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

doi:10.1136/bmj.b613

Published 24 March 2009, doi:10.1136/bmj.b613
Cite this as: BMJ 2009;338:b613

Research

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

K M Venables, reader in occupational medicine¹, C Brooks, data manager ¹, L Linsell, medical statistician¹, T J Keegan, research fellow¹, T Langdon, assistant data manager¹, T Fletcher, senior lecturer in environmental epidemiology², M J Nieuwenhuijsen, research professor in environmental epidemiology, visiting professor³^,4, N E S Maconochie, senior lecturer in epidemiology and medical statistics⁵, P Doyle, professor of epidemiology⁵, V Beral, professor and director ⁶, L M Carpenter, reader in statistical epidemiology¹

¹ Department of Public Health, University of Oxford, Oxford OX3 7LF, ² Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, ³ Centre for Research in Environmental Epidemiology, IMIM and CIBERESP, 08003 Barcelona, Spain, ⁴ Division of Epidemiology, Public Health and Primary Care, Imperial College, London, ⁵ Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, ⁶ Cancer Epidemiology Unit, University of Oxford, Oxford

Correspondence to: K M Venables kate.venables{at}dphpc.ox.ac.uk; L M Carpenter lucy.carpenter{at}dphpc.ox.ac.uk

Objective To investigate any long term effects on mortalityin participants in experimental research related to chemicalwarfare agents from 1941 to 1989.

Design Historical cohort study.

Data sources Archive of UK government research facility at PortonDown, UK military personnel records, and national death andcancer records.

Participants 18 276 male members of the UK armed forces whohad spent one or more short periods (median 4 days between firstand last test) at Porton Down and a comparison group of 17 600non-Porton Down veterans followed to 31 December 2004.

Main outcome measures Mortality rate ratio of Porton Down comparedwith non-Porton Down veterans and standardised mortality ratioof 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 Downveterans in year of enlistment (median 1951) but had longermilitary service (median 6.2 v 5.0 years). After a median follow-upof 43 years, 40% (7306) of Porton Down and 39% (6900) of non-PortonDown veterans had died. All cause mortality was slightly greaterin Porton Down veterans (rate ratio 1.06, 95% confidence interval1.03 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 deathsattributed to infectious and parasitic (1.57, 1.07 to 2.29),genitourinary (1.46, 1.04 to 2.04), circulatory (1.07, 1.01to 1.12), and external (non-medical) (1.17, 1.00 to 1.37) causesand decreased for deaths attributed to in situ, benign, andunspecified neoplasms (0.60, 0.37 to 0.99). There was no clearrelation between type of chemical exposure and cause specificmortality. The mortality in both groups of veterans was lowerthan that in the general population (standardised mortalityratio 0.88, 0.85 to 0.90; 0.82, 0.80 to 0.84).

Conclusions Mortality was slightly higher in Porton Down thannon-Porton Down veterans. With lack of information on otherimportant factors, such as smoking or service overseas, it isnot possible to attribute the small excess mortality to chemicalexposures at Porton Down.

© Venables et al 2009
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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