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May 15, 1998
Urban Btk Spray Alert
A notice in today's Chronicle Herald (May 15, 1998) announces a
tree spraying program in the Halifax Regional Municipality, a so-called
"Biological Insect Control Program". The spraying will take place in urban
areas of Halifax and Dartmouth, starting May 26, unless there is enough
opposition to stop it! They are planing to carry out periodic spraying until
July 12.
One of the sprays is Foray 48B - active ingredient Bacillus thuringiensis
kurstaki (Btk), and it will be used against cankerworms, gipsy moth larvae,
forest tent catepillars, etc. (This is exactly the same spray that is being used
against the tussock moth over large rural areas of Nova Scotia this summer.)
The usual line is given, namely that it is "considered harmless to humans,
animals
and beneficial insects such as honey bees." The claim is that this is a
biological
spray, but this is not true, because it also contains chemical so-called inerts.
There is a very important 19-page ruling by the BC Environmental Appeal Board
of April 15, 1998, which will be helpful in fighting Btk spraying anywhere. Toby
Vigod was chair of the board.
The ruling was that:
- There was to be no aerial spraying of Foray 48B (same trade name for NS Btk
spray) in the Victoria area.
- Ground spraying was only to be on "appropriate deciduous vegetation",
concentrating on gypsy moth "epicenters".
- No spraying on school properties or open grassy areas, where children play.
It was ruled that
"The Panel finds that aerial spraying will create an unacceptable risk of health
problems among the residents of these densely populated areas. In particular,
the Panel agrees with the Appellants that there is a risk to the health of
children,
people of all ages who have allergies, asthma, and other respiratory ailments,
people with immuno deficiencies, chemical hypersensitivities, and the
elderly. It
also poses an unreasonable adverse effect to the environment (non-target
species)."
You can obtain the document APPEAL NO. 98-PES-03(b) from the following
web site:
http://www.eab.gov.bc.ca/pest/98pes03b.htm
Below is the summary (done by David Orton) of an article from the _Journal
of Pesticide Reform_, which gives the real view of this biological/chemical
insecticide. Some of the inerts in past formulations of Foray 48B are also
listed.
Helga Hoffmann
* * * * * * * * * * * * * * * * * * * *
We just received a paper: "Insecticide Fact Sheet: Bacillus
Thuringiensis (B.t.)", by Carrie Swadener, _Journal Of
Pesticide Reform_, Fall 1994, Vol.14, No.3, pp. 13-20. It is
heavily footnoted and is a survey really of the literature
from a critical perspective. I found this paper extremely
helpful. Here are some points from this paper which were
useful for me:
B.t. is "a live microorganism" or "microbial organism".
Testing for the possible hazards of B.t. is conducted
differently that for conventional pesticides. Microbial
toxicity is described using pathogenicity (the ability of
the microbe to cause disease) and infectivity (the
ability of the organism to reproduce within the body.)
The United States Environmental Protection Agency (EPA)
requires no testing of B.t. for carcinogenicity,
mutagenicity, or chronic toxicity.
"Exposed people carry B.t. in their tissues."
There is "a close relationship between B.t. and
disease-causing pathogens":
B.t. belongs to a small group of closely related Bacillus
species, including B. cereus, a bacteria that is an agent
of food poisoning, and B. anthracis, the pathogen of the
virulent animal disease, anthrax. These three bacteria
are so similar it has been theorized that they are all
varieties of the same species. If B. cereus is cultured
with B.t. cells, genetic material is transferred to the
B. cereus cells that allows B. cereus to produce B.t.'s
crystal proteins. Transfers of genetic material between
B. anthracis and B.t. have also occurred.
Contaminants:
In the mid 1980s, several B.t. products were
contaminated with other bacteria, including Streptococcus
faecium and S. faecalis. While B.t. products are
routinely monitored for bacterial contaminants, the risk
of contamination with a disease-causing bacteria is
always present.
Inert ingredients: "The 'inert' ingredients are potentially
the most toxic components of the formulations." These are
considered trade secrets. The article gives the following
very important information:
Foray 48B has contained sodium hydroxide, sulfuric acid,
phosphoric acid, methyl paraben, and potassium
phosphate, as 'inerts.' While these ingredients make up
less than 10 percent of Foray 48B, they pose
hazards. Sodium hydroxide, more commonly known as lye,
causes 'severe corrosive damage to the eyes, skin, mucous
membranes and digestive system.... Breathing sodium
hydroxide dust or mist leads in mild cases to irritation
of the mucous membranes of the nose... and in severe
cases to damage of the upper respiratory tract.' Sulfuric
acid and phosphoric acid are both corrosive. Sulfuric
acid can cause severe deep skin burns and permanent loss
of vision. When inhaled as a mist, sulfuric acid may
cause severe bronchial constriction, and
bronchitis. Phosphoric acid is an irritant to skin and
mucous membranes, and its vapors may cause coughing and
throat irritation. Both methyl paraben and potassium
phosphate were once registered by EPA as pesticide active
ingredients.
Perhaps in view of the above it is not surprising that Foray
48B is highly acidic:
Foray 48B at high concentrations (about 3 percent) is
acutely toxic to rainbow trout, probably because the
product is highly acidic.
Resistance: "Eight insect species have been studied because
of their ability to develop resistance to B.t." Some
examples are, the Indian meal moth, the diamondback moth,
the tobacco budworm, and the Colorado potato beetle.
Ecological impacts: This paper shows the impact of using
B.t.k. on the ecology. But unfortunately, except for the
reference above, the examples given do not directly refer to
Foray 48B but to other commercial formulations of B.t.k.
Some of these other formulations e.g. Thuricide, Dipel,
Novabac and Futura have, in the past, been used in forest
spraying operations in Nova Scotia. (See my Alternatives
Dec. 1987/Jan. 1988 paper, "The Case Against Forest Spraying
with the Bacterial Insecticide Bt"). The general situation
is given by the following quote from Carrie Swadener's
paper:
Some of the most serious concerns about widespread use of
B.t. as a pest control technique come from the effects it
can have on animals other than the pest targeted for
control. All B.t. products can kill organisms other than
their intended targets. In turn, the animals that depend
on these organisms for food are also impacted.
Keeping in mind the above caution, the following examples are
interesting: aphid-eating flies were reduced by Dipel
treatment; "Dipel also has caused mortality of the cinnabar
moth, used for the biological control of the weed tansy
ragwort"; and "B.t. applications can disturb insect
communities";
This paper shows with examples from various studies, impacts
from spraying B.t. on aquatic insects and birds.
David Orton, May 14/98
* * * * * * * * * * * * * * *
For further information, contact
David Orton, coordinator
Green Web
(902) 925-2514
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