OP
sheepdip used on troops
In light of the recent revelation (4 October
1996) by Nicholas Soames, Minister of State for
the Armed Services, that he had inadvertently
misled the Defence Committee in December 1994 as
to the scale of use of organophosphate (OP)
insecticides in the Gulf War, it is now clear
that at least some of the symptoms experienced by
hundreds of personnel who returned from the
conflict could have been caused by such exposure.
Reports, held by the OP
Information Network (OPIN), written by Sgt
Anthony Worthington, an Environmental Health
Technician who served with the 4th Armoured
Brigade, show that two types of OP pesticides
were brought from the UK to be used for purposes
of 'disinfestation'. These were diazinon, also
one of the sheep dip active ingredients, and
fenitrothion. The pesticides were applied to kill
sand-flies and mosquitoes, as well as fleas and
lice, all of which can spread disease. Five
compounds containing carbamates and several
synthetic pyrethroids were also among the array
of chemicals, though these were not apparently as
effective as fenitrothion.
When stocks of the latter ran
out Sgt Worthington ordered his team of sprayers
to use the diazinon, but they soon became so ill
that he ordered them to bury the remaining cans.
During the whole of the period he served in the
Gulf, he complained to his senior officers in the
Royal Army Medical Corps that, although the data
sheets demanded complete protective clothing for
the sprayers, none was ever delivered. Since
returning home he has suffered from weakness,
exhaustion, severe breathing problems and
depression, and has been receiving constant
medication.
It is clear that all sectors of
the British army must have been supplied with
similar insecticides. Many soldiers report that
they experienced being sprayed in their tents
even while they were eating, and some claim
aerial spraying was carried out. The scale of
exposure is unquantifiable, but the fact that it
occurred cannot be denied.
Protective clothing
The refusal of the army to allow Sgt
Worthington's sprayers to wear their nuclear,
biological and chemical (NBC) suits to carry out
their duties should be investigated. However two
studies(1,2) by the Institute of Occupational
Medicine (IOM) at Edinburgh University revealed
that absorption of OPs was the same among
improperly protected sheep-dippers and those
wearing full recommended personal protective
clothing (PPE). The measurements of metabolites
in the urine of dippers in both studies led the
IOM to conclude that, although the concentrations
of urinary metabolites were low, the similarity
of the results indicated a need for further
investigation. The IOM postulates: "a number
of hypothesis to explain this finding ¼
including routes of absorption other than skin,
derived or actual impurities in the dipping bath
liquid and insensitivity or inappropriateness of
the biological indices."
Government bodies, such as the
Health and Safety Executive and the Veterinary
Medicines Directorate, have consistently denied
that inhalation is a possible potent route of
exposure in all but very exceptional
circumstances. In light of the Edinburgh findings
they need to examine the currently acceptable
biological indices, such as those employed to
detect aerosol absorption. The National Office of
Animal Health (which represents the animal health
industry) funded the second IOM study(3), and one
would hope it would now commission further
research, as suggested by the team in Edinburgh.
Current research
into OP poisoning
Typical symptoms of OP exposure, experienced by
growing numbers of sheep farmers, include chronic
breathing problems, joint and muscle pains,
fatigue, headaches, trembling hands and legs,
depression and occasional uncontainable rage. In
some cases heart and digestive problems have
arisen, and there are suspicions that genetic
abnormalities could be linked to OP exposure.
These are also the types of health problems
experienced by Gulf Veterans.
Dr Goran Jamal, a consultant
neurologist from Glasgow, has been carrying out
highly sophisticated neurophysiological tests on
both the farming community and Gulf Veterans for
a number of years. He has discovered specific
patterns of neurological damage and the results
of his latest research will be published soon. He
is applying for independent funding to extend his
work, but was recently unaccountably turned down
by the Medical Research Council (MRC), whose task
it is to allocate funding for further research
into Gulf War Syndrome. Another application
submitted to the MRC, by a group of scientists at
Liverpool University led by a professor in
medical genetics, was also rejected with no
explanation.
