Markers of oxidative damage of nucleic acids and proteins among workers exposed to TiO2 (nano) particles.

OBJECTIVE: The use of nanotechnology is growing enormously and occupational physicians have an increasing interest in evaluating potential hazards and finding biomarkers of effect in workers exposed to nanoparticles. METHODS: A study was carried out with 36 workers exposed to (nano)TiO2 pigment and 45 controls. Condensate (EBC) titanium and markers of oxidation of nucleic acids (including 8-hydroxy-2-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-OHG), 5-hydroxymethyl uracil (5-OHMeU)) and proteins (such as o-tyrosine (o-Tyr), 3-chlorotyrosine (3-ClTyr) and 3-nitrotyrosine (3-NOTyr)) were analysed from samples of their exhaled breath. RESULTS: In the production workshops, the median total mass 2012 and 2013 TiO2 concentrations were 0.65 and 0.40 mg/m(3), respectively. The median numbers of concentrations measured by the scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) were 1.98 × 10(4) and 2.32 × 10(4) particles/cm(3), respectively; and about 80% of those particles were smaller than 100 nm in diameter. In the research workspace, lower aerosol concentrations (0.16 mg/m(3) and 1.32 × 10(4) particles/cm(3)) were found. Titanium in the EBC was significantly higher in production workers (p<0.001) than in research workers and unexposed controls. Accordingly, most EBC oxidative stress markers, including in the preshift samples, were higher in production workers than in the two other groups. Multiple regression analysis confirmed an association between the production of TiO2 and the levels of studied biomarkers. CONCLUSIONS: The concentration of titanium in EBC may serve as a direct exposure marker in workers producing TiO2 pigment; the markers of oxidative stress reflect the local biological effect of (nano)TiO2 in the respiratory tract of the exposed workers.

LC-ESI-MS/MS method for oxidative stress multimarker screening in the exhaled breath condensate of asbestosis/silicosis patients.

The sensitive assay method was developed for a parallel, rapid and precise determination of the most prominent oxidative stress biomarkers: 8-iso-prostaglandin F(2α) a lipid oxidation biomarker, o-tyrosine an amino acid oxidation biomarker and 8-hydroxy-2'-deoxy-guanosine a nucleic acid oxidation biomarker. The method consisted of a pre-treatment part, freeze drying (lyophilization), serving the purpose of biomarkers concentration from the exhaled breath condensate and detection method LC-ESI-MS/MS, where the selected reaction-monitoring mode was used for its extremely high degree of selectivity and the stable-isotope-dilution assay for its high precision of quantification. The developed method is characterized by the following parameters: the precision was higher than 84.3% and the mean accuracy (relative error) was determined lower than 11.6%. The method was tested on samples obtained from patients diagnosed with asbestosis and silicosis, occupational diseases induced by oxidative stress, and then compared with samples from healthy subjects. The difference in biomarkers' concentration levels found between the two groups was statistically significant.