Non-malignant kidney diseases in Danish firefighters

Objectives Firefighters face a range of hazards, including strenuous tasks in high-temperature environments and exposure to chemicals. These hazards may increase the risk of kidney diseases. However, limited evidence supports this hypothesis within this occupational group. Hence, this study aimed to assess the relationship between firefighting and kidney diseases. Methods A cohort comprising 10 094 male Danish firefighters was analysed, including 3455 full-time and 6639 part-time/volunteer firefighters. Diagnoses of kidney disease from 1994 to 2014 were retrieved from the Danish National Patient Registry. Morbidity among firefighters was compared with that of a sample of the male working population, and standardised incidence ratios (SIR) were used to estimate relative risks. Results The results indicated a positive association between full-time firefighting and urolithiasis (SIR 1.36; 95% CI 1.13 to 1.63). Shorter employment (<5 years) was associated with a higher risk of glomerulonephritis and chronic kidney disease, whereas longer employment (≥5 years) was linked to lower risks for most outcomes, except for urolithiasis, which remained elevated regardless of employment duration. Full-time specialised smoke divers were indicated to have a higher risk of glomerulonephritis, renal failure and chronic kidney disease. Urolithiasis risk was associated with an elevated risk in both regular and specialised full-time firefighters. Risk estimates for the assessed kidney diseases among part-time/volunteer firefighters generally reflected a lower risk. Conclusions This study provides evidence for elevated risks of certain kidney diseases in full-time firefighters, especially urolithiasis. Awareness of sufficient hydration in relation to extreme heat exposures may be particularly important among firefighters.