OBJECTIVETo investigate the possible effects of long-term exposure to dust containing thorium and thoron progeny on dust-exposed miners.

METHODSA negative, high voltage, exhaled thoron progeny measurement system was used to estimate the miners' thorium lung burden.

RESULTSThe highest thorium lung burden of 638 miners was 11.11 Bq. The incidence of stage 0(+) pneumoconiosis was higher among dust-exposed miners. Lung cancer mortality of the dust-exposed miners was significantly higher than that of controls (P < 0.005).

CONCLUSIONThere is a difference in cancer rates between those who have long-term exposure to dust containing thorium (in which carcinogenic ThO(2) and SiO(2) exist) and thoron progeny and those who have not.

Air Pollutants, Radioactive ; adverse effects ; Body Burden ; China ; epidemiology ; Dust ; Follow-Up Studies ; Humans ; Lung Neoplasms ; epidemiology ; Mining ; Occupational Diseases ; epidemiology ; Occupational Exposure ; adverse effects ; Thorium ; adverse effects

Objective To study the effect of nano-ceria on doxorubicin-induced cardiotoxic injury and its effect on P53 gene expression,and to explore the mechanism of nano-ceria on doxorubicin-induced cardiotoxic injury.Methods H9C2 myocardial cells were cultured and randomly divided into five groups:control group,model group(1μmol/L adriamycin),nano-cerium oxide group(10μg/ml nano-cerium oxide),experimental group(1μmol/L adriamycin +10μg/ml nano-cerium oxide),and positive control group(1μmol/L adriamycin+10μmol/L dexperimine).The adriamycin induced cardiotoxicity model was established,and the viability of myocardial cells was measured by CCK-8 method.The contents of lactate dehydrogenase(LDH)and malondialdehyde(MDA)in myocardial cells were detected by biochemical method.The levels of reactive oxygen(ROS)and the apoptosis rate in myocardial cells were detected by flow cytometry.The expressions of Bax,Bcl-2 and P53 proteins in myocardial cells were detected by Western blot.Results Compared with the control group,the cell viability was decreased in the model group,the cell LDH and MDA contents were increased,the intracellular ROS level and apoptosis rate were increased,the expressions of Bax and P53 proteins were increased,and the expression of Bcl-2 protein was decreased,and the ratio of Bcl-2/Bax was decreased(all P<0.001).Compared with the model group,the experimental group showed increased cell viability,decreased cell LDH and MDA contents,decreased cell ROS content and apoptosis rate,decreased Bax and P53 protein expressions,and increased Bcl-2 protein expression,and the Bcl-2/Bax ratio was increased(all P<0.001).Conclusion Ceria nanoparticles can effectively prevent adriamycin-induced cardiotoxic injury,and its effect may be related to the down-regulation of P53 gene to inhibit cardiomyocyte apoptosis.