Epidemiological principles for EMF and EMR studies - Lincoln ...

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a cotton mill were chronically exposed to dust and fibre and showed elevated rates
of respiratory disease. The disease rates were consistently elevated about three
times higher than average, but never significantly. The evidence was strong
enough that it was concluded that it was a causal effect because "The evidence
was so clear cut", Hill (1965). Sir Austin addresses the question of statistical
significance in the assessment of a causal relationship. He states in relation to the
question of causation:
“No formal tests of significance can answer these questions. Such tests can, and
should, remind us of the effects that the play of chance can create, and they will
instruct us in the likely magnitude of those effects. Beyond that they contribute
nothing to the ‘proof’ of the hypothesis.”
Again, modern epidemiology often uses the term “criteria” for the Bradford Hill
viewpoints. This is treating this approach as a sine qua non, directly contrary to Sir
Austin’s strong statement. I believe that this is placing the public and workers at
much higher risk levels by significantly raising the level of evidence thresholds for
deciding about causal effects. This results in setting public health protection
standards that allow exposures at levels that are extremely significantly higher than
those which have been shown to cause serious health effects found from multiple
independent epidemiological studies.
Third Epidemiological Principle:
Association to Causation - the Bradford Hill Approach:
To deal with the question of whether there is a causal relationship Sir Austin gives
us “Here then are nine different viewpoints from all of which we should study
association before we cry causation. What I do not believe - and this has been
suggested - is that we can usefully lay down some hard-and-fast rules of evidence
that must be obeyed before we accept cause-and-effect. None of my nine
viewpoints can bring indisputable evidence for or against the cause-and-effect
hypothesis and none can be required as a sine qua non [essential requirement].
What they can do, with greater or less strength, is help us to make up our minds on
the fundamental question – it is to any other way of explaining the set of facts
before us, is there any other answer equally or more likely, than cause and effect?”
Sir Austin Bradford Hill provides a well-established and very sensible health
protection approach to the assessment of the available evidence of association to
causation of human exposure to a disease agent and illness. Sir Austin’s approach
has commonly been applied to the assessment of the effects of chemicals.
Sir Austin Bradford Hill set out his nine viewpoints as (1) Strength; (2)
Consistency; (3) Specificity; (4) Temporality; (5) Biological Gradient; (6)
Plausibility; (7) Coherence; (8) Experiment and (9) Analogy, Hill (1965).
Sir Austin discusses each of his viewpoints and gives examples to clarify the
context of how the assessment was being considered. Only one, temporality, is
essential because the exposure must take place before it can be associated with