|
<br />-I'
<br />
<br />.JOURNAL OF PESTICIDE REFORMl FALL 1994. VOL.14. NO.3
<br />
<br />toxin. The beta-exotoxin is toxic to verte-
<br />brates, with an LD50 (median lethal dose;
<br />the dose that kills 50 percent of a popula-
<br />tion of test animals) of13~18 milligrams
<br />per kilogram of body weight. (mglkg) in
<br />mice when injected into the abdomen. An
<br />oral dose of 200 mglkg per day killed mice
<br />after eight days.2O Beta-ex:otoxin. also causes
<br />genetic damage to human blood cellsP B.t.
<br />formulations containing beta-exotoxin have
<br />not been used in most countries2O although
<br />attempts are currently being made to regis- '
<br />ter beta-exotoxin as an insecticide In the
<br />United States.8 Another toxin produced by
<br />B.t. is the alpha-exotoxin that is highly
<br />acutelv toxic to mice.20 Current B.t. oro-
<br />ducti~n methods are such that alpha~o-
<br />toxin is not a "significant component" of
<br />B.t. formulations.8
<br />: Related Bacteria: B.t. belongs to a small
<br />gro~p of closely rdated BaciOus species, in-
<br />cluding B. cereus, a bacteria that is ari agent
<br />of food poisoning, and B. anthracis, the
<br />pathogen of the virulent animal disease,
<br />anthrax. These three bacteria are so similar
<br />it has been theorized that they are all variet-
<br />ies of the same species.28.29 If B. cereus is
<br />cultured with B.t. cells, genetic material is
<br />transferred to the B. CertU.f cells that allows
<br />B. cereus to produce B.t.'s crystal proteins.28
<br />Transfers of genetic material between B.
<br />anthracis and B.c. have also occurred.3O
<br />A toxin produced by B. cereus that
<br />causes diarrhea in monkeys is also produced
<br />by certain strains of B.t.,3O although this
<br />toxin is not likely to be present in B.t. spore
<br />formulations.28 Human volunteers suffered
<br />from nausea, vomiting, diarrhea, colic-like
<br />pains, and fever after eating food contami-
<br />nated with one B.t. strain, B.t. var.
<br />galkriae.31 These examples indicate the dose
<br />relationship between B.t.and disease-caus-
<br />ing pathogens.
<br />Increased Susceptibility: People with
<br />compromised immune systems or preexist-
<br />ing allergies may be particularly susceptible
<br />to the effects of B.t. In mice with reduced
<br />immune function. me dose required to kill
<br />more than 50 percent of the mice when
<br />injected was several orders of magnitude
<br />smaller than the highest dose tested in nor-
<br />mal mice.32 Mice with impaired immune
<br />function also showed higher mortality than
<br />
<br />regular mice when one dose of B.d. was
<br />injected into the abdominal cavity.33 Al-
<br />though no definite cases have been reponed
<br />ofB.t. infecting humans with compromised
<br />immune systems, the OregOn Health Divi-
<br />sion .suggested before a B.t.k. spray pro-
<br />gram that "individuals with...physician-di~
<br />agnosed causes of severe immune disorders
<br />may consider leaving the area during the
<br />accualsprapn~"~ .
<br />A memo from Novo Nordisk, the manu-
<br />fucturer of Foray 48B, states that the amount
<br />of the spray a person would be exposed to
<br />would be too small to devdop new aller- .
<br />gies. However, "It is possible that someone
<br />that already has developed an allergy to one
<br />of the components of Foray 48B or has
<br />asthma ... could be affected by exposure to
<br />small quantities of Foray 48B. "35 The 1991
<br />Material Safety. Data Sheet for Foray 48B
<br />states "Repeated exposure via inhalation can
<br />resUlt in sensitization and allergic responSe
<br />in hypersensitive individuals."36
<br />Contllmin:lnts: In me mid 1980s, sev-
<br />eral B.t. products were contaminated with
<br />other bacteria, including Strtptococcus
<br />fiucium and S. fiiecalis.37 While B.t. prod-
<br />ucts are routindy monitored for bacterial
<br />contaminants,2 the risk of contamination
<br />with a disease-causing bacteria. is always
<br />present.25
<br />
<br />Inert Ingredients
<br />
<br />All B.t. products contain ingredients
<br />other than B.t.. These are identified only as
<br />"inen" ingredients and are called trade se-
<br />crets by the manufacturers of the products.
