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Acute symptom-reporting after routine exposure to
organophosphate pesticides in sheep
dip Institute of Occupational Health University
of Birmingham for the Health and Safety
Executive C.A.Jackson A.Spurgeon
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(No Transcript)
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• Dippers Flu
• Dipping sheep with Organophosphate Pesticides
• Traditionally tied to collection of non-specific
  symptoms
• Manifests shortly after dipping
• Alleviation usually after 48 hours

General weakness Muscle weakness Fever Aches and
pains Headaches Loss of appetite
Is there really any truth in this collection of
symptoms?
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Past work Previous study Investigated symptom
reports in 82 farmers recently exposed to OPs
when dipping sheep, compared with controls
(quarry workers) Overall symptom reporting, and
reporting of symptom groups was not elevated in
exposed relative to controls This was not
consistent for all symptoms. Possible that this
(intuitive) grouping of symptoms may mask some
genuine symptom patterns.
A statistical approach was needed . . .
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Aims Objectives a) Establish plausible basis
for grouping of symptoms b) Identify
recognisable core-symptoms consistently present
in exposed workers c) Determine if exposed and
controls differ in these core-symptoms e)
Determine if any excess in core-symptoms is
dose- related
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Strategy for Re-analysis a) Cluster analysis of
symptom data using original symptom groups b)
Rank individual symptoms by frequency c) Chi
square analyses of individual symptoms d)
Factor analysis of 73 original
symptoms e) Investigation of dose-effect
relationships f) Cluster analysis of the symptom
data
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Ranking individual symptoms
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Rank individual symptoms cont.
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Individual symptoms at 24 hours after dipping
12 symptoms reported more by exposed than
controls 15 symptoms reported more by controls
than exposed
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Factor Analysis of all symptoms
Twenty-one unwieldy factors
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Scree Analysis
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Factor Analysis

• 6 factors remained as the best representation of
  symptom data
• The product of 38 individual symptoms
• Accounted for 47 of the variance in symptom
  scores

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Factor Analysis
Little physiological commonality between symptoms
in each factor
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Dose-effect relationship?

• Weak association between 6 factors flock size
  (R20.4)
• Flock size as surrogate exposure estimate is too
  simplistic
• Statistical problem - 38 symptoms and only 82
  cases

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Top 21 symptoms 21 symptoms reported most
frequently Subjected to K-Means cluster
analysis Produced 5 distinct symptom clusters
With seemingly useful physiological explanations
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Testing the 5 cluster model Scores on the 5
clusters compared between exposed and
controls Significant differences were
consistently to the detriment of the exposed
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Conclusions High frequency of symptoms in both
occupational groups (approx. 50-50) No evidence
of more dippers flu symptoms in exposed than the
controls No plausible pattern was evident in
symptoms reported by the exposed Cluster
analysis of the original 9 symptom groups showed
globalized and non-specific symptoms were being
reported more than localised specific symptoms -
suggesting general malaise than specific target
organ systems Factor analysis provided little
clarification of the data - it reduced 21
unwieldy factors down to 6 factors, though with
little physiological plausibility in the grouping
together of some symptoms K means cluster
analysis identified 5 distinct symptom clusters
of better plausibility, 3 of which were
significantly worse in exposed
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Summary Tentative support for the view that
certain symptoms can be identified occurring
more frequently in those exposed to OPs. Such
symptoms are consistent with a flu like illness.
Further verification is needed from studies
specifically targeted at a definition of symptom
groups following acute OP exposure.