Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

of the reference value at a blood Pb concentration of 0.68 mg/kg ww (wet weight).
Protoporphyrin concentrations showed a 4.2-fold increase at this same concentration.
Henny et al. (1991) studied osprey along the Coeur d=Alene River. There were no
observations of death, behavioral abnormalities, or reduced productivity related to Pb exposure,
although inhibition of blood ALAD and increased protoporphyrin concentrations were measured
in ospreys. Henny et al. (1991) hypothesized that no impacts to osprey were observed, even
though swan mortality was documented in the area because swans feed at a lower trophic level
(i.e., Pb does not biomagnify, and thus is found at higher concentrations in lower trophic level
organisms).
Hoffman et al. (2000a) also studied the effects of Coeur d’Alene River sediment on
waterfowl, focusing on mallard ducklings for 6 weeks after hatching. The study revealed that a
90% reduction in ALAD activity and a greater than 3-fold increase in protoporphyrin
concentration occurred when blood Pb reached a concentration of 1.41 mg/kg ww as a result of
the ducklings being fed a diet composed of 12% sediment (3449 mg/kg Pb). Those ducklings
fed a diet composed of 24% sediment were found to have a mean blood Pb concentration of
2.56 mg/kg ww and a greater than 6-fold increase in protoporphyrin concentration. Hoffman
et al. (2000b) also studied Canada Geese (Branta canadensis) goslings in a similar fashion.
The results revealed that, while blood Pb concentrations in goslings were approximately half
(0.68 mg/kg ww) of those found in ducklings under the same conditions (12% diet of
3449 mg/kg sediment Pb), goslings showed an increased sensitivity to Pb exposure. Goslings
experienced a 90% reduction in ALAD activity and a 4-fold increase in protoporphyrin
concentration, similar to conditions found in the ducklings, although blood Pb concentrations
were half those found in the ducklings. More serious effects were seen in the goslings when
blood Pb reached 2.52 mg/kg, including decreased growth and mortality.
Redig et al. (1991) reported a hawk LOAEL (lowest observed adverse effect level) of
0.82 mg/kg-day for effects on heme biosynthetic pathways. Lead dosages as high as 1.64 to
6.55 mg/kg-day caused neither mortality nor clinical signs of toxicity. A dose of 6.55 mg/kg-day
resulted in blood Pb levels of 1.58 µg/mL. There were minimal changes in immune function
(Redig et al., 1991).
Repeated oral administration of Pb resulted in biochemical alterations in broiler chickens
(Brar et al., 1997a,b). At a dose of 200 mg/kg-day Pb-acetate, there were significant increases in
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