Long term mortality and morbidity of Italian soldiers after deployment in Iraq as related to biomarkers assessment: Results of the SIGNUM study.

INTRODUCTION: The health profile of military veterans deployed in foreign operative theatres was assessed by several international studies because of potential exposure to depleted uranium and other pollutants. Here we reported results of 15-year epidemiological surveillance assessing long-term health effects in a cohort of Italian soldiers deployed in Iraq in 2004-2005 and participating in a biomonitoring campaign to identify potential genotoxic exposure to environmental xenobiotics before and after deployment (n = 981, SIGNUM cohort). METHODS: We evaluated mortality and hospitalization risks of the SIGNUM cohort retrospectively until 2016 and 2018 respectively. A wide cohort of military personnel never deployed abroad (n = 114,260) and the general Italian population were used as control populations in risk assessment. Causes of death and diagnoses of hospitalization were derived through deterministic record linkage with official national databases of mortality and hospital discharge. Standardized Mortality Ratio (SMR) and Standardized Hospitalization Ratio (SHR) were computed adjusting according to sex, age, area of birth, and calendar year. Differential pre-post deployment in xenobiotics concentrations and early effect biomarkers (oxidative DNA alterations and micronuclei) measured in blood serum were analysed in relation to cancer hospitalization. RESULTS: Mortality risk due to pathologies was more than halved compared to the general population (SMR = 0.41, 95% CI 0.11-1.05) and not significantly different compared to soldiers never deployed abroad (SMR = 0.69, 95% CI 0.19-1.68). Similarly overall hospitalization risk due to pathologies was decreased with respect to the general population (SHR = 0.86, 95% CI 0.80-0.92) and comparable to the control military group (SHR = 0.99, 95% CI: 0.93-1.06). For haematological cancers a decreased hospitalization risk compared to the Italian general population was observed (SHR = 0.38, 95% CI 0-0.92). No statistically significant differences emerged in the patterns of biomarkers in association with cancer hospitalization. CONCLUSION: The study confirms the so called 'healthy warrior' effect for the SIGNUM veterans and showed no correlation between cancer occurrence and biomonitoring markers measured on field.