Past occupational dust exposure, depressive symptoms and anxiety in retired Chinese factory workers: the Guangzhou Biobank Cohort Study

Our plain-English summary of Past occupational dust exposure, depressive symptoms and anxiety in retired Chinese factory workers: the Guangzhou Biobank Cohort Study, by Q.H. Lin, C.Q. Jiang, T.H. Lam, et al (Journal of Occupational Health, 2014).

The study

• Authors: Q.H. Lin, C.Q. Jiang, T.H. Lam, L. Xu, Y.L. Jin, K.K. Cheng
• Journal: Journal of Occupational Health
• Published: 2014;56(6):444-52
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: Few studies have systematically investigated the impact of past occupational dust exposure on mental health. We examined whether retired factory workers exposed to any of the 4 dusts of silica, cement, coal and asbestos had more depressive symptoms and anxiety in southern China, which has experienced rapid economic development.

Methods: We used data from the Guangzhou Biobank Cohort Study phase 3. Exposures, lifestyle, symptoms and medical history of the participants were assessed with a structured interview. Self-reported intensity and duration of past occupational dust exposure were used to derive cumulative exposure. Outcome measures were assessed by the 15-item Chinese version of the Geriatric Depression Scale (score ≥5) and the single-item on anxiety.

Results: The results revealed that 359 workers were exposed to at least one of the 4 dusts and that 1,253 were unexposed (controls). After adjustment of multiple confounders, greater risks of depressive symptoms were associated with high exposure to silica (odds ratio (OR) of 3.12, 95% CI of 1.17-8.31) and asbestos (OR of 6.90; CI of 1.29-36.75). Risks of anxiety were higher in those with low or high exposures to dust (OR of 2.01 and CI of 1.04-3.87 and OR of 2.29 and CI of 1.30-4.03, respectively) and cement (OR of 3.20 and CI of 1.27-8.07 and OR of 2.30 and CI of 1.09-4.87, respectively), and those with high exposure to silica (OR of 5.29, CI of 1.76-15.92).

Conclusions: Past occupational exposures to silica, cement, coal and asbestos dusts were associated with adverse mental health outcomes in retired factory workers. The mechanism underlying the relationship between occupational exposures and psychological symptoms in later life needs to be further studied.

In plain English

This study used interview data from phase 3 of the Guangzhou Biobank Cohort Study in southern China, which the authors describe as a cross-sectional design. It compared 359 retired factory workers who said their longest-held job exposed them to silica, cement, coal or asbestos dust (32 of them to asbestos) with 1,253 workers who reported no exposure. Workers' own reports of exposure intensity and years were combined into low or high exposure. Depressive symptoms were measured with a 15-item scale and anxiety with a single question. After adjusting for other factors, high exposure was associated with depressive symptoms for silica (odds ratio 3.12, 95% CI 1.17 to 8.31) and asbestos (6.90, 1.29 to 36.75). The high-asbestos group had 23 workers, 5 of them with symptoms. Anxiety was associated with any dust, cement and high silica exposure. For high asbestos exposure, the anxiety odds ratio (4.52, 0.77 to 26.55) was not statistically significant. The authors concluded that past dust exposure was associated with these symptoms. They noted that the design could not establish cause, that exposure was self-reported, and that there was no psychiatric confirmation.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Cross-sectional analysis of interview data from a cohort study (Guangzhou Biobank Cohort Study, phase 3)
• Who was studied: 1,612 retired factory workers aged 50 or older from phase 3 (2006 to 2008) of the Guangzhou Biobank Cohort Study, Guangzhou, China. 359 reported exposure to at least one of the 4 dusts (89 silica, 155 cement, 83 coal, 32 asbestos) and 1,253 reported no exposure (controls).
• Exposure: Self-reported past occupational exposure to silica, cement, coal or asbestos dust in the longest-held job. Workers rated intensity (mild, moderate, heavy) and gave duration in years, which were combined into low or high cumulative exposure. No fiber type of asbestos was specified.
• Main results:
  • Depressive symptoms were present in 20.6% of the dust-exposed group and 14.8% of the unexposed group. Anxiety was present in 14.5% of the exposed group and 7.9% of the unexposed group.
  • In the highest exposure category, adjusted odds ratios for depressive symptoms were 3.12 (95% CI 1.17 to 8.31) for silica and 6.90 (1.29 to 36.75) for asbestos.
  • Of 23 workers with high asbestos exposure, 5 (21.7%) had depressive symptoms. The crude odds ratio was 1.60 (0.59 to 4.37) and the adjusted odds ratio was 6.90 (1.29 to 36.75). None of the 9 workers with low asbestos exposure had depressive symptoms.
  • For anxiety among workers with high asbestos exposure, the crude odds ratio was 3.24 (1.18 to 8.91) and the adjusted odds ratio was 4.52 (0.77 to 26.55). The adjusted odds ratio was not marked as statistically significant.
  • Anxiety risk was higher with low exposure to any of the 4 dusts (adjusted OR 2.01, CI 1.04 to 3.87) and with high exposure (OR 2.29, CI 1.30 to 4.03).
  • Anxiety risk was higher with high silica exposure (adjusted OR 5.29, CI 1.76 to 15.92).
• The authors' conclusion: The authors concluded that past workplace dust exposure was significantly associated with depressive symptoms and anxiety disorder in older retired Chinese factory workers. They said the mechanism is unclear and further studies are needed to clarify and confirm the results.
• Limitations the authors state:
  • The cross-sectional design could not establish the direction of causality.
  • The exposure classification was crude and self-reported, so random misclassification could have weakened the associations.
  • Workers with depression or anxiety might have reported their exposure differently.
  • The outcome measures were simple, with no psychiatric confirmation.
  • Case numbers were too small to examine specific dusts other than silica in never smokers.

Topics

Medical terms in this study, explained in our Lexicon: Cohort Study, Cumulative Exposure, Odds Ratio, Occupational Exposure.

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