<br />The "inen" ingredients are potentially the
<br />most toxic components of the formulations.8
<br />For example, during the 1992 Asian gypsy
<br />moth spray program in Oregon, a woman
<br />who was exposed to Foray 48B had a. pre-
<br />existing allergy to a carbohydrate that was
<br />present as an inen ingredient. Within 45
<br />minutes of exposure, the woman suffered
<br />from joint pain and neurological symp-
<br />toms.38
<br />Because "inem" are called trade secrets,
<br />there is little public information about their
<br />identity, but the information that is avail-
<br />able indicates theY could cause health prob-
<br />lems. Foray 48B has contained sodium hy-
<br />droxide, sulfuric acid, phosphoric acid,39
<br />
<br />methyl paraben,40 and potassium phos-
<br />phate, 41 as "inem." While these ingredients
<br />make up less than 1 0 percent of Foray
<br />48B,39 they pose hazards. Sodium hydrox-
<br />ide, more commonly known as lye, causes
<br />"severe corroSive damage to the eyes, skin,
<br />mucous membranes and digestive system
<br />.....Breathing sodium hydroxide dust or mist
<br />leads in mild cases to irritation of the mu-
<br />cous membranes of the nose ... and in severe
<br />cases to damage of the upper respiratory
<br />tract."42 Sulfuric acid and phosphoric acid
<br />are both corrosive. Sulfuric acid can cause
<br />. severe deep skin burns and permanent loss
<br />of vision. When inhaled as a mist, sulfuric
<br />acid may cause severe bronchial constriction,
<br />and bronchiris.43 Phosphoric 3€id is an ir-
<br />ritant to skin and mucous membranes, and
<br />its vapors may cause coughing and throat
<br />irritarion.43 Both methyl paraben and po-
<br />tassium phosphate were once registered by
<br />EPA as pesticide active ingredients.44
<br />Sodium sulfite has been identified as an
<br />inert ingredient of the B.t.k. formulation
<br />Dipd SAF.45 Up tQ ten per cent of asth-
<br />matics (about one million people in the
<br />United States) may react to sulfices, par-
<br />ticularly those people who are treated with
<br />steroids.42 Symptoms of exposure in those
<br />sensitive to sulfites usually involve the res-
<br />piratory system, and can also include nausea,
<br />diarrhea, lowered .blood pressure, hives,
<br />shock, and loss of consciousness.42
<br />
<br />Environmental Fate
<br />
<br />Very little is known about the natural
<br />ecology of B.t. It occurs naturally in many
<br />soils. In one study, Bot. was isolated from
<br />70 per cent of soil samples taken from.
<br />around the world. and was most abundant
<br />in samples taken in Asia. More than half of
<br />these isolates were undescribed varieties of
<br />B.t.46 B.t. has also been isolated from insect
<br />bodies, tree leaves and aquatic environ-
<br />ments? It has even been recovered from
<br />paperY
<br />Soil: B.t. generally persists only a shon
<br />time in soil. The half life of the insecticidal
<br />activity (the time in which half of the in-
<br />secticidal activity is lost) of the crystal is
<br />about 9 days.48 However, small amounts can
<br />be quite persistent. In one experiment, B.t.
<br />spore numbers declined by one order of
<br />
<br />16
<br />
<br />NORTHWEST COALITION FOR ALTERNATIVES TO PESTICIDES/NCAP
<br />P.O. BOX 1393, EUGENE, OREGON 97440 / (503)344-5044
<br />
|