APPENDIX II-AF: West Nile Virus and Insecticides – Sankey.
article cites documented evidence cited in (Ann N Y Acad
Sci 917:944-50 2000) “that exposure of healthy
mammals to solvents such as those associated with most pesticides damages the
blood-brain barrier, thus greatly increasing the risk of encephalitis by West
Thie following article is found at:
West Nile Virus and Insecticides
It seems that some people demand that a 'crisis' be present at all times. If
one doesn't exist, it is created. One of the current creations is West Nile
It was first recognized in Uganda
in the late 1930's. It may have been introduced to North America
by a germ warfare laboratory near New York City,
and released when the lab was destroyed by a hurricane. Anyway, it's here now,
West Nile is a virus of birds. It is probably spread
by waterfowl, ducks and geese, but is lethal to corvids
- crows and jays. It is spread between birds by a few species of mosquitos that live off birds, almost totally Culex spp. On occasion, a human
is infected by one of those mosquitos. Nearly always,
human infection is minor, even totally unnoticed by those infected. And, unlike
many viral diseases, influenza in particular, there is no evidence that one
person with West Nile can transmit it to another.
However, in one person out of ten thousand or so, West Nile
gets into their brain resulting in encephalitis. In about 10% of these cases,
the person dies. The death rate is trivial compared to many other human deseases, influenza in particular.
The reaction to West Nile, particularly that of the press, has become a triumph of
panic over both science and common sense. (As usual, of course, those who panic
are the first to accuse those who disagree with them as being unscientific and
irrational.) Many jurisdictions, Manitoba
for one, are dispensing pesticides all over the landscape on the scale that
Rachel Carson despaired of half a century ago. The Province
of Quebec has passed emergency
legislation to override local health officials and bylaws, such as those in Chelsea,
and spray Malathion if West Nile
virus appears in an area.
This response is grossly anti-science, and anti-health. Spraying of neurotoxins
such as Malathion makes the danger to us of West
Nile worse, not less, in many ways:
First, predators are more active than their prey, or they couldn't catch
them. Neurotoxins such as Malathion target the source
of animal activity - the nervous system. So, spraying will kill mosquito
predators faster than it will kill the mosquitos
themselves. Amongst the data confirming this is some from a wetland in the
State of New York: populations of mosquitos increased
15-fold over 11 years of insecticide spraying. Not only that,
but the percentage of species that bite humans increased their percentage over
the period. (J.Amer.Mosquito Control 13(4):315-325
It has also been shown that Malathion absorbed at
only 1 ppm of body weight by frogs depresses their
immune systems to the point that they are almost defenseless against diseases
in their environment. (Env.Toxicol.Chem.
22(1):101-110 2003) Frogs are a significant predator of mosquitos,
both larva and adult.
Second, mosquitos which transmit West
Nile are suspected of having damaged stomach linings, which allow
the virus to move past the lining and into the mosquito's salivary glands. Many
scientists believe that mosquitos primarily develop
such damage from sub-lethal doses of insecticides. That would increase the
likelihood that they would transmit viruses from birds to mammals. Those 15x mosquitos are probably transmitting more than 15x the
number of viruses to humans.
Third, West Nile virus only seriously affects people
with impaired immune system or damaged blood-brain barrier. Even Health Canada
admits that "most people infected with West Nile
virus experience no symptoms". It is only the elderly or those who are
already ill who may (and even then rarely) develop serious complications. Human
exposure to neurotoxins is known to impair our immune system, especially when
the exposure exceeds our body's ability to detoxify them. There is also
documented evidence (Ann N Y Acad Sci
917:944-50 2000) that exposure of healthy mammals to solvents such as those associated
with most pesticides damages the blood-brain barrier, thus greatly increasing
the risk of encephalitis by West Nile. So, exposure of people to Malathion and its solvents will increase their chances of
having severe health effects if bitten by a mosquito, compared to people who
have had no exposure to pesticides.
Fourth, widespread use of toxins to kill insects breeds genetic resistance.
This is well documented in malarial regions of the world. (cf. Insect Mol.Biol. 11,409 2002) We should not use any toxin in a
widespread manner against insects unless the health benefits are sufficient to
outweigh the need to continually adapt those toxins to the resistant insects
that result. In the case of West Nile Virus, no such benefit exists.
Spraying to kill mosquitos will increase the
threat of West Nile to us, not decrease it. The
appearance of West Nile in an area should be the signal
to cease all spraying of toxins, to redouble our efforts to promote human
health, rather than the reverse.
Some further reading and references:
Maine Environmental Policy
Environment & Health News