Asthma Prevalence Overall
Asthma is one of the most common chronic respiratory diseases in both adults and children. In 2010 an estimated 7.0 million children (0-17 years of age) and 18.7 million adults (≥ age 18) in the U.S. currently had asthma. Rates of asthma in the U.S. have been increasing for several decades, reaching a peak prevalence of 8.4% in 2010 (Moorman, 2012). The estimated prevalence of current asthma in Minnesota in 2010 from a statewide survey was 7.0% of children and 7.6% of adults. This means an estimated 302,000 adults and 90,000 children in Minnesota currently had asthma in 2010. Rates are even higher (10.9%) when considering the prevalence of adults who have ever had asthma (whether or not they still have asthma). In general, asthma rates are higher among children than adults, females, blacks, those below the poverty level, and those who are obese. As noted below, rates are also higher among people employed in certain occupations and industries. Further information on the occurrence and management of asthma in Minnesota can found at the Minnesota Asthma Program.
Asthma Related to Occupational Exposures
Asthma is one of the most prevalent occupational respiratory diseases. Work-related asthma (WRA) is often divided into two categories:
- adult-onset asthma caused by workplace exposure, and
- existing asthma that is worsened or exacerbated by workplace exposures.
Portion of adult asthma due to occupational exposures
Estimates of the proportion of adult asthma that is caused by or exacerbated by occupational exposures vary widely depending on many factors. A commonly-cited proportion is 15%, based on the median of 21 studies, with proportions ranging from 4% to 58% (Balmes, 2003). A more recent review of 26 studies reported a median of 17.6% with a range of 7% to 51% (Toren, 2009) while another review of 12 studies of asthma that is worsened by work reported a median of 21.5%. (Henneberger, 2011). Data from the 2010 National Health Interview Survey indicated that 6.7% of employed adults aged 18-64 who currently had asthma had been told by a doctor or other health professional that their asthma was caused by or worsened by current or previous work. (CDC, 2011).
Statewide data on prevalence of work-related asthma
Statewide data on work-related asthma come primarily from two sources: the Behavioral Risk Factor Surveillance System (BRFSS) and Worker’s Compensation Claims. The CDC-funded BRFSS program is a state-based randomized telephone survey of state residents aged 18 or above that collects data on health behaviors, health care utilization, and health status. An analysis of data from 38 states (not including Minnesota) for the years 2006-2009 indicated that 9.0% of ever-employed adults with current asthma had been told by a health professional that their asthma was related to a job that they had had (Knoeller, 2012). The range among individual states was 4.8% to 14.1%. An analysis of 2005 BRFSS data from three states (Michigan, Minnesota, and Oregon) found that 53% of the respondents from each state with current asthma reported that their asthma was caused by or aggravated by exposures at some job they have held (Lutzker, 2010). Based on the 2003 estimate of the proportion of asthma due to occupation (15% of adult asthma) and the 2005 MN BRFSS survey results (53%), it can be estimated that between 45,000 and 160,000 Minnesotans have had asthma caused by or worsened by a job they have held.
Worker’s compensation claims data are frequently used to monitor occupational injury and illness rates and costs. However, for a variety of reasons, these data are generally considered poor indicators of occupational diseases. This limitation can readily be seen with asthma data. During 2005-2009, an average of 30 workers compensation claims for asthma were filed each year, representing a very small fraction of the number of potential work-related asthma cases in Minnesota.
Work-related asthma frequently under-diagnosed
Numerous studies have indicated that work-related asthma is considerably under-diagnosed. For a variety of reasons, occupational histories and potential workplace exposures among adult asthma patients are not typically explored by physicians and their patients or documented in the medical record. Given the proportion of adult asthma that is potentially work-related and the significant medical and socioeconomic consequences of undiagnosed work-related asthma, many researchers recommend that occupational factors should be considered in all individuals with adult-onset asthma.
