Graded associations of blood lead and urinary cadmium concentrations with oxidative-stress-related markers in the U.S. population: results from the third National Health and Nutrition Examination Survey

Abstract

Although oxidative stress has been proposed as a mechanism of lead and cadmium toxicity mostly based on in vitro experiments or animal studies, it is uncertain whether this mechanism is relevant in the pathogenesis of lead- or cadmium-related diseases in the general population with low environmental exposure to lead and cadmium. We examined associations of blood lead and urinary cadmium levels with oxidative stress markers of serum gamma-glutamyltransferase (GGT), vitamin C, carotenoids, and vitamin E among 10,098 adult participants in the third U.S. National Health and Nutrition Examination Survey. After adjusting for race, sex, and age (plus serum total cholesterol in the case of serum carotenoids and vitamin E), blood lead and urinary cadmium levels both showed graded associations, positive with serum GGT and inverse with serum vitamin C, carotenoids, and vitamin E (p for trend < 0.01, respectively). These associations were consistently observed among most subgroups: non-Hispanic white, non-Hispanic black, men, women, all age groups, nondrinkers, drinkers, nonsmokers, ex-smokers, current smokers, and body mass index (< 25, 25-29.9, and > or = 30). The strong association of blood lead and urinary cadmium levels with oxidative stress markers in this population suggests that oxidative stress should be considered in the pathogenesis of lead- and cadmium-related diseases even among people with low environmental exposure to lead and cadmium.

Figure 1

Geometric means of serum GGT (A), vitamin C (B), carotenoids (C), and vitamin E (D) by deciles of blood lead or urinary cadmium levels, adjusted for race, sex, age, education, and poverty income ratio. Concentrations of carotenoids and vitamin E were additionally adjusted for serum cholesterol. Serum carotenoids were the sum of α-carotene, β-carotene, β-cryptoxanthin, zeaxanthin/lutein, and lycopene.