Breathless at work: HCWs face asthma hazards

Cleaning agents trigger onset of asthma

Health care workers are breathing easier thanks to a widespread shift toward powder-free latex gloves. But other workplace hazards remain that make health care one of the industries with the greatest prevalence of occupational asthma.

Cleaning products are one of the leading causes of occupational asthma in the health care industry, studies and surveillance data indicate. Solvents and infectious diseases also contribute to occupational asthma.

Health care workers are diagnosed with occupational asthma more frequently than expected based on their workforce representation, according to an analysis of 1,879 work-related asthma reports.1 The cases came from physician reports and hospital discharge data from Massachusetts, Michigan, New Jersey, and California from 1993 to 1997.

About 16% of the confirmed work-related asthma cases occurred among health care workers, although they represented only 8% of the workforce, says Elise Pechter, MPH, CIH, an industrial hygienist with the Massachusetts Department of Public Health in Boston and lead author of the study. Personal interviews confirmed the work-related onset of the asthma and provided additional information about cases. Two-thirds (67%) of the health care workers had a new onset of their asthma related to workplace exposures; one-third had a work-related aggravation of asthma. The findings show that health care workers are at risk for occupational asthma, says Pechter, although she cautions that they may be over-represented in the surveillance system because they are more likely to access health care, receive an accurate diagnosis, and identify asthmagens in the workplace.

"These are health care workers who never had asthma in their lives or had been symptom-free for two years or more," Pechter says. "In our data, based on interviews with the people who have asthma, the most commonly reported exposure was cleaning products, including ammonia, bleach, disinfectants, and floor strippers."

Asthma has been recognized as a workplace hazard for health care workers since 1994 in surveillance reports collected by the National Institute for Occupational Safety and Health (NIOSH). The most recent NIOSH Work-related Lung Disease (WoRLD) report shows higher-than-average rates of occupational asthma among several health care occupations. Respiratory therapists have a higher proportionate mortality ratio from occupationally related asthma, and of the top 25 occupations for asthma mortality, nine are health-related occupations, including "health diagnosing practitioners," registered nurses, and health aides, notes Lee Petsonk, MD, senior medical officer at NIOSH's division of respiratory disease studies in Morgantown, WV.

In the surveillance data analyzed by Pechter and colleagues, nurses represented the largest health care occupation with occupational asthma.

"It's a rather consistent finding," says Petsonk. "Different approaches [to surveillance] have highlighted a group of health care workers, not just one occupational category."

Latex has been a significant trigger for work-related asthma in health care. But the widespread switch to powder-free, low-protein gloves has reduced the new cases of sensitization, says Kevin Kelly, MD, chairman of the department of pediatrics at Children's Mercy Hospital and Clinics in Kansas City, MO, and a latex allergy expert. He also is chief of pediatrics at the University of Missouri-Kansas City School of Medicine.

A German study found that about a third of health care workers with natural rubber latex allergy or sensitization had a loss of sensitization after about three years of avoiding contact with latex and working among co-workers who used only powder-free gloves. Their latex allergy or sensitization had initially been symptom-free, but their sensitization was confirmed by natural rubber latex-specific IgE serum antibodies.2

It's too soon to quantify the impact of powder-free, low-protein gloves on occupational asthma rates because of the lag in reporting and surveillance. Kelly is conducting a prospective study looking at new sensitizations among health care workers. But he sees a major shift.

"I used to see two to four new patients per week. If I see two patients per year with this disease, that would be the maximum," says Kelly, who previously chaired the allergy and immunology division at the Medical College of Wisconsin in Milwaukee.

Sensitized individuals may be able to return to work if they use synthetic gloves while their co-workers use powder-free, low-protein latex gloves, says Kelly. "If you remove those powdered, high-protein latex gloves from their use and their environment, a percentage of [latex-allergic employees] lose their sensitization to latex," he says.

Cleaners, sterilizers are culprits

Yet other health care-related asthma concerns remain. While latex accounted for 20% of the occupational asthma among health care workers identified in the four-state surveillance, cleaning products were the trigger in 24% of the cases. Gluteraldehyde accounts for 9% of cases and formaldehyde for 5%.

Benzalkonium chloride is one irritant that has been documented to trigger occupational asthma. It is commonly found in cleaning products, but its potential as an asthmagen is not well recognized, says John W. Burress, MD, MPH, FACOEM, medical director of the department of occupational and environmental medicine at Boston Medical Center.

"Because of its ubiquitous use [in cleaning products], even if the incidence rate of an allergy-mediated asthma is low, it still represents a significant risk for health care workers," he says.

Burress recalls one case of an allergic phlebotomist who worked in a small community hospital, which had made an effort to remove products containing benzalkonium chloride, or BAC. However, one day a co-worker unknowingly sprayed a disinfectant that contained BAC on a lab bench at least 25 feet away. "Within seconds, [the phlebotomist] developed a tightening in her throat, began to get a tightness in her chest, and began to wheeze," says Burress.

She was treated in the emergency department with bronchodilators and solumedrol and observed before discharging to home on prednisone taper and close follow up, says Burress. "She was able to continue working after another search of the whole facility had been made to remove any other benzalkonium chloride-containing products," he says.

However, the nature of her symptoms convinced Burress that it was a type one reaction, similar to the latex allergic response. Although sensitization to BAC is very infrequent, because of its common use, employee health professionals should be aware of its potential to cause allergy-mediated asthma among health care workers, he says.

Respiratory therapists at risk

Why are respiratory therapists at greater risk from occupational asthma? No one knows, but possible clues range from the aerosolized treatments to the exposure to infectious diseases.

Initially, epidemiologists wondered if people with asthma were simply more likely to choose respiratory therapy as a profession. "The studies that have been done have excluded that [as a cause of the high rates of occupational asthma]," says Petsonk. "In general, the majority had symptom onset that occurred while they were working, not before."

Respiratory therapists are exposed to a number of hazards, including sterilants used to sterilize the equipment, coughing patients, and the aerosolized treatments themselves. They should give the treatments while the patient sits in a protective booth, advises Petsonk. An emphasis on respiratory hygiene — placing a mask on a coughing patient, if possible — is also important, he says.

"The role of infectious agents like viruses in asthma is not well defined," he says. "But there is a suspicion that certain viruses can either stimulate people with asthma to get sicker or to cause damage to the airways that can cause asthma."

Much more needs to be learned about occupational asthma in health care. But an awareness of the possible asthma triggers can help health care workers avoid the hazards and provide valuable information to employee health professionals.

References

1. Pechter E, Davis LK, Tumpowsky C, et al. Work-related asthma among health care workers: Surveillance data from California, Massachusetts, Michigan, and New Jersey, 1993–1997. Am J Ind Med 2005; 47:265-275.

2. Rueff F, Schopf P, Putz K, and Przybilla B. Effect of reduced exposure on natural rubber latex sensitization in health care workers. Ann Allergy Asthma Immunol 2004; 92(5):530-537.