Definition of Problem
Use and operation of radiation sources in New Hampshire is regulated through licensing and registration of persons who possess, own, receive or transfer these sources. Approximately 100 specific licensees (radioactive material users) and approximately 1100 registrants (radiation machine users) continuously strive to keep radiation exposure in New Hampshire to levels ALARA (as low as reasonably achievable). Scant resources and staff reductions coupled with an ever increasing workload of the regulatory agency, increases the possibilities of misuse of radiation and unnecessary exposure to persons, thereby increasing the associated risks.
The problem(s) associated with waste storage and disposal currently are minimal since New Hampshire’s waste is being accepted at sites located in Utah and South Carolina. Should either or both of these sites close, then New Hampshire would be forced to implement the Low Level Radioactive Waste Policy Act of 1985 (PL 99-240) as amended and seek a solution for permanent disposal of its low level radioactive waste. New Hampshire laws (RSA 125-77:b) prohibit licensing of a low-level radioactive waste storage facility or disposal site in-state. Therefore, until such time that New Hampshire were to implement the Act, the waste would have to be stored on-site at the licensed facilities. Such facilities are not designed for long-term waste storage and therefore would present an increased risk for radiation exposure to New Hampshire citizens.
Packaging and transportation of radioactive materials are regulated by the U.S. Nuclear Regulatory Commission, Agreement States, and the U.S. Department of Transportation. The people exposed to the greatest risk from routine transportation and transportation accidents are the drivers and handlers of the materials. Transportation accidents, although infrequent, do occur. However, if the radioactive material is packaged properly for transport, there is rarely an accident in which radioactive material is released in amounts that would present a public health threat.
Exposure from handling and transport of radioactive materials such as
wastes, will increase in the future, at least for a time due primarily
to the decommissioning of nuclear power plants. Whether this results
in an increased human health risk depends on the adequacy of precautions
taken, including the adequacy of training and the readiness of response
teams.
Data
The National Council on Radiation Protection and Measurements
(NCRP) Report No. 93, entitled “Ionizing Radiation Exposure of the Population
of the United States”: attempts to provide a comprehensive database
and dose assessment for the population of the United States for six categories
of radiation exposures: natural sources, occupational exposure, the
nuclear fuel cycle, consumer products, miscellaneous environmental services
and medical diagnosis and therapy.
The data indicate that the natural sources make the greatest contributor
to the average effective dose equivalent for members of the U.S. population.
Among man-made or enhanced or concentrated natural sources, medical exposures
contribute the largest dose. These exposures however differ from
inadvertent exposures in that they contribute to the benefit of the specific
individual receiving them.
For New Hampshire, data relating to radiation exposure from all sources in use, waste and transportation are virtually non existent. Only specific situations incorporating “worst case” scenarios or possible individual, (usually occupational), exposures provide dose estimates for the public or the exposed individual. Such data however has not been compiled into a central database.
Confidence:
High with respect to data that high exposure to radiation does increase the risk of developing cancer.
Low with respect that low exposure to radiation increases the risk.
Low with respect to specific cases of exposure linked to specific occurrence
of cancers in New Hampshire.
Exposures and Health Impacts
All citizens of New Hampshire are inevitably exposed to sources of radiation involving one of three types: those of natural origin unperturbed by human activities, those of natural origin “enhanced” by human activities and man-made sources. However, unnecessary exposure to sources of radiation in New Hampshire is minimal due particularly to the strict state regulations on the use, possession, receipt and transfer of these sources by the New Hampshire Department of Health and Human Services. Recommended limits for exposure to ionizing radiation are based on the risk of mortality from such exposure. The National Council on Radiation Protection, Report 116 (NCRP) 1993 recommends that the annual exposure, from man-made sources not exceed 100 millirem/year (mrem/yr) for the public. The NCRP considers this equitable with the risks of mortality from all causes as stated to be between 1 in 10,000 and 1 in 100,000 per year. The New Hampshire Rules for the Control of Radiation, He-P 4020, sets limits for public and occupational exposure which are in addition to exposure from natural sources, including radon. These rules also implement the goal of keeping radiation exposures to a level as low as reasonably achievable (ALARA).
In some cases, the health impacts from exposure to radiation can be beneficial. Radiation used in medical diagnosis (e.g., x-ray and nuclear medicine procedures) can help identify possible detrimental and life threatening conditions at a very early stage (e.g., mammography), thus allowing for treatment, even radiation therapy, and the extension of a healthy life. This is only true, however, if a good quality assurance program accompanies these procedures so that a quality diagnosis can be assured at a minimum radiation exposure for the patient.
In other cases, the health impacts may be detrimental in that an unnecessary exposure to radiation has occurred through contamination, misuse, misadministration, non-compliance with the rules or non-application of the ALARA philosophy. Here, members of the public, or the occupationally exposed individuals have received an exposure to radiation over and above their natural background exposure and with no related benefit. This exposure will be cumulative and in time increases the risks of adverse health effects.
