âä%”läi
"Ê1fï añmwz œcu:æz 11 g nnmairî mäîïî ïî ïï&
ff"
_
w mfîÏiwDiff
Éaäîi% (Wi %lmn prmnpæd €Éæ Fûf êlîfï U‘î'lfë
"_Ë
m
$“lîîfîä; of tîœ &!ilâ pmdtæf:
Êfî
1mmeî it”:
m 111; 5
—î—
% Wm1Ætæ &. æ'iæ;
33
Æ£_Î
xma:f
Làe
mt the Late
rte:
::
me“! F‘Ef=
%nnaæ lf && pæt'Æit attack of 8621 la:mpr£f”- 3Ï’ï za:
Ηf—‘Î @
up mnän :m £;æai Laher iron: the Atlantic
,
_
_
noi or3‘ made the coho saîmon m :; =“£Ëi£ ?îî EîΗræ
…le the man—induced a]reraoŒ m :n. 55ng 3:
… E—
1451 …50
tested 5yi@51gan Üenm n:_
…
;:
âhcvæ :tamicæ :svnrp‘mm5 iii… ËÈJUËUEËË EEE {57355 î_Æ1
%mmnïæ ‘läe Êüngm… ing:
m‘aŒ âme Z!Œ:ËI Ëmm în Es—i En… mi m È:r mnn zhnm1_
same enrnärŒ… we must ŒÆn‘niÿ are cîoæ 111 the iæ1ger 3ŒDL
îî
we :mmm‘:æræmÿ amat
ahxihp.
ier—. the hmidup occurred, mi it seems unlikelÿ te drap 5harplv ter some
time, despite bans on must Wideæale uses of DDT insztŒed &ÎŒ 5368 m
Michigan amd Wïæonän. E1 1970, for example, coho saLmon tested bv d1e
Fisherv Laboratory had average DDT concentrations of l—i.l
,
ppm. Theaverage£orl9 lake—trontwas 19 ppm, With the range
om 11 to 28
ppm. These and OËLEI tests showed no downward trend £rom concentrations
The 1970 Great Lakes Fishery Laboratory tests also revealed an average
concatraon of 0.27 ppm of dieldm‘n (a chemical cousin of DDT) in the lake
trout and 0.12 ppm in the larger coho salmon. These averages exceeded the
maximum value of 0.1 ppm for this pesticide in sh recommended by the In—
terstate Pesticide Committee formed under the auspices of the Lake MÏCh—
igan conferences and they approached the FDA actionable level of 0.3 ppm;
a number of individual sh did have dieldrin concentrations exceeding the 0-3
ppm level. Persistent levels of chlonated hydrocarbon pesticides like DDT
and dieldn, despite closer regulation, may result from accumulations in
0430
older sh over a period of years, a factor that will be hard to assess until
younger fish are examined in the future. The levels also reect the presence
in
_
the environment of & widespread reservoir of durable chemicals that has built
up since World War II and that Will be With us for many years to come [10]This chemical reservoir is the critical factor in the extent of long—term
16
Assault on a Lake
"Ê1fï añmwz œcu:æz 11 g nnmairî mäîïî ïî ïï&
ff"
_
w mfîÏiwDiff
Éaäîi% (Wi %lmn prmnpæd €Éæ Fûf êlîfï U‘î'lfë
"_Ë
m
$“lîîfîä; of tîœ &!ilâ pmdtæf:
Êfî
1mmeî it”:
m 111; 5
—î—
% Wm1Ætæ &. æ'iæ;
33
Æ£_Î
xma:f
Làe
mt the Late
rte:
::
me“! F‘Ef=
%nnaæ lf && pæt'Æit attack of 8621 la:mpr£f”- 3Ï’ï za:
Ηf—‘Î @
up mnän :m £;æai Laher iron: the Atlantic
,
_
_
noi or3‘ made the coho saîmon m :; =“£Ëi£ ?îî EîΗræ
…le the man—induced a]reraoŒ m :n. 55ng 3:
… E—
1451 …50
tested 5yi@51gan Üenm n:_
…
;:
âhcvæ :tamicæ :svnrp‘mm5 iii… ËÈJUËUEËË EEE {57355 î_Æ1
%mmnïæ ‘läe Êüngm… ing:
m‘aŒ âme Z!Œ:ËI Ëmm în Es—i En… mi m È:r mnn zhnm1_
same enrnärŒ… we must ŒÆn‘niÿ are cîoæ 111 the iæ1ger 3ŒDL
îî
we :mmm‘:æræmÿ amat
ahxihp.
ier—. the hmidup occurred, mi it seems unlikelÿ te drap 5harplv ter some
time, despite bans on must Wideæale uses of DDT insztŒed &ÎŒ 5368 m
Michigan amd Wïæonän. E1 1970, for example, coho saLmon tested bv d1e
Fisherv Laboratory had average DDT concentrations of l—i.l
,
ppm. Theaverage£orl9 lake—trontwas 19 ppm, With the range
om 11 to 28
ppm. These and OËLEI tests showed no downward trend £rom concentrations
The 1970 Great Lakes Fishery Laboratory tests also revealed an average
concatraon of 0.27 ppm of dieldm‘n (a chemical cousin of DDT) in the lake
trout and 0.12 ppm in the larger coho salmon. These averages exceeded the
maximum value of 0.1 ppm for this pesticide in sh recommended by the In—
terstate Pesticide Committee formed under the auspices of the Lake MÏCh—
igan conferences and they approached the FDA actionable level of 0.3 ppm;
a number of individual sh did have dieldrin concentrations exceeding the 0-3
ppm level. Persistent levels of chlonated hydrocarbon pesticides like DDT
and dieldn, despite closer regulation, may result from accumulations in
0430
older sh over a period of years, a factor that will be hard to assess until
younger fish are examined in the future. The levels also reect the presence
in
_
the environment of & widespread reservoir of durable chemicals that has built
up since World War II and that Will be With us for many years to come [10]This chemical reservoir is the critical factor in the extent of long—term
16
Assault on a Lake