BSE Inquiry / Statement No 23B Mr Mark Purdey
SECOND SUPPLEMENTARY STATEMENT OF MARK PURDEY
- This statement is made in response to the supplementary witness statement of
Mr Roger Cook
- I reiterate that the overall rate of active ingredient used to treat warbles
(20mg/kg) is not the same as the rate employed for lice (10mg/kg). This is clearly stated
on all of the packages representing the different brands of pour-on phosmet employed in
agriculture package labels which have been supplied/shown by me to the Inquiry
Secretariat in 1998.
- However, whilst I understand that NOAH say that a 14 day repeat treatment of
the 10mg/kg lice rate of phosmet could be used for lice control if the problem of
infestation persisted (eg; the two separate applications adding up to a total dose of
20mg/kg), I should point out that a 14 day repeat treatment was also recommended following
use of phosmet at its 20mg/kg warble fly dose rate (producing a total dose of 30mg/kg).
- However, it should also be pointed out that toxicological effects can be
markedly different when a 20mg/kg dose of a given substance is applied to a mammal on a
single occasion, as opposed to a treatment strategy which involves two separate lower dose
applications of 10mg/kg of the same substance 14 days apart. (See; Professor Dayans
toxicological briefing to the BSE Inquiry which outlines this most basic toxicological
principle (IA Vol.1 Tab 19)).
- What I am saying is that the prion protein will be rendered susceptible to
its initial conversion into an infectious BSE misfolded isoform once
concentrations of phosmet in brain cells exceed a threshold level that results from
treatments at the 20 mg/kg warble dose rate.
- I have also supplied the Inquiry with labels of the phosmet lice fluid
currently being applied exclusively as a 10mg/kg dose in Australia and New Zealand. The
wording on these labels does not state the need or recommendation for a 14 day repeat
- Mr Cook also states that European type, phosmet based warblecides were
used in South America without BSE developing. Again, I must stress that warbles have
never existed in South America, indicating that phosmet can only have ever been used at
its lice dose rate of 10mg/kg presumably to control the skin parasite, dermatobia,
which is cited by NOAH in paragraph 33 of their initial statement 270 (WS 270).
- However, I must state that the South American pesticide registration
authorities did not imply that they have utilised phosmet when they responded
to the survey that I circulated around various countries respective pesticide licensing
authorities in 1996.
- They did however indicate that they have been utilising fenthion
and trichlorphon types of OP pour on at the 10mg/kg dose rate. This is
confirmed in para 14 of Bayers submission to the 5/11/98 hearing of the Inquiry (WS
- The use of Phosmet at the non-warble dose of 10mg/kg would virtually debar
the possibility of BSE arising. Furthermore, putting aside the status of phosmet usage in
S America, other aetiological prerequisites would have to be simultaneously fulfilled
before one could predict whether BSE would be likely to emerge or not.
- Even if I had changed my theory as Mr Cook suggests, the number of times that
it has been changed is totally irrelevant to the issue at stake the reality of
whether or whether not phosmet plays an actual role in the aetiology of BSE.
- Mr Cook suggests I am changing my theory by isolating and listing select
aspects of my multifactorial thesis which infers that I am simultaneously presenting
several different pathogenic mechanisms, each of which contradicts the viability of the
- However all of the different aspects that Mr Cook has listed do in fact mesh
together to form a unified, homogenous hypothesis.
- Since no proper extensive research programme has ever been commissioned into
investigating my theory, then in the interests of sound lateral scientific thinking it has
been necessary to propose various optional pathogenic mechanisms over the years whereby
phosmet could feasibly play a role in BSE aetiology.
- The tiny errors in my supplementary statement (WS 023A) surrounding letter dates, whether Roger
Cook represented UKASTA or NOAH at a given time, or whether a particular communication was
a fax or letter do not hold any relevance whatsoever to the science of the putative role
that phosmet may have played in BSE aetiology.
Issued on behalf of the witness by:
The BSE Inquiry Press Office
6 th Floor Hercules House
London SE1 7DU
Tel: 0171 261 8383 / 8385 / 8377
Fax: 0171 803 0893