Agents, old and new, causing occupational asthma

Safety evaluation of the food enzyme β-galactosidase from the non-genetically modified Papiliotrema terrestris strain AE-BLC

The food enzyme β-galactosidase (β-d-galactoside galactohydrolase; EC 3.2.1.23) is produced with the non-genetically modified Papiliotrema terrestris strain AE-BLC by Amano Enzyme Inc. The food enzyme was considered free from viable cells of the production organism. It is intended to be used in the production of galacto-oligosaccharides (GOS) from lactose. Dietary exposure to the food enzyme-total organic solids (TOS) was estimated to be up to 0.441 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90-day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1800 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, resulted in a margin of exposure of at least 4082. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that a risk of allergic reactions upon dietary exposure to this food enzyme cannot be excluded, but the likelihood is low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Aziz SF, Aizad Za’bah AK, Dapari R, Hassan MR, Che Dom N, Syed Abdul Rahim SS. Factors associated with occupational asthma among food industry workers: A systematic review

INTRODUCTION

Occupational asthma (OA) is a type of Work-Related Asthma characterised by variable airflow limitation and/or inflammation due to causes and conditions attributable to a particular occupational environment, and not to stimuli encountered outside the workplace. There is an increasing need to extend the depth of knowledge of OA to better manage this condition, especially among food industry workers who are affected by it.

OBJECTIVE

This systematic review aimed to determine the factors associated with occupational asthma among food industry workers by electronically collecting articles from two databases (Medline and Scopus).

METHODS

This systematic review was prepared in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta Analyses) updated guideline. Two independent reviewers screened the titles and abstracts of the collected data, which were then stored in Endnote20 based on the inclusion and exclusion criteria. The included articles have been critically appraised to assess the quality of the studies using the Mixed Methods Appraisal Tool (MMAT).

RESULT

The search yielded 82 articles from Medline and 85 from SCOPUS, resulting in 167 unique hits. Only 22 articles have been included in the full-text assessment following a rigorous selection screening. Of the 22 articles identified, five were included in the final review. Several factors were found to have contributed to occupational asthma among food industry workers. They were classified into two categories: (1) work environment-related factors; and (2) individual factors.

CONCLUSION

Several work environment and individual-related factors were found to be associated with OA among food industry workers. A better understanding of the development of the disease and its potential risk factors is needed because it can affect worker's quality of life. Pre-employment and periodic medical surveillance should be conducted to assess and detect any possible risk of developing occupational asthma among workers.

Safety evaluation of the food enzyme β-galactosidase from the genetically modified Kluyveromyces lactis strain KLA

The food enzyme β‐galactosidase (β‐d‐galactoside galactohydrolase; EC 3.2.1.23) is produced with the genetically modified Kluyveromyces lactis strain KLA by DSM Food Specialties B.V. The genetic modifications did not give rise to safety concerns. The food enzyme was considered free from viable cells of the production organism and its DNA. The food enzyme is intended to be used for the lactose hydrolysis in milk processing, production of fermented milk products and whey processing. It is also intended for lactose hydrolysis in milk products at home. Dietary exposure to the food enzyme–total organic solids (TOS) was estimated to be up to 11.876 mg TOS/kg body weight per day in European populations. The production strain of the food enzyme fulfils the requirements for the Qualified Presumption of Safety (QPS) approach to safety assessment. As no concerns arising from its genetic modification or from the manufacturing process have been identified, the Panel considered that toxicological tests are not needed for the assessment of this food enzyme. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is low. The Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

The Impact of Ambient Environmental and Occupational Pollution on Respiratory Diseases

Ambient pollutants and occupational pollutants may cause and exacerbate various lung and respiratory diseases. This review describes lung and respiratory diseases in relation to ambient pollutants, particularly particulate matter (PM_2.5), and occupational air pollutants, excluding communicable diseases and indoor pollutants, including tobacco smoke exposure. PM_2.5 produced by combustion is an important ambient pollutant. PM_2.5 can cause asthma attacks and exacerbations of chronic obstructive pulmonary disease in the short term. Further, it not only carries a risk of lung cancer and death, but also hinders the development of lung function in children in the long term. It has recently been suggested that air pollution, such as PM_2.5, is a risk factor for severe coronavirus disease (COVID-19). Asbestos, which causes asbestosis, lung cancer, and malignant mesothelioma, and crystalline silica, which cause silicosis, are well-known traditional occupational pollutants leading to pneumoconiosis. While work-related asthma (WRA) is the most common occupational lung disease in recent years, many different agents cause WRA, including natural and synthetic chemicals and irritant gases. Primary preventive interventions that increase awareness of pollutants and reduce the development and exacerbation of diseases caused by air pollutants are paramount to addressing ambient and occupational pollution.

Occupational Health and Safety Statistics as an Indicator of Worker Physical Health in South African Industry

Operations in general industry, including manufacturing, expose employees to a myriad of occupational health hazards. To prevent exposure, occupational health and safety regulations were enacted, with both employers and workers instituting various risk reduction measures. The analysis of available occupational disease and injury statistics (indicators of worker physical health) can be used to infer the effectiveness of risk reduction measures and regulations in preventing exposure. Thus, using the READ approach, analyses of occupational disease and injury statistics from South African industry, derived from annual reports of the Compensation Fund, were conducted. The publicly available database of occupational disease and injury statistics from the South African general industry is unstructured, and the data are inconsistently reported. This data scarcity, symptomatic of an absence of a functional occupational disease surveillance system, complicates judgement making regarding the effectiveness of implemented risk reduction measures, enacted occupational health and safety regulations and the status of worker physical health from exposure to workplace hazards. The statistics, where available, indicate that workers continue to be exposed to occupational health impacts within general industry, notwithstanding risk reduction measures and enacted regulations. In particular, worker physical health continues to be impacted by occupational injuries and noise-induced hearing loss. This is suggestive of shortcomings and inefficiencies in industry-implemented preventive measures and the regulatory state. A robust national occupational disease surveillance system is a regulatory tool that should detect and direct policy responses to identified occupational health hazards.

Work-related asthma

Work-related asthma (WRA) is highly prevalent in the adult population. WRA includes occupational asthma (OA), which is asthma caused by workplace exposures, and work-exacerbated asthma (WEA), also known as work-aggravated asthma, which is preexisting or concurrent asthma worsened by workplace conditions. In adults, the estimated prevalence of OA is 16.0%, whereas that of WEA is 21.5%. An increasing number of chemicals used in industrial production, households, and services are associated with the incidence of adult-onset asthma attributable to exposure to chemicals. This review article summarizes the different types of WRA and describes diagnostic procedures, treatment, prevention, and approaches to patient management. It is not always easy to distinguish between OA and WEA. It is important to establish a diagnosis (of sensitizer-/irritant-induced OA or WEA) in order to prevent worsening of symptoms, as well as to prevent other workers from being exposed, by providing early treatment and counseling on social security and work-related issues.

