poisoning of raptors with organophosphorus and carbamate ...

M•mcvI 1999 PESTICIDE POISONING OF RAPTORS 27
Table 14. Extended.
% POSITIVE
FOR EXPOSURE
TO CHE
INHIBITORS
12%
3%
6%
3%
o%
3%
74%
39-40%
COMMENTS
Impact trauma most frequent
cause of death.
Only 22 AChE tests carried out.
AChE tests on 17 B.O. and 3 Pueo.
Principally Red-tailed Hawks.
Range reflects two criteria for exposure
(plasma ChE reduced by
50% or 2 SD below the mean).
6.0-20% Range reflects two criteria for exposure
(plasma ChE reduced by
50% or 2 SD below the mean).
10-15% Reduction relative to 1990-95 may
reflect selective removal of more
6.7-17%
toxic
alternatives.
Several ChE-inhibiting products are used on and
around livestock. In the U.S., for example, they include
such potentially toxic compounds as coumaphos,
dichlorvos, phosmet, diazinon and tetrachlorvinfos
as well as fenthion and famphur. A
review of the potential for exposure and intoxication
in raptors and other species is clearly warranted.
Granular Insecticides. Although secondary poisoning
of raptors resulting from liquid applications
of pesticides appeared to be restricted to
extremely toxic products (e.g., carbofuran, parathion,
monocrotophos, fenthion), granular formulations
delivered the insecticide in such a high
concentration that a broader selection of products
resulted in toxicity to scavenging birds of
prey. A good example is the series of Bald Eagle
and Red-tailed Hawk poisonings in the Fraser Valley
of British Columbia, Canada. Kills were initially
seen with the extremely toxic carbofuran
and fensulfothion (Mineau 1993, Elliott et al.
1996). Then came a number of phorate incidents
(Elliott et al. 1997) when farmers switched to that
granular product. When phorate was voluntarily
withdrawn by the manufacturer, incidents involving
terbufos and then fonofos were recorded (Tables
4, 8). This indicated that, under the particular
conditions, the answer is to be found in
products of much lower acute toxicity (probably
nonChE-inhibiting insecticides), nongranular formulations
or nonpesticidal control strategies.
Whereas modifying the granule base may meet
with some success in reducing kills of songbirds
and other species actively seeking pesticide granules,
it will not solve that particular problem
which has at its root the 'passive' taking of pesticide
granules from puddles and flooded field ar-
eas.
CONCLUSIONS
16% Known uses of granular carbofuran
in vicinity. Higher numbers in
the winter season as seen by Elliott
et al. 1996, 1997.
The loss of birds of prey to ChE-inhibiting pesticides
is real and can be significant. The more we
look for evidence, the more we find. Whether or
not current levels of mortality from labeled uses of
pesticides are high enough to affect local populations
is less important than the fact that most of
this mortality is easily preventable. A few regulatory
actions in North America would be sufficient to
solve most problems. Both in North America and
Europe, more education and enforcement are
needed to prevent pesticide abuse.
Recommendations for Future Research and