sJ'
'
water damage, and local bans on pesticide use are only partial barriers to in—
uxes from the reservoir. To give one illustration, Wisconsin ihvestigators
analyzed clams and other invertebrates near the months of rivers owing into
Lake Michigan and Lake Superior. In certain locations, they discovered
somewhat high levels of dieldrin and sought out the sources of the pesticide
upstream. One was a wool—dying operation where dieldrin was used to moth—
proof the wool; some of the chemical was washed into the plant’s sewage sys—
tem and subsequently into a stream. Once plant ofcials stopped using diel—
drin for mothproong, everyone thought all would be well, but new tests
indicated that lesser amounts of dieldrin were still present in the plant’s ef—
uent. Puzzled investigators nally tested the virgin wool shipped into the
plant and discovered that it, too, contained traces of dieldrin. They concluded
that the wool had become contaminated even before it was sheared from the
sheep’s back, probably when the range animal was routinely treated with a
disinfectant mixture containing dieldrin.
An unwitting addition to the reservoir of dangerous, long—lived materials
in man’s environment has been the aCCÎdental release of another chlorinated
hydrocarbon called polychlorinatedbiphenyls (PCBS). Ulized for number
of industrial purposes, this material is noW Widespread in the biosphère, like
_
DDT, has become concentrated along the food chain [il]. In lusreport on
the 1970 pesticide _assays in Lake Michigan, Dr. Mount pointed outthatlake
water samples exammed in one laboratory contained 50to75partspertiil—
lion of
comparison, studies in the late lQGOsbyÏthfä
.
Resources Commission indicatedthat the
always less than 10 parts
trillion in open lake water.
f
Concentrations of PCBs albng the food chain
found in
marine life, seabirds, and birds
prey[12]. T_he hazards of “PCB are not yet
completely
complicated by the fact that some PCB
mixtures,
maufactur—ed in Europe and ]apan, appear
to be
contarhinated With
«of toxic impurities. Although concentra—
muCh too small to be a direct threat to human
health, PCB levels of only a few parts per billion (ppb) are toxic to some ma—
.
rine crustaceans, mollusks, and sh. The chemicals have affected the repro—
ductive system in some birds, although apparently not as markedly as has
DDT, and laboratory tests have shown that concentrations as low as 10 to 25
ppb inhibit the growth of two types of one—celled algae found in the ocean
[13]. Environmental hazards are increased by interactions between PCBs,
DDT, and other chlorinated pesticides which produce an effect that is greater
than that caused by one of the chemicals alone [14].
Other chemicals called phthalates are also accumulating in Lake Mich—
…,
igan. These substances are Widely used as plasticizers to impart exibility to
_
polyvinyl plastics; they also have been used in insecticides [15]. Even though
chemically different from DDT, the capacity of phthalates to become con- '
,
centrated along the food chain in the same fashion as DDT has
lished at the Fish—Pesticide Research Laboratory in Columbia,
though the chemicals were of fairly low direct. toxicity to
mtests
‘
,
:ChemicaiPlH
17
*
'
water damage, and local bans on pesticide use are only partial barriers to in—
uxes from the reservoir. To give one illustration, Wisconsin ihvestigators
analyzed clams and other invertebrates near the months of rivers owing into
Lake Michigan and Lake Superior. In certain locations, they discovered
somewhat high levels of dieldrin and sought out the sources of the pesticide
upstream. One was a wool—dying operation where dieldrin was used to moth—
proof the wool; some of the chemical was washed into the plant’s sewage sys—
tem and subsequently into a stream. Once plant ofcials stopped using diel—
drin for mothproong, everyone thought all would be well, but new tests
indicated that lesser amounts of dieldrin were still present in the plant’s ef—
uent. Puzzled investigators nally tested the virgin wool shipped into the
plant and discovered that it, too, contained traces of dieldrin. They concluded
that the wool had become contaminated even before it was sheared from the
sheep’s back, probably when the range animal was routinely treated with a
disinfectant mixture containing dieldrin.
An unwitting addition to the reservoir of dangerous, long—lived materials
in man’s environment has been the aCCÎdental release of another chlorinated
hydrocarbon called polychlorinatedbiphenyls (PCBS). Ulized for number
of industrial purposes, this material is noW Widespread in the biosphère, like
_
DDT, has become concentrated along the food chain [il]. In lusreport on
the 1970 pesticide _assays in Lake Michigan, Dr. Mount pointed outthatlake
water samples exammed in one laboratory contained 50to75partspertiil—
lion of
comparison, studies in the late lQGOsbyÏthfä
.
Resources Commission indicatedthat the
always less than 10 parts
trillion in open lake water.
f
Concentrations of PCBs albng the food chain
found in
marine life, seabirds, and birds
prey[12]. T_he hazards of “PCB are not yet
completely
complicated by the fact that some PCB
mixtures,
maufactur—ed in Europe and ]apan, appear
to be
contarhinated With
«of toxic impurities. Although concentra—
muCh too small to be a direct threat to human
health, PCB levels of only a few parts per billion (ppb) are toxic to some ma—
.
rine crustaceans, mollusks, and sh. The chemicals have affected the repro—
ductive system in some birds, although apparently not as markedly as has
DDT, and laboratory tests have shown that concentrations as low as 10 to 25
ppb inhibit the growth of two types of one—celled algae found in the ocean
[13]. Environmental hazards are increased by interactions between PCBs,
DDT, and other chlorinated pesticides which produce an effect that is greater
than that caused by one of the chemicals alone [14].
Other chemicals called phthalates are also accumulating in Lake Mich—
…,
igan. These substances are Widely used as plasticizers to impart exibility to
_
polyvinyl plastics; they also have been used in insecticides [15]. Even though
chemically different from DDT, the capacity of phthalates to become con- '
,
centrated along the food chain in the same fashion as DDT has
lished at the Fish—Pesticide Research Laboratory in Columbia,
though the chemicals were of fairly low direct. toxicity to
mtests
‘
,
:ChemicaiPlH
17
*