Assessment of Worker Exposure to Occupational Organic Dust in a Hemp Processing Facility

The cultivation and processing of industrial hemp, Cannabis sativa L., is a developing industry in Australia. Exposure to hemp dust is demonstrated as producing reactive and respiratory health effects, potentially causing permanent lung disease or damage. The aim of this study was to assess the airborne organic dust concentrations generated in an Australian hemp processing facility. Personal sampling, in the breathing zone of exposed workers was undertaken for exposure to respirable dust, along with parallel static sampling for airborne concentrations of inhalable and respirable dust fractions. Both static and personal sampling showed that respirable dust concentrations (mg m-3) exceeded the Australian Institute of Occupational Hygienists (AIOH) recommended maximum exposure limit of 1 mg m-3 (respirable fraction) for dusts not otherwise specified, with mean exposures (mg m-3) of M = 1.33, standard deviation (SD) = 1.09 (range 0.07-3.67 mg m-3) and M = 4.49, SD = 4.49 (range 0.77-11.08 mg m-3). The results of the investigation indicate that workers in the hemp processing industry are at risk of developing permanent and disabling respiratory disease due to high dust exposure. There is no Australian occupational exposure limit specifically for hemp dust. It is recommended further research is needed and industry-specific guidance material or model code of practice developed to effectively control exposures.

Methodological evaluation of human research on asthmagenicity and occupational cleaning: a case study of quaternary ammonium compounds ("quats")

In this paper, we review methodological approaches used in studies that evaluated the association between occupational exposure to quaternary ammonium compounds (quats) and occupational asthma. This association is of interest because quats are a common active ingredient of disinfectants and have been linked to work-related asthma in some circumstances. However, any evidence-based assessment of an exposure-outcome association needs to consider both strengths and limitations of the literature. We focus on publications cited by various US and international organizations. Eighteen investigations included in the review fall into two broad categories: case reports and challenge studies of individual patients and population studies that examined the association between quats and asthma occurrence in groups of subjects. We evaluated these studies guided by questions that address whether: exposure data on specific quat(s) and other agents that may cause asthma were included, new asthma cases were differentiated from asthma exacerbation, and information on respiratory sensitivity versus irritation was given. We also assessed consistency across studies. Studies of individual patients, particularly those that provided detailed information on challenge test results, document cases of asthma induced by exposure to quats. By contrast, studies of occupational groups with the highest potential for quats exposure (e.g., cleaners and farmers) do not consistently report increased incidence of asthma due specifically to quats. The unresolved methodological issues include: poor understanding of exposure pathways considering that quats are non-volatile, lack of quantitative data allowing for identification of an asthmagenicity threshold, insufficient information on whether quats are sensitizers or act via dose-dependent irritation or some other mechanism, and inability to quantify risk of new-onset asthma attributable to quats. Another important area of uncertainty is the lack of information on the specific quats being used. There is also a lack of data capable of distinguishing the effects of quats from those of other chemical and biological workplace exposures. The current state-of-the-science does not allow a proper assessment of the potential link between quats and occupational asthma.

Isocyanates in Australia: Current exposure to an old hazard

Exposure to isocyanates has consistently been reported as the most common cause of occupational asthma. The objectives of this study were to assess how many Australian workers are currently exposed to isocyanates, identify the occupations with highest proportion of exposed workers and identify the main circumstances of exposures. Data comes from the Australian Workplace Exposure Study-Asthma, a national telephone survey which explored the prevalence of current occupational exposure to 227 asthmagens, grouped into 27 groups, among current Australian workers aged 18-65 years. A web-based tool, OccIDEAS, was used to collect job task information and to assign exposure to asthmagens, including isocyanates. Of the 4,878 eligible participants, 2.5% of them were deemed to be probably exposed to isocyanates at work in their current job (extrapolated to 3.0% of the Australian working population). The majority of those exposed were males (90.8%). The most common tasks undertaken that led to these exposures were using expanding foam fillers/sprays and isocyanate and/or polyurethane paints. Exposure occurred mainly among construction workers, wood workers, and painters or printers. This study investigating occupational exposure to isocyanates in a national working population provides information that can be used to inform the direction of occupational interventions and policies to decrease occupational asthma.

Role of clusterin/progranulin in toluene diisocyanate-induced occupational asthma

Toluene diisocyanate (TDI) exposure induces oxidative stress and epithelial cell-derived inflammation, which affect the pathogenesis of TDI-induced occupational asthma (TDI-OA). Recent studies suggested a role for clusterin (CLU) and progranulin (PGRN) in oxidative stress-mediated airway inflammation. To evaluate CLU and PGRN involvement in airway inflammation in TDI-OA, we measured their serum levels in patients with TDI-OA, asymptomatic exposed controls (AECs), and unexposed healthy normal controls (NCs). Serum CLU and PGRN levels were significantly lower in the TDI-OA group than in the AEC and NC groups (P < 0.05). The sensitivity and specificity for predicting the TDI-OA phenotype were 72.4% and 53.4% when either CLU or PGRN levels were below the cutoff values (≤125 μg/mL and ≤68.4 ng/mL, respectively). If both parameters were below the cutoff levels, the sensitivity and specificity were 58.6% and 89.8%, respectively. To investigate CLU and PGRN function, we evaluated their production by human airway epithelial cells (HAECs) in response to TDI exposure and co-culturing with neutrophils. TDI-human serum albumin stimulation induced significant CLU/PGRN release from HAECs in a dose-dependent manner, which positively correlated with IL-8 and folliculin levels. Co-culturing with neutrophils significantly decreased CLU/PGRN production by HAECs. Intracellular ROS production in epithelial cells co-cultured with neutrophils tended to increase initially, but the ROS production decreased gradually at a higher ratio of neutrophils. Our results suggest that CLU and PGRN may be involved in TDI-OA pathogenesis by protecting against TDI-induced oxidative stress-mediated inflammation. The combined CLU/PGRN serum level may be used as a potential serological marker for identifying patients with TDI-OA among TDI-exposed workers.

Occupational respiratory allergy in peach crop workers

BACKGROUND

Occupational respiratory diseases in workers of peach tree crops have been reported punctually and have been associated with sensitization to proteins present in both pollen and leaf tree. We report the study of 37 workers with respiratory symptoms related to occupational exposure to peach trees.

METHODS

Prick tests and specific IgE determinations were performed with extracts from leaves and branches of peach tree. Immunodetection in leaf extract was realized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis SDS-PAGE-immunoblotting with patient sera and rabbit serum anti-Pru p 3. Immunodetection inhibition was performed with rPru p 3 and pollen profilins. The clinical relevance of sensitization was demonstrated by specific bronchial challenge test (SBCT) with peach leaf extract.

