3.1. Radiation Units and Radiation Workers and Their Distribution
There are almost 70,000 radiation employers with about 350,000 radiation workers in China at present. About 60%–70% of the total is involved in medical diagnosis (X-ray and nuclear medicine imaging) and radiation therapy. In addition, 10% are in the sectors of industrial radiography and irradiation installations, 10% are in education and research sectors, and the remaining 10% are in nuclear industry sectors. Among these workers, 223,000 radiation workers are working in 53,000 medical diagnoses and radiation therapy institutions.
In the non-nuclear industrial sectors, radiation workers are distributed mainly in eastern and central China. In the nuclear industrial sector, most of the radiation workers are working in uranium mines. There are more than 10,000 workers in nuclear power plants, which are expected to greatly increase in the future. At present, in addition to the operating China Experimental Fast Reactor (CEFR) at the China Institute of Atomic Energy (CIAE), there are 27 nuclear units in operation, 23 under construction, and some others pending construction licenses or in the early preparatory phase.
After years of efforts, the coverage of individual monitoring has risen steadily, currently at about 90% [5
]. The difference of the coverage from region to region and industry to industry is obvious. Depending on the differences of emphasis on individual monitoring of the radiation units and the differences of law enforcement dynamics of the health supervision departments in different regions, the coverage of individual monitoring of radiation workers in eastern China is higher compared with that in western China on the whole. Being the first sector to conduct individual monitoring in China, the nuclear industrial sector has always attached great importance to individual monitoring, and individual monitoring of radiation workers in the nuclear power plant is fully covered. Average annual effective dose of radiation workers from 1985 to 2012 has shown a significant downward trend. The coverage of individual monitoring in Shanghai and Beijing is more than 95%.
3.2. Laws and Regulations Governing Individual Monitoring
The laws and regulations governing individual monitoring are listed in Table 1
Under Qualification Conditions of Individual Monitoring Services for Radiation Workers [7
], the service providers should meet the following requirements:
Having legal representative qualifications or legal-authorized qualification;
Being capable of carrying out corresponding technical service work independently;
Having a permanent office and workplace and working conditions;
Having a reasonable post setting and well-defined responsibility scope;
Having robust quality assurance system.
Personnel should meet the following requirements:
Being fit for management, technique and quality control required by the programs;
Being familiar with the relevant laws, standards and documents as well as quality management manuals;
Technical director of individual monitoring with junior college diploma or above, or the intermediate technical titles or above and having experiences in related work more than three years;
Being qualified through training and examination;
Total number of operators is not less than three.
Instruments and equipment should meet the following requirements:
Having corresponding instruments and equipment required for carrying out technical service of individual monitoring;
Type, quantity, performance, range and precision of the instruments and equipment are capable of meeting the needs of the work, and the instruments and equipment can run well;
Being regularly subject to metrological verification;
Having a complete set of operating procedures.
Under Management Methods for Occupational Health of Radiation Workers (MMOHRW) [3
], the provincial health administrative departments are responsible for the qualification examination and approval of individual monitoring services. When applying for qualification of radiological health technical services, the following materials shall be submitted to the health administrative departments: application form; the legal representative qualification certificates materials; the brief introduction to the applicant; the directory of quality management handbook and procedures document; the list of professionals and technical workers; the certificates of technical titles and certificates of training and examination; lists of related equipment; certificate of workplace use; and certificate of meteorology authentication.
The qualification certificate of radiological health services is valid for four years. Change and extension of qualification certificate are allowed if necessary. Radiological health service units can provide the trans boundary technical services across the administrative areas but shall submit the application, for the record, to the local provincial health administrative department and accept the possible supervision and inspection.
GBZ 207-2008 [8
] specifies the performance testing, evaluation and requirements of routine performance testing, as well as the quality control of performance testing of external exposure individual dose system.
3.3. Individual Monitoring Services Providers
There were 190 individual monitoring services in 2009, and in the year of 2012, the number increased to 203. CDCs (Centers for disease control and prevention) and institutions of prevention and treatment of occupational disease represent the overwhelming majority of the monitoring services. Other monitoring services are distributed in the nuclear industry, commercial companies, universities, environmental protection agencies, etc. The distribution of the individual monitoring services is not uniform throughout the country. Most of the monitoring services are distributed in eastern China. Jiangsu and Shandong possess the most individual monitoring services among 34 provincial administrative regions.
At present, the vast majority of monitoring services can only provide the monitoring data of annual effective dose from external gamma and X-ray exposure [9
], and are unable to provide adequate monitoring of alpha- and beta-radiation, and dose to lens/hands and internal exposure. Three services can monitor more than 10,000 workers annually, 10 services can monitor 4000 to 10,000 workers annually, 30 services can monitor 1000 to 4000 workers annually, and the others can monitor less than 1000 workers annually. Internal individual monitoring has not been implemented in most areas of China. This is especially true for medical radiation workers.
