Environmental Engineering Reference
In-Depth Information
The pyrethroids are very persistent when used indoors. As much as 10%
of the initial concentration of permethrin and deltamethrin is found in house
dust 2 years after application. Pyrethroids are commonly observed in dust
samples collected in buildings with prior pest control treatment. Dust con-
centrations in the range of 2 to 320 mg/kg permethrin and 2 to 12 mg/kg
deltamethrin have been reported. Though less persistent, the catalyst PBO
can still be detected 2 years after application. Pyrethroids are only observed
in the gas phase immediately after application. At that time, high concen-
trations are associated with suspended particles, decreasing by 90+% 2 days
later and relatively slowly thereafter.
b. Biological levels.
Concentrations of pesticides in human tissues and
body fluids such as blood and urine may be an important indicator of
exposure. Population exposures to organochlorines, organophosphates, and
chlorophenoxy pesticides or their metabolites were evaluated in urine col-
lected from a sample of U.S. citizens in the second National Health and
Nutritional Examination Survey (NHANES) conducted during 1976-1980.
Pentachlorophenol (PCP) was the most frequently occurring (72% of the
sample population) pesticide residue observed in quantifiable concentra-
tions (geometric mean of 6.3 ng/ml). An estimated 119 million individuals
age 12 to 74 years old had been exposed to PCP at the time of the study.
PCP was used as a wood preservative and insecticide. It may be present in
biological samples as a metabolite of the insecticide lindane and the fungi-
cide hexachlorobenzene.
Other quantified pesticide residues included 3,5,6-trichloro-2-pyrindol
(a metabolite of chlorpyrifos, 5.8%), 2,4,5-trichlorophenol (3.4%),
p
-nitrophe-
nol (2.4%), dicambra (1.4%), malathion dicarboxylic acid (0.5%), malathion
α
-monocarboxylic acid (1.1%), and 2,4-D (0.3%). Dicambra and 2,4-D are
used as herbicides; 2,4,5-trichlorophenol as an antimicrobial biocide. Expo-
sures were likely to have been inadvertent as a result of their direct use,
indoor contamination, or with the possible exception of chlorpyrifos, resi-
dues on food.
Exposure to airborne PCP in U.S. PCP-treated log homes has been
reported to result in elevated blood serum PCP levels, ranging from 69 to
1340 ppb (w/v), with a geometric mean of 330 ppb. Geometric mean con-
centrations were significantly higher in children aged 2 to 7 years (510 ppb).
Serum PCP levels in a control population, on the other hand, were consid-
erably lower, ranging from 15 to 75 ppb, with a geometric mean of 37 ppb.
Elevated cyclodiene organochlorine insecticides (dieldrin, aldrin, hep-
tachlor, chlordane) in human breast milk have been reportedly associated
with termiticidal applications on soil around home perimeters. The greatest
contributor was heptachlor, presumably because of its higher volatility.
3. Lawn care products
Lawn care chemicals are used by approximately 18 million U.S. households
to control weed species, insect pests, and fungal pathogens. They may be
