antigens in an at-risk but unselected population of health care workers.

METHODS

Health care workers underwent duplicate latex and serologic testing for latex specific IgE with the CAP assay and ELISA from June 1, 1998, through December 31, 2002. Logistic regression with receiver operating characteristic curve analysis determined the values, resulting in 98% and 99% specificity for the CAP assay and ELISA, respectively.

RESULTS

Results of paired skin and serologic tests were available for 792 participants. Forty duplicate skin test results (5%) were positive. For the CAP assay, sensitivity was 35%; specificity, 98%; positive predictive value, 48.3%; and negative predictive value, 96.6%. ELISA demonstrated similar results. Multivariable logistic regression yielding a 98% or 99% specificity for the various ELISAs demonstrated that the adjusted odds of a positive skin test result significantly increased with positive CAP assay and ELISA results using a powdered glove extract.

CONCLUSIONS

The performance of the FDA-cleared antilatex IgE serologic test for latex allergy has much lower sensitivity than previously reported. This finding confirms that this serologic test should be used only for patients with a history of latex allergy and not for screening the population with a low prevalence of latex sensitization.

Latex medical gloves: time for a reappraisal

Many hospitals have implemented policies to restrict or ban the use of devices made of natural rubber latex (NRL) in healthcare as precautionary measures against the perceived risk of NRL allergy. Changes in glove technology, progress in measuring the specific allergenic potential of gloves and a dramatic decrease in the prevalence of NRL allergies after interventions and education prompted us to revisit the basis for justifiable glove selection policies. The published Anglophone literature from 1990 to 2010 was reviewed for original articles and reviews dealing with the barrier and performance properties of NRL and synthetic gloves and the role of glove powder. The review shows that NRL medical gloves, when compared with synthetic gloves, tend to be stronger, more flexible and better accepted by clinicians. The introduction of powder-free gloves has been associated with reductions in protein content and associated allergies. Recently, new methods to quantify clinically relevant NRL allergens have enabled the identification of gloves with low allergenic potential. The use of low-protein, low-allergenic, powder-free gloves is associated with a significant decrease in the prevalence of type I allergic reactions to NRL among healthcare workers. Given the excellent barrier properties and operating characteristics, dramatically reduced incidences of allergic reactions, availability of specific tests for selection of low-allergen gloves, competitive costs and low environmental impact, the use of NRL gloves within the hospital environment warrants reappraisal.

Trends in occupational airway diseases in German hairdressers: frequency and causes

BACKGROUND

Hairdressers are exposed to several allergens and irritants known to cause obstructive airway diseases (OAD). In the early 1990s, high incidence rates of OAD were observed in German hairdressers. It was expected that modification of formulations would resolve the problem of high OAD rates in hairdressers.

METHODS

The numbers of confirmed cases are reported of allergen-, latex- and irritant-induced OAD in German hairdressers, as registered by the responsible compensation board during 1998 and 2007. Hairdressing components reported as causative for OAD in hairdressers were analyzed. The incidence rates of OAD in hairdressers were compared with rates in healthcare professionals, as both occupations had high rates of OAD in the 1990s.

RESULTS

From 1998 until 2003, the total number of confirmed cases of allergen-, latex- and irritant-induced OAD stayed at a plateau of 60 cases annually in hairdressers, after which a downward trend was apparent. The number of irritant-induced OAD cases did not fall during this overall downward trend. Hair dyes and acid perms were most often identified as the substances causing OAD in hairdressers. In healthcare professionals, the downward trend in OAD is more pronounced than in hairdressers, mainly due to a decrease in latex-induced cases.

CONCLUSIONS

The number of allergen- and irritant-induced cases of OAD in German hairdressers is still high. Exposure to known airway irritants is still occurring in spite of modification of the formulations. Continuous medical surveillance of hairdressers is recommended, in order to detect individual susceptibility, especially in apprentices.

Time trends in occupational asthma in Belgium

OBJECTIVES

There is little information on the changes in the pattern of occupational asthma (OA) over time. The objective of this study was to evaluate the time trends in the incidence and causes of immunological OA in Belgium using workers' compensation data.

METHODS

Cases of OA were identified through a retrospective review of all claims submitted by salaried workers to the Belgian Workers' Compensation Board from 1993 to 2002. The likelihood of OA was categorized as definite, probable, or possible based upon the results of from diagnostic procedures. Time trends were evaluated using Spearman's rank correlation for crude numbers of cases and through the negative binomial regression for incidence rates of OA per industry.

