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HISTORY

Radiation standards and organizations: An historical perspective

Radiation standards
The world's scientists have been studying radiation for more than 100 years. They have found that radiation is easy to detect and easy to control. It has been 70 years since international organizations began establishing recommendations and regulations for the protection of people and the environment from any harmful effects of radiation.

In the United States, the NRC, the EPA and the Department of Transportation are the principal federal agencies responsible for establishing radiation protection regulations. This authority comes from the Atomic Energy Act of 1954 as amended, the Clean Air Act and a variety of other authorities. In individual states, regulation is usually handled by the department of environmental quality or the health department. The federal agencies work with international organizations to ensure that their regulations are based on internationally recognized scientific studies.

Standard-setting organizations
The uses of man-made radiation are subject to very stringent regulations to ensure proper controls. Government agencies at the international, federal, state and local levels regulate the manufacture, use, transport and disposal of man-made and some naturally occurring radioactive materials to ensure the protection of public and worker health and safety and the environment. Regulatory limits on exposures for both workers and the general public are set conservatively, far below the levels at which health effects have been observed.

International standards—Two international organizations recommend radiation protection levels: the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA).The International Commission on Radiological Units and Measurements (ICRU) recommends the units used in designating radiation protection levels.

The ICRP was established in 1928 by the Second International Congress of Radiology. It was initially concerned with the safety of medical radiology. The name "ICRP" was adopted in 1950. Its purpose is "to deal with the basic principles of radiation protection and to leave to various national protection committees the responsibility of introducing the detailed technical regulations, recommendations or codes of practice best suited to the needs of their individual countries." The ICRP is the principal source of recommendations on radiation levels. Members come from 20 countries and include scientists, physicians and engineers.

The IAEA is a specialized agency of the United Nations. It was organized in 1956 to promote peaceful uses of nuclear energy. It is concerned with the practical application of the ICRP recommendations.

Under its statute, IAEA applies radiation protection standards to its own operations and to operations it assists or with which it is directly associated. Authorities receiving assistance are required to observe relevant health and safety measures prescribed by the IAEA.

All of the 124 member nations have representatives in the General Conference, the governing body that determines policy. Smaller executive bodies within IAEA, such as the Scientific Advisory Committee, consist of scientists, engineers and administrators from member states. The IAEA publishes both standards and recommendations, in addition to books on nuclear science and technology written by consultants or groups of experts invited from member states.

The ICRU was created in 1925. Its principal objective is the development of international recommendations regarding quantities and units of radiation and radioactivity, procedures for their measurement and application in clinical radiology and radiobiology, and physical data needed to ensure uniformity in reporting on their applications.

Its operating policy is that "it is the responsibility of national organizations to introduce their own detailed technical procedures for the development and maintenance of standards. However, it urges that all countries adhere as closely as possible to the internationally recommended basic concepts of radiation quantities and units." The ICRU consists of members, senior advisers, consultants and representatives of report committees in 12 countries. The report committees consist of scientists, engineers and physicians—primarily from colleges and universities, with some from government and industry.

U.S. standards—U.S. organizations involved with recommending radiation standards include the National Council on Radiation Protection and Measurements (NCRP), the EPA and the NRC. The NCRP was founded in 1929 as the Advisory Committee on X-ray and Radium Protection. Congressionally chartered in 1964, it is concerned with the scientific and technical aspects of radiation protection. It is a nonprofit corporation, not a federal agency, although its recommendations are part of the basis of federal, state and local regulations dealing with radiation hazards.

The NCRP consists of members and those participants who serve on its scientific committees. The members, selected purely on the basis of their scientific expertise, are drawn from public and private universities, medical centers, national and private laboratories, and industry. The scientific committees are composed of experts in the particular area of the committee's interest. The Federal Radiation Council (FRC) was established in 1959. Its purpose was to advise the president on radiation matters directly or indirectly affecting health, and to offer guidance to federal agencies in the formulation of radiation standards. The FRC was purely an advisory group with no regulatory powers. Under the Presidential Reorganization Plan No. 3 of 1970, the FRC was dissolved, and its functions were transferred to the EPA.

The EPA is responsible for recommending federal guidance on radiation protection for use by federal agencies in their regulatory processes and for establishing standards to protect the general environment from radioactive material under a variety of authorities, including the Clean Air Act, the Safe Drinking Water Act, Superfund and the Atomic Energy Act.

The Nuclear Regulatory Commission was founded in 1974 and grew out of the Atomic Energy Commission. Its responsibility is to protect public health and safety. To accomplish this, the NRC prescribes and enforces separate limits on the amount of radiation that workers and members of the public can receive from all pathways, such as air and water. These regulations apply to operators of nuclear power plants, and industrial and medical facilities licensed to use man-made radioactive materials. The NRC bases its regulations on recommendations made by the NCRP and the ICRP, and on the EPA's federal guidance and standards.

