Haematological parameters as predictors of blood lead and indicators of lead poisoning in the black duck ( Anas rubripes)

Abstract

The validity of various haematological parameters as indicators of blood lead concentration and lead poisoning in the black duck ( Anas rubripes) is discussed. Elevated (>40 μg dl −1) blood lead (PbB) levels were recorded in 41% of the 229 wild birds examined. No correlation was found between PbB concentration and haematocrit. Zinc protoporphyrin (ZPP) was positively correlated with PbB. Haemoglobin, δ-aminolevulinic acid dehydratase (ALA-d) activity and non-activated/activated ALA-d ratios were negatively correlated with PbB. The minimum PbB levels at which these parameters were affected varied greatly. ZPP and haemoglobin were relatively insensitive to PbB concentrations; whilst ALA-d activity and ALA-d ratio were influenced by PbB concentrations of <5 μg dl −1. Log 10 ALA0-d ratio was more strongly correlated with PbB (r = −0·953) than log 10 ALA-d activity (r = −0·914) and the predictive validity (% false −ve and +ve predictions) of the ratio method was higher. The high individual variability in ALA-d activities at low PbB levels was greatly reduced by the use of the ALA-d ratio method. The ALA-d ratio method proved the most efficient for screening black duck for lead poisoning in the field.