Are fingernail lead levels a reliable biomarker of lead internal dose?

BACKGROUND: Potentially toxic elements, such as lead, can bioaccumulate and alter human physiology. Human biomonitoring is an essential tool to evaluate chemical exposures in different biological matrices (blood, urine, saliva, nails, and hair). Of these biological matrices, nails are favorable for their ease of sampling, transport and storage. The aim of this study was to investigate possible correlations between blood lead levels (BLL) and washed and non-washed fingernail lead levels (FLL) in 55 adults living in a lead-contaminated area. METHOD: Venous blood and fingernail (thumbs and forefingers) samples were collected. Nails from the left hand were washed with Triton X-100 (0.5 % m/v) and HNO3 solution, while nails from the right hand were not submitted to the pre-analytical procedures. Samples were analyzed by graphite furnace atomic absorption spectrometry, and pairwise correlations were used to correlate lead concentrations between BLL and FLL; nails from fingers of the same hand and between washed and unwashed fingernails. Principal component analysis was performed and scatter diagrams were plotted to investigate correlations. RESULTS: A non-significant positive correlation was found between BLL and washed forefinger nails lead (r = 0.219, p = 0.112) and between BLL and thumbnail lead levels (r = 0.182, p = 0.191). Comparison of fingernails from the same hand (thumb and forefinger), showed that lead concentrations of non-washed nails varied widely, even on analyses of transversal fragments from the same nail. Lead levels in non-washed forefinger nails were not correlated with non-washed thumbnails (r = 0.169, p = 0.219). Conversely, washed thumb and forefinger nails were found to be correlated (r = 0.39, p = 0.003). Washed and non-washed nails were also found to be correlated (p < 0.0001). CONCLUSION: In conclusion, the results showed that non-washed nails are not a reliable biomarker for lead exposure. Although washing nails before analysis may reduce external contamination, the correlation of lead concentrations between fingers is poor for fingernail lead levels to serve as an internal dose biomarker to lead exposure. In addition, levels in washed nails were not significantly correlated with blood lead levels. Fingernail lead levels seem to serve as an indicator of lead exposure sources in contact with the individual, but not as a reliable biomarker of internal dose.

Characteristics of radiographically diagnosed pneumonia in under-5 children in Salvador, Brazil.

OBJECTIVE: To assess the association of demographic and clinical aspects with radiographically diagnosed pneumonia. DESIGN: By active surveillance, the admitted pneumonia cases by the pediatrician on duty were identified in a 2 year period. Demographic, clinical and radiographic data were registered into standardized forms. SETTING: A public university pediatric hospital in Salvador, Northeast Brazil. PATIENTS: Children <5 years-old. MAIN OUTCOME MEASURES: Radiographically diagnosed pneumonia based on detection of pulmonary infiltrate/ consolidation. RESULTS: 301 cases had the chest X-ray evaluated by a pediatric radiologist blinded to clinical information, among whom pulmonary infiltrate and consolidation were described in 161 (54%) and 119 (40%), respectively. Chest X-ray was read normal for 140 cases. Overall, the median age was 17 months (mean 20±14, range 12 days-59 months). Pulmonary infiltrate was less frequently described among patients aged under 1 year (41.3% vs 59.9%, P=0.002, OR [95% CI] = 0.47 [0.29-0.76]) and hyperinflation was significantly more frequent in this age group (27.9% vs 4.1%, P<0.001, OR [95% CI] = 9.14 [4.0-20.9]). By multiple logistic regression, fever on admission was independently associated with pulmonary infiltrate (OR [95% CI] = 1.68 [1.03-2.73]) or consolidation (1.79 [1.10-2.92]), wheezing was independently associated with absence of pulmonary infiltrate (0.53 [0.33-0.86]) or of consolidation (0.53 [0.33-0.87]). The positive likelihood ratio of fever on examination for pulmonary infiltrate and consolidation was 1.49 (95% CI:1.11-1.98) and 1.49 (95% CI: 1.14-1.94), respectively. CONCLUSION: Presence of fever enhanced 2.5 times the chance of children hospitalized with lower respiratory tract disease to have radiographically diagnosed pneumonia.