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Johansen et al. (2004) found that lead contamination of the
meat of seabirds killed using lead shot occurred even though
shot was removed after cooking. Pain et al. (2010) found a
mean lead concentration of 1.181 mg/kg in meals prepared
from 121 wild-shot gamebirds of six species, with no significant
variation among species. Lead concentrations in the meals
were statistically related to both the number of shotgun pellets
and large fragments of lead removed before chemical analysis,
and the number of small radio-dense fragments, detected by
X-radiography of the gamebirds, which could not readily be
removed. High concentrations of lead occurred in some meals
prepared frombirds inwhichnowhole pellets or large fragments
were apparent on X-rays. The only plausible mechanism for this
is that lead particles remain in the meat after the removal of
whole shot and large fragments.
An arithmetic mean concentration of 0.414 mg/kg (414 ppb)
was found in twelve samples of pheasant meat purchased in the
UK and reported in FSA (2007).
Many other data on concentrations of lead in game meat are
summarised in EFSA (2010), but it is not clear whether or not
visible shot and bullet fragments had been removed prior to
analysis.
To protect human health, the European Commission sets
maximum levels (MLs) for contaminants, including lead, inmany
foods (Commission Regulation 1881/2006)(EC 2006). The ML for
lead in non-game meat (excluding offal) is 0.1 mg/kg, but no ML
has been set for game meat. The results presented above show
that lead concentrations in the meat of wild game animals shot
with lead ammunition and eaten by humans are often one or
two orders of magnitude higher than the non-game meat ML.
Bioavailability of
ammunition-derived lead
present in game meat and the
effect of its ingestion on blood
lead concentration
As described above, both lead shot and lead bullets fragment
when fired into quarry animals and produce pieces of lead of a
wide range of sizes which are embedded in the tissues. Some of
these are at a considerable distance from the wound and remain
after butchery and food preparation. Several studies indicate
elevation in the concentration of lead in the blood (B-Pb) of
people who eat game animals killed using lead ammunition,
which indicates that some ingested ammunition-derived lead
is absorbed (Bjerregaard et al. 2004, Johansen et al. 2006, Iqbal
2009, Dewailly et al. 2001, Bjermo et al. 2013, Meltzer et al.
2013, Knutsen et al. 2015). Analysis of stable isotope ratios of
lead in blood samples indicates that exposure to ammunition-
derived lead is the main cause of elevated blood lead (B-Pb) in
indigenous people in Canada (Tsuji et al. 2008).
Hunt et al. (2009) performed an experiment on pigs to assess
whether their B-Pb increased when they were fed on minced
meat from deer shot with lead-based bullets. Statistically
significant increases in their B-Pb were observed compared
with controls fed on meat that contained no fragments. Mean
blood lead concentrations in pigs peaked at 2.29 μg/dl two days
following first ingestion of fragment-containing venison, which
was 3.6 times higher than that of controls (0.63 μg/dl). Isotope
ratios of lead in the meat matched those of the lead in the
bullets used to shoot the deer, supporting the contention that
the absorption by the pigs was of dietary lead derived from the
ammunition.
These findings indicate that B-Pb of humans tends to increase
in association with consumption of game meat containing
ammunition-derived lead due to absorption of ammunition-
derived lead from the alimentary canal. However, without
further analysis, they do not indicate what proportion of the
ammunition-derived lead ingested is absorbed or how much
B-Pbisincreasedperunitofdietaryleadingested. Suchestimates
require either in vitro gastrointestinal simulation experiments
which attempt to simulate conditions in the human alimentary
canal or empirical studies in which both the intake of lead and
the elevation of B-Pb are measured.
The absolute bioavailability of dietary lead derived from
ammunition (the proportion of the ingested amount which
is absorbed and enters the blood) might be expected to be
lower than that of lead in the general diet because some of the
ingested ammunition lead may remain as metallic fragments
after cooking and processing in the alimentary canal. Metallic
lead, especially that remaining in large fragments, may not be
totally dissolved nor be absorbed in the intestine as readily as
more soluble lead salts and complexes (Barltrop and Meek 1975,
Oomen et al. 2003).
Mateo et al. (2011) used cookedmeat frompartridges killed with
UK human health risks from ammunition-derived lead