Generally, there are a small number of individual monitoring services in developed countries, which are characterized by their big size and large amount of tasks [10
]. However, most Chinese units feature a small size and small amount of work. Furthermore, most units are unable to undertake comprehensive tasks of individual monitoring due to weak capacity [11
3.5. Dose Record Management and National Dose Register
There was no statistical and reporting system available before the 1980s. With the policy of reform and openness in the 1980s, nuclear and radiation technology applications were more frequently used in medicine, industry and other sectors. In 1979, the Ministry of Health and other ministries issued a revised MMOHRW, reaffirming the establishment of license registration and radiation event reporting systems. In 1985, an individual monitoring system was formally established. With the popularity of computer and information technology, the health and other relevant departments made a useful exploration for the gradual establishment of health monitoring statistics automation, including radiological health.
The Service Center of Occupational Exposure Dose Management for Nuclear Industry was set up in 1985, under the auspices of the China National Nuclear Corporation (CNNC), with the responsibility for development of data management systems, collection and analysis of monitoring data from nuclear power plants, and submission of annual assessment reports. In 1998, the Industrial Hygiene Laboratory of the Ministry of Health developed software for data processing and file management of individual monitoring for radiation workers (DPFM), in an attempt to unify the data management of individual monitoring in the medical field. Problems existing in the software of individual monitoring information management system were discussed in selected references [13
Health supervision was separated from technical service due to the reform of the system of health and epidemic prevention. After effective control of SARS (Severe Acute Respiratory Syndrome) in 2003, more attention was paid to collecting information for each case associated with disease control and prevention as well as to direct reporting to higher authorities by use of computer information technology. In October 2003, the Chinese Center for Disease Control and Prevention began to run an information system of the health hazard monitoring, with a direct-reporting-card of individual monitoring being included.
Relevant institutions have made some attempts in preparation for radiation health reports, especially individual monitoring data reports. However, the effort was not very successful for various reasons. Several factors led to difficulty in system extension, such as a lack of professional quality control measures, unreasonable data reporting and rough demand analysis. A large number of papery records were hardly regarded as a scientific basis for radiation health decision-making. Reporting format of data did not meet the requirements of International Atomic Energy Agency (IAEA) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).
As pointed out by the IAEA Occupational Radiation Protection Appraisal Service (ORPAS), when visiting China in August 2004, a data reporting system of individual monitoring of radiation workers in China should be completely reconstructed. It was strongly suggested that China establish a national central database and improve quality control and quality assurance of individual monitoring. Since 2005, funded by IAEA, China began to establish the occupational health management system of radiation workers inside the system of Ministry of Health under the framework of the IAEA CPR (CPR/9/037). As a result, the China Register of Radiation Workers (CRRW) was officially released by the Ministry of Health on 25 November 2009. The system has authorized 212 users, including 180 individual monitoring services and 32 supervision departments. By 2014, there had been 2 million monitoring records in the central database of 330,000 workers belonging to 35,000 radiation users countrywide.
The database information of the system of CRRW includes individual monitoring services, equipment, radiation users (employers), radiation workers (employees), doses, occupational health management, etc.
From Figure 1
, we can see that CRRW consists of two parts, an offline version and online version, respectively. The offline version is comprised of seven function modules (new, dose data, reports, query, system management, export and exit). Uniformed annual reports, periodic reports, and suspicious data inspection sheets can be generated by using the offline version. The online version is comprised of six function modules, such as query, statistical analysis, data management, report cards, system management and exit. Summary tabulations can be generated by using the online version [16
Name, age, sex, working unit, unique identification number, occupational exposure category, quarterly and annual effective doses among others are uploaded by each monitoring service and kept in the register. Backup systems including optical disks and hard disks in different places are used to store the dose records safely.
The Ministry of Health issued a notification in 2009 to enable the individual dose management system and request qualified agencies to upload the relevant information timely. In addition, the Ministry of Health commissioned the NIRP to be responsible for technical service, maintenance, management of the individual dose management system, the local technical guidance, etc.
According to the notification of the Ministry of Health, individual monitoring services began to upload relevant information from the end of 2009. The quality problem of the uploaded information includes: the lack of professional category and improper filling out of the professional category; the small-scale institutions changing the name of the entity frequently, multiple institutions being identified by the system; mistakenly filling out beginning and ending dates; and uploading the test results as the final dose report owing to unfinished large dose verification.
Due to the lack of clear guidance, the process of large dose verification varies throughout the country, and the phenomenon of long verification cycles and low return rates is very common. As a result, many unfinished large dose test results are uploaded as the final dose, with dosage value overvalued.