RESULTS

Most patients suffered symptoms when peach trees had leaves, specifically during thinning and harvesting fruit (rhinoconjunctivitis: 100% and asthma: 67.5%). Sensitization to leaf extract was demonstrated in 86% of patients. IgE-immunoblotting with peach leaf extract revealed in six patient sera a pair of bands of 10 and 16 kDa, and in nine a 16-kDa band. Those bands could be two isoforms of peach leaf lipid transfer proteins( LTP), so the recognition frequency of some LTP isoform by our patient sera was 42%. 33% of the sera recognized a doubled band of about 14.5 kDa and this recognition was inhibited by nPho d 2. The SBCT with peach leaf extract was positive in the asthmatic sensitized patients tested.

CONCLUSIONS

Sensitization to peach leaves was the cause of occupational respiratory symptoms in our patients. Some patient sera revealed IgE-binding proteins matching LTP and/or profilin.

OCCUPATIONAL ALLERGY

An estimated 11 million workers in the USA are potentially exposed to agents that can become a cause of allergic diseases such as occupational asthma and allergic contact dermatitis, which can adversely affect health and well-being. Hundreds of chemicals (e.g. metals, epoxy and acrylic resins, rubber additives, and chemical intermediates) and proteins (e.g. natural rubber latex, plant proteins, mould, animal dander) present in virtually every industry have been identified as causes of allergic disease. In general, allergens can be classified as low molecular weight (chemical) allergens and high molecular weight (protein) allergens. These agents are capable of inducing immunological responses that are both immunoglobulin E and non-immunoglobulin E-mediated. Interestingly, the same chemical can induce diverse immune responses in different individuals. As new hazards continue to emerge, it is critical to understand the immunological mechanisms of occupational allergic disease. Specific understanding of these mechanisms has direct implications in hazard identification, hazard communication, and risk assessment. Such efforts will ultimately assist in the development of risk management strategies capable of controlling workplace exposures to allergens to prevent the induction of sensitisation in naïve individuals and inhibit elicitation of allergic responses. The purpose of this short review is to give a brief synopsis of the incidence, agents, mechanisms, and research needs related to occupational allergy.

Occupational Allergy

An estimated 11 million workers in the USA are potentially exposed to agents that can become a cause of allergic diseases such as occupational asthma and allergic contact dermatitis, which can adversely affect health and well-being. Hundreds of chemicals (e.g. metals, epoxy and acrylic resins, rubber additives, and chemical intermediates) and proteins (e.g. natural rubber latex, plant proteins, mould, animal dander) present in virtually every industry have been identified as causes of allergic disease. In general, allergens can be classified as low molecular weight (chemical) allergens and high molecular weight (protein) allergens. These agents are capable of inducing immunological responses that are both immunoglobulin E and non-immunoglobulin E-mediated. Interestingly, the same chemical can induce diverse immune responses in different individuals. As new hazards continue to emerge, it is critical to understand the immunological mechanisms of occupational allergic disease. Specific understanding of these mechanisms has direct implications in hazard identification, hazard communication, and risk assessment. Such efforts will ultimately assist in the development of risk management strategies capable of controlling workplace exposures to allergens to prevent the induction of sensitisation in naïve individuals and inhibit elicitation of allergic responses. The purpose of this short review is to give a brief synopsis of the incidence, agents, mechanisms, and research needs related to occupational allergy.

Potential Inhibitory Influence of miRNA 210 on Regulatory T Cells during Epicutaneous Chemical Sensitization

Toluene diisocyanate (TDI) is a potent low molecular weight chemical sensitizer and a leading cause of chemical-induced occupational asthma. The regulatory potential of microRNAs (miRNAs) has been recognized in a variety of disease states, including allergic disease; however, the roles of miRNAs in chemical sensitization are largely unknown. In a previous work, increased expression of multiple miRNAs during TDI sensitization was observed and several putative mRNA targets identified for these miRNAs were directly related to regulatory T-cell (T_reg) differentiation and function including Foxp3 and Runx3. In this work, we show that miR-210 expression is increased in the mouse draining lymph node (dLN) and T_reg subsets following dermal TDI sensitization. Alterations in dLN mRNA and protein expression of T_reg related genes/putative miR-210 targets (foxp3, runx3, ctla4, and cd25) were observed at multiple time points following TDI exposure and in ex vivo systems. A T_reg suppression assay, including a miR-210 mimic, was utilized to investigate the suppressive ability of T_regs. Cells derived from TDI sensitized mice treated with miR-210 mimic had less expression of miR-210 compared to the acetone control suggesting other factors, such as additional miRNAs, might be involved in the regulation of the functional capabilities of these cells. These novel findings indicate that miR-210 may have an inhibitory role in T_reg function during TDI sensitization. Because the functional roles of miRNAs have not been previously elucidated in a model of chemical sensitization, these data contribute to the understanding of the potential immunologic mechanisms of chemical induced allergic disease.

A Role for Regulatory T Cells in a Murine Model of Epicutaneous Toluene Diisocyanate Sensitization

Toluene diisocyanate (TDI) is a leading cause of chemical-induced occupational asthma which impacts workers in a variety of industries worldwide. Recently, the robust regulatory potential of regulatory T cells (Tregs) has become apparent, including their functional role in the regulation of allergic disease; however, their function in TDI-induced sensitization has not been explored. To elucidate the kinetics, phenotype, and function of Tregs during TDI sensitization, BALB/c mice were dermally exposed (on each ear) to a single application of TDI (0.5-4% v/v) or acetone vehicle and endpoints were evaluated via RT-PCR and flow cytometry. The draining lymph node (dLN) Treg population expanded significantly 4, 7, and 9 days after single 4% TDI exposure. This population was identified using a variety of surface and intracellular markers and was found to be phenotypically heterogeneous based on increased expression of markers including CD103, CCR6, CTLA4, ICOS, and Neuropilin-1 during TDI sensitization. Tregs isolated from TDI-sensitized mice were significantly more suppressive compared with their control counterparts, further supporting a functional role for Tregs during TDI sensitization. Last, Tregs were depleted prior to TDI sensitization and an intensified sensitization response was observed. Collectively, these data indicate that Tregs exhibit a functional role during TDI sensitization. Because the role of Tregs in TDI sensitization has not been previously elucidated, these data contribute to the understanding of the immunologic mechanisms of chemical induced allergic disease.

