insufficiency causes spasm of the involuntary muscles, resulting in respiratory failure
(a) Malathion. Malathion is a yellow to dark-brown liquid that is only
slightly soluble in water and of limited solubility in petroleum solvents, but which can be
readily mixed with most organic solvents. It is a broad-spectrum insecticide, being
effective against a wide range of pests including houseflies, cockroaches, and
mosquitoes, many of which are resistant to chlorinated hydrocarbons. It has also been
recommended for control of vegetation pests, sand flies, bedbugs, fleas, ticks, and
stored product pests. Malathion is not as long lasting as the chlorinated hydrocarbons,
but it is used as a residual insecticide. It is not toxic to plants at concentrations normally
used on vegetation, but it will damage ornamentals at concentrations used to control
flies. Because of its low toxicity to mammals (LD50 1,000-1,375 mg/kg), malathion has
become one of the most commonly used insecticides. An objection to malathion for
household use is its disagreeable odor.
(b) Diazinon. Diazinon is a pale to dark brown liquid that is readily
soluble or miscible in most organic solvents. It is much more toxic to both insects and
animals (LD50 76-108 mg/kg) than is malathion, but it is diluted to much lower
concentrations. Diazinon is the insecticide of choice for controlling many household
insects, particularly German cockroaches. It is also used extensively for fly control as a
residual spray, in sugar-bait formulations, and for impregnating fly cords. Diazinon has
a somewhat longer residual effect than malathion, but at strengths of equal
effectiveness, malathion is preferred for routine military use because of its lower
mammalian toxicity. Diazinon is preferred over malathion in areas frequented by
people, because of the offensive odor of malathion.
(c) Dichlorvos. Dichlorvos (also known commercially as DDVP or
Vapona) is a relatively new insecticide that has a short residual life, but is remarkable
because of its high volatility. It gives off vapors slowly from impregnated resin strips
and is effective as a space insecticide. It is also added to dry and liquid fly baits to add
quick knockdown and its toxic vapor aids in "clean out" applications on hard-to-reach
infestations of cockroaches and dog ticks. It is more toxic than diazinon, having an oral
LD50 value of 56-80 mg/kg and a dermal LD50 value of 75-107 mg/kg.
(d) Naled. Naled (Dibrom) is an organophosphate insecticide that is
closely related chemically to dichlorvos. It is a contact and stomach poison with a
limited amount of vapor toxicity. The principle military use of naled is as a fog for adult
mosquitoes and flies. It is also effective, in a commercial form, as a bait or spot
treatment for flies. The LD50 value of naled is 250 mg/kg.
(e) Chlorpyrifos. Chlorpyrifos (Dursban) is used in the military
primarily for control of mosquito larvae and cockroaches. It also offers good control of
turf pests such as chinch bugs and sod webworms. It has an LD50 value of 135-163
mg/kg and may be irritating to the eyes.