Mortality in British military participants in human experimental research into chemical warfare agents at Porton Down: cohort study

A 39 Year mortality study of survivors exposed to sulfur mustard agent: A survival analysis

Background

The primary objective of this study was to analyze the long-term survival of 48,067 chemical warfare survivors who suffered from pulmonary, cutaneous, and ocular lesions in the decades following the Iran-Iraq war.

Methods

The data for this study were obtained from the Veterans and Martyr Affair Foundation (VMAF) database. The survivors were divided into two groups based on whether they were evacuated/admitted (EA) to a hospital or not evacuated/admitted (NEA) to a hospital. The proportional hazard (PH) assumption for age categories, gender, exposure statuses, and eye severity was not satisfied. Therefore, we used a Generalized Gamma (GG) distribution with an Accelerated Failure Time (AFT) model for analysis.

Results

The study included a total of 48,067 observations, and among them, 4342 (9.03 %) died during the study period. The mean (SD) age of the survivors was 55.99 (7.9) years. The mortality rate increased with age, and higher rates were observed in males. Survival probabilities differed significantly among age categories, provinces, lung severity, and eye severity based on log-rank tests (p-value<0.05 for all). The GG model results showed that higher age and being male were associated with a shorter time to death. The study also found that the mortality rate was significantly higher in the EA group compared to the NEA group.

Conclusion

The present study showed no significant difference in survival time between the EA and NEA groups. The findings suggest that pulmonary lesions caused by mustard gas are more likely to be fatal compared to skin and eye lesions. The results also indicate a potential association between survival time and the severity of lung damage.

Cancer morbidity in British military veterans included in chemical warfare agent experiments at Porton Down: cohort study

OBJECTIVE

To determine cancer morbidity in members of the armed forces who took part in tests of chemical warfare agents from 1941 to 1989.

DESIGN

Historical cohort study, with cohort members followed up to December 2004.

DATA SOURCE

Archive of UK government research facility at Porton Down, UK military personnel records, and national death and cancer records.

PARTICIPANTS

All veterans included in the cohort study of mortality, excluding those known to have died or been lost to follow-up before 1 January 1971 when the UK cancer registration system commenced: 17,013 male members of the UK armed forces who took part in tests (Porton Down veterans) and a similar group of 16,520 men who did not (non-Porton Down veterans).

MAIN OUTCOME MEASURES

Cancer morbidity in each group of veterans; rate ratios, with 95% confidence intervals, adjusted for age group and calendar period.

RESULTS

3457 cancers were reported in the Porton Down veterans compared with 3380 cancers in the non-Porton Down veterans. While overall cancer morbidity was the same in both groups (rate ratio 1.00, 95% confidence interval 0.95 to 1.05), Porton Down veterans had higher rates of ill defined malignant neoplasms (1.12, 1.02 to 1.22), in situ neoplasms (1.45, 1.06 to 2.00), and those of uncertain or unknown behaviour (1.32, 1.01 to 1.73).

CONCLUSION

Overall cancer morbidity in Porton Down veterans was no different from that in non-Porton Down veterans.