Lead Toxicity in Mute Swans

irds had the lowest median level during the moulting period, June­
August (Fig. 3).
Blood Lead Level and Protoporphyrin as measures of exposure.
There was a considerable range of protoporphyrin values from a
maximum of 40.00 ug PPIX/ gHb in acutely lead poisoned birds to 1.90 ug
PPIX/ gHb in normal healthy birds (6.0 umoles - 0.10 umoles, n = 357).
In both caged and field individuals, there was no difference in the
protoporphyrin level either during the day or night.
To determine
whether FRBCP alone would confidently predict lead poisoning in swans, a
sample of 357 specimens with different lead levels were run 'blindly'
for FRBCP.
The distribution of blood lead and FRBCP are given in
Fig.4.
The percentage of birds detected with elevated lead levels,
using whole blood lead as a measure, was 44.00% (Fig.4) being higher
than the proportion detected using FRBCP, which was 34.50% (Fig. 4a,
4b).
However, of the 158 birds detected as having elevated lead, using
whole blood lead, only 43% showed elevated FRBCP.
Similarly of the
samples with elevated FRBCP, 50% had low lead levels and were thus false
positives by this criterion. These false positives were eliminated from
the analysis and the distribution of PP IX values is presented in Fig.
4C. The details of the birds eliminated are' as follows: 10 birds were
moulting, five birds had just completed moult, nine were cygnets of less
than 6 months old, one was anaemic, 10 birds had high blood lead levels
from two months to one year before being sampled for protoporphyrin and
in some cases the blood lead levels in the interval were low and 25 were
anomalous on the basis that no other sample was available· prior to the
PP IX reading.
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