Lead Toxicity in Mute Swans

the maximum tolerable limit for lead was calculated as follows:
2.20umoles/L X 207 1
142
- 3.00 ug Pb/ g Rb.
1 =atomic weight of lead.
thus, values of whole blood lead > 3.00ug Pb/g Rb is considered
elevated. Similarily values of greater than 1.07 umoles/L (60.00ug/
lOOmls) protoporphyrin have been adopted as indicative of excess lead
exposure after Bush~ al., (1982).
On the same . basis as lead, the
limit can be calculated as follows:
2
l.07umoles X 5612
142
molecular weight of PPIX.
- 4.00 ug PPIX/ gRb
thus samples with in excess of 4.00 ugPPIX/ gRb are considered to have
been exposed to elevated lead.
Age and physiological state were taken
into consideration for values of protoporphyrin IX and haemoglobin after
O'Ralloran ~al.,
(b, in press).
Statistics
All statistical calculations were carried out using a Minitab
statistical package (Pennsylvania University, U.S.A.) on a Vax VMS.
A
B.M.D.P. PLR stepwise logistic regression analysis was used to examine
the observed pattern of the proportion of birds of each class and age
with elevated lead at Cork Lough.
Medians and 25% percentiles were
calculated to describe the distribution of blood lead levels over the
two year sampling period.
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