Sources of data used to set radiation standards
Two series of reports provide much of the data used in setting radiation standards. The reports are produced by the National Academy of Sciences' Committee on the Biological Effects of Ionizing Radiations (NAS/BEIR) and the United Nations Scientific 

The BEIR Reports—The National Academy of Sciences chartered the first BEIR report in 1956 and has chartered four additional reports. These reports provide a quantitative basis for limiting the radiation exposure of the whole population. They focus on the risk factors—the probability of health effects associated with a given dose of radiation.

The latest BEIR report of interest, BEIR V in 1990, defined low-level radiation as anything below 10,000 millirem. The findings were based on revised dose estimates for the survivors of the Hiroshima and Nagasaki atomic bombs. The survivors were exposed to both acute doses (i.e., doses delivered in seconds or minutes) and doses spread out over months and years.

In 1996, the Environmental Protection Agency asked the National Academy of Sciences to investigate whether sufficient new evidence exists—especially on the issue of the linearity of the radiation dose-response rate at low levels—to warrant a reexamination of the 1990 BEIR V conclusions. The BEIR VII Committee was formed in 1997 to consider the request. In January 1998, the committee concluded that sufficient information has become available since the publication of the BEIR V report to proceed with a comprehensive reexamination of health effects associated with low levels of ionizing radiation. A new BEIR VII committee has been formed to carry out the re-examination. Publication of the BEIR VII report is expected in 2001.

The UNSCEAR Reports—UNSCEAR has produced recommendations from studies of Hiroshima and Nagasaki survivors. In 1988, the UNSCEAR report stated that, due to new dosimetry, risk estimates from high exposure to radiation had increased. The report also changed the dose projection model used to calculate lifetime risk. These are similar to the conclusions in BEIR V. In 1993, UNSCEAR issued its next report, which made no substantial change to the risk estimates.

Both UNSCEAR and NAS consider new data as they become available from studies of workers and members of the public. When the data indicate that the current risk estimates need to be revised, either up or down, the committees prepare new reports to reflect this. For example, BEIR V—issued in 1990—concluded that some risk estimates should be increased. The latest UNSCEAR report, issued in 1993, considered that its earlier risk estimates continued to be appropriate. The next UNSCEAR report—a comprehensive review of radiation issues—will be issued in late 2000 or early 2001.

Radiation: Types and uses
Radiation is divided into two categories: ionizing and non-ionizing. Ionizing radiation removes electrons from atoms, causing the atoms to become electrically charged ions. Examples include X-rays and radiation used in medicine or industry.

Ionizing radiation's uses include medical diagnosis and treatment, nuclear energy, archaeological dating, smoke detectors and sterilization of medical equipment.

Non-ionizing radiation does not remove electrons from the atoms it encounters. Examples include radiowaves, microwaves, and visible and ultraviolet light. Its uses include lighting, lasers and heating.

Every plant, animal and human that has ever lived on Earth has been bathed in radiation for every second of its life.

Ionizing radiation is easily detected through a variety of means. Measurements of this radiation are based on the energy it deposits in the body or in a particular part of the body. "Absorbed dose" is the quantity of energy absorbed by a mass of matter, such as tissue. One unit of absorbed dose of ionizing radiation is expressed as a "rad." However, this quantity does not distinguish between the abilities of different ionizing radiation to cause harm. "Dose equivalent" is used to refer to the absorbed dose weighted for harmfulness of different forms of radiation (alpha, beta, gamma). Dose equivalent is expressed in units of rem. A "rem" serves as the measure for evaluating potential biological effects of radiation. A "millirem" is a thousandth of a rem.

Chronology

1925—The first International Congress of Radiology is held to establish a committee to develop and reach international agreement on a standard method and unit by which to measure radiation. The International Commission on Radiation Units and Measurements (ICRU) is formed.

1928—The second International Congress of Radiology adopts the German version of the Roentgen as the international X-ray unit and provides the first international recommendations for radiation protection. The International Commission on X-ray and Radium Protection, precursor to the International Commission on Radiological Protection (ICRP), is created.

1929—The U.S. Advisory Committee on X-ray and Radium Protection, precursor to the National Council on Radiation Protection and Measurements (NCRP), is formed.

1931—The third International Congress of Radiology ratifies the Roentgen as the international X-ray unit.

1934—The fourth International Congress of Radiology recommends a tolerance dose of about 0.2 international Roentgens per day without undue harm.

