Whole blood lead levels are associated with radiographic and symptomatic knee osteoarthritis: a cross-sectional analysis in the Johnston County Osteoarthritis Project

Abstract Introduction Lead (Pb) is known to affect bone, and recent evidence suggests that it has effects on cartilage as well. As osteoarthritis (OA) is a highly prevalent disease affecting bone and cartilage, we undertook the present analysis to determine whether whole blood Pb levels are associated with radiographic and symptomatic OA (rOA and sxOA, respectively) of the knee. Methods The analysis was conducted using cross-sectional data from the Johnston County Osteoarthritis Project, a rural, population-based study, including whole blood Pb levels, bilateral posteroanterior weight-bearing knee radiography and knee symptom data. rOA assessment included joint-based presence (Kellgren-Lawrence (K-L) grade 2 or higher) and severity (none, K-L grade 0 or 1; mild, K-L grade 2; moderate or severe, K-L grade 3 or 4), as well as person-based laterality (unilateral or bilateral). SxOA was deemed present (joint-based) in a knee on the basis of K-L grade 2 or higher with symptoms, with symptoms rated based on severity (0, rOA without symptoms; 1, rOA with mild symptoms; 2, rOA with moderate or severe symptoms) and in person-based analyses was either unilateral or bilateral. Generalized logit or proportional odds regression models were used to examine associations between the knee OA status variables and natural log-transformed blood Pb (ln Pb), continuously and in quartiles, controlling for age, race, sex, body mass index (BMI), smoking and alcohol drinking. Results Those individuals with whole blood Pb data (N = 1,669) had a mean (±SD) age of 65.4 (±11.0) years and a mean BMI of 31.2 (±7.1) kg/m2, including 66.6% women and 35.4% African-Americans, with a median blood Pb level of 1.8 μg/dl (range, 0.3 to 42.0 μg/dl). In joint-based analyses, for every 1-U increase in ln Pb, the odds of prevalent knee rOA were 20% higher (aOR, 1.20; 95% CI, 1.01 to 1.44), while the odds of more severe rOA were 26% higher (aOR, 1.26; 95% CI, 1.05 to 1.50, under proportional odds). In person-based analyses, the odds of bilateral rOA were 32% higher for each 1-U increase in ln Pb (aOR, 1.32; 95% CI, 1.03 to 1.70). Similarly for knee sxOA, for each 1-U increase in ln Pb, the odds of having sxOA were 16% higher, the odds of having more severe symptoms were 17% higher and the odds of having bilateral knee symptoms were 25% higher. Similar findings were obtained with regard to ln Pb in quartiles. Conclusions Increases in the prevalence and severity measures for both radiographically and symptomatically confirmed knee OA (although statistically significant only for rOA) were observed with increasing levels of blood Pb, suggesting that Pb may be a potentially modifiable environmental risk factor for OA

Differential accumulation of lead and zinc in double-tidemarks of articular cartilage

The trace elements Lead (Pb) and Zinc (Zn) are of great biological impact. Long-term exposure to increased Pb concentrations is associated with several chronic diseases whereas Zn is essential for numerous enzymes. In a recent study we found remarkably elevated concentrations of Pb and Zn in the tidemark (TM), which is a mineralization front of human articular cartilage. Duplication or multiplication of TMs occurs with advancing age or degeneration. We hypothesized that trace elements accumulate in TMs as a function of time. Thus, in cases of double TMs, the inner (older) TM should have higher Pb and Zn levels than the outer (younger) TM. Undecalcified tissue from articular cartilage and subchondral bone of femoral heads and patellae was examined by synchrotron radiation induced confocal micro X-ray fluorescence analysis (SR µ-XRF) and by quantitative backscattered electron imaging to determine the local distribution of Ca, Zn and Pb in this tissue. The evaluation of x-ray fluoresence intensities in double TMs revealed in average a 2.6 fold higher Pb-level in the inner TM compared to the outer TM while the Zn concentrations were simmilar. The biochemical composition of the TM seems to selectively accumulate Pb from the interstitial fluid of articular cartilage. In contrast, Zn is supposed to be a fixed constituent of the TM. The results might be of clinical importance, when during degenerative processes in osteoarthritis the tidemark region is destroyed and remarkable concentrations of Pb (up to the 62 fold of the bone level) are released into the body fluid

Source Term Identification of Environmental Radioactive Pu/U Particles by their Characterisation with Non-Destructive Analytical Techniques.

Abstract not availableJRC.E-Institute for Transuranium Elements (Karlsruhe