Characterization and comparative analysis of 2,4-toluene diisocyanate and 1,6-hexamethylene diisocyanate haptenated human serum albumin and hemoglobin

Diisocyanates (dNCOs) are low molecular weight chemical sensitizers that react with autologous proteins to produce neoantigens. dNCO-haptenated proteins have been used as immunogens for generation of dNCO-specific antibodies and as antigens to screen for dNCO-specific antibodies in exposed individuals. Detection of dNCO-specific antibodies in exposed individuals for diagnosis of dNCO asthma has been hampered by poor sensitivities of the assay methods in that specific IgE can only be detected in approximately 25% of the dNCO asthmatics. Apart from characterization of the conjugates used for these immunoassays, the choice of the carrier protein and the dNCO used are important parameters that can influence the detection of dNCO-specific antibodies. Human serum albumin (HSA) is the most common carrier protein used for detection of dNCO specific-IgE and -IgG but the immunogenicity and/or antigenicity of other proteins that may be modified by dNCO in vivo is not well documented. In the current study, 2,4-toluene diisocyanate (TDI) and 1,6-hexamethylene diisocyanate (HDI) were reacted with HSA and human hemoglobin (Hb) and the resultant adducts were characterized by (i) HPLC quantification of the diamine produced from acid hydrolysis of the adducts, (ii) 2,4,6-trinitrobenzene sulfonic acid (TNBS) assay to assess extent of cross-linking, (iii) electrophoretic migration in polyacrylamide gels to analyze intra- and inter-molecular cross-linking, and (iv) evaluation of antigenicity using a monoclonal antibody developed previously to TDI conjugated to Keyhole limpet hemocyanin (KLH). Concentration-dependent increases in the amount of dNCO bound to HDI and TDI, cross-linking, migration in gels, and antibody-binding were observed. TDI reactivity with both HSA and Hb was significantly higher than HDI. Hb-TDI antigenicity was approximately 30% that of HSA-TDI. In conclusion, this data suggests that both, the extent of haptenation as well as the degree of cross-linking differs between the two diisocyanate species studied, which may influence their relative immunogenicity and/or antigenicity.

Prevalence of Work-Related Asthma in Primary Health Care: Study Rationale and Design

Background :

Occupational Asthma (OA) is the most frequent origin of occupational respiratory diseases in industrialized countries and accounts for between 5% and 25% of asthmatic patients. The correct and early diagnosis of OA is of great preventive and socio-economic importance. However, few studies exist on OA’s prevalence in Catalonia and in Spain and those affected are mainly treated by the public health services and not by the occupational health services, which are private.

Objective :

To determine the prevalence of OA in patients diagnosed with asthma in the Primary Healthcare system and to evaluate the socio-economic impact of OA in the Primary Healthcare system.

Methods/Design :

We will carry out an observational, transversal and multi-center study in the Primary Healthcare Service in the Barcelona region (Catalonia, Spain), with 385 asthmatic workers aged between 16 and 64 who are currently working or have been working in the past. We will confirm the asthma diagnosis in each patient, and those meeting the inclusion criteria will be asked to answer a questionnaire that aims to link asthma to the patient’s past employment history. The resulting diagnosis will be of either occupational asthma, work-aggravated asthma or common asthma. We will also collect socio-demographic information about the patients, about their smoking status, their exposure outside of the workplace, their work situation at the onset of the symptoms, their employment history, their symptoms of asthma, their present and past medical asthma treatment, and, in order to estimate the economic impact in the Primary Healthcare system, where they have been attended to and treated. Prevalence will link OA or work-aggravated asthma to the total of patients participating in the study with a asthma diagnosis.

Discussion :

The results will show the prevalence of OA and work-aggravated asthma, and shall provide valuable information to set out and apply the necessary personal and technical measures, either in the public or in the occupational health services. No studies evaluating the costs generated by the OA in the Primary Healthcare system have been carried out.

Prevalence of Work-Related Asthma and its Impact in Primary Health Care

BACKGROUND AND OBJECTIVE

To determine the prevalence of occupational asthma (OA) and work-exacerbated asthma (WEA) among asthmatic patients diagnosed in Primary Health Care (PHC). To analyze the impact at PHC level caused by under-diagnosis and inappropriate referral of OA.

PATIENTS AND METHODS

A descriptive, cross-sectional multicenter study in patients aged between 16 and 64years diagnosed with asthma, according to their medical record; all were working or had worked, and were assigned to one of 16 PHC centers in a healthcare district. Based on the responses to the questionnaire completed at the study visit, which included a thorough review of the subject's entire working history, patients were classified into three categories by an expert in occupational asthma: OA, WEA or common asthma (CA).

RESULTS

Three hundred and sixty-eight patients completed the questionnaire. The prevalence of OA was 18.2% (25% in men and 14.6% in women, P=.046), and 54 patients (14.7%) were classified as WEA. The proportion of patients with work-related asthma (WRA) was therefore 32.9%. Asthmatic patients with WRA took more sick leave than CA patients (P<.001).

CONCLUSIONS

A high prevalence of WRA was found, mostly treated in PHC. Under-diagnosis of WRA is widespread in PHC.

Characterization of methylene diphenyl diisocyanate-haptenated human serum albumin and hemoglobin

Protein haptenation by polyurethane industrial intermediate 4,4'-methylene diphenyl diisocyanate (MDI) is thought to be an important step in the development of diisocyanate (dNCO)-specific allergic sensitization; however, MDI-haptenated albumins used to screen specific antibody are often poorly characterized. Recently, the need to develop standardized immunoassays using a consistent, well-characterized dNCO-haptenated protein to screen for the presence of MDI-specific IgE and IgG from workers' sera has been emphasized and recognized. This has been challenging to achieve due to the bivalent electrophilic nature of dNCOs, leading to the capability to produce multiple cross-linked protein species and polymeric additions to proteins. In the current study, MDI was reacted with human serum albumin (HSA) and hemoglobin (Hb) at molar ratios ranging from 1:1 to 40:1 MDI/protein. Adducts were characterized by (i) loss of available 2,4,6-trinitrobenzene sulfonic acid (TNBS) binding to primary amines, (ii) electrophoretic migration in polyacrylamide gels, (iii) quantification of methylene diphenyl diamine following acid hydrolysis, and (iv) immunoassay. Concentration-dependent changes in all of the above noted parameters were observed, demonstrating increases in both number and complexity of conjugates formed with increasing MDI concentrations. In conclusion, a series of bioanalytical assays should be performed to standardize MDI-antigen preparations across lots and laboratories for measurement of specific antibody in exposed workers that in total indicate degree of intra- and intermolecular cross-linking, number of dNCOs bound, number of different specific binding sites on the protein, and degree of immunoreactivity.

Genetic variants in antioxidant genes are associated with diisocyanate-induced asthma

Diisocyanates are a common cause of occupational asthma, but risk factors are not well defined. A case-control study was conducted to investigate whether genetic variants of antioxidant defense genes, glutathione S-transferases (GSTM1, GSTT1, GSTM3, GSTP1), manganese superoxide dismutase (SOD2), and microsomal epoxide hydrolase (EPHX1) are associated with increased susceptibility to diisocyanate-induced asthma (DA). The main study population consisted of 353 Caucasian French-Canadians from among a larger sample of 410 diisocyanate-exposed workers in three groups: workers with specific inhalation challenge (SIC) confirmed DA (DA(+), n = 95); symptomatic diisocyanate workers with a negative SIC (DA(-), n = 116); and asymptomatic exposed workers (AW, n = 142). Genotyping was performed on genomic DNA, using a 5'-nuclease PCR assay. The SOD2 rs4880, GSTP1 rs1695, and EPHX1 rs2740171 variants were significantly associated with DA in both univariate and multivariate analyses. In the first logistic regression model comparing DA(+) and DA(-) groups, SOD2 rs4880, GSTM1 (null), GSTP1 rs762803, and EPHX1 rs2854450 variants were associated with DA (p = 0.004, p = 0.047, p = 0.021, p <0.001, respectively). Genotype combinations GSTT1*GSTP1 rs762803, GSTM1*EPHX1 rs2854450, EPHX1 rs2740168*EPHX1 rs1051741, and GSTP1 rs762803*EPHX1 rs2740168 were also associated with DA in this model (p = 0.027, p = 0.002, p = 0.045, p = 0.044, respectively). The GSTP1 rs1695 and EPHX1 rs1051741 and rs2740171 variants showed an association with DA in the second model comparing DA(+) and AW groups (p = 0.040, p = 0.019, p = 0.002, respectively). The GSTM3 rs110913*EPHX1 rs1051741 genotype combination was also associated with DA under this model (p = 0.042). The results suggest that variations in SOD2, GST, and EPHX1 genes and their interactions contribute to DA susceptibility.

