Exposures Recorded for Participants in the UK Chemical Warfare Agent Human Research Programme, 1941–1989

Sarin exposure, mortality and cancer incidence in UK military veterans involved in human experiments at Porton Down: 52-year follow-up

OBJECTIVES

We investigated whether UK military personnel exposed to sarin during the 'Service Volunteer Programme' at Porton Down had increased rates of mortality or cancer incidence over a 52-year follow-up.

METHODS

A historical cohort study assembled from UK military records, comprising male veterans exposed to sarin during the 'Service Volunteer Programme' at Porton Down, UK (n=2975) and a comparison group of similar veterans who did not attend (n=2919). Mortality and cancer incidence data were obtained from national registries up to December 2019. Analysis was conducted using Cox regression adjusted for age, year of birth and service characteristics.

RESULTS

Over a median follow-up of 52.2 years (range 2 days to 74.6 years), 1598 (53.7%) sarin-exposed veterans and 1583 (54.3%) non-exposed veterans died. Adjusted HRs for all-cause mortality were raised for any sarin exposure (HR=1.08, 95% CI 1.01 to 1.16), two or more exposures (HR=1.25, 95% CI 1.04 to 1.49) and higher doses (air >15 mg.min/m3) (HR=1.15, 95% CI 1.02 to 1.30). For cause-specific mortality, sarin exposure was associated with deaths from 'other' circulatory diseases (excludes ischaemic and cerebrovascular diseases) (HR=1.41, 95% CI 1.06 to 1.87) and alcohol-attributable deaths (HR=2.66, 95% CI 1.40 to 5.07). There was no association between sarin exposure and overall cancer incidence (HR=1.01, 95% CI 0.93 to 1.10), but cancer incidence was higher for alcohol-related neoplasms (HR=1.24, 95% CI 1.01 to 1.51).

CONCLUSIONS

Sarin exposure was associated with increased rates of mortality over a 50-year follow-up. The strongest associations were observed for deaths attributable to alcohol and 'other' circulatory diseases.

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.

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

OBJECTIVE

To investigate any long term effects on mortality in participants in experimental research related to chemical warfare agents from 1941 to 1989.

DESIGN

Historical cohort study. Data sources Archive of UK government research facility at Porton Down, UK military personnel records, and national death and cancer records. Participants 18,276 male members of the UK armed forces who had spent one or more short periods (median 4 days between first and last test) at Porton Down and a comparison group of 17,600 non-Porton Down veterans followed to 31 December 2004.

MAIN OUTCOME MEASURES

Mortality rate ratio of Porton Down compared with non-Porton Down veterans and standardised mortality ratio of each veteran group compared with the general population. Both ratios adjusted for age group and calendar period.

RESULTS

Porton Down veterans were similar to non-Porton Down veterans in year of enlistment (median 1951) but had longer military service (median 6.2 v 5.0 years). After a median follow-up of 43 years, 40% (7306) of Porton Down and 39% (6900) of non-Porton Down veterans had died. All cause mortality was slightly greater in Porton Down veterans (rate ratio 1.06, 95% confidence interval 1.03 to 1.10, P<0.001), more so for deaths outside the UK (1.26, 1.09 to 1.46). Of 12 cause specific groups examined, rate ratios in Porton Down veterans were increased for deaths attributed to infectious and parasitic (1.57, 1.07 to 2.29), genitourinary (1.46, 1.04 to 2.04), circulatory (1.07, 1.01 to 1.12), and external (non-medical) (1.17, 1.00 to 1.37) causes and decreased for deaths attributed to in situ, benign, and unspecified neoplasms (0.60, 0.37 to 0.99). There was no clear relation between type of chemical exposure and cause specific mortality. The mortality in both groups of veterans was lower than that in the general population (standardised mortality ratio 0.88, 0.85 to 0.90; 0.82, 0.80 to 0.84).

CONCLUSIONS

Mortality was slightly higher in Porton Down than non-Porton Down veterans. With lack of information on other important factors, such as smoking or service overseas, it is not possible to attribute the small excess mortality to chemical exposures at Porton Down.