Joint association of cumulative workplace environmental exposures and shift work with long-term work-limiting health conditions: a prospective cohort study from the UK Biobank.

Background: Workplace environmental exposures (WEEs) and shift work are common occupational hazards, but their joint associations with working-age health and healthy working years are not well characterised. Methods: Data were from the UK Biobank. Lifetime WEEs (toxic substances, passive smoking, extreme temperatures, noise) and shift work (day, mixed or night shifts) were derived from complete job histories and classified as cumulative years (never, <10, >=10 years). 20 prevalent multisystem long-term work-limiting health conditions before age 70 were ascertained via linked health records. Survival analyses including Cox proportional hazards and accelerated failure time models were conducted. Results: Among 34 413 workers aged 38-54 years, half experienced WEEs or shift work. Over 13.9±1.0 years, WEEs and shift work were associated with all 20 conditions, and some associations were more pronounced or only significant in women. Specifically, workers exposed to both exposures for >=10 years (vs both never) had 154% higher risks of new-onset carpal tunnel syndrome, followed by chronic obstructive pulmonary disease, spondylopathy, diabetes and depression (increased risks: 124%-100%). They also lost 8.88 healthy working years due to incident carpal tunnel syndrome, followed by depression, spondylopathy, intervertebral disc diseases and psoriasis (years lost: 7.33-6.44). The joint impacts of multifaceted WEEs and shift work varied, but few multiplicative/additive interactions were observed. Conclusions: Co-occurrence of WEEs and shift work is associated with substantial excess risks of long-term work-limiting health conditions and loss of healthy working years. Strengthening control of WEEs and health surveillance for shift workers may be needed to protect working-age health and sustain productive employment.