Standardised mortality ratios in people exposed to sulphur mustard during the Iran-Iraq war: a retrospective study with 39-year follow-up.

Objectives: Sulphur mustard (SM) is a chemical weapon agent that was extensively used by Iraqi troops during the Iran-Iraq war (1980-1988), resulting in exposure among Iranian military personnel and civilians. However, there is limited and conflicting information about the long-term mortality effects of SM exposure. This study aimed to determine the standardised mortality ratios (SMRs) in individuals exposed to SM gas during the Iran-Iraq war.
Study Design: This was a retrospective follow-up study.
Methods: Data were obtained from the Veterans and Martyr Affair Foundation of Iran (VMAF) regarding all confirmed individuals who were exposed to SM during the Iran-Iraq war (1980-1988) up to 30 March 2019. The mortality rate, cumulative mortality and SMR with 95 % confidence intervals (CIs) were calculated to assess mortality in chemical warfare survivors (CWS), and results were compared with the general Iranian population. Overall survival was analysed using the Kaplan-Meier curve, and the log-rank test was employed to compare survival probability across different categories.
Results: Among the 48,067 confirmed CWS, a total of 4358 (9.1 %) individuals had died by the end of the study period (30 March 2019), with a mean age of 55.5 ± 14.4 years at the time of death. Overall, at the 39-year follow-up, the mortality rate due to all causes of death for people who were exposed to SM was lower than the general Iranian population (SMR: 0.70, 95 % CI: 0.68-0.72). However, cause-specific SMR analysis showed that the mortality rate due to liver cancer (SMR: 1.98, 95 % CI: 1.59-2.45), poisonings (SMR: 1.92, 95 % CI: 1.52-2.38), respiratory disorders (SMR: 1.59, 95 % CI: 1.46-1.73) and multiple myeloma (SMR: 1.72, 95 % CI: 1.06-2.62) were approximately twofold higher in CWS than the general population.
Conclusions: This study provides valuable insights into the mortality effects of SM exposure among the Iranian population affected by the Iran-Iraq war. The results emphasise the importance of continued monitoring and support for individuals exposed to SM, particularly in the context of managing and addressing the heightened risks associated with liver cancer, poisonings, respiratory disorders and multiple myeloma. Further research and interventions may be necessary to mitigate these specific health challenges in the affected population.
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