Occupational asthma: new low-molecular-weight causal agents, 2000-2010

Background. More than 400 agents have been documented as causing occupational asthma (OA). The list of low-molecular-weight (LMW) agents that have been identified as potential causes of OA is constantly expanding, emphasizing the need to continually update our knowledge by reviewing the literature. Objective. The objective of this paper was to identify all new LMW agents causing occupational asthma reported during the period 2000-2010. Methods. A Medline search was performed using the keywords occupational asthma, new allergens, new causes, and low-molecular-weight agents. Results. We found 39 publications describing 41 new LMW causal agents, which belonged to the following categories: drugs (n = 12), wood dust (n = 11), chemicals (n = 8), metals (n = 4), biocides (n = 3), and miscellaneous (n = 3). The diagnosis of OA was confirmed through SIC for 35 of 41 agents, peak expiratory flow monitoring for three (3) agents, and the clinical history alone for three (3) agents. Immunological tests provided evidence supporting an IgE-mediated mechanism for eight (8) (20%) of the newly described agents. Conclusion. This paper highlights the importance of being alert to the occurrence of new LMW sensitizers, which can elicit OA. The immunological mechanism is explained by a type I hypersensitivity reaction in 20% of all newly described LMW agents.

Chemical sensitization and allergotoxicology

Chemical sensitization remains an important environmental and occupational health issue. A wide range of substances have been shown to possess the ability to induce skin sensitization or respiratory sensitization. As a consequence, there is a need to have appropriate methods to identify sensitizing agents. Although a considerable investment has been made in exploring opportunities to develop methods for hazard identification and characterization, there are, as yet, no validated nonanimal methods available. A state of the art of the different in vitro approaches to identify contact and respiratory capacity of chemicals is covered in this chapter.

Biomarkers predicting isocyanate-induced asthma

Three diisocyanates can cause occupational asthma (OA): toluene diisocyanate (TDI), 4,4 diphenylmethane diisocyanate (MDI), and 1,6-hexamethylene diisocyanate (HDI). We analyzed potential biomarkers of isocyanate-induced OA, based on investigated immunologic, genetic, neurogenic, and protein markers, because there is no serological testing method. The prevalence of serum IgG to cytokeratin (CK)18 and CK19 in TDI-OA was significantly higher than in controls, although the prevalence of these antibodies was too low for them to be used as biomarkers. Another candidate biomarker was serum IgG to tissue transglutaminase (tTG), because the prevalence of serum specific IgG to tTG was significantly higher in patients with TDI-OA than in controls. The human leukocyte antigen (HLA) DRB1*1501-DQB1*0602-DPB1*0501 haplotype may be used as a genetic marker for TDI-OA in Koreans via enhanced specific IgE sensitization in exposed subjects. The genetic polymorphisms of catenin alpha 3, alpha-T catenin (CTNNA3) were significantly associated with TDI-OA. Additionally, examining the neurokinin 2 receptor (NK2R) 7853G>A and 11424 G>A polymorphisms, the NK2R 7853GG genotype had higher serum vascular endothelial growth factor (VEGF) levels than the GA or AA genotypes among Korean workers exposed to TDI. To identify new serologic markers using a proteomic approach, differentially expressed proteins between subjects with MDI-OA and asymptomatic exposed controls in a Korean population showed that the optimal serum cutoff levels were 69.8 ng/mL for ferritin and 2.5 µg/mL for transferrin. When these two parameters were combined, the sensitivity was 71.4% and the specificity was 85.7%. The serum cytokine matrix metalloproteinase-9 (MMP-9) level is a useful biomarker for identifying cases of TDI-OA among exposed workers. Despite these possible biomarkers, more effort should be focused on developing early diagnostic biomarkers using a comprehensive approach based on the pathogenic mechanisms of isocyanate-induced OA.

Soluble human leucocyte antigen-G and interleukin-10 levels in isocyanate-induced asthma

BACKGROUND

We previously reported that in moderate-to-severe asthma there is a deficit of IL-10 secretion that could prevent the production of soluble HLA-G (sHLA-G), a non-classical human leucocyte antigen class I molecule with tissue-protective properties in inflammatory responses.

OBJECTIVE

Our objective was to investigate the production of sHLA-G and the secretion of IL-10 by peripheral blood mononuclear cells (PBMCs) in asthma induced by isocyanates and to compare the results with those obtained in non-occupational allergic asthma.

METHOD

sHLA-G and IL-10 were measured by ELISA in the culture supernatants of unstimulated or lipopolysaccharide (LPS)-stimulated PBMCs obtained from 20 subjects with isocyanate asthma, 16 asymptomatic subjects exposed to isocyanates, 18 subjects with non-occupational allergic asthma, and 26 healthy control subjects.

RESULTS

Occupational exposure to isocyanates was associated with high baseline levels of secretion of IL-10 by PBMCs, whether or not the exposed subjects had asthmatic symptoms. However, spontaneous production of sHLA-G by PBMC was significantly higher in subjects with isocyanate asthma compared with asymptomatic-exposed controls. In contrast, PBMCs from subjects with non-occupational allergic asthma produced sHLA-G only after LPS stimulation.

CONCLUSIONS

sHLA-G production and IL-10 secretion are influenced by workplace exposure to isocyanates and by development of asthma. The different behaviour of both sHLA-G and IL-10 in asthma induced by isocyanates compared with non-occupational allergic asthma suggests a heterogeneous biological role for HLA-G molecules and for IL-10, a key cytokine of immune and inflammatory responses.

Serum ferritin and transferrin levels as serologic markers of methylene diphenyl diisocyanate-induced occupational asthma

BACKGROUND

Although methylene diphenyl diisocyanate (MDI) may induce occupational asthma in the workplace, the pathogenic mechanisms are unclear.

OBJECTIVES

By using bronchoalveolar lavage fluid, we sought to identify proteins that were differentially expressed between subjects with MDI-induced occupational asthma (MDI-OA) and asymptomatic exposed controls (AECs).