RESULTS

From a total of 1852 claims, 971 were categorized as having definite, probable, or possible OA. There was a downward trend in the annual number of cases due to the main causes of OA (i.e. flour, isocyanates, woods, and enzymes) and an apparent increase in cases of latex-induced OA. The estimated average annual incidence of OA was 29.4 (95% CI: 27.6-31.3) new cases per million salaried workers during the 1993-2002 period. There was a significant decline in the overall incidence rate of OA throughout the study period from 35.5 new cases per million salaried workers in 1993 to 25.8 in 2002.

CONCLUSIONS

These compensation-based data indicate that there has been a global downward trend in the incidence of OA during the nineties, although the factors that determined this reduced incidence should be further investigated.

Occupational asthma: etiologies and risk factors

The purpose of this article is to critically review the available evidence pertaining to occupational, environmental, and individual factors that can affect the development of occupational asthma (OA). Increasing evidence suggests that exploration of the intrinsic characteristics of OA-causing agents and associated structure-activity relationships offers promising avenues for quantifying the sensitizing potential of agents that are introduced in the workplace. The intensity of exposure to sensitizing agents has been identified as the most important environmental risk factor for OA and should remain the cornerstone for primary prevention strategies. The role of other environmental co-factors (e.g., non-respiratory routes of exposure and concomitant exposure to cigarette smoke and other pollutants) remains to be further delineated. There is convincing evidence that atopy is an important individual risk factor for OA induced by high-molecular-weight agents. There is some evidence that genetic factors, such as leukocyte antigen class II alleles, are associated with an increased risk of OA; however, the role of genetic susceptibility factors is likely to be obscured by complex gene-environment interactions. OA, as well as asthma in general, is a complex disease that results from multiple interactions between environmental factors and host susceptibilities. Determining these interactions is a crucial step towards implementing optimal prevention policies.

Work-related asthma in health care in Ontario

BACKGROUND

The health of workers in health care has been neglected in the past. There are few reports regarding occupational asthma (OA) in this group, and work-exacerbated asthma (WEA) has rarely been considered.

METHODS

We examined the frequency of claims for OA and WEA allowed by the compensation board in Ontario, Canada for which industry was coded as "health care" between 1998 and 2002, to determine the frequency of OA and WEA, causative agents, and occupations.

RESULTS

During this period, five claims were allowed for sensitizer OA, two for natural rubber latex (NRL), and three for glutaraldehyde/photographic chemicals. The two NRL cases occurred in nurses who had worked for >10 years prior to "date of accident." There were 115 allowed claims for WEA; health care was the most frequent industry for WEA. Compared to the rest of the province, claims in health care made up a significantly greater proportion of WEA claims (17.8%) than OA (5.1%) (odds ratio, 4.1, 95% CI 1.6-11.6; P = 0.002). The rate of WEA claims was 2.1 times greater than that in the rest of the workforce (P < 0.0001). WEA claims occurred in many jobs (e.g., clerk), other than "classic" health care jobs such as nurses, and were attributed to a variety of agents such as construction dust, secondhand smoke, and paint fumes.

CONCLUSIONS

WEA occurs frequently in this industrial sector. Those affected and attributed agents include many not typically expected in health care. The incidence of OA claims in this sector in general was low; the continued low number of OA claims due to NRL is consistent with the successful interventions for prevention.

Asthma and rhinitis in the workplace

Accumulating evidence indicates that the workplace environment substantially contributes to the global burden of asthma and rhinitis. Work-related asthma and rhinitis represent a public health concern due to their health and socioeconomic impacts. This article summarizes the scientific evidence on sensitizer-induced occupational asthma and rhinitis that has been published during the past 5 years. The review addresses the strategies for diagnosing and managing these highly prevalent occupational diseases.

Risk factors, predictors, and markers for work-related asthma and rhinitis

The burden of asthma attributable to occupational exposures is significant. A better evaluation of markers of asthma and rhinitis in occupational settings may help reduce the frequency of occupational asthma (OA) and rhinitis (OR). This publication reviews articles published in 2008 and 2009 to provide an update on aspects related to markers of asthma and rhinitis. Markers derived from occupational exposure assessment, questionnaires, clinical data, and noninvasive tests such as functional tests or measures of serum antibodies are used to develop prediction models for the likelihood of OA and OR development. Findings from prospective studies highlight the course of preclinical signs and markers of airway inflammation in the natural history of OA and OR. Airway inflammation, evaluated by quantification of cells and mediators in induced sputum or nasal lavage and by exhaled nitric oxide, is associated with OA and OR; however, the sensitivity and specificity of these means, especially exhaled nitric oxide, have not been sufficiently assessed.

