Trace Elements in Tears: Comparison of Rural and Urban Populations Using Particle Induced X-ray Emission

We aimed to evaluate the types and concentrations of trace elements in tears of individuals living in urban and rural environments using particle induced X-ray emission (PIXE) and the possible association with exposure to air pollution and suggest a novel method for tear-based biomonitoring studies. This cross-sectional pilot study comprised 42 healthy subjects, 28 living in a rural area and 14 in an industrial city. Tears were collected with Schirmer paper and characterized by PIXE. Trace element concentrations from both eyes were averaged together with environmental pollution data. Main outcome measures were between-group differences in types and concentrations of trace elements in tears and comparison to environmental data. The rural group included 12/28 men, mean age 45.2 ± 14.8 years. The urban group consisted of 11/14 men of mean age 27 ± 5.9 years. Six rural and all urban were active smokers. Air pollution data showed more toxic elements in the rural environment. On PIXE analysis, chlorine, sodium, and potassium were found in similar concentrations in all samples. Normalizing to chlorine yielded higher values of aluminum, iron, copper, and titanium in the rural group; aluminum was found only in the rural group. The higher levels of certain trace elements in the rural group may, in part, be a consequence of exposure to specific environmental conditions. No direct association was found with air pollution data. PIXE is useful to analyze trace elements in tears, which might serve as a marker for individual exposure to environmental pollutants in biomonitoring studies.

Relationship between Trace Element in Tumor and Prognosis in Lung Cancer Patients

Background and Objectives: This study aimed to observe the relationship between trace element concentrations in lung tissue from lung non-small cell lung carcinoma (NSCLC) patients and prognosis. Materials and Methods: The concentrations of various trace elements in the lung tissues were measured by a particle-induced X-ray emission (PIXE) system, and the results were analyzed for statistical significance. Eight essential trace elements, Cr, Mn, Fe, Co, Cu, Zn, Se, and Mo, were analyzed. We investigated the relationship between trace element concentrations and disease-free survival (DFS) and overall survival (OS) in NSCLC patients. Results: A total of 129 NSCLC patients and 20 control patients were included in this study. As for DFS, Co was the only element that showed a significant difference, and the high Co group had better DFS (HR: 0.352, 95% CI = 0.128–0.97). No significant difference was observed for Cr, Mn, Fe, Se, or Mo, but DFS tended to be better in the high trace element group. No significant difference was observed for Cu and Zn, but DFS tended to be good in the low trace element group. As for OS, Cr was the only element that showed a significant difference, and the high Cr element group had better OS (HR: 0.477, 95% CI = 0.128–0.97). Conclusions: This study suggests that the prognosis is good in lung cancer cases with high intratumoral concentrations of Co and Cr. The dynamics of trace elements in body and in tumor tissue have not been well established, and we consider that more research is necessary in the future.