METHODS

To find proteins that were differentially expressed between the MDI-OA and AEC groups, 2-dimensional electrophoresis was performed by using bronchoalveolar lavage fluid obtained from subjects after MDI-specific inhalation challenge. The selected protein spots were then identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The clinical relevance of the differentially expressed spots was compared by ELISA using sera from the MDI-OA/eosinophilic bronchitis, AEC, and unexposed healthy control groups. Receiver operating characteristic curves were then plotted, and the sensitivity and specificity were determined.

RESULTS

Twenty-three protein spots were identified that distinguished the subjects with MDI-OA from those in the AEC group. Among them, ferritin expression was downregulated whereas transferrin expression was upregulated in subjects with MDI-OA compared with AEC; these results were validated by ELISA using sera from the MDI-OA/EB and AEC groups. To identify subjects with MDI-OA, the optimal serum cutoff levels were 69.84 ng/mL for ferritin and 2.48 microg/mL for transferrin. When these 2 parameters were combined, the sensitivity was 71.43% and the specificity was 85.71%.

CONCLUSION

Serum ferritin and transferrin levels are associated with the phenotype of MDI-OA.

Clinical and immunologic findings of methylene diphenyl diisocyanate-induced occupational asthma in a car upholstery factory

BACKGROUND

Although methylene diphenyl diisocyanate (MDI) is widely used in many industries, there have been few immunological studies of MDI-induced occupational asthma.

OBJECTIVES

We investigated the effects of MDI exposure on the clinical and immunologic condition of workers in a single car upholstery factory.

METHODS

Fifty-eight MDI-exposed workers were studied. Work-related lower-respiratory symptoms (WRRS) were identified using a questionnaire. Serum-specific IgE and IgG antibodies to MDI-human serum albumin conjugate were detected by ELISA. Atopy was evaluated using a skin prick test. MDI-induced occupational asthma was confirmed in the symptomatic workers with a positive result on an MDI-specific inhalation test.

RESULTS

Thirteen (22.4%) of the subjects complained of WRRS. MDI-induced occupational asthma was confirmed in five (8.6%) of the workers, and occupational eosinophilic bronchitis was confirmed in two (3.5%). The prevalence of specific IgG antibodies (20.7%) was higher than that of specific IgE antibodies (8.6%). The prevalence of MDI-induced occupational asthma/eosinophilic bronchitis was strongly associated with the presence of both WRRS and serum-specific IgG antibodies to an MDI-human serum albumin conjugate (P<0.01, <0.05, respectively).

CONCLUSION

These findings suggest that MDI could be a causative agent of occupational asthma among MDI-exposed workers. The prevalence of MDI-induced occupational asthma was 8.6%, and MDI-induced eosinophilic bronchitis was confirmed in two workers. The presence of work-related lower-respiratory symptoms and serum-specific IgG antibodies to an MDI-human serum albumin conjugate may be used to predict MDI-induced occupational asthma/eosinophilic bronchitis in MDI-exposed workers.

Work-related asthma in automobile spray painters: two case reports

This report describes two patients who had developed asthma after working as automobile painters with isocyanate-based aerosol paint for two years or over. In both patients asthma was confirmed using the standard diagnostic procedure. One of the subjects was atopic. One was ex-smoker and the other had never smoked. Neither had a family history of asthma. The symptoms occurred after workplace exposure lasting two years in one patient and three in the other. As both reported work-relatedness of the symptoms, they underwent serial peak expiratory flow rate (PEFR) measurement and bronchoprovocation testing. Significant work-related changes in PEFR diurnal variations and in non-specific bronchial hyperresponsiveness (NSBH) were observed in one patient, suggesting allergic occupational asthma (OA), while the other patient was diagnosed work-exacerbated asthma (WEA). Our data confirm that spray painting is an occupation with increased risk of respiratory impairment and asthma.

Asthma and allergy: short texts and recommendations of the expert conference of the French Speaking Pneumology Society (SPLF), in partnership with the French Society of Allergology and Clinical Immunology (SFAIC), the French Society of Occupational Medicine (SFMT) and the "Asthma-Allergy" association

The Asthma Plan published by the French Health Ministry in 2002, the experts conferences edited by ANAES on therapeutic education and follow-up of asthma, the inclusion of this disease in the Public Health Law have been remarkable steps in France during the last few years. The medical community, more particularly the pneumological community, has shown its commitment in the treatment of this public health problem. But allergy was not sufficiently taken into account, although it is responsible for nearly 50 to 60% cases of asthma. In most so-called developed countries the prevalence of asthma and of allergies has increased in the last twenty years. Its progress varies according to country and age group: the increased prevalence of allergy, more specifically of rhinitis and eczema, is most marked in children aged 6-7 year. The prevalence of asthma seems to have reached a plateau in certain northern countries or seems to have decreased in 13-14 year olds (Anglo-Saxon countries). There were multiple reasons, generally attributed to changes in life-style. Asthma is the result of an interaction between a genetic predisposition and the environment, where allergens are present, but also smoking. The relationships between allergy and asthma are complex. This conference discussed the various essential issues that face doctors who treat patients with asthma in their daily practice. The risk factors, the methods of exploration in children and adults and the specific treatments are, indeed, essential issues to be evaluated in a frequent pathology that interests a large number of physicians. The variety of experts is wide, representing pneumology (French Speaking Pneumology Society), the occupational medicine world (French Society of Occupational Medicine), the allergic pathology (French Society of Allergology and Clinical Immunology), and patients with the patient association "Asthma & Allergy", physicians belonging to the general medicine community, general hospitals, private hospitals and academic hospitals in France. The proposed guidelines are aimed at helping practitioners in distinguishing what is established from what remains to be demonstrated and/or assessed with respect to the different modalities for the exploration or treatment of allergic asthma.

Cell types involved in allergic asthma and their use in in vitro models to assess respiratory sensitization

This review first describes the mechanism and cell types involved in allergic asthma, which is a complex clinical disease characterized by airway obstruction, airway inflammation and airway hyperresponsiveness to a variety of stimuli. The development of allergic asthma exists of three phases, namely the induction phase, the early-phase asthmatic reaction (EAR) and the late-phase asthmatic reaction (LAR). In the induction phase, antigen-presenting cells play a major role. Most important cells in the EAR are mast cells, and during the LAR, various cell types, such as eosinophils, neutrophils, T cells, macrophages, dendritic cells (DCs), and cells that endow structure are involved. In occupational asthma, this immunological mechanism is involved in 90% of the cases. The second part of this review gives an overview of in vitro models to assess the hazardous potential of high- and low-molecular weight chemicals on the respiratory system. In order to develop a good in vitro model for respiratory allergy, the choice of appropriate cell types is important. Epithelial cells, macrophages and DCs are currently the most used models in this field of research.

Histamine release and inflammatory cell infiltration in airway Mucosa in methylene diphenyl diisocyanate (MDI)-induced occupational asthma

INTRODUCTION

Although methylene diphenyl diisocyanate (MDI) is widely used in industries, there have been few studies of the pathogenic mechanisms of MDI-induced occupational asthma (MDI-OA).

