Human consumers of wildlife killed with lead ammunition may be exposed to health risks associated with lead ingestion. This hypothesis is based on published studies showing elevated blood lead concentrations in subsistence hunter populations, retention of ammunition residues in the tissues of hunter-killed animals, and systemic, cognitive, and behavioral disorders associated with human lead body burdens once considered safe. Our objective was to determine the incidence and bioavailability of lead bullet fragments in hunter-killed venison, a widely-eaten food among hunters and their families. We radiographed 30 eviscerated carcasses of White-tailed Deer (Odocoileus virginianus) shot by hunters with standard lead-core, copper-jacketed bullets under normal hunting conditions. All carcasses showed metal fragments (geometric mean = 136 fragments, range = 15–409) and widespread fragment dispersion. We took each carcass to a separate meat processor and fluoroscopically scanned the resulting meat packages; fluoroscopy revealed metal fragments in the ground meat packages of 24 (80%) of the 30 deer; 32% of 234 ground meat packages contained at least one fragment. Fragments were identified as lead by ICP in 93% of 27 samples. Isotope ratios of lead in meat matched the ratios of bullets, and differed from background lead in bone. We fed fragment-containing venison to four pigs to test bioavailability; four controls received venison without fragments from the same deer. Mean blood lead concentrations in pigs peaked at 2.29 µg/dL (maximum 3.8 µg/dL) 2 days following ingestion of fragment-containing venison, significantly higher than the 0.63 µg/dL averaged by controls. We conclude that people risk exposure to bioavailable lead from bullet fragments when they eat venison from deer killed with standard lead-based rifle bullets and processed under normal procedures. At risk in the U.S. are some ten million hunters, their families, and low-income beneficiaries of venison donations.
Dedicated to J. Hoover Mackin, who initiated study of the Indian Peak-Caliente ignimbrite fi eld with his recognition in the 1950s that the "lava fl ows" near Cedar City are actually widespread ignimbrites, including the unusual trachydacitic Isom-type tuffs and the colossal Needles Range monotonous intermediates.
Measurable molybdenum isotope fractionation in
molybdenites from different ore deposits through time
provides insights into ore genesis and a new technique to
identify open-system behavior of Re–Os in molybdenites.
Molybdenite samples from six porphyry copper deposits,
one epithermal polymetallic vein deposit, four skarns, and
three Fe-oxide Cu–Au deposits were analyzed. The δ97Mo‰
(where δ97Mo = [(97Mo/95Mosample)/(97Mo/95MoICPMS standard)]-1 x 1000 ) for
all samples varied from 1.34±0.09‰ to −0.26±0.04‰. This
is the largest molybdenum isotopic variation in molybdenite
from high-temperature ore deposits recorded to date.
δ97Mo‰ of molybdenite varies as a function of the
deposit type and the rhenium and osmium concentrations
of the samples. Isotope values for Mo also vary within the
individual deposits. In general, molybdenites from porphyry
copper deposits have the lightest values averaging
0.07±0.23‰ (1σ). Molybdenites from the other deposit
types average 0.49±0.26‰ (1σ). The variations could be
related to the fractionation of Mo into different mineral
phases during the ore-forming processes. A comparison of
the Mo isotope ratios and the Re–Os ages obtained from
the same aliquot may possess a geochronological evaluation
tool. Samples that yielded robust ages have different
Mo isotopic compositions in comparison to samples that
yielded geologically unreasonable ages. Another observed
relationship between the Re–Os andMo isotope data reveals a
weak correspondence between Re concentration and Mo
isotope composition. Molybdenites with higher concentrations
of Re correspond to lighter Mo isotope values.This material is based upon work supported by
the National Science Foundation under grant nos. CHE-0431328 and
EAR 05-19144
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