MONDAY, Jan. 21 (HealthDay News) -- The type of jobs people have may increase their risk for developing asthma as an adult, a new British study suggests.

Rebecca Ghosh, of Imperial College London, and her colleagues found one in six cases of the condition was linked to the workplace. They noted the development of adult asthma was clearly associated with 18 different occupations, particularly cleaning jobs where people are exposed to chemicals. Other job categories linked to adult asthma were farming, hairdressing and printing.

The study involved 7,500 British adults born in 1958. The researchers examined information on the participants' job histories up to the age of 42. They also compiled information on their symptoms of asthma or wheezy bronchitis at the ages of 7, 11, 16, 33 and 42. The study participants' sensitivity to allergens and lung power was also assessed at the ages of 42 and 45.

Using the Asthma Specific Job Exposure Matrix, the researchers then calculated the participants' exposure to compounds with a known link to asthma, including respiratory irritants and high-risk agents such as flour, enzymes, cleaning or disinfectant products, metal and metal fumes, and textile production.

The study was published online Jan. 21 in the journal Thorax.

Of the study's participants, 25 percent were smokers by the time they were 42. At this age, 9 percent of the adults had asthma and 87 percent had jobs. More than half, or 55 percent, of those who were employed had office jobs.

The researchers also pointed out that 25 percent of the participants never held a job that increased their risk for asthma. The study did reveal, however, that 8 percent had been exposed to high-risk agents and 28 percent were exposed to low-risk agents. Meanwhile, 34 percent were exposed to both high-risk and low-risk agents.

After taking other factors into account, the investigators found 16 percent of adult-onset asthma cases among the participants could be explained by their jobs. While the study found an association, it did not prove that the nature of their occupations caused the onset of asthma.

The study showed those exposed to low-risk agents were 20 percent more likely to develop asthma as an adult. The people exposed to high-risk agents were 53 percent more likely to be diagnosed with the respiratory condition. The participants exposed to both types of agents had a 34 percent greater risk of developing asthma.

The findings suggest jobs involving cleaning or cleaning agents showed the strongest link to adult asthma. Meanwhile, farming more than quadrupled the risk for the condition, hairdressing doubled the risk and printing work tripled the risk, the study authors pointed out in a journal news release.

More information

The U.S. Centers for Disease Control and Prevention provides more information on the prevention of occupational asthma.