Honest science or propaganda?
Epidemiology began with a fellow called John Snow investigating to
find the cause of a cholera epidemic in London in the 19th Century. He had
the idea that it might be coming from contamination in a water well.
So he took a map showing the locations of wells and plotted the incidence
the disease on the map. Sure enough they were mostly in close proximity to
one particular well. He had the well put out of service and there were no
more new cases of cholera. That is a simple story of logic and surveying
intelligently applied to test a theory.
It is very unfortunate that it was so simple to solve. He might then
have left a better example for his followers.
What if he had found that the 166* total cholera cases were scattered
over the map pretty evenly but that they all had pink carnations on their
coats? One hundred thousand people wore pink carnations and 99,874 did not
What does he do now? Well if he were a tobacco investigator he would
government to do something about pink carnations. But let's say he is a
He decides to go and interview the cholera cases in more depth.
He asks them all kinds of questions about themselves and about pink
carnations - how many years have they been wearing them? How old were they
when they started? etc. etc. He gathers all the data and looks for
similarities. He gets a few things and tabulates them. He then interviews
other people who don't have cholera but who do have pink carnations. He
all the same questions again and tries to find something about pink
carnations that is consistent among those who don't have cholera and is
absent from those who do, or vice versa.
He finds one item in common. The cholera sufferers all work in
the City though they live all over London. There are lots of carnation
the other group who also work in the City and don't have cholera. So he
knows that working in the City isn't the cause either so he correctly
correlation just like pink carnations. But he now has two correlating
of data and a line of enquiry worth following.
He now goes back to the cholera group and asks a single new question.
can you tell me about working in the City and wearing pink carnations?"
tell him it is the thing to do. They tell him all the ladies like it. They
tell him their bosses like it. They tell him they buy them from a vendor
right next to St Paul's Cathedral. etc. He notes their responses and
tabulates them again. He asks the same thing of the non cholera group that
also works in the City. They give him lots of very similar answers but on
where they buy them from the answers vary and none of them are anywhere
St Paul's Cathedral. So he now has a third correlation and this one is far
more promising as it is entirely absent from the non cholera group. He
knows it isn't the cause itself because lots of people who go to St Pauls
don't also get cholera but in combination with pink carnations he knows it
is a significant correlation.
He gets the vendor to close down for a few weeks to see if it makes a
difference to the number of new cholera cases. There are no new cases
after 10 weeks where formally there had been several new cases each week.
This is progress he thinks. He
could stop right here, have the vendor permanently closed down and that
might be enough to prevent further cases. But as he still doesn't
understand how pink carnations and a vendor near St Pauls can be the cause
of a cholera epidemic he continues to investigate.
He sets up a watching station opposite the vendor and sits there for
watching him ply his trade. He notices one thing that seems to offer a
really plausible cause covering all the factors he has so far noted. A
woman empties a huge chamber pot into a hole immediately behind the boxes
of pink carnations. The scientist walks over and sees that some of the
former contents of the woman's chamber pot have spilt into the boxes
holding the carnations. He finds they contain the feces of several cholera
victims the woman tends to.
It wasn't as easy a case to crack but it does illustrate
what a scientist dedicated to truth and who won't compromise with logic
In the case of smoking research I would say that back when the
study of 1956 was done an honest and worthwhile conclusion
We now know that most cases of lung cancer occur in
smokers of a certain amount of tobacco after a long period of time in a
very small number of cases relative to the number of smokers who smoke
that amount for that long. Tobacco smoking isn't the cause of lung cancers
but it is connected in
some way that we don't yet understand. We can predict that many more
smokers will get lung cancer than will non smokers. Something like 24
as many. But we must also say again that
there are far
more smokers than there will ever be cases of lung cancer. This in itself
makes it obvious that something else is involved.
Further because we can predict that a very small fraction of all
account for the majority of lung cancer
victims, and that because we don't know why this is so, we must
smokers of this increase in risk. We must also inform smokers that the
risk, whilst small compared to all smokers, is of a grave disease that is
likely to be very painful and also fatal. Obviously smokers themselves
to decide if they want to cut down or quit smoking altogether because, as
a scientist, our job is to research and discover threats to life but that
it is the individual's responsibility to act on that information as he
We now have something new to discover. Most cases of lung cancer
occur in a small number of smokers, but if smoking were the cause of those
cases then what is preventing it in so many more cases? If smoking is not
the cause of lung cancer then what factor is present in those smokers who
do get it but which is not present in those who don't?
That to me would have been a logical, decent and honest approach. It
may not have been so easy to understand as "Smoking causes lung cancer"
but it would have been a whole lot more honest and the consequences of
that could have changed subsequent history in many dramatic ways, and
might have led some curious researchers into the field who would have
known that there were still very significant questions to get answered,
and they may have been capable of getting those answers by now.
Instead they told the government that tobacco was causing lung cancer
and demanded that something be done about
tobacco! Wrong target and thoroughly irresponsible as scientists in my
opinion. That was a
defining moment in the history of tobacco and it has been in decline ever
since. Unfortunately so has epidemiology.
* Don't know what the actual number was. This was to make it closer
Hill/Doll found with regard to lung cancer and smokers. 166 out of 100,000
after decades of 25 grams per day..
Copyright 2003 by Bernie Greene. All Rights Reserved
I once worked for a tobacconist shop. I am also a pipe smoker. I'm not a scientist and I could be wrong. I would appreciate being shown where with logical rather than ad hominem argument.
Competing interests: No competing interests