An international team led by researchers from the Barcelona Institute for Global Health (ISGlobal), a centre supported by the “la Caixa” Foundation, has provided new evidence about the role of occupational exposures as an important risk factor for chronic obstructive pulmonary disease (COPD). A study with more than 3,300 participants has linked exposure to biological dusts, gases, fumes and pesticides with a higher incidence of COPD.
The research was carried out within the European Community Respiratory Health Survey (ECRHS), a longitudinal multi-centre study. A total of 3,343 participants from 24 centres in 12 countries were selected between 1991 and 1993 and followed-up 20 years later. Spirometric lung function tests were performed after recruitment and at follow-up, while exposures in the workplace were estimated from the information obtained at interviews with participants in combination with an external job exposure matrix.
After assessing occupational exposure to 12 different agents, results showed that participants exposed to biological dust had a 60% higher risk of COPD compared with those unexposed. Participants exposed to gases and fumes had a 50% higher risk of COPD, while in the case of those exposed to pesticides the risk was a 120% higher.
However, the effect observed with pesticides was based on a small number of cases.
Overall, results showed that 21% of the in total 96 cases of COPD detected at follow-up were associated with these occupational exposures. “Previous studies had estimated that about 15% of COPD cases are attributable to workplace exposures. Our results strengthen this evidence base substantially,” says Jan-Paul Zock, ISGlobal researcher and lead author of the study. “To our knowledge, this is the first study to demonstrate an effect of biological dust exposure on the incidence of COPD in a prospective fashion in a general population cohort,” he adds.
One of the main questions that this study leaves open to future research is whether the observed effects are modified by smoking, since tobacco smoking is the primary risk factor for COPD. Other remaining questions for further research are how the observed effects interplay with asthma and what are the specific risks with respect to particular occupations, activities and noxious agents.
Background: Occupational exposures have been associated with an increased risk of COPD. However, few studies have related objectively assessed occupational exposures to prospectively assessed incidence of COPD, using postbronchodilator lung function tests. Our objective was to examine the effect of occupational exposures on COPD incidence in the European Community Respiratory Health Survey.
Methods: General population samples aged 20–44 were randomly selected in 1991–1993 and followed up 20 years later (2010–2012). Spirometry was performed at baseline and at follow-up, with incident COPD defined using a lower limit of normal criterion for postbronchodilator FEV1/FVC. Only participants without COPD and without current asthma at baseline were included. Coded job histories during follow-up were linked to a Job-Exposure Matrix, generating occupational exposure estimates to 12 categories of agents. Their association with COPD incidence was examined in log-binomial models fitted in a Bayesian framework.
Findings: 3343 participants fulfilled the inclusion criteria; 89 of them had COPD at follow-up (1.4 cases/1000 person-years). Participants exposed to biological dust had a higher incidence of COPD compared with those unexposed (relative risk (RR) 1.6, 95% CI 1.1 to 2.3), as did those exposed to gases and fumes (RR 1.5, 95% CI 1.0 to 2.2) and pesticides (RR 2.2, 95% CI 1.1 to 3.8). The combined population attributable fraction for these exposures was 21.0%.
Interpretation: These results substantially strengthen the evidence base for occupational exposures as an important risk factor for COPD.
Theodore Lytras, Manolis Kogevinas, Hans Kromhout, Anne-Elie Carsin, Josep M Antó, Hayat Bentouhami, Joost Weyler, Joachim Heinrich, Dennis Nowak, Isabel Urrutia, Jesús Martinez-Moratalla, José Antonio Gullón, Antonio Pereira-Vega, Chantal Raherison-Semjen, Isabelle Pin, Pascal Demoly, Bénédicte Leynaert, Simona Villani, Thorarinn Gislason, Cecilie Svanes, Mathias Holm, Bertil Forsberg, Dan Norbäck, Amar J Mehta, Nicole Probst-Hensch, Geza Benke, Rain Jogi, Kjell Torén, Torben Sigsgaard, Vivi Schlünssen, Mario Olivieri, Paul D Blanc, Roel Vermeulen, Judith Garcia-Aymerich, Deborah Jarvis, Jan-Paul Zock