Dr Mohamed Abou-Donia, a
professor from Duke University, North Carolina,
US, has recently published a paper(4) describing
research he carried out (funded by US
presidential candidate Ross Perot) in which he
fed the protective Nerve Agent Pretreatment Sets
(pyrodistigmine bromide) given to all British and
US personnel in the Gulf, to laboratory animals
which he then exposed to pesticides. The results
showed that the combination produced much more
severe reactions than exposure to one or the
other individually. He reported to OP Information
Network that US troops in the Gulf were
instructed to spray the inside of their NBC suits
with an insecticide before putting them on; the
absorption rate of a chemical under such
conditions would be very high. He has found that
the US Department of Defense is very reluctant to
fund any research into possible health effects of
pesticide exposure among US forces, and one can
only applaud the suggestion that Dr Jamal and Dr
Abou-Donia are to collaborate in their future
research, even without the assistance of their
respective governments.
It is widely recognised that OP
compounds can affect the cholinesterase levels in
acute exposures, causing potential severe
neurological damage. An enzyme, neuropathy target
esterase (NTE), affected by some OP compounds can
cause delayed neuropathy. It has recently been
acknowledged that a number of other enzymes can
be affected, including one, described by the MRC
Toxicology Unit at Leicester as a 'novel
protein'(5). This can be affected at exposure
levels seen in agricultural use. As the MRC
admits that they do not understand the functions
of this 'novel protein' under normal conditions
it is hard to estimate what effects the reaction
with an OP might cause. This research is
continuing, and will be watched with interest.
An orthopaedic surgeon in
Nottingham and a doctor in the Department of
Human Metabolism and Clinical Biology in
Sheffield are currently investigating the
possibility that metabolic bone disease can be
caused by exposure to OPs in agriculture. OPs can
damage bone marrow, which affects
blood-chemistry. Could this explain the
increasing incidence of osteoporosis among farm
workers under the age of 40?
A paper on industrial health
and safety published by the European
Commission(6) in 1986 states that cholinesterase
levels do not have to be affected for
neurological damage to occur. In his address
given at the British Medical Association/National
Farmers Union conference on OPs at the Royal
Society in June 1995, Dr Tim Marrs referred to
the hen-test, used for many years to establish
the neuro-toxic status of OPs for purposes of
licensing them for sale to the public. He said:
"There have been two recent bits of work
which have raised questions about whether this
hen test does exclude all the ones (ie the OPs
which affect the NTE) that you think they do....
Even if you do have a prediction method for
delayed neuropathy and it does work, that does
not exclude some sort of other peripheral nervous
problem."
|
Sheep dipping can lead to high levels of OP exposure |
Neuropsychiatric and
cognitive effects of OPs
The neuropsychiatric
effects of OPs are being researched by Dr
Bob Davies, a consultant psychiatrist
from Taunton. He has published one paper
on affective disorders and suicide(7),
and is preparing to publish a second
paper on the same lines. He has found a
distinct pattern of growing numbers of
farmers in the West country who have been
using OPs.
Their chronic symptoms do not
correspond with any other neuropsychiatric
disturbance, which is crucial for diagnostic
purposes. The initial criterion for diagnosis is,
of course, a history of repeated exposure to OPs,
and the report published by the Department of
Occupational Health at Birmingham University(8)
on chronic cognitive impairment among a group of
sheep-dippers showed that damage was clearly
dose-related. This study looked at a group of men
who had no awareness that their exposure to OPs
had had any effect on their cognitive abilities,
and yet a distinct pattern emerged of poor
concentration, slow reaction-times, difficulty
with using language and susceptibility to mental
disturbance.
A recent paper(9) noted the
sharp rise in the suicide rate among Spanish
agricultural workers when OP pesticides were
introduced into their areas. This corresponds
with reports of unexplained high suicide rates
among sheep farmers in Wales and the Scottish
Highlands. The government explanation of this
phenomenon includes financial worries and
isolation. However, a Scottish doctor told OPIN
that these factors may well contribute to
depression, but were not new factors in these
farming areas; what was new was the added factor
of the government's insistence on the use of OPs,
which are known to cause depression and sudden
mood-swings, as well as confusion and anxiety.
OPs and politics
Paul Tyler MP has led an all-party group of MPs
for the last three years. They want OPs withdrawn
pending further research.
