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

• one man had 5 of 17 pairs with jitter readings over 55 µs three days after and 8 of
17 pairs in that range four months later.
The report went on to note that a previous study, in which volunteers were exposed to GB at
5 mg.min/m 3 while testing nerve agent treatment, had resulted in abnormal SFEMG readings
three days after exposure [121].
Two points might be made here:
• First, the report of the SFEMG readings published in 1985 was a preliminary
interpretation which contained some flaws. The analysis and conclusions of the
completed study were published in the open press in 1996 [122].
• Second, SFEMG seems to have been an instance where measurement
technique outstripped medical knowledge. SFEMG was extremely sensitive, so it
was difficult to understand what the measurements meant [120]. No
neuromuscular abnormality was detected in the clinical examination conducted
on the volunteers after the experiments and before they left Porton.
Notwithstanding the second point, the volunteers involved in the study were asked to return
for further examinations and specialist opinion was sought. In the interim, all exposures of
volunteers to 15 mg.min/m 3 were prohibited in September 1984 [123]. Specialist opinion was
sought from the Royal Free Hospital and National Hospitals. London Hospital agreed [124]
the SFEMG findings at Porton seemed abnormal but, because of the sensitivity of the
technique, the practical significance of the findings was open to question.
This advice was received in 1985. All human studies with GB were suspended until the
significance of the SFEMG changes was clarified [126]. The volunteers returned, when it was
convenient to them and their units, for further SFEMG studies during 1985 and 1986.
SFEMG studies were conducted at London Hospital and the volunteers also had eye
movements checked at Queen's Square and retinal function examined at Moorfields Eye
Hospital [127].
By November 1986 SFEMG examinations had been completed and the changes observed
after the exposure at Porton in 1984 were not apparent. It was concluded that any effect GB
might have on neuromuscular transmission was reversible [121, 128]. The MC concluded in
February 1987 [129] that this result posed no bar to continuing low dose GB exposures at
5 mg.min/m 3 .
The Medical Committee decided in March 1987 that SFEMG would be used as a screening
procedure for future experiments with GB [130] and, from then on, a careful watch seems to
have been maintained on SFEMG readings. Apparently abnormal SFEMG readings were
observed after exposures in 1988 and reviewed by the committee in November [131], but,
because the readings "were essentially no different to those seen previously", it was decided
that experiments could continue.
9.6.5. Electroencephalography (EEG)
A report in 1987 reviewed the toxicology of GB and GD [132]. The review was conducted by
surveying Porton documents and external reports. The points made were as follows:
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• from the survey, it was evident that GB and GD can produce both short-term and
long-term effects at sub-lethal doses;
• most of the information on symptoms following exposure to anti-ChE compounds
comes from literature on poisoning due to OP insecticides. In the early work at
Porton into the effect of nerve agents on man, the "emphasis was on generalised
symptoms immediately following exposure, with no follow-up investigation of
persistent clinical signs (including psychological effects)";