Environmental Engineering Reference
In-Depth Information
and usually are not disclosed. They often include a mixture of relatively low-
volatility solvent oils which help to dissolve and suspend insecticidal com-
pounds applied as emulsion sprays.
1. Organochlorines
Chlordane, heptachlor, lindane, aldrin, dieldrin, and
p
-dichlorobenzene are
chlorinated hydrocarbons. Their use and availability has been sharply
restricted in North America and Europe because of their suspected human
carcinogenicity. Therefore, indoor exposures are unlikely to be associated
with recent applications. However, because they are persistent, exposures
may continue for several decades after a single building-associated applica-
tion.
Para
-dichlorobenzene is one of the few chlorinated hydrocarbons still
widely used in residences and other buildings (moth balls, cakes, and flakes,
and as a deodorizing substance).
2. Organophosphates
Organophosphate insecticides used indoors have included dichlorvos, chlo-
rpyrifos, diazinon, and malathion. Dichlorvos has been widely used in bug
bombs (because of its relatively high volatility, 10
-2
mm Hg), slow-release
insecticidal strips, and flea collars for dogs and cats. Because of health
concerns, its use has dramatically declined in the U.S. since 1988. Chlorpy-
rifos has been one of the most widely used indoor pesticides. It was used
in most termiticidal treatments, to control cockroaches, and to control house-
hold flea infestations. These uses were phased out in the year 2000 as a
consequence of a USEPA/industry agreement.
3. Carbamates
The carbamates are widely used insecticides. They are N-substituted esters
of carbamic acid
(NH
2
-C=O)
OH
Commonly used carbamate insecticides include carbaryl, aldicarb, carbofu-
ran, propoxur, and bendiocarb. Carbaryl, also called Sevin
TM
, is the most
widely used of these compounds. Both carbaryl and propoxur have been
detected in indoor environment samples.
4. Pyrethrins and pyrethroids
Pyrethrins and pyrethroids represent a class of related insecticidal chemicals.
Pyrethrins are components of a natural extract of a
Chrysanthemum
species.
The six main pyrethrin components are cyclopropane esters. Because of their
sensitivity to photochemical degradation, use has been limited to indoor
applications such as fly sprays. In the last two decades, however, synthetic
