Over 300 workplace substances have been identified to cause new-onset asthma and the list continues to grow ^{1, 2}. Other substances can aggravate pre-existing asthma, causing increased illness and medication requirements. Work-related asthma (WRA) comprises both new-onset and work-aggravated asthma³. An estimated 15-55% of all adult asthma is related to work^4-7.

Since 1988, Michigan has received funding from the National Institute for Occupational Safety and Health (NIOSH) for the development and continuation of a WRA surveillance and workplace intervention program. Other states have intermittently conducted WRA surveillance, but Michigan is the only state to track WRA consistently for 31 years. Furthermore, Michigan is the only state where the surveillance program is part of a regulatory program to conduct enforcement inspections at the workplaces of the individuals identified with WRA. A recent article, “The Burden of Work-Related Asthma in Michigan,” reported on the 3,634 confirmed cases of WRA identified over 31 years in Michigan. Key findings were:

Overall, the confirmed cases of WRA in Michigan have decreased over the 31 years. The cumulative incidence rate of WRA decreased from 3.5 during 1988-1997 to 2.0 cases per 100,000 Michigan workers during 2008-2018. Surveillance systems in other countries have also reported a downward trend in WRA.

There were decreases in cases from specific exposures to well-known causes of WRA such as isocyanates and metal working fluids and in the cumulative incidence rate in the overall manufacturing sector (11.6 to 5.6 cases per 100,000 workers). This decrease was consistent with improved workplace engineering and controls such as enclosure of work processes, product substitution and use of personal protective gear.

However, for cleaning products, which are found across all industries, generally with less standardized work practices than those applied in a manufacturing setting there was an increase over time in the number of cases and percentage of cases associated with cleaning products from 5% to 20%.

Sixty-six percent of WRA cases had an emergency department visit, with a median of two and an average of five visits, and 35% were hospitalized for their WRA, with a median of one and average of four hospitalizations.

Despite the high morbidity and cost of WRA, only 49% had applied for workers’ compensation.

Nine individuals died from an asthma attack from a workplace exposure (the paper describes one of the deaths). Table 1 below summarizes the deaths. The decedents ranged from 19 to 77 years. Five were men. Five worked in manufacturing and one each worked in construction, agriculture, food services, and automotive repair. Four were exposed to isocyanates, and one case each was exposed to secondhand cigarette smoke, milk tank cleaning agents, construction chemicals, mold machine release spray, and welding fume.

WRA cases are useful for targeting workplace enforcement inspections. The confirmed cases worked in 2,601 facilities. Michigan OSHA inspected 806 of those facilities. During the inspections, 10,493 co-workers of the index cases completed a confidential respiratory questionnaire; 1,622 (15%) reported being bothered at work by daily or weekly chest tightness, shortness of breath or wheezing, or having new-onset asthma since beginning to work at the facility. Symptomatic co-workers decreased over time from 18% to 12%.

While the WRA cases have declined in Michigan, it remains an important, complex, and often overlooked issue^4-7. New-onset WRA is divided into two types of asthma: One type typically develops after months to years of low-level exposure to a known asthma-inducer (occupational asthma), and the other type of asthma develops from a one-time high-level acute exposure to an irritant (Reactive Airways Dysfunction Syndrome). WRA from chronic exposure to low-to-moderate levels of irritants has also been described. Work aggravated asthma occurs when an individual with pre-existing asthma has an increase in respiratory symptoms and/or need for medications from workplace exposure(s). Guidelines emphasize consideration of WRA in all adults with asthma to increase early diagnosis and removal from exposure to increase the likelihood of reversing the condition⁸. Since health care practioners may overlook WRA, OSHA has developed a fact sheet for workers/patients to share with their doctors about the diagnosis of WRA⁹.

We are interested in your thoughts and comments on this summary. Please click here to visit the blog post on the NIOSH website and leave a comment below the post. 

More information about the Michigan program can be found at: www.oem.msu.edu. Funding for Michigan’s work-related asthma surveillance comes from NIOSH through a cooperative agreement to support state surveillance programs. More information about this funding can be found at: https://www.cdc.gov/niosh/oep/statesurv.html. This blog is part of a series highlighting extramural research funded by NIOSH through the Office of Extramural Programs.

References

1. Rosenman KD, Beckett WS. Web based listing of agents associated with new onset work-related asthma. Respir Med 2015; 109:625-631.
2. Quirce S, Sastre J. New causes of occupational asthma. Curr Opin Allergy Clin Immunol 2011; 11:80-85.
3. Tarlo SM, Lemiere C. Occupational asthma. N Engl J Med 2014; 370:640-649.
4. Balmes J, Becklake M, Blanc P, Henneberger P, Kreiss K, Mapp C, Milton D, Schwartz D, Toren K, Viegi G. American Thoracic Society statement: occupational contribution to the burden of airway disease. Am J Respir Crit Care Med 2003; 167:787-797.
5. Henneberger PK, Redlich CA, Callahan DB, Harber P, Lemiere C, Martin J, Tarlo SM, Vandenplas O, Toren K. An official American Thoracic Society statement: work-exacerbated asthma. Am J Respir Crit Care Med 2011; 184:368-378.
6. Lutzker LA, Rafferty AP, Brunner WM, Walters JK, Wasilevich EA, Green MK, Rosenman KD. Prevalence of work-related asthma in Michigan, Minnesota, and Oregon. J Asthma 2010; 47:156-161.
7. Blanc PD, Annesi-Maesano I, Balmes JR, Cummings KJ, Fishwick D, Miedinger D, Murgia N, Naidoo RN, Reynolds CJ, Sigsgaard T, Torén K, Vinnikov D, Redlich CA. 2019. The Occupational Burden of Nonmalignant Respiratory Diseases. An Official American Thoracic Society and European Respiratory Society Statement. Am J Respir Crit Care Med; 199:1312-1334.
8. Tarlo SM, Balmes J, Balkissoon R, Beach J, Beckett W, Bernstein D, Blanc PD, Brooks SM, Cowl CT, Daroowalla F, Harber P, Lemiere C, Liss GM, Pacheco KA, Redlich CA, Rowe B, Heitzer J. Diagnosis and management of work-related asthma. American College of Chest Physicians Consensus Statement. Chest 2008; 134:1S-41S.
9. OSHA Fact Sheet. Do You Have Work-Related Asthma? A Guide for YOU and YOUR DOCTOR. https://oem.msu.edu/images/annual_reports/OSHAAsthmaFactSheet.pdf (accessed 12/10/19)