4.1 Work-Related Asthma4. Airways Diseases | 4.1a) Prevent and Reduce Latex-Induced Asthma
WRA is the most common respiratory disease treated in occupational health clinics in the U.S., accounting for a substantial share of all asthma among adults. A 2003 statement of the American Thoracic Society indicates that 15 percent of asthma among adults is attributable to work. Under cooperative agreements, NIOSH-funded researchers have since estimated that 29 percent to 33 percent of new-onset adult asthma is attributable to work. In addition, RDRP scientists estimate that 23 percent of existing adult asthma is exacerbated by work. Assuming that about 25 percent of asthma is attributable to work, at least 2.25 million Americans between the ages of 15 and 65 have experienced onset or exacerbation of their asthma due to workplace conditions (A4-1).
Challenges to conducting research on WRA involve issues of identification, causality, and implementation:
RDRP has established a significant track record in the asthma arena, as evidenced by 3108 separate records found in NIOSHTIC-2 (the comprehensive NIOSH bibliography) that pertain to asthma and asthma-inducing agents, such as latex and isocyanates.
The following sections illustrate how RDRP has contributed to addressing these challenges through pursuing its research and prevention objectives in:
RDRP has contributed in part to documented outcomes associated with these specific objectives, which are an increased awareness that natural rubber latex is an asthma sensitizer, a decrease in the use of natural rubber latex products, and a concomitant decrease (25-fold) in WRA incidence due to exposure to natural rubber latex. In the case of isocyanates there is a growing awareness among manufacturers of products that contain isocyanates that exposure to their products carries a risk of WRA. However, it will take more time and effort to convert this to a reduction in isocyantate induced asthma.
RDRP scientists are raising awareness of the problem of methyl diisocyanate (MDI) asthma associated with spray-on truck-bed liner application. They have helped two states, Michigan and Washington to post their Alerts and RDRP has recently released a NIOSH Alert on application of spray-on bed liners.
RDRP has developed a five-year prospective collaborative project involving industry, labor, and government, in which a standardized approach to hazard and health monitoring, agreed upon by all primary producers of Toluene Diisocyanate (TDI) is to be implemented. The collaboration is undergoing formal scrutiny for feasibility and effectiveness. The protocol describes a finalized, formal analysis plan to document the level of implementation of recommended approaches and to evaluate subsequent changes in exposures and health outcomes, including the diagnosis of diisocyanate-induced asthma among plant workers (A4-2).
Asthma in relation to indoor air quality problems in schools and offices has been addressed for years and in many workplaces via RDRP responses to requests for HHEs. In recent years, RDRP has undertaken evaluations at several work locations in the northeastern U.S. under a research protocol. There is documentation that some RDRP recommendations for intervention, including provision of alternate work locations and building modifications or renovations, have been implemented at evaluated worksites. Studies are now in progress to determine if these interventions have been effective in mitigating exposures and improving health outcomes.
A major challenge in detecting WRA pertains to the high prevalence of asthma in the general population. In another activity, RDRP provided leadership in the development of a health monitoring software package designed to facilitate the evaluation of individuals at risk of WRA. This package has been made readily available to physicians, and should assist in the clinical diagnosis of WRA. The development of a standardized respiratory questionnaire will also assist physicians and researchers in addressing this problem.