Part III - Historical Survey of the Porton Down Service Volunteer ...

More documents

Recommendations

Info

8.4.5. Bronchial constriction. The study conducted in 1952 [51] to link ChE inhibition with vapour dose also looked at the effect of those doses on respiratory functions. Breathing rates, maximum breathing capacity and air velocity index (among others) were measured as indicators of bronchial constriction. But the report concluded that none of these functions showed any "marked and consistent variation" after GB vapour exposures of up to the equivalent of about 20 mg.min/m 3 were administered. These results were considered to be "somewhat vague" and so further work was conducted in 1953 to explore bronchial constriction [50]. Features of GB poisoning included impaired functioning of the muscles controlling breathing, a narrowing of the airways and an increase in the secretion of mucus into the airways. The last two effects obstruct the flow of air to the lungs (equivalent to increasing airway resistance) and can impede artificial respiration [50]. A single breath study was carried out in which 18 men breathed in doses between 0.78 and 2.87 µg/kg to establish if airway resistance was increased by low doses of GB vapour. The main conclusions were as follows: • 10 mg.min/m 3 produces a measurable increase in airway resistance; • with this exposure level, resistance was 3 to 4 times higher than normal in some men. But this increase did not cause any significant "respiratory embarrassment" (or breathing difficulty). This was because in healthy humans the respiratory reserve is large and substantial airflow resistance can be tolerated; • however, it might be inferred that with larger doses "other factors reducing available respiratory effort" would make airway resistance or bronchial constriction less tolerable. 8.4.6. Psychological effects of GB vapour The 1945 trial assessing the ability of infantrymen and Porton civilian staff to perform tasks after being exposed to GA suggested some impairment in function [18], but the results were uncertain because not much was known about the intelligence of the participants. Two studies were carried out in 1952 and 1953 each using tests to measure intellectual and visual performance, rate of learning and weariness/boredom. These tests were conducted by the participants before and after exposure to GB vapour. The intelligence of the men taking part was assessed before exposure. The first study [53] exposed 20 men to GB at 10 mg.min/m 3 (t = 2 mins), while 8 other men who performed the same tests underwent no exposure and served as a control group. The main results were as follows: • normal physiological symptoms (miosis, headache, tightness of chest) developed as expected. The men exposed to vapour felt lethargic and "couldn't be bothered", even though they were not feeling bored or resentful. No deterioration was observed in intelligence. Efficiency in visual tasks was impaired and learning was slower; • general anxiety dreams were reported by several men; • the average ChE inhibition induced by the dose of GB vapour was 31.4% but it was not possible to link personal ChE inhibition with scores obtained in the performance tests. The second study [54] followed similar lines. The GB exposure was higher, 14.7 mg.min/m 3 (t = 2 mins); 12 men experienced this exposure. A control group of 12 men was exposed to a tear gas (CN). Intelligence ratings of the men involved were obtained from the Services. The report concluded: 68
• even though the vapour exposure was higher, the men in this second study were less disturbed than those in the first. This was probably because the men in this study were "educationally and intellectually a cut above" those in the previous one; • the feeling of lassitude observed was again evident here. Again, there was no real change in intellectual ability; • a sharp depression in self-confidence was observed; • average ChE inhibition was 48%. As before, it was not possible to link personal inhibition with performance test scores. The conclusion drawn from these experiments was that GB vapour induced no psychological changes. Feelings of lassitude and loss of self-confidence might have an effect on military performance but, if these were expected, officers could act to mitigate their effects. 8.4.7. A GD demonstration As the raw material required to produce it was scarce, GD was not chosen for use in offensive weapons. A demonstration with GD vapour was performed in December 1951 but was reported only in 1961 [55]. By that time, interest in GD had revived partly because a more convenient way of producing it had been developed. It is not clear why the GD demonstration was carried out in December 1951, but it is recounted here for completeness. The demonstration was laid on for senior War Office officials and held at "Mytchett" [55], presumably in Surrey close to Farnborough. Six volunteers took part in the demonstration; they were exposed to GD at Porton and later driven to Mytchett. All were exposed to GD at 5.5 mg.min/m 3 (t = 1 min 40 seconds): three wearing oro-nasal respirators and three with no protection. The L(Ct)50 of GD vapour for man had been estimated in 1949 to be 180-270 mg.min/m 3 [24]. The symptoms suffered were much more severe than had been imagined from a dose that was expected to inhibit ChE by 50%. One man collapsed. The maximum ChE depressions observed in the unprotected men, in each case one day after exposure, were 62, 41 and 74%. 8.4.8. Respirator and protective clothing tests In August and September 1948, and February and March 1949, human studies were conducted with GA and GB to assess the efficacy of existing equipment [16]. Various US and British respirators were tested and respirator face-pieces with spectacles were also evaluated [16]. American and British respirators were tested by fully protected men in experiments in December 1950 and January 1951. GA vapour was used in these tests [48]. Other work from October 1948 to 1949 examined whether GA and GB vapour remained in clothing and thereby posed a hazard. In these experiments clothing was hung up in the chamber and exposed to vapour, then stored in a "cold bin" for some time. Men would then wear the clothing in the open air or indoors and their symptoms would be recorded [16]. 8.5 Human studies with liquid nerve agents 8.5.1 LD50 estimations for liquid nerve agent on bare skin Human studies with liquid nerve agents were conducted from 1951 to 1953. The delay in starting these studies was due to the fact that work with animals to estimate the lethal dose in man had taken some time to complete. Animal studies were conducted with liquid nerve agents from 1945 [10]. Initially, the work used animals whose fur was clipped closely to their skin. Liquid nerve agent was then placed on the clipped fur. By December 1946 this work 69
Page 1 and 2: Part III. Human studies with nerve
Page 3 and 4: 8.1. Discovery of the "Ideal War Ga
Page 5 and 6: Bren gun), map reading and visual i
Page 7 and 8: Fifteen of the sixteen men were exp
Page 9 and 10: the nature of the smell differed fr
Page 11: Scientists hoped that, from these s
Page 15 and 16: G Agent Bare skin Clothed skin GB 4
Page 17 and 18: lood supply. Nine of the 14 men who
Page 19 and 20: • After the incident the man's su
Page 21 and 22: 9.1 Adrian Committee Chapter 9. G A
Page 23 and 24: Service volunteers took part in stu
Page 25 and 26: Animal work in 1958 suggested that
Page 27 and 28: induced by the inhibition of ChE in
Page 29 and 30: • the GB dose to halve the pupil
Page 31 and 32: GB exposure (mg.min/m 3 ) Number of
Page 33 and 34: Animal work continued at Porton. In
Page 35 and 36: ing which is attached to the lens o
Page 37 and 38: • "the main problems, as far as v
Page 39 and 40: 10.1. Background 10.1.1. The nature
Page 41 and 42: Porton Medical Officers Service Vol
Page 43 and 44: The second study with volunteer med
Page 45 and 46: Condition Respiratory protection? L
Page 47 and 48: References Chapter 8 1. WO32/21200
Page 49 and 50: 43. COSHE 17 th meet 24 Sep 65. [C]
Page 51 and 52: 21. TG1009 Policy regarding tests o

Part III - Historical Survey of the Porton Down Service Volunteer ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?