968 PESTICIDES
azinphos, malathion, dimethoate, dichlorvos, diazinon, chlor-
pyrifos, fenthion, mevinphos, phosphamidon, naled, and
fenitrothion; the carbamates carbaryl, carbofuran, aldicarb,
propoxur, and Zectran ® ; and the organochlorine compounds
aldrin, dieldrin, heptachlor, lindane; and the arsenicals. The
newer synthetic pyrethroids such as permethrin, fenvalerate,
deltamethrin, and flucythrinate are extremely toxic to bees
with LD 50 values 0.01 μ g per bee.
Group II moderately toxic LD 50 2.0–10.99 μ g per bee
includes DDT, endrin, endosulfan, mirex, chlordane, disul-
foton, phorate, demeton, ronnel, coumaphos, temephos, and
carbophenothon.
Group III relatively non-toxic LD 50 greater than 11.0 μ g
per bee includes all the common acaricides, trichlorfon,
cryolite, DDD, methoxychlor, rotenone, ryania, toxaphene,
the fungicides, the herbicides, and the defoliants.
Simple precautions such as avoiding insecticide applica-
tions during bloom, or applying toxic insecticides only as
soil and seed treatments can greatly minimize bee losses.PESTICIDES AND HUMANSHumans, in an ecological sense, are consumers at the top
of the food pyramid and are exposed to pesticide residues
contained nearly everywhere in cereals, fruits and vegeta-
bles, and in meat, fish and poultry. Additionally humans
are exposed directly to pesticides from occupational use
of aerosol products in the home, from home and garden
sprays, and from effluents from agricultural operations.
Therefore it is not surprising that traces of the stable
organochlorine insecticides are found in the body fats of
humans everywhere.DDT in HumansElaborate monitoring studies of pesticide residues in humans
have been reported by Hayes (1966), Durham (1969) and
Mrak (1969). DDT was first found in human fat in 1948 and
at least 9 general surveys of the DDT content of human fat
have been made in various areas of the United States. These
show that DDT is stored in the body fat of everyone in the
United States, with a mean storage level in the 1960’s of
about 8 ppm combined DDT and its principal metabolite
DDE. With the revoking of the registrations of DDT in 1973
and aldrin and dieldrin in 1974, the levels of these insecti-
cide residues in human body fat have declined slowly over
the next decade as shown in Table 10. However, detectable
tissue levels of oxychlordane, the principal persistent metab-
olite of chlordane, very widely used for household pest con-
trol have persisted unchanged (Table 10).
The storage levels of DDT and DDE in people in other
countries have also been investigated (Durham, 1969). The
levels were lowest in countries where little DDT is used,
for example Denmark with DDT 0.6 and DDE 2.7 ppm;
and highest in countries such as India, DDT 16 and DDE10 ppm, where large amounts of DDT are used in malaria
eradication.
The storage of DDT in human fat is a direct function
of level of intake and is lowest in meat abstainers, DDT 2.3
and DDE 3.6 ppm; and Eskimos, DDT 0.8 and DDE 2.2
ppm, whose diets contained the lowest amounts of DDT.
Volunteers given 35 mg per day orally stored DDT 281 and
DDE 40 ppm, and a formulator in a DDT factory had DDT
648 and DDE 483 ppm; yet these men remained in good
health (Hayes, 1966).
DDT and its metabolites DDE and DDD are also found
in other human tissues: blood DDT 0.0068 and DDE 0.0114
ppm, milk 0.08–0.13 ppm, adrenal glands 0.7 ppm (Durham,
1969). DDT ingested by humans is excreted slowly as 4,4-
dichlorodiphenyl acetic acid (DDA) which is present in the
urine of the general U.S. population at 0.02–0.18 ppm
(Hayes, 1966). The levels of DDA in human blood and urine
roughly parallel the rate of intake and can be used to monitor
the exposure (Mrak, 1969).
The significance of levels of DDT and its metabolites
DDE and DDD in the general population is complex.
Food is generally believed to contribute as much as 89%
of the total intake of DDT but recent studies showing sub-
stantial fat storage of DDT in Eskimos and in institutional
patients where DDT intake is very low suggest that non-
dietary sources such as house dust may contribute up to 50%
of the total body burden (Mrak, 1969). The non-white popu-
lation of the U.S. has significantly higher fat storage of DDT
than the white population suggesting the influence of dietary
factors and socioeconomic factors resulting in greater use of
house-hold insecticides. Fat storage of DDE increases with
the age of the population, especially in non-whites where
the level increased from 4.06 ppm in the 0–5 yrs category
to 8.61 ppm in 41–50 years, and 15.50 ppm at 90+ yrs.
Accumulation in states with cooler climates averaged 4.85
ppm as compared with 9.21 ppm in warmer States. There
is no clear cut evidence of a sex difference in fat storage of
DDT or in positive association with specific disease condi-
tions (Mrak, 1969).TABLE 10
Insecticide residues in human body fat—United StatesaYear DDT-Tppm in fatdieldrin oxychlordane1972 6.97 0.18 0.10
1974 5.15 0.14 0.12
1976 4.35 0.09 0.11
1978 3.52 0.09 0.11
1980 2.82 0.10 0.12
1983 1.67 0.06 0.10
a Council on Environmental Quality, 17th Report, 1987.C016_004_r03.indd 968C016_004_r03.indd 968 11/18/2005 11:00:08 AM11/18/2005 11:00:08 AM