METHODS

We performed immunohistochemical analyses, measured inflammatory mediators and cytokines, and quantified histamine release (HR) from peripheral basophils in MDI-OA patients. Thirteen MDI-exposed workers (five MDI-OA, two MDI-induced esoinophilic bronchitis, and six asymptomatic exposed controls, AEC) were enrolled.

RESULTS AND DISCUSSION

Immunochemical analyses indicated significantly increased anti-eosinophilic cationic protein-stained cells in MDI-OA patients as compared with controls (P < 0.05). Sputum eosinophil cationic protein levels were increased after MDI-specific inhalation challenge test in MDI-OA/EB patients (P < 0.02). Sputum eosinophil counts were highly correlated with IL-8 and MMP-9 levels (P < 0.05 and P < 0.01, respectively). Basophil HR was significantly increased in MDI-OA patients after stimulations with anti-IgG4 and MDI-human serum albumin conjugates (both P < 0.05). Eosinophil activation is a major feature of airway inflammation in MDI-OA patients. Increased HR by MDI may contribute to the pathogenic mechanisms of MDI-OA.

Serial exhaled nitric oxide measurements in the assessment of laboratory animal allergy

BACKGROUND

Laboratory animal allergy (LAA) may cause eosinophilic airway inflammation, for which exhaled nitric oxide (FE(NO)) measurements are sensitive and specific. Our objective was to assess whether serial FE(NO) measurements might detect exposure-related inflammation in laboratory animal workers. METHODS. Fifty laboratory animal workers participated. Measurements of FE(NO) and spirometry were obtained at baseline (Friday) and twice-daily following a weekend with no animal contact.

RESULTS

Eleven of 50 subjects had work-related symptoms, and 2 of 11 had positive serology for LAA. Baseline FE(NO) was high (> 150 ppb) in the two seropositive subjects and increased progressively during the working week in one subject, confirming exposure-driven airway inflammation. In seronegative subjects, mean FE(NO) levels were 19.8 (standard deviation [SD], 20.1) and 21.7 (SD, 20.8) in the symptomatic and nonsymptomatic groups, respectively, with no significant changes in FE(NO) over time.

CONCLUSION

Serial FE(NO) measurements may provide complementary information in the assessment of possible occupational sensitisation. The sensitivity and specificity of this approach to diagnosing occupational asthma requires further evaluation.

Prevalence of work-related symptoms and serum-specific antibodies to wheat flour in exposed workers in the bakery industry

BACKGROUND

Although baker's asthma (BA) is a common occupational asthma, there have been few reports on this disease in Korean subjects.

OBJECTIVES

We evaluated the prevalence of serum-specific IgE, IgG1, and IgG4 antibodies in relation to work-related respiratory symptoms in a single industrial bakery.

METHODS

Three hundred and ninety-two bakery workers were administered and taken a questionnaire regarding respiratory symptoms. For symptomatic workers, the methacholine bronchial challenge test and specific bronchoprovocation tests with wheat extracts were carried out. Skin prick tests were performed and serum-specific IgE, IgG1, and IgG4 antibodies to wheat flour were detected. The IgE- and IgG4-binding components were identified by immunoblotting.

RESULTS

Sixty-seven workers (17.1%) complained of work-related upper and lower respiratory symptoms. The prevalence of BA based on positive bronchoprovocation test results was 1.5%. The sensitization rate to wheat flour was 5.9% by skin prick test and 6.5% by ELISA, and was closely associated with the presence of atopy and work-related lower respiratory symptoms (P<0.001 for both). IgE immunoblotting revealed six major IgE-binding components (27, 31, 36, 43, 54, and 72 kDa). The presence of wheat-specific IgG1 and IgG4 antibodies was found to be significantly associated with exposure intensity (P<0.05 for both).

CONCLUSIONS

The overall prevalence of wheat sensitization in a Korean bakery was 5.9%. We confirmed that an IgE-mediated response is the major pathogenic mechanism for the induction of work-related symptoms in wheat-exposed workers. Wheat-specific IgG antibodies may represent current or previous exposure to wheat dust.

Controlling occupational allergies in the workplace

OBJECTIVES

In recent years, the prevalence of work-related asthma has increased. Therefore, more attention needs to be paid to occupational allergens and their avoidance and control in workplaces. However, risk assessment of occupational allergen exposure is difficult because the relationship between exposure concentration, sensitization, and symptoms has not been fully established. This paper introduces a systematic and comprehensive approach to assessing and managing allergen risks at workplaces.

MATERIALS AND METHODS

This approach relies on the cooperation and active communication during the whole process between management, employees, and health care personnel, with the assistance of experts when needed. In addition to gathering background information, including allergic symptoms, through questionnaires addressed to the management and employees, hazard identification is also processed in the workplace through observations and measurements. The methods generally recommended to reduce allergen exposure are compared with those used in the workplace. The process is to be carefully planned and documented to allow later follow-up and re-evaluation.

RESULTS

The multi-faceted approach encompasses several risk assessment techniques, and reveals the prevalence of work-related allergic symptoms. The process effectively focuses on the potential means for controlling allergen exposure.

CONCLUSION

Based on this approach, the synopsis on the critical points that require implementation of effective control measures can be presented.

[Epidemiology and etiologic agents of occupational asthma]

INTRODUCTION

Occupational asthma is, by definition, a disease that can be prevented through appropriate protective strategies. Epidemiological information is required to guide these interventions, and we here examine epidemiological data on the burden, causes, and risk factors for this condition.

STATE OF THE ART

Population-based surveys indicate that approximately 15% of adult asthma is attributable to the workplace environment. The most common occupational agents implicated include flour, isocyanates, latex, and persulphate salts. The occupations in which occupational asthma has been most commonly reported are bakers, spray painters, health-care workers, hairdressers, and cleaners. The level of exposure to sensitizing agents seems to be the most relevant risk factor. Atopy is a significant risk factor only for the development of sensitization to high molecular weight agents. The role of other individual determinants, such as genetic factors, has been less consistently established. Occupational asthma is associated with a substantial adverse impact on the employment and financial status of affected workers.

PERSPECTIVES

Methodological improvements are required in order to distinguish more accurately between occupational and work-exacerbated asthma. Further investigations of the effectiveness of primary and secondary preventive interventions are also needed.

Occupational asthma in subjects occupationally exposed to herbal and fruit tea dust

We performed a cross-sectional study to detect occupational asthma (OA) in 63 subjects occupationally exposed to herbal and fruit tea dust and in 63 corresponding controls. The evaluation included a questionnaire, skin prick tests to workplace and common inhalant allergens, spirometry, and histamine challenge test. The evaluation of the work-relatedness of asthma in the exposed workers was based on serial peak expiratory flow rate (PEFR) measurements and bronchoprovocation tests. We found a higher prevalence of respiratory symptoms in the exposed workers, whereas spirometric parameters were significantly lower. The prevalence of sensitisation to allergens and of bronchial hyperresponsivenss (BHR) did not differ significantly between the groups. The prevalence of asthma was also similar in both groups (8.0 % vs. 6.4 %; P=0.540). Work-relatedness of symptoms was reported by all asthmatic tea workers and by no control with asthma. Significant work-related changes in PEFR diurnal variations and in non-specific BHR, suggesting allergic OA, were found in one tea worker with asthma (1.6 %). No specific workplace agent causing OA in the affected subject was identified. None of the tea workers with asthma met the criteria for medical case definition of the reactive airway dysfunction syndrome (RADS). Our data confirm workplace exposure to herbal and fruit tea dust as a risk factor for OA.

