1 Introduction
Lead is a naturally occurring and highly toxic element that has no known biological
function. Lead can affect all body systems due to its ability to compete with calcium
for binding sites, disrupting calcium-mediated functions such as cell to cell communication,
cell division and communication, and organization of the cytoskeleton
(Goyer and Clarkson 2001 ). Lead poisoning has been documented in humans for at
least 2500 years and in waterfowl from spent lead shot for over 100 years (Grinnell
1894 ; Hough 1894 ; Eisler 2000 ). In that time, the ecotoxicological properties of
lead have been extensively reviewed (Eisler 2000 ). Today lead is primarily used in
the manufacture of storage batteries, alloys, pigments and chemicals, and in
ammunition.
Wildlife can be exposed to lead from numerous sources, including mining and
smelter emissions, lead-based paint, lead fi shing sinkers, and spent ammunition.
Incidental mortality from waterfowl hunting reached population-level effects when
over two million ducks and geese (~2 % of all waterfowl) were poisoned annually
by ingestion of spent lead shot deposited in sediments (Bellrose 1951 ). Later, effects
to bald eagles ( Haliaeetus leucocephalus ) preying upon lead exposed waterfowl
were documented (Griffi n et al. 1980 ; Pattee and Hennes 1983 ). To alleviate this
problem, between 1986 and 1991 the United States Fish and Wildlife Service
( USFWS ) phased-in a nationwide restriction on the use of lead shot for hunting
waterfowl and American coots ( Fulica Americana ; USFWS 1986 , 1995 ). While
this ban resulted in a reduction of exposure in waterfowl (Anderson et al. 2000 ),
lead shot and rifl e bullets are still widely used for hunting upland birds and large and
small game animals. Therefore, lead poisoning from the ingestion of ammunition
and fragments persists in some groups of avian species. In addition to waterfowl,
lead exposure and poisoning has been reported in a variety of avian species in the
United States, including those protected under the Migratory Bird Treaty Act , the
6.5 Southwest ………………………………………………………………………………………………… 157
6.6 Bald Eagles in the Midwest ………………………………………………………………………… 158
6.7 California Condor ……………………………………………………………………………………… 160
7 Association of Lead Exposure with Spent Ammunition ………………………………………….. 163
7.1 Temporal Association with Hunting Season ………………………………………………….. 163
7.2 Detection of Ammunition …………………………………………………………………………… 164
7.3 Isotopic Ratios in Lead-Exposed Birds …………………………………………………………. 165
8 Alternate Sources of Lead as Potential Exposure Routes ………………………………………… 169
8.1 Fishing Sinkers and Lures …………………………………………………………………………… 169
8.2 Microtrash and Other Metal Objects …………………………………………………………….. 170
8.3 Paint ………………………………………………………………………………………………………… 171
8.4 Mine Tailings ……………………………………………………………………………………………. 172
8.5 Shooting Ranges ……………………………………………………………………………………….. 173
9 Toxicity of Alternative Metals Used in Ammunition ……………………………………………… 174
9.1 Non-toxic Shot Approval Process ………………………………………………………………… 174
9.2 Toxicity of Alternative Metals …………………………………………………………………….. 176
10 Conclusion ……………………………………………………………………………………………………….. 178
References ……………………………………………………………………………………………………………….. 179
N.H. Golden et al.
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Endangered Species Act , and the Bald and Golden Eagle Protection Act (Bellrose
1959 ; Pain et al. 2009 ). This review focuses specifi cally on scavenging avian species
exposed to spent lead via foraging habits.
A Review and Assessment of Spent Lead Ammunition and Its Exposure and Effects to Scavenging Birds in the United States