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.

P4737Complete surgical revascularization: the impact of the different definitions on mortality

Introduction

The concept of complete revascularization arises from the early stages on coronary artery bypass grafting (CABG). There are several different definitions applied across the literature, promoting a difficult comparison between studies. Despite the established importance of complete revascularization, there is no agreement which definition has the most impact on mortality.

Objectives

Evaluate the impact of the different definitions of complete surgical revascularization in late mortality.

Methods

Single center retrospective study of all consecutive patients submitted to isolated CABG with previous myocardial viability assessment (myocardial perfusion scintigraphy) from 2011 to 2016. Exclusion criteria: emergent procedures and previous cardiac surgery. The primary end-point was follow-up mortality (n=20). The population of study was162 patients with 22,2% female gender and a mean age of 66 years. The follow-up was complete in 98,8%, median time of 4,1 (IQR 3,0–5,5) years.

The completeness of revascularization was classified in all patients according to four different definitions (n=162 for each definition): Numerical (the number of stenotic vessels must equal the number of distal anastomoses applied); Functional (all ischemic myocardial territories are reperfused; areas of old infarction with no viable myocardium are not required to be reperfused); Anatomical Conditional (all stenotic main-branch vessels are revascularized) and Anatomical Unconditional (all stenotic vessels are revascularized, irrespective of size and territory supplied).

For each definition, statistical analysis was performed using the Kaplan-Meier method with log rank test and Cox proportional analysis (EuroSCORE II and revascularization definition).

Results

On univariate analysis, there was no significant statistical association between each definition of complete revascularization and follow-up mortality: numerical (p=0,694); anatomical unconditional (p=0,294); but a trend was found on functional (p=0,063) and anatomical conditional (p=0,084).

On multivariate analysis, incomplete functional revascularization increased the risk of follow-up mortality in 2,89 folds and anatomical conditional in 3,28 folds (Figure 1). The other definitions were not statistically associated with late mortality.

Conclusion

According to this study, complete functional and anatomical conditional revascularization definitions are determinants of follow-up mortality in a multivariate model including EuroScore II. The revascularization of all stenotic main-branch vessels (anatomical conditional) seems to have the highest impact, fact that we should be taken in consideration on daily work.

Peat as a natural solid-phase for copper preconcentration and determination in a multicommuted flow system coupled to flame atomic absorption spectrometry

The physical and chemical characteristics of peat were assessed through measurement of pH, percentage of organic matter, cationic exchange capacity (CEC), elemental analysis, infrared spectroscopy and quantitative analysis of metals by ICP OES. Despite the material showed to be very acid in view of the percentage of organic matter, its CEC was significant, showing potential for retention of metal ions. This characteristic was exploited by coupling a peat mini-column to a flow system based on the multicommutation approach for the in-line copper concentration prior to flame atomic absorption spectrometric determination. Cu(II) ions were adsorbed at pH 4.5 and eluted with 0.50 molL(-1) HNO(3). The influence of chemical and hydrodynamic parameters, such as sample pH, buffer concentration, eluent type and concentration, sample flow-rate and preconcentration time were investigated. Under the optimized conditions, a linear response was observed between 16 and 100 microgL(-1), with a detection limit estimated as 3 microgL(-1) at the 99.7% confidence level and an enrichment factor of 16. The relative standard deviation was estimated as 3.3% (n=20). The mini-column was used for at least 100 sampling cycles without significant variation in the analytical response. Recoveries from copper spiked to lake water or groundwater as well as concentrates used in hemodialysis were in the 97.3-111% range. The results obtained for copper determination in these samples agreed with those achieved by graphite furnace atomic absorption spectrometry (GFAAS) at the 95% confidence level.

Multielement electrothermal atomic absorption spectrometry: a study on direct and simultaneous determination of chromium and manganese in urine

A study was carried out on the direct determination of Cr and Mn in urine using simultaneous atomic absorption spectrometry (SIMAAS). The heating program conditions, the absorbance signal profiles, the influence of different chemical modifiers, and the urine sample volume delivery into the tube were optimized to perform the calibration with aqueous solutions. Among several chemical modifiers tested, the best recovery and repeatability results were obtained for 3 microg Mg(NO3)2. On using this modifier, the pyrolysis and atomization temperatures for simultaneous determination of Cr and Mn were 1,300 degrees C and 2,500 degrees C, respectively. Urine samples were diluted (1+1) with 2.0% (v/v) HNO3 + 0.05% (w/v) Triton X-100 prepared in high purity water. A 20-microL aliquot of analytical solution and 10 microL of chemical modifier solution were delivered to the graphite tube. The characteristic masses were 7.8 pg for Cr (RSD=4.0%) and 4.6 pg for Mn (RSD=2.6%). The limits of detection were 0.08 microg L(-1) (n=20, 3s) for Cr and 0.16 microg L(-1) (n=20, 3s) for Mn. Recovery studies for 1.0 or 2.5 microg L(-1) of Cr and Mn added to different urine samples showed acceptable results for Cr (100%, RSD=14%) and Mn (88%, RSD=5.6%).