ABSTRACT
Objective To conduct metal elements analysis and risk assessment of carcinogenicity on Particulate Matter 2.5 ( PM2.5) collected from Shenzhen and Taiyuan. Methods PM2.5 samples were collected in Shenzhen and Taiyuan from 2017 to 2018. Ten heavy metal elements in PM2.5 samples were detected by inductively coupled plasma mass spectrometry (ICP-MS). Health risk assessment was conducted using the recommended United States Environmental Protection Agency (EPA) model. Results Metal elements found in PM2.5 samples from Shenzhen included (in decreasing order of concentration) Al, Pb, Mn, Cr, Cu, V, As, Ni, Cd and Co. Their levels were 1 807.67, 31.02, 30.63, 17.37, 17.32, 11.59, 6.98, 4.76, 2.24, 2.20 ng/m3, respectively. Metal elements in PM2.5 samples from Taiyuan included Al, Mn, Pb, Cr, Cu, As, Ni, V, Cd and Co. Their levels were 2 817.64, 91.04, 63.33, 26.56, 24.69, 11.82, 10.39, 4.46, 3.42, 1.01 ng/m3, respectively. There were significant differences among Pb, Mn, As, Ni levels between Shenzhen and Taiyuan (all P1.00×10-4), then followed by As, Ni and Cd (1.00×10-6-1.00×10-4). Pb had the lowest risk (<1.00×10-6). Conclusion Some of the metal elements in PM2.5 samples collected from Shenzhen and Taiyuan have carcinogenicity risk. Further researches and measures for prevention and control should be considered.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate DNA methylation variation in human cells induces by B(a)P, and to explore the role of PARP1 during this process.</p><p><b>METHODS</b>The changes of DNA methylation of 16HBE and its PARP1-deficient cells exposed to B(a)P (1.0, 2.0, 5.0, 10.0, 15.0, 30.0 µmol/L) were investigated by immunofluorescence and high performance capillary electrophoresis, and simultaneously, the expression level of PARP 1 and DNMT 1 were monitored dynamically.</p><p><b>RESULTS</b>The percentage of methylated DNA of overall genome (mCpG%) in 16HBE and 16HBE-shPARP1 cells were separately (4.04 ± 0.08)% and (9.69 ± 0.50)%. After being treated by 5-DAC for 72 hours, mCpG% decreased to (3.15 ± 0.14)% and (6.07 ± 0.54)%. After both being exposed to B(a)P for 72 hours, the mCpG% in 16HBE group (ascending rank) were separately (5.10 ± 0.13), (4.25 ± 0.10), (3.91 ± 0.10), (4.23 ± 0.27), (3.70 ± 0.15), (3.08 ± 0.07); while the figures in 16HBE-shPARP1 group (ascending rank) were respectively (10.63 ± 0.60), (13.08 ± 0.68), (9.75 ± 0.55), (7.32 ± 0.67), (6.90 ± 0.49) and (6.27 ± 0.21). The difference of the results was statistically significant (F values were 61.67 and 60.91, P < 0.01). For 16HBE group, expression of PARP 1 and DNMT 1 were 141.0%, 158.0%, 167.0%, 239.0%, 149.0%, 82.9% and 108.0%, 117.0%, 125.0%, 162.0%, 275.0%, 233.0% comparing with the control group, whose difference also has statistical significance (t values were 11.45, 17.32, 32.24, 33.44, 20.21 and 9.87, P < 0.01). For 16HBE-shPARP1 group, expression of PARP 1 and DNMT 1 were 169.0%, 217.0%, 259.0%, 323.0%, 321.0%, 256.0% and 86.0%, 135.0%, 151.0%, 180.0%, 229.0%, 186.0% comparing with the control group, with statistical significance (t values were 9.06, 15.92, 22.68, 26.23, 37.19 and 21.15, P < 0.01). When the dose of B(a)P reached 5.0 µmol/L, the mRNA expression of DNMT 1 in 16HBE group (ascending rank) were 125.0%, 162.0%, 275.0%, 233.0% times of it in control group, with statistical significance (t values were 12.74, 24.92, 55.11, 59.07, P < 0.01); while the dose of B(a)P reached 2.0 µmol/L, the mRNA expression of DNMT 1 in 16HBE-shPARP1 group were 135.0%, 151.0%, 180.0%, 229.0%, 186.0% of the results in control group, and the differences were statistically significant (t values were 23.82, 40.17, 32.69, 74.85, 46.76, P < 0.01).</p><p><b>CONCLUSION</b>The hypomethylation of 16HBE cells induced by B(a)P might be one important molecular phenomenon in its malignant transformation process. It suggests that PARP1 could regulate DNA methylation by inhibiting the enzyme activity of DNMT1, and this effect could be alleviated by PARP1-deficiency.</p>