The Labour Party's shadow
environmental protection spokesperson, Michael
Meacher published a document on 1 November 1996
entitled Dangerous Dips, in which he said that
the Labour Party demanded a moratorium on the use
of OPs as sheep dips, and that proper and
accurate health warnings should be on the labels
of all products containing OP for domestic use.
It shows how successive governments have failed
woefully to implement advice given over many
years in documents available to them, from
Professor Zuckerman's report on toxic
agricultural chemicals to the Agriculture
Committee in 1951, to the Health and Safety
Executive document MS17 of 1981. Both the above
reports recommend further research as a matter of
urgency, all warn of the hazards of potential
chronic damage to those exposed, and the need for
proper education of users and doctors whose
patients may be suffering long-term ill-health.
Mr Meacher's report demands
that funding must be put into clinical
investigation of the growing number of farmers
and their families reporting typical OP poisoning
symptoms. It also highlights the need for an
immediate overhaul of the licensing system for
OPs to reduce the reliance on manufacturers'
toxicity data, and to implement a procedure for
revoking licenses where there is evidence of
suspected danger to public health. Monitoring and
licensing of toxic chemicals might be better
handled by the Environment Agency rather than
MAFF.
Doctors' initiative
It has been suggested by a
group of doctors in the West country that the OP
Information Network and the Pesticides Trust [now PAN UK]
should set up a database on the Internet of
recent scientific papers and research projects on
chronic OP poisoning, to be made easily available
to doctors and researchers. The difficulty of
discovering such papers in the existing medical
databases, which are very expensive and contain
hundreds of historical documents on acute OP
poisoning, deter all but the most dedicated
researchers.
Another suggestion made by
doctors is that a short handbook of symptoms of
chronic OP poisoning, drawn from respected
scientific documents, plus a list of UK
consultants who have specialist understanding of
the subject to whom doctors can refer suspected
cases, would be extremely valuable.
Conclusion
It is clear that there is a need for substantial
funding for research into all aspects of
potential chronic OP damage. This has become more
urgent in light of recent anecdotal evidence of
damage caused both to children being treated for
head-lice infestation with OP-based shampoos,
which are left on the head for many hours, and
people using other OPs in fly sprays, domestic
disinfestation products and garden pesticides.
It is vitally important to
institute a programme for the toxicological
education of doctors. There should be a new
process for the licensing of all OP compounds,
and the monitoring of possible effects; all OP
products should be clearly, and comprehensively
labelled; and there must be funding for a
programme of clinical investigations by
independent experts of those claiming
health-damage from OP exposure.
References
1. Occupational Hygiene Assessment of Exposure to Insecticides and the Effectiveness of Protective Clothing during Sheep Dipping Operations,
Institute of Occupational Medicine, February 1994, Report No TM94/04.
2. Occupational Hygiene Assessment of Sheep Dipping Practices and Processes, Institute of Occupational Medicine, October 1993, Report No TM/93/03.
3. Ibid.
4. Mohamed Abou-Donia, M., et al, Neurotoxicity resulting from coexposure to pyridostigmine bromide, DEET and permethrin: implications of Gulf War chemical exposures, Journal of Toxicology and Environmental Health, 1996, 48:35-56.
5. Pers. comm.
6. Alessio, L., Biological indicators for the assessment of human exposure to industrial chemicals, Joint Research Centre ISPRA Establishment, Director-General for Employment and Social Affairs, Commission of the European Communities, 1986.
7. Davies, D.R., Organophosphates, affective disorders and suicide, Journal of Nutritional & Environmental Medicine, 1995, 5:367-374.
8. Stevens, R., et al., An investigation into the possible chronic neuropsychological and neurological effects of occupational exposure to OPs in sheep dips, HSE Report No 74/1995, Institute of Occupational Health Birmingham, 1995.
9. Parron, T., et. al., Increased risk of suicide with exposure to pesticides in an intensive agriculture area: A 12 year retrospective study, Forensic Science International, 1996, 79:53-63.
Elizabeth Sigmund is the founder of the OP Information Network, Heathfield Farmhouse, Callington, Cornwall, PL17 7HP, Tel. 01579 384492, Fax 01579 384586.
[This
article first appeared in Pesticides News No. 34,
December 1996, pages 4-5]