1946—The Atomic Energy Commission (AEC) is created. The NCRP informally recommends a maximum permissible dose of 0.3 rem per week.

1950s—The concept of rad and rem becomes widely accepted. Radiation standards are set only for those who are exposed on the job.

1954—The NCRP states that a threshold on exposure can no longer be assumed and that exposure is justified only after a possible risk has been weighed against expected benefits. The NCRP adopts the term "permissible dose," and recommends a maximum permissible dose of 0.3 rem/week for critical organs and 0.6 rem/week for the skin.

1955—The ICRP adopts a maximum permissible dose of 0.3 rem/week for critical organs for radiation workers and recommends limiting radiation to people not exposed on the job. The ICRP also recommends that the dose to the public from prolonged exposures should be 10 times lower than for people exposed on the job.

The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) is formed.

1956—The National Academy of Sciences' Committee on the Biological Effects of Ionizing Radiations (BEIR) report is issued and recommends that: (1) excluding background, the average accumulated gonad dose to the general population be limited to 10 rem/person from conception up to age 30 and (2) for individuals in the general population, this dose should be limited to 50 rem up to age 40.

The ICRP recommends limiting occupational exposure to about 5 rem/year.

1957—The NCRP recommends limiting occupational exposure to 5 rem/year. The AEC issues 10 CFR Part 20, its first set of regulations governing the use of radioactive material. These regulations state a maximum permissible dose of 0.3 rem/week to radiation workers.

1958—The NCRP introduces the concept of no occupational exposure below age 18. For radiation workers, exposure should average less than 5 rem/year over their working life, with limited exposure to less than or equal to 3 rem in any 13 consecutive weeks or 12 rem in a year for unusual circumstances. It recommends a maximum whole body dose for members of the public of less than 0.5 rem/year, with an average body burden not to exceed one-tenth that of radiation workers.

The ICRP redefines the maximum permissible dose and adopts the NCRP recommendations.

1959—The AEC amends 10 CFR Part 20 to be consistent with the recommendations of the NCRP. The Federal Radiation Council (FRC) is created.

1960—The FRC issues its first set of guidance.

1970—The Environmental Protection Agency (EPA) is created and the FRC dissolved.

1971—The NCRP recommends a limit on the dose equivalent to the U.S. population of 0.17 rem/person/year for whole body and gonad exposure, and limits fetal exposure to less than 0.5 rem as a result of the mother's occupational exposure.

1973—A memorandum is issued by the Office of Management and Budget clarifying the roles of the AEC and EPA with regard to standards for the uranium fuel cycle.

1974—The Energy Reorganization Act of 1974 splits the AEC into the Nuclear Regulatory Commission (NRC) and Energy Research and Development Administration (ERDA).

1977—The ICRP makes major revisions to its basic recommendations. It introduces the concept of effective dose equivalent (which combines external and internal dose), adopts the policy of As Low As Reasonably Achievable (ALARA) and recommends an effective dose-equivalent limit of 5 rem per year for workers.

The U.S. Congress amends the Clean Air Act, charging the EPA with issuing emission standards for hazardous air pollutants, including radionuclides.

1987—The EPA issues guidance to federal agencies, based on the 1977 ICRP recommendations, regarding regulations to ensure protection of workers who are occupationally exposed to radiation.

1991—The NRC revises 10 CFR Part 20 to incorporate the 1987 EPA guidance. As part of its revised rule, NRC adopts a radiation dose limit for members of the public of 0.1 rem/year. The rule takes effect Jan. 1, 1994.

The ICRP issues new basic recommendations, which include limiting occupational dose to less than 10 rem in five years (i.e., an average of 2 rem/year), and limiting radiation dose to members of the public to less than 0.1 rem/year.

1995—The EPA proposes an update to its guidance to federal agencies on dose limits for the public. The proposed guidance generally reflects the 1991 ICRP recommendations.

The EPA issues a final rule that exempts nuclear power plants from EPA radiation air emission standards because the plants' emissions are adequately monitored and controlled under NRC regulations. (Other NRC-licensed facilities were not exempted from EPA standards at this time.)

1996—In a follow-on action, the EPA issues a final rule that exempts NRC-licensed facilities (other than nuclear power plants (from EPA radionuclide air emissions standards because the facilities' emissions are also adequately monitored and controlled under NRC regulations.

1997—At the request of the EPA, the BEIR VII committee is formed to determine if sufficient new scientific data is available to warrant reassessment of low-level ionizing radiation health effects.

1998—The BEIR VII committee concludes that sufficient data has become available since 1991 to warrant a reexamination of the health effects of low levels of ionizing radiation.

The Department of Energy initiates a 10-year program of research on molecular responses to low levels of radiation.