Adequate dietary calcium mitigates osteopenia induced by chronic lead exposure in adult rats

The effect of lead on bone mineral properties from female adult C57/BL6 mice

Lead toxicity is a significant problem in the U.S. with elevated blood lead levels being highest among very young children and older adults >50 years old. Bone is the major reservoir of body lead, accounting for 75% in children and 90% in adults. Very little is known about the effect of lead on bone mineral properties in adults. We investigated the effect of lead on the femora from adult, 6 month old female C57/BL6 mice who were administered lead in the drinking water (250 ppm, blood lead 33 μg/dL) for 4 months. Bone mineral properties were examined using Fourier Transform Infrared Microscopy (FTIRM), quantitative microcomputed tomography (microCT) and whole bone mechanical testing. Lead significantly decreased the bone mineral density in the cortical and proximal cancellous bone and increased the marrow area in the cortical bone with microCT. Whole bone three-point bending showed a trend of decreased maximum and failure moments in the lead treated bones compared to controls. Lead significantly decreased the mineral/matrix ratio, collagen maturity and crystallinity in the trabecular bone as measured by FTIRM. In the cortical bone lead significantly decreased collagen maturity and bone crystal size by FTIRM. In contrast to cell culture studies, lead significantly increased serum osteocalcin levels. Lead also significantly increased the bone formation and resorption markers suggesting increased bone turnover. These data show that lead increases bone turnover resulting in weaker cortical bone in adult female mice and suggest that lead may exacerbate bone loss and osteoporosis in the elderly.

Lead exposure and periodontitis in US adults

BACKGROUND AND OBJECTIVE

Lead is known to have significant effects on bone metabolism and the immune system. This study tested the hypothesis that lead exposure affects periodontitis in adults.

MATERIAL AND METHODS

This study used the data from the Third National Health and Nutrition Examination Survey (NHANES III, 1988-94). It analyzed data from 2500 men and 2399 women, 20-56 yr old, who received complete periodontal examination. Periodontitis was defined as the presence of > 20% of mesial sites with >or= 4 mm of attachment loss. Lead exposure was grouped into three categories: < 3; 3-7; and > 7 microg/dL. Covariates were cotinine levels, poverty ratio, race/ethnicity, education, bone mineral density, diabetes, calcium intake, dental visit, and menopause (for women). All analyses were performed separately for men and women and considering the effect design. Univariate, bivariate, and stratified analysis was followed by multivariable analysis by estimating prevalence ratios through poisson regression.

RESULTS

After adjustment for confounders, the prevalence ratios, comparing those with a lead blood level of > 7 microg/dL to those with a lead blood level of < 3 microg/dL was 1.70 (95% confidence interval (CI): 1.02, 2.85) for men and 3.80 (95% CI: 1.66, 8.73) for women.

CONCLUSION

The lead blood level was positively and statistically associated with periodontitis for both men and women. Considering the public health importance of periodontitis and lead exposure, further studies are necessary to confirm this association.