Chemistry Reference
In-Depth Information
One of the earliest reports of cyclodiene poisoning in the field came from a coastal
area of the Netherlands (Koeman et al. 1967, Koeman and van Genderen 1970,
Koeman 1972), where sandwich terns (
Sterna sandvicensis
) died showing symptoms
of cyclodiene poisoning. Both adults and chicks were affected. Upon analysis, they
were found to contain residues of dieldrin, endrin, and telodrin at high-enough lev-
els, singly or in combination, to cause lethal toxicity. The source turned out to be a
neighboring factory that was synthesizing the compounds. These mortalities were
linked to a local decline in the sandwich tern population that began around 1962.
During the period 1965-1966, a decline of the buzzard (
Buteo buteo
) occurred in
the Netherlands, which brought the species close to extinction in certain agricultural
areas. Following investigation, this decline was attributed very largely to lethal poi-
soning by dieldrin (Fuchs 1967). Analysis of birds found in the field that had shown
symptoms of cyclodiene poisoning before dying contained a mean dieldrin concen-
tration of 18 ppm in their livers. From Britain came the evidence of widespread
decline of the sparrowhawk (
Accipiter nisus)
and the peregrine (
Falco peregrinus
).
The declines coincided in time with the introduction of aldrin, dieldrin, and hep-
tachlor into the country in 1956, and occurred in areas where the chemicals were
widely used (Ratcliffe 1993, Newton 1986; see Figures 5.7 and 5.8). Both species
are bird-eating raptors, which were exposed to high levels of dieldrin and heptachlor
epoxide in the tissues of the grain-eating birds on which they preyed. Cyclodiene
poisoning was confirmed in individual cases on the grounds of lethal tissue levels of
dieldrin or heptachlor epoxide or both, and toxic symptoms shown before death.
Sparrowhawks declined very sharply in the agricultural areas of eastern England
where cyclodienes were widely used, becoming virtually extinct in parts of East
Anglia where they had once been common. Such declines were not seen, however,
140
120
100
80
60
40
20
Restrictions on cyclodienes and DDT
4thEC ban
1st 2nd
3rd
0
1930
1950
55
60
Ye ar
62 64
67 69 71
76
79 80
90 91
fIgure 5.7
Peregrine population size in Britain (1930-1939 = 100) showing the 1961
population decline and subsequent recovery, together with an outline of pesticide usage (from
Ratcliffe 1993).
Search WWH ::
Custom Search