Characteristics of patients with work-related asthma seen in the New York State Occupational Health Clinics

OBJECTIVE

The objective of this study was to characterize the work-related asthma population seen by the New York State Occupational Health Clinic Network (OHCN) to determine which industries, occupations, and causal agents are associated with work-related asthma in New York State (NYS).

METHODS

The OHCN patient database was analyzed to identify those patients with a diagnosis of work-related asthma and medical charts were then abstracted for data on demographics, clinical history, disease severity, industry, occupation, and putative agent.

RESULTS

The OHCN patients with work-related asthma were most commonly employed in the service and manufacturing industries. Common occupations included teachers, farm operators/managers, and construction trades. The most frequently reported putative agents associated with work-related asthma were dust, indoor air, mold, and solvents.

CONCLUSIONS

Our findings suggest the potential importance of prevention of workplace exposure in reducing adult asthma in NYS.

Alveolar macrophages have a dual role in a rat model for trimellitic anhydride-induced occupational asthma

Occupational exposure to low molecular weight chemicals, like trimellitic anhydride (TMA), can result in occupational asthma. Alveolar macrophages (AMs) are among the first cells to encounter inhaled compounds. These cells can produce many different mediators that have a putative role in asthma. In this study, we examined the role of AMs in lung function and airway inflammation of rats exposed to TMA. Female Brown Norway rats were sensitized by dermal application of TMA or received vehicle alone on days 0 and 7. One day before challenge, rats received intratracheally either empty or clodronate-containing liposomes to deplete the lungs of AMs. On day 21, all rats were challenged by inhalation of TMA in air. Lung function parameters were measured before, during, within 1 h after, and 24 h after challenge. IgE levels and parameters of inflammation and tissue damage were assessed 24 h after challenge. Sensitization with TMA led to decreased lung function parameters during and within 1 h after challenge as compared to non-sensitized rats. AM depletion alleviated the TMA-induced drop in lung function parameters and induced a faster recovery compared to sham-depleted TMA-sensitized rats. It also decreased the levels of serum IgE 24 h after challenge, but did not affect the sensitization-dependent increase in lung lavage fluid IL-6 and tissue TNF-alpha levels. In contrast, AM depletion augmented the TMA-induced tissue damage and inflammation 24 h after challenge. AMs seem to have a dual role in this model for TMA-induced occupational asthma since they potentiate the immediate TMA-induced decrease in lung function but tended to dampen the TMA-induced inflammatory reaction 24 h later.

Occupational asthma

Substantial epidemiologic and clinical evidence indicates that agents inhaled at work can induce asthma. In industrialized countries, occupational factors have been implicated in 9 to 15% of all cases of adult asthma. Work-related asthma includes (1) immunologic occupational asthma (OA), characterized by a latency period before the onset of symptoms; (2) nonimmunologic OA, which occurs after single or multiple exposures to high concentrations of irritant materials; (3) work-aggravated asthma, which is preexisting or concurrent asthma exacerbated by workplace exposures; and (4) variant syndromes. Assessment of the work environment has improved, making it possible to measure concentrations of several high- and low-molecular-weight agents in the workplace. The identification of host factors, polymorphisms, and candidate genes associated with OA is in progress and may improve our understanding of mechanisms involved in OA. A reliable diagnosis of OA should be confirmed by objective testing early after its onset. Removal of the worker from exposure to the causal agent and treatment with inhaled glucocorticoids lead to a better outcome. Finally, strategies for preventing OA should be implemented and their cost-effectiveness examined.

Food allergy and additives: triggers in asthma

Exposure to food allergens can cause a varied pattern of respiratory symptoms, with allergic responses ranging from asthma symptoms to occupational asthma. Food allergy in a patient presenting as asthma tends to indicate a more severe disease constellation. Patients with underlying asthma experience more severe and life-threatening allergic food reactions. When a food reaction involves respiratory symptoms, it is almost always a more severe reaction compared with reactions that do not involve the respiratory tract. Susceptible patients may even react to a causative food on inhalation without ingestion. However, isolated asthma or rhinitis symptoms without concomitant cutaneous or gastrointestinal symptoms are rare events.

Diesel exhaust, solvents, and other occupational exposures as risk factors for wheeze among farmers

Farmers engage in activities that result in exposure to diesel exhaust, solvents, welding fumes, and other respiratory irritants. Using the Agricultural Health Study, a cohort of pesticide applicators in Iowa and North Carolina, we evaluated the odds of wheeze associated with nonpesticide occupational exposures. We used logistic regression models controlling for age, state, smoking, and history of asthma or atopy to evaluate odds of wheeze in the past year among the 20898 farmers who provided complete information on all covariates. Driving diesel tractors was associated with elevated odds of wheeze (odds ratio = 1.31; 95% confidence interval = 1.13, 1.52); the odds ratio for driving gasoline tractors was 1.11 (95% confidence interval = 1.02, 1.21). A duration-response relationship was observed for driving diesel tractors but not for driving gasoline tractors. Activities involving solvent exposure, including painting and use of solvents for cleaning, were associated with an increased odds of wheeze in a duration-dependent fashion. The highest odds of wheeze for farm activities were for daily painting (odds ratio = 1.82; 95% confidence interval = 0.89, 3.73), an indication of daily solvent exposure. These results add to the growing body of evidence of adverse respiratory effects of diesel exposure on the lung and suggest exposure to solvents may contribute as well.

Lack of association of HLA class I genes and TNF alpha-308 polymorphism in toluene diisocyanate-induced asthma

BACKGROUND

Toluene diisocyanate (TDI)-induced asthma is a common cause of occupational asthma and it affects 5-15% of the exposed population suggesting an underlying genetic susceptibility.

METHODS

To investigate the role of genetic factors in the development of TDI-induced asthma, we analyzed the distribution of human leukocyte antigen (HLA) class I genes and of tumor necrosis factor (TNF)-alpha A-308G polymorphism in 142 patients with TDI-induced asthma and in 50 asymptomatic exposed subjects.

RESULTS

Neither the distribution of HLA class I antigens nor the distribution of TNF-alpha A-308G polymorphism was different between patients with TDI-induced asthma and asymptomatic exposed subjects.

CONCLUSIONS

These results suggest that HLA class I antigens and TNF-alpha A-308G are not associated with susceptibility or resistance to the development of TDI-induced asthma.