Increase of Exhaled Nitric Oxide (eNO) after Methylene Diphenyl Diisocyanate (MDI) Exposure in Isocyanate Workers with Bronchial Hyperresponsiveness

Background: : Isocyanates have become one of the most important causes of occupational asthma in industrialized countries. Increased exhaled nitric oxide (eNO) levels have been shown to be associated with allergic airway inflammation. The objective of this study was to investigate the influence of isocyanate on eNO levels and to elucidate whether the latter are associated with specific sensitization and/or unspecific bronchial hyperresponsiveness (BHR). Additionally, we wanted to compare eNO changes of smokers and non-smokers. Methods: We determined eNO during diagnostic isocyanate challenges in workers with suspected isocyanate asthma. Results: : Fourteen of 22 symptomatic isocyanate workers showed BHR and five of these 14 developed an asthmatic response upon challenge with methylene diphenyl diisocyanate (MDI). In comparison with the group without BHR, subjects with BHR had higher basal eNO and a significant increase in eNO 22 hrs after MDI challenge. Four of the asthmatic responders and six of the nine MDI non-responders with BHR revealed an eNO increase of > 30%. There was also a positive association between the eNO change and the increase in airway resistance in isocyanate workers with BHR. The highest eNO change was found in subjects with IgE-mediated sensitization to MDI and low MDI thresholds. Only one of the eight MDI non-responders without BHR exhibited an eNO increase of > 30%. Conclusions: : Isocyanate workers with BHR show increased MDI responses both of airway resistance and of the inflammatory marker eNO. eNO measurement is obviously a new suitable tool for monitoring isocyanate workers under respiratory risk

What are the benefits of medical screening and surveillance?

Pre-employment examination is considered to be an important practice and is commonly performed in several countries within the European Union. The benefits of medical surveillance programmes are not generally accepted and their structure is often inconsistent. The aim of this review was to evaluate, on the basis of the available literature, the usefulness of medical screening and surveillance. MEDLINE was searched from its inception up to March 2010. Retrieved literature was evaluated in a peer-review process and relevant data was collected following a systematic extraction schema. Pre-placement screening identifies subjects who are at an increased risk for developing work-related allergic disease, but pre-employment screening is too low to be used as exclusion criteria. Medical surveillance programmes can identify workers who have, or who are developing, work-related asthma. These programmes can also be used to avoid worsening of symptoms by implementing preventive measures. A combination of different tools within the surveillance programme, adjusted for the risk of the individual worker, improves the predictive value. Medical surveillance programmes provide medical as well as socioeconomic benefits. However, pre-employment screening cannot be used to exclude workers. They may act as a starting point for surveillance strategies. A stratified approach can increase the effectiveness and reduce the costs for such programmes

What are the benefits of medical screening and surveillance?

Pre-employment examination is considered to be an important practice and is commonly performed in several countries within the European Union. The benefits of medical surveillance programmes are not generally accepted and their structure is often inconsistent. The aim of this review was to evaluate, on the basis of the available literature, the usefulness of medical screening and surveillance. MEDLINE was searched from its inception up to March 2010. Retrieved literature was evaluated in a peer-review process and relevant data was collected following a systematic extraction schema. Pre-placement screening identifies subjects who are at an increased risk for developing work-related allergic disease, but pre-employment screening is too low to be used as exclusion criteria. Medical surveillance programmes can identify workers who have, or who are developing, work-related asthma. These programmes can also be used to avoid worsening of symptoms by implementing preventive measures. A combination of different tools within the surveillance programme, adjusted for the risk of the individual worker, improves the predictive value. Medical surveillance programmes provide medical as well as socioeconomic benefits. However, pre-employment screening cannot be used to exclude workers. They may act as a starting point for surveillance strategies. A stratified approach can increase the effectiveness and reduce the costs for such programmes

Two variants of occupational asthma separable by exhaled breath nitric oxide level.

UNLABELLED Exhaled nitric oxide (FE(NO)) has been used as a marker of asthmatic inflammation in non-occupational asthma, but some asthmatics have a normal FE(NO). In this study we investigated whether, normal FE(NO) variants have less reactivity in methacholine challenge and smaller peak expiratory flow (PEF) responses than high FE(NO) variants in a group of occupational asthmatics. METHODS We measured FE(NO) and PD(20) in methacholine challenge in 60 workers currently exposed to occupational agents, who were referred consecutively to a specialist occupational lung disease clinic and whose serial PEF records confirmed occupational asthma. Bronchial responsiveness (PD(20) in methacholine challenge) and the degree of PEF change to occupational exposures, (measured by calculating diurnal variation and the area between curves score of the serial PEF record in Oasys), were compared between those with normal and raised FE(NO). Potential confounding factors such as smoking, atopy and inhaled corticosteroid use were adjusted for. RESULTS There was a significant correlation between FE(NO) and bronchial hyper-responsiveness in methacholine challenge (p = 0.011), after controlling for confounders. Reactivity to methacholine was significantly lower in the normal FE(NO) group compared to the raised FE(NO) group (p = 0.035). The two FE(NO) variants did not differ significantly according to the causal agent, the magnitude of the response in PEF to the asthmagen at work, or diurnal variation. CONCLUSIONS Occupational asthma patients present as two different variants based on FE(NO). The group with normal FE(NO) have less reactivity in methacholine challenge, while the PEF changes in relation to work are similar

Work-related allergies to storage mites in Parma (Italy) ham workers

OBJECTIVES: To investigate the role of storage mites in the development of allergic diseases among ham production workers, and to search for early alterations in lung function tests and early inflammation markers in exhaled air. Respiratory allergies due to storage mites have been reported in people with various occupations but, although such mites are unavoidable when curing ham, there are no published data concerning ham production workers. SETTING: Secondary care. DESIGN: Experimental cross-sectional study. PARTICIPANTS: 220 participants (110 ham production workers and 110 controls) were recruited. PRIMARY AND SECONDARY OUTCOME MEASURES: Workers answered a medical questionnaire, and underwent spirometry and fraction of exhaled nitric oxide at 50 mL/s (FeNO50) measurements. Those with allergic symptoms also underwent skin prick tests to determine their sensitisation to airborne allergens. A methacholine test was performed in symptomatic participants when spirometry was normal to assess airways hyper-responsiveness. RESULTS: Symptomatic storage mite sensitisation was observed in 16 workers (14.5%) (rhinoconjunctivitis in 15 (63%) and asthma in (4%)) and 2 controls (1.8%; p=0.001). Higher FeNO50 values in exposed symptomatic workers compared with healthy control participants (34.65±7.49 vs 13.29±4.29 ppb; p<0.001) suggested bronchial and nasal involvement, although their lung function parameters were normal. Regardless of exposure, a FeNO50 value of 22.5 ppb seems to be 100% sensitive and 99.4% specific in distinguishing allergic and non-allergic participants. Multivariate analysis of FeNO50 values in the symptomatic participants showed that they were positively influenced by IgE-mediated allergy (p=0.001) and reported symptom severity (p=0.041), and negatively by smoking status (p=0.049). CONCLUSIONS: Ham processing workers, as well as workers involved in any meat processing work that includes curing, should be informed about the occupational risk of sensitisation to mites