Developmental Toxicity of Lead-Contaminated Sediment to Mallard Ducklings

Abstract

Sediment ingestion has been identified as an important exposure route for toxicants in waterfowl. The toxicity of lead-contaminated sediment from the Coeur d'Alene River Basin (CDARB) in Idaho was examined on posthatching development of mallard (Anas platyrhynchos) ducklings for 6 weeks. Day-old ducklings received either untreated control diet, clean sediment (24%) supplemented control diet, CDARB sediment (3,449 microg/g lead) supplemented diets at 12% or 24%, or a positive control diet containing lead acetate equivalent to that found in 24% CDARB. The 12% CDARB diet resulted in a geometric mean blood lead concentration of 1.41 ppm (WW) with over 90% depression of red blood cell ALAD activity and over threefold elevation of free erythrocyte protoporphyrin concentration. The 24% CDARB diet resulted in blood lead of 2.56 ppm with over sixfold elevation of protoporphyrin and lower brain weight. In this group the liver lead concentration was 7.92 ppm (WW), and there was a 40% increase in hepatic reduced glutathione concentration. The kidney lead concentration in this group was 7.97 ppm, and acid-fast inclusion bodies were present in the kidneys of four of nine ducklings. The lead acetate positive control group was more adversely affected in most respects than the 24% CDARB group. With a less optimal diet (mixture of two thirds corn and one third standard diet), CDARB sediment was more toxic; blood lead levels were higher, body growth and liver biochemistry (TBARS) were more affected, and prevalence of acid-fast inclusion bodies increased. Lead from CDARB sediment accumulated more readily in duckling blood and liver than reported in goslings, but at given concentrations was generally less toxic to ducklings. Many of these effects are similar to ones reported in wild mallards and geese within the CDARB.

Effects of lead exposure on oxidative stress biomarkers and plasma biochemistry in waterbirds in the field

“…This effect was also observed in previous studies with mallard ducklings experimentally exposed to Pb with sediment contaminated with Pb acetate (828 mg/g Pb dry weight; Hoffman et al, 2000), adult mute swans exposed to Pb contaminated sediment (700 mg/g Pb dry weight; Day et al, 2003) and mallard ducks with Pb contaminated food (1840 mg/g Pb dry weight; Mateo et al, 2003b). Alkaline phosphatase is an indicator of osteoblastic activity (Campbell, 1986), and Pb exposure has been associated with altered bone mineralization in birds (Gangoso et al, 2009).…”

Evidence of species-specific detoxification processes for trace elements in shorebirds

“…Nonetheless, in contrast to terrestrial birds and some waterbirds (e.g. Anatidae) for which oxidative stress related to trace elements has been demonstrated in the wild or experimentally (Hoffman et al 2000;Hoffman 2002;Mateo et al 2003;Berglund et al 2007;Lucia et al 2009), cellular damages due to trace elements are relatively unexplored in shorebirds. Filling in these gaps in the data is crucial for these endangered species.…”

Relating the ability of mallards to ingest high levels of sediment to potential contaminant exposure in waterfowl

“…These blood chemistries are indicative of an animal's general health, and the methods used to make the hematocrit and blood plasma chemistry measurements are discussed in an earlier article [6].…”