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

Nutritional Factors
Diet is a significant modifier of Pb absorption and of toxic effects in many species of
birds and mammals (Eisler, 1988). Dietary deficiencies in calcium, zinc, iron, vitamin E, copper,
thiamin, phosphorus, magnesium, fat, protein, minerals, and ascorbic acid increased Pb
absorption and its toxic effects (Eisler, 1988).
Mateo et al. (2003b) studied intraspecies sensitivity to Pb-induced oxidative stress, by
varying the vitamin E content of mallard diets. Vitamin E can protect against peroxidative
damage and was found to decrease the lipid peroxidation in nerves of birds; however, it did not
alleviate any sign of the Pb poisoning. The authors hypothesize that inhibition of antioxidant
enzymes and interaction with sulfhydryl groups of proteins may have a greater influence on Pb
toxicity than lipid peroxidation (Mateo et al., 2003b). The effects observed by Mateo et al.
(2003b) were associated with very high concentrations of Pb in diet (1840 mg Pb/kg diet), much
higher than would be found generally in the environment, and high enough that the birds
decreased their food intake.
Mallard ducklings were exposed to Pb-contaminated sediment and either a low nutrition
or optimal nutrition diet (Douglas-Stroebel et al., 2005). Lead exposure combined with a
nutritionally inferior diet caused more changes in behavior (as measured by time bathing, resting,
and feeding) than Pb exposure or low-nutrition diet alone. These effects may be due to the lownutrition
diet being deficient in levels of protein, amino acids, calcium, zinc, and other nutrients.
Zebra finches (Taeniopygia guttata) were exposed to Pb-acetate via drinking water at
20 mg/L for 38 days, along with either a low- or high-calcium diet (Snoeijs et al., 2005). Lead
uptake into tissues was enhanced by a low-calcium diet. Lead did not affect body weight,
hematocrit, or adrenal stress response. Lead suppressed the humoral immune response only in
females on a low-calcium diet, suggesting increased susceptibility of females to Pb (Snoeijs
et al., 2005).
Interactions with Other Pollutants
Lead can interact with other pollutants to exert toxicity in an antagonistic (less than
additive), independent, additive, or synergistic (more than additive) manner. Concurrent
exposure to Pb and additional pollutant(s) can affect the ability of plants to uptake Pb or the
other pollutant. However, the uptake and toxic response of plants exposed to Pb combined with
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