IgE-mediated latex allergy--an exciting and instructive piece of allergy history

Natural rubber latex represents a potent allergen, which for many years had an important impact on occupational health problems but especially on certain risk groups such as spina bifida. Luckily, these problems decreased when powder-free, latex-poor gloves were introduced. Latest data show that in children with spina bifida, who grew up completely latex-free from birth on, sensitization to NRL as well as clinical relevant allergy significantly decreased. Furthermore, sensitization to aeroallergens also went down and even the prevalence of allergic diseases decreased significantly to rates of the general population. This new data clearly indicates that potent allergens (such as latex) in high-risk groups (such as spina bifida) can induce sensitization spreading, and corresponding avoidance can reverse this development. In conclusion, it can be stated that 'new' allergies can suddenly arise, there are allergen-specific risk groups, local IgE-production is also possible in the CNS, allergen avoidance can be very effective in terms of primary prevention, sensitization spreading can be made reversible by effective prevention, and finally, certain allergies can luckily become history within a relatively short period of time. Furthermore, these new findings clearly end the debate about whether patients with spina bifida have a disease-inherited risk for allergy to NRL and show that the cause is the meningi and the multiple surgical interventions - and therefore sequelae can be reversed by implementing preventive measures.

Occupational rhinitis

Work-related rhinitis, which includes work-exacerbated rhinitis and occupational rhinitis, may be two to three times more common than occupational asthma. Both high molecular weight proteins and low molecular weight chemicals have been implicated as causes of occupational rhinitis. A diagnosis is established based on occupational history and, if appropriate, documentation of IgE-mediated sensitization to the causative agent. Management of work-related rhinitis is similar to that of non-work-related rhinitis and includes elimination or reduction of exposure to offending agents combined with pharmacotherapy. If treatment allergens are commercially available, allergen immunotherapy may also be considered if appropriate.

Occupational rhinitis and asthma: where do we stand, where do we go?

This review provides an overview of current and emerging issues regarding occupational rhinitis (OR) and occupational asthma (OA), focusing on studies discussing concepts and results that are relevant to both diseases. OA and OR are conditions that affect the upper and lower airways, are characterized by reduced airway caliber and hyperresponsiveness and by inflammation, and are caused by agents present in the workplace. To explain disease expression, research is moving from the T-helper type 1/type 2 cells paradigm to consider the contribution of diverse alternative pathways such as neural inflammation, a dysfunctional epithelial barrier, and autoimmune mechanisms, among others. Objective assessment of OR and OA has been improved and tested for research and, currently, clinical application. Further developments in the field of OR are expected to lead to more generalized clinical applications, following the example of what has been achieved for OA.

Risks of exposure to occupational asthmogens in atopic and nonatopic asthma: a case-control study in Taiwan

RATIONALE

Asthma is often work-related and can be classified as atopic or nonatopic on the basis of its pathogenesis. Few studies have reported an association between exposure to occupational asthmogens and asthma with and without atopy.

OBJECTIVES

We investigated, in adults with asthma, whether occupational exposure to asthmogens influenced the risk of having atopic or nonatopic asthma, and their level of lung function.

METHODS

We recruited 504 hospital-based adults with current asthma, 504 community-based control subjects, and 504 hospital-based control subjects in southern Taiwan. Asthma with atopy was defined as having asthma in combination with an increase in total IgE (≥100 U/ml) or a positive Phadiatop test (≥0.35 Pharmacia arbitrary unit/L) (Pharmacia ImmunoCAP; Pharmacia, Uppsala, Sweden). Occupational exposure to asthmogens was assessed with an asthma-specific job exposure matrix.

MEASUREMENTS AND MAIN RESULTS

We found a significant association between atopic asthma and exposure to high molecular weight asthmogens (adjusted odds ratio [AOR], 4.0; 95% confidence interval [CI], 1.8-8.9). Nonatopic asthma was significantly associated with exposure to low molecular weight asthmogens (AOR, 2.6; 95% CI, 1.6-4.3), including industrial cleaning agents and metal sensitizers. Agriculture was associated with both atopic and nonatopic asthma (AOR, 7.8; 95% CI, 2.8-21.8; and AOR, 4.1; 95% CI, 1.3-13.0, respectively). The ratio of FEV₁ to FVC in the high-risk group was significantly lower than in the no-risk group (P = 0.026) in currently employed patients with asthma.

CONCLUSIONS

In adults with asthma, occupational exposure to high and low molecular weight asthmogens appears to produce differential risks for atopic and nonatopic asthma.