Causes of Work-Related Asthma
Over 350 workplace substances and processes and numerous occupations are associated with work-related asthma (Vandenplas, 2011). More complete listings of substances can be found in the General Information Sources listed below. A few examples of substances include:
- Many plant materials – such as latex, flour, grain dust, wood dust
- Many animal materials – hair, dander, saliva
- Diisocyanates – widely used in spray painting, insulation, plastics
- Enzymes used in detergents
- Chlorine gas, sulfur dioxide, ammonia, formaldehyde and other respiratory irritants
- Cleaning products
- Metal fumes and dusts, metalworking fluids
Some of the many occupations that may confer a higher risk:
- Grain elevator workers
- Metal workers and welders
- Health care workers, particularly nurses
- Cleaners (domestic and industrial)
- Plastics workers
- Spray painters and foam insulation workers
- Laboratory workers and animal handlers
- Woodworkers and foresters
- Hairdressers/salon workers
Collaboration with MDH Asthma Program
One of the goals of the Minnesota Occupational Health and Safety Surveillance Program is to collaborate with the MDH Minnesota Asthma Program to identify and/or implement feasible strategies to reduce the burden of work-related asthma in Minnesota. The Asthma Program at MDH was initially funded by CDC in 1999 and has been in continuous operation since that time. While focusing primarily on asthma education, management and prevention in children in schools and homes, it was decided in 2005 that WRA should be incorporated into Minnesota’s strategic plan for addressing asthma. An advisory workgroup was established to assist Asthma Program staff to determine priorities and establish recommendations. A “Strategic Plan for Addressing Work-Related Asthma in Minnesota” was published in November 2006. This plan along with other information can be found at Asthma in the Work Place. A new work-related asthma advisory group was established by the Asthma Program in 2011 to provide input to MDH on priorities and activities to reduce the burden of work-related asthma. Staff from the Occupational Health & Safety Surveillance Program have participated with the advisory workgroup since 2005. In addition to participating with the WRA advisory group, the occupational surveillance program collaborated on the development of a 2011 MDH fact sheet and press release warning salon owners and their customers of the risk of asthma and other health hazards from the use of formaldehyde-containing hair straightening products.
Survey of Cosmetologists, Manicurists, and Estheticians
In 2012, Minnesota Asthma Program staff developed and conducted an online health and safety survey of cosmetologists, manicurists, and estheticians licensed by the Minnesota Board of Cosmetologist Examiners. Approximately 1,900 cosmetologists and associated professionals completed the survey, providing information on work history, smoking history, training and knowledge of chemical hazards, respiratory symptoms, whether they have asthma, demographic data, and other characteristics. Staff from the Occupational Health & Safety Surveillance Program are assisting with the analysis and interpretation of the survey data.
General Sources of Information on Work-Related Asthma
- Haz-Map is an occupational health database hosted by the U.S. National Library of Medicine. Haz-Map shows links between occupational diseases and various agents. Haz-Map Occupational asthma:
- NIOSH Web Pages for Occupational Asthma:
- US OSHA Web Page for Occupational Asthma
- Mayo Clinic
- Occupational Health and Safety Commission of Quebec, Canada (extensive list of agents causing WRA)
- CDC (2011). "QuickStats: Percentage of Employed Adults Aged 18-64 Years with Current Asthma, Skin Condition, or Carpal Tunnel Syndrome Who Were Told Their Condition Was Work-Related, by Sex - National Health Interview Survey, 2010." MMWR 60(50): 1712. MMWR.
- Balmes, J., M. Becklake, P. Blanc, P. Henneberger, K. Kreiss, C. Mapp, D. Milton, D. Schwartz, K. Toren and G. Viegi (2003). "American Thoracic Society Statement: Occupational contribution to the burden of airway disease." Am J Respir Crit Care Med 167(5): 787-797. PubMed.
- Henneberger, P. K., C. A. Redlich, D. B. Callahan, P. Harber, C. Lemiere, J. Martin, S. M. Tarlo, O. Vandenplas and K. Toren (2011). "An Official American Thoracic Society Statement: Work-Exacerbated Asthma." Am J Respir Crit Care Med 184(3): 368-378. PubMed.
- Knoeller, G. E., J. M. Mazurek and J. E. Moorman (2012). "Work-related asthma--38 states and District of Columbia, 2006-2009." MMWR Morb Mortal Wkly Rep 61(20): 375-378. PubMed.
- Lutzker, L. A., A. P. Rafferty, W. M. Brunner, J. K. Walters, E. A. Wasilevich, M. K. Green and K. D. Rosenman (2010). "Prevalence of work-related asthma in Michigan, Minnesota, and Oregon." J Asthma 47(2): 156-161. PubMed.
- Moorman, J. E., L. J. Akinbami, C. M. Bailey, H. Zahran, M. E. King, C. A. Johnson and X. Liu (2012). “National Surveillance of Asthma: United States, 2001-2010.” National Center for Health Statistics, Hyattsville, M.D. Vital and Health Statistics 3(35). http://www.cdc.gov/nchs/data/series/sr_03/sr03_035.pdf
- Toren, K. and P. D. Blanc (2009). "Asthma caused by occupational exposures is common - a systematic analysis of estimates of the population-attributable fraction." BMC Pulm Med 9: 7. PubMed.
- Vandenplas, O. (2011). "Occupational asthma: etiologies and risk factors." Allergy Asthma Immunol Res 3(3): 157-167. PubMed.