- A leading American scientist says he
believes pesticides may be a far more serious public health threat than
anyone has realised.
- Nicholas Ashford, Professor of Technology
and Policy at Massachusetts Institute of Technology, says he thinks chemicals
are the most serious environmental problem facing industrialised countries
- Professor Ashford - who is also an advisor
to the United Nations Environment Programme - is known for his work on
the theory of multiple chemical sensitivity (MCS).
- The theory suggests people can become
sensitised by exposure to one form of contamination so that they are then
liable to be affected by a whole range of other pollutants, including detergents,
traffic fumes and tobacco smoke.
- There is no known cure for MCS.
- Evidence in the UK
- It may sound a far-fetched theory. But
the experience of many British sheep farmers gives it credence.
- Hundreds of them have become ill after
dipping their animals in organophosphate (OP) sheep dips. The symptoms
range from the fairly mild sneezing and runny eyes of 'dipping 'flu' to
muscle spasms, insomnia and overpowering fatigue. Some farmers say they
have been driven to the brink of suicide.
- OPs are highly toxic, derived from the
same group of chemicals that the Nazis used in World War Two to manufacture
nerve gases. Crucially, many farmers report that after exposure to OPs,
they find that their symptoms can then be triggered off by exposure to
a range of other chemicals.
- And Professor Ashford thinks that OPs
may be one of the most common initiators of MCS.
- Patients become sensitised
- OPs are not used exclusively in sheep
dips. They are also used for fumigating public transport vehicles, in shampoos,
and in flea collars. So they are widely available.
- The other chemical which Professor Ashford
believes may be a principal cause of MCS is a compound called permethrin,
which is used as a woodworm treatment. It is sprayed in about 5,000 British
homes every week.
- He and his colleagues have found that
some patients, once sensitised by exposure to a chemical, react to subsequent
levels of exposure so low that the techniques available in most laboratories
cannot detect them at all.
- Doctors baffled
- And the baffled doctors, he says, unable
to find a clear cause for the problem, tend to assume that it is all in
- Professor Ashford believes the huge rise
in pesticide use over the last half century could explain many illnesses,
ranging from skin rashes and breathing problems to cancers and birth defects.
- Other research in the United States suggests
that about one-third of the population -- sixty million people -- may be
affected in some way.
- Professor Ashford says: 'Pesticides are
nerve poisons; they damage the brain and they are also known to be endocrine
disruptors' (synthetic chemicals which interfere with naturally produced
- He wants to see an immediate reduction
in pesticide use until the effects are better understood, and is pressing
for the formation of a European Union environment unit to study the problem.
- The Health and Safety Executive has commissioned
a British study of MCS from the Institute of Medicine. A report on OP sheep
dips, by the Royal College of Physicians and the Royal College of Psychiatrists,
is due to be published in November.