ABSTRACT
Oro-maxillofacial cone-beam CT (CBCT) is the most widely used three-dimensional imaging method in the field of oral and maxillofacial radiology. It has been widely used in China, while radiation safety, examination indications and other issues still lack comprehensive regulations and standards. Over the years, clinical guidelines and position statements for the rational use of CBCT examinations have been issued in the world, providing standardized instructions for local practitioners. This paper reviewed these guidelines to provide reference for the formulation of relevant guidelines in China.
Subject(s)
Cone-Beam Computed Tomography , Radiology , Cone-Beam Computed Tomography/methods , Imaging, Three-Dimensional/methods , China , Radiation DosageABSTRACT
PURPOSE: Urbanization and industrialization in China has resulted in a dramatic increase in the volume of wastewater and sewage sludge produced from wastewater treatment plants. Problems associated with sewage sludge have attracted increasing attention from the public and urban planners. How to manage sludge in an economically and environmentally acceptable manner is one of the critical issues that modern societies are facing. METHODS: Sludge treatment systems consist of thickening, dewatering, and several different alternative main treatments (anaerobic digestion, aerobic digestion, drying, composting, and incineration). Agricultural application, landfill, and incineration are the principal disposal methods for sewage sludge in China. However, sewage sludge disposal in the future should focus on resource recovery, reducing environmental impacts and saving economic costs. RESULTS: The reuse of biosolids in all scenarios can be environmentally beneficial and cost-effective. Anaerobic digestion followed by land application is the preferable options due to low economic and energy costs and material reuse. CONCLUSION: It is necessary to formulate a standard suitable for the utilization of sewage sludge in China.
Subject(s)
Sewage , Waste Disposal, Fluid/methods , Agriculture , China , Cities , Environment , Incineration , Sewage/chemistry , Sewage/statistics & numerical data , SoilABSTRACT
About 0.05 mg Cd l-1 was found in the irrigation water contaminated by the wastewater discharged from tungsten ore dressing plants, and about 1 mg Cd kg-1 was found in irrigated acid soils. The main sources of cadmium intake by residents of the polluted areas are agricultural products. The average intake of cadmium was 367-382 micrograms day-1, and for smokers 417 micrograms day-1. Among the residents who have been exposed to cadmium for more than 25 years, cadmium absorption (urinary cadmium greater than or equal to 10 micrograms g-1 creatine) was 60% and an early effect on the target organ (urinary cadmium greater than or equal to 15 micrograms g-1 creatinine and urinary beta 2-microglobulin greater than 500 micrograms g-1 creatinine) was detected in 17% of the sample of 433 persons. Levels of urinary cadmium and blood cadmium exceeded the critical value in the exposed group. The concentrations of urinary calcium, beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase were significantly higher in residents of contaminated areas than in those of control areas. Case-control study of the residents shows that many have suffered from a nephropathy with tubulo-interstitial abnormalities. Owing to the combined cadmium effect, the cases with fractional beta 2-microglobulin excretion greater than 0.10 were 46% in the exposed population, and were much higher than that in the control group (20.3%).
