disease organism has never been shown to infect 
anything other than Japanese beetles and certain 
closely related beetles. Application of up to 2000 
pounds per acre of milky disease spore powder to 
pastures caused no discernible harm to the turf. 
The effect of temperature is a line of defense of 
verfebrates against infection by milky disease 
bacteria. The maximum temperature for multipli¬ 
cation of B. popilliae is below the minimum body 
temperature of domesfic vertebrafes. The orga¬ 
nism has been shown not to germinate in the 
digestive tract or persist in the feces of vertebrates 
in these tests. 
Bacillus thuringiensis has been commercially 
available in the United States since 1958 and is 
widely used to control caterpillar pests of food 
crops, fiber crops and forests. Both laboratory and 
commercial preparations of 6 . thuringiensis have 
been evaluated for specificity and possible 
toxicity-pathogenicity to vertebrates since 1957. 
International Minerals and Chemical Corp. (IMC) 
produced the first commercial preparations of 6. 
thuringiensis (Thuricide R) in July 1957. Toxicol¬ 
ogy of Thuricide was included in a petition to the 
Food and Drug Administration (FDA) that resulted 
in a temporary exemption from folerance in 
December 1958 and a full exemption from toler¬ 
ance for use on food and forage crops in April 
1960. The Canadian Department of Agriculture 
granted a similar registration for Thuricide in 
November 1961. Another petition, that contained 
safety evaluation data, was submitted by Nutrile 
Products, Inc. (NPI) for their preparation of B. thu¬ 
ringiensis (Biotrol-BTB R) in June 1 959. The pefi- 
tion on Biotrol-BTB presented results on the 
following studies: intraperitoneal injection in the 
mouse, guinea pig, rabbit, swine, and chick; serial 
blood passage after intraperitoneal injection into 
mice; and ingestion by the rat, chick and human. 
Subsequent studies by NPI included subacute 
feeding fests in birds and mammals. Anofher com¬ 
mercial preoaration of 6 . thuringiensis (var. kur- 
staki, Dipel R), produced by Abbott Laboratories, 
was recently developed and registered in 1970 
(EPA registration No. 275-18-AA). Preparations 
were evaluated for their safety to fishes, birds, and 
mammals, including man. Initial studies were 
designed to establish that 8 . thuringiensis or its 
varieties were neither pathogenic, allergenic, nor 
able to persist in mammals or to answer questions 
concerning the possibility that 8. thuringiensis 
may mutate or be selected for pathogenicity to 
humans. Acute and subacute studies were carried 
out to establish requirements for registrafion of 
commercial preparations of 8. thuringiensis. 
The results (Anonymous, 1978) demonstrated 
that 8. thuringiensis has no known adverse effect 
on man, pets, birds, fish, earthworms, beneficial 
insects or plants. Other studies revealed no evi¬ 
dent differences in densify of snails, Forficula, 
myriapodes, and wood lice affer freafment (Benz 
and Altwegg, 1975). Millions of pounds of Dipel 
have been used without a single human toxicity or 
environmental damage report. Repeated tests 
have shown that 8 . thuringiensis does not inhibit 
plant growth and was non-phytotoxic after testing 
for phyfotoxicity on more than 140 species of 
plants. No evidence of acufe or chronic foxicity in 
rats, guinea pigs, mice, swine, humans or other 
mammalian test animals has been found. 8. thu¬ 
ringiensis. either in the form of fhe commercial 
product (Dipel) or as naturally occuring 8. thurin¬ 
giensis has no harmful effecf on the environment 
for several reasons, all of which are characferisfic 
of the bacteria (Anonymous, 1978; Forsberg etal., 
1 976): (1) Natural 8. thuringiensis numbers in the 
soil are limited by its metabolic requirements; it is 
apparently unable to compete effectively with 
other soil bacteria and unlike 8. cereus, 8. thurin¬ 
giensis is seldom isolated and reported from soil 
buf is found and isolated from disease larvae. 
Cadavers of insects killed by 8. thuringiensis con- 
tain vegetative cells but few spores and crysfals, 
the principal agents of mortality rarely build up in 
the insect population. (2) Conditions on the surfa¬ 
ces of living plants are not suitable for subsfantial 
growth of 8. thuringiensis, (3) Numbers of 8. thu¬ 
ringiensis organisms and spores in fhe environ- 
menf are reduced quickly, even after applying 
concentrated commercial formulations, by ultravi¬ 
olet light, i.e., the number of recoverable 6 . thurin¬ 
giensis spores usually falls fo background levels 
of natural Bacillus populations in 2 or 3 days, (4). 
8. thuringiensis is toxic to target insects only when 
ingested, and (5) there is little prolific multiplication 
of 8. thuringiensis in insect larvae and when it 
does occur it takes place just before or after death 
of the larvae (Prasertphon et ai, 1973). The orga¬ 
nism has been proven harmless to vertebrates 
and invertebrates in terrestial, marine and fresh 
water environments even when test dose levels of 
1000 to 2000 times the normal use rate were used. 
Laboratory studies indicated that ingested 8. thu¬ 
ringiensis is eliminated from test animals within 
hours after ingestion (Anonymous, 1978). Other 
studies have demonstrated vegetative cell counts 
of 8. thuringiensis decreased by 90 percent within 
4 hours when bacterial suspensions were intro¬ 
duced into the rumens of cattle with commercial 
spore preparations decreasing after 24 hours 
(Adams and Flartman, 1965). No spore germina¬ 
tion of spores in the rument were noted in that 
study. Studies of the survival of 8. thuringiensis in 
the digestive tracts and feces of mammals and 
birds showed similar results although spores sur¬ 
vived passage (Smirnoff and MacLeod, 1961). 
Extensive experimental work on safety of 8. thu¬ 
ringiensis (and certain strains of 8. cereus) has 
4 
