Adult occupational exposure more likely in those with better early lung function
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Key takeaways:
- Adolescents with better lung function had greater odds for exposure to dust and smoke at work.
- These children also worked at dust exposed jobs for longer periods of time.
As measures of adolescent lung function increased, so did the likelihood for occupational exposure as an adult, according to results published in Annals of the American Thoracic Society.
“We know that adults with significant lung disease tend to either avoid jobs with adverse exposures or prematurely leave them — sometimes termed the ‘healthy worker effect’ in epidemiology,” Philip Harber, MD, MPH, professor in the community, environment and policy division at The University of Arizona Mel & Enid Zuckerman College of Public Health, told Healio. “While one might expect that children with severe problems, such as poorly controlled asthma, later avoid heavily exposed jobs, we found this effect across a range of lung function in childhood (ie, even more mild abnormalities matter).”
Using the Tucson Children’s Respiratory Study, Harber and colleagues analyzed 392 individuals (53.8% women) born between 1980 and 1984 to see how lung function at 11 years old is related to various workplace exposures in the first job.
Adolescent lung function was evaluated through various measures including percent predicted FEV1, FVC, FEV1:FVC ratio and forced expiratory flow (FEF) from 25% to 75% of vital capacity. To capture workplace dust, smoke and fumes/gas exposure, researchers interviewed individuals at 26 years old. Researchers then assessed both factors together through logistic regression.
Exposure, lung function
Of the total cohort, the most common exposure was dust (51.3%), followed by fumes/gas (24.2%) and smoke (19.6%).
At an individual’s initial job, elevated exposure to dust was related to higher measures of adolescent percentage predicted prebronchodilator FEV1:FVC ratio. Researchers found that individuals had a 30% greater chance for this type of exposure with every 10% rise in percentage predicted FEV1:FVC ratio (OR for 1% increase = 1.03; 95% CI, 1-1.06).
Heightened occupational exposure to smoke was also linked to higher lung function, specifically FVC before bronchodilator (OR for 1% increase = 1.01; 95% CI, 1.01-1.05) and FVC after bronchodilator (OR for 1% increase = 1.03; 95% CI, 1.01-1.05).
After bronchodilator, an adolescent FVC of 80% predicted was related to a 10% predicted chance of exposure to smoke, whereas an adolescent FVC of 110% predicted was linked to a 19% predicted exposure probability, according to researchers.
Of the total cohort, 70 adolescents had asthma when their lung function was measured, so researchers conducted another analysis without them and found comparable results to the main analysis. Further, several covariates had no link to occupational exposures: maternal education, regular maternal smoking, maternal age, Hispanic ethnicity and smoking at 22 years old.
First job length
“Having lower lung function in childhood has two distinct types of effects: 1) less likelihood of selecting an additional job with adverse exposures; 2) less likely to remain in a dust exposed job for at least 12 months,” Harber told Healio.
When evaluating the duration of the first job, more individuals kept this job for 12 months or longer than those who left during the first 12 months (81.4% vs. 18.6%).
“Many cross-sectional studies of workers in a particular job may underestimate the impact of exposures because persons who have respiratory disorders are less likely to be hired or to remain in the job and would therefore be missed in such cross-sectional studies,” Harber told Healio. “Comparing the results for initial hire and those still present 1 year later shows the importance of both the healthy hire and healthy survivor components of the ‘healthy worker effect.’”
Researchers found that working in a job with dust exposure for more than 1 year was related to increased adolescent lung function measures prebronchodilator (FEV1, P = .003; FVC, P = .01) and after bronchodilator (FEV1, P < .001; FVC, P = .018; FEV1:FVC ratio, P = .031; FEF 25-75, P = .016). This finding indicates that if the initial job had dust, children who possessed greater lung function would have a higher likelihood of working in that job for more than 1 year, but this does not mean that they choose jobs with bad air, Harber told Healio.
“Those with suboptimal lung function avoid such jobs,” he said. “Hence, children with better lung function are later overrepresented proportionally. I do not believe this occurs simply because someone with lower lung function as a child may be more likely to have lower lung function later in life. Rather, I strongly suspect there is probably a more direct link, perhaps by setting expectations in the transition from adolescence to adulthood.”
Similar relationships between lung function and dust exposure were also found when looking only at individuals who worked at their first job for 12 months or longer, specifically for measures of FEV1 and FEV1:FVC ratio before and after bronchodilator, according to researchers.
Based on this analysis, researchers noted that length of time at the first job modifies the link between lung function and job exposure.
Importantly, in both good and poor lung function quartiles, adolescent lung function was related to adulthood exposure at work, according to researchers.
Implications
“This further underscores the importance of preventing and treating respiratory disorders in children,” Harber told Healio. “While clinicians and employers should avoid discriminating in employment recommendations for persons with mild lung function variations, clinicians may wish to emphasize the use of careful work practices, respirators, etc, for persons with mild respiratory conditions. This is analogous to emphasizing smoking avoidance in such individuals.
“Clinicians should consider the interaction of pulmonary conditions and workplace conditions,” he added. “A few simple questions about work conditions in patient encounters can be remarkably beneficial.”
Future studies are needed to assess outcomes that happen over longer periods of time, Harber told Healio.
“Full lifecycle studies are needed to appreciate long-term consequences both on traditional measures such as COPD or spirometry, but also on occupational opportunities,” Harber told Healio. “Since the first job is/may often set the pattern for future employment, the consequences may be lifelong. Further, do members of vulnerable populations such as poor and marginalized populations have less opportunity to modify their job selection than others? While we statistically adjusted for some social factors, much more insight is needed here.”
For more information:
Philip Harber, MD, MPH, can be reached at pharber@arizona.edu.