Populations of Concern:
Members of the public, occupationally exposed persons, pregnant workers
and fetuses.
Technical Assessment of Risk
|
|
|
| Severity | 5 |
| Distribution | 5 |
| Reversability | 1 (deterministic effects)
4-5 (stochastic effects) |
| Uncertainty - Toxicity | 4 |
| Uncertainty - Exposure Data | 5 |
Data Gaps:
There is continuing uncertainty and debate about the risks of low doses of radiation, particularly when delivered at low dose rates. The NCRP, Report No. 93 and its 1997 successor NCRP, Report No. 126, also recognizes that various uncertainties exist, some of the order of a factor of two or three, which ultimately reflects substantial limitations in the accuracy of the data.
The use of the effective dose equivalent for regulation of radiation exposure has made it possible to combine exposures from several different source categories and thus to determine an average annual effective dose equivalent which may give meaning to the overall somatic risk. In doing this, however, additional uncertainties are introduced regarding the relative risks between different organs.
For New Hampshire, the data to estimate exposure to all sources of radiation
associated with use and operation, waste storage and disposal and transportation
are basically nonexistent. Only specific studies related to accidents
or incidents can validate the dose estimates for the public and the maximally
exposed individual. Risk for New Hampshire citizens and workers is
calculated using national guidelines and data.
Summary
The principal health risk associated with radiation, particularly low
to moderate doses, is cancer. High doses can lead to acute effects,
including death at doses in the hundreds of rem.
The risks of developing cancer from ionizing radiation exposure, derived
from epidemiological studies, show that the risk is proportional to the
dose received down to about 10 rems. That is, low risk for a low
dose and increasing risk with an increasing dose of ionizing radiation.
This relationship is not clear at doses <10 rems, therefore, risks for
low dose have been extrapolated from the higher dose numbers. The
National Academy of Science (1990) sponsored report has placed the risk
of all cancers at 8 in 100,000 for an exposure of 100 mrem. A one
in 1,000,000 lifetime risk would occur for an exposure of about 1 mrem.
Based on the linear extrapolation, the dose from all sources of ionizing
radiation is considered to be cumulative over an individual’s lifetime.
At low doses, such as those we receive every day from background radiation, the cells repair the damage rapidly. At higher doses (up to 100 rem), the cells might not be able to repair the damage, and the cells may either be changed permanently or they die. Most cells that die can be replaced by the body. Cells changed permanently may go on to produce abnormal cells when they divide and may eventually become cancerous. There is a relationship between an increased radiation dosage and an increased number of mutations, either at the gene or chromosomal level. This is the origin of our increased risk of cancer, as a result of radiation exposure. Furthermore, congenital abnormalities are known to result from X-ray exposure in utero. Sensitivity to radiation is many times greater during fetal development since rapid development and differentiation of tissues is occurring during this time. The most pronounced impact of fetal irradiation is on the central nervous system which causes mental retardation, but possibly with a threshold dose of about 10 rem. Once the embryonic nerve cells are injured or killed by ionizing radiation, the damage is permanent.
Radiation exposure in New Hampshire are regulated by the Department
of Health and Human Services, Bureau of Radiological Health. In addition,
the principal of ALARA is enforced. The setting of these standards
and their enforcement greatly reduces the potential for unnecessary exposure
to radiation in New Hampshire.
References
1. National Council on Radiation Protection and Measurements, Report No. 93. “Ionizing Radiation Exposure of the Population of the United States.” September 1, 1987.
2. Maine Environmental Priorities Project. “Technical Appendix Volume 2: Background Papers Prepared by Members of the Human Health Technical Working Group.” July 1995.
3. Maine Environmental Priorities Project. “Summary of the Reports from the Technical Working Groups to the Steering Committee.” July 1995 and August 1995.
4. Maine Environmental Priorities Project. “Technical Appendix Volume 1: Background Papers Prepared by the Members of the Ecological Health and Quality of Life Technical Working Groups.” July 1995.
5. Ignatius, Amy, L., and Diane E. Tefft, “Radiation.” New Hampshire Comparative Risk Project.
6. Maine Environmental Priorities Project. “Report from the Steering Committee, Consensus Ranking of Environmental Risks Involving Maine.” January 1996.
7. Caron, Rosemary M., “New Hampshire Comparative Risk Project Technical Report: Public Health and Radiation.” January 1998.
8. Matanaski, G.M., “Health Effects of Low-Level Radiation in Shipyard Workers.” Report of US/DOE and Johns Hopkins School of Hygiene and Public Health. DE-AC02-79EV10095 (1991).
9. NCRP, “Uncertainties in Fatal Cancer Risk Estimates Used in Radiation Protection.” NCRP Report 126, October 17, 1997.
10. E. Cardis, E.S. Gilbert et al “Effects of Low Doses and Low Dose Rates of External Ionizing Radiation: Cancer Mortality Among Nuclear Industry Workers in Three Countries (USA, Canada, UK).” Radiation Research 142, 117-132 (1995).