UN Scientific Committee Cites Medical Radiation Use as Growing Source of World Population’s Exposure

Medical use of ionizing radiation currently accounts for up to 98 percent of the world population’s exposure from all artificial radiation sources, according to a report issued by the United Nations scientific committee on the effects of atomic radiation.

“Medical exposures account for 98 percent of the contribution from all artificial sources and are now the second largest contributor to the population dose worldwide, representing approximately 20 percent of the total,” stated the U.N. Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The group reported on the study to the U.N. General Assembly an Aug. 17, 2010.

The committee data collected from the years 1997 to 2007 indicate that about 3.6 billion x-ray examinations per year were performed during that decade. The exams ordered represented a 40 percent, or 1.1 billion, increase from the previous 10-year span. In turn, a majority of the medical radiation exposure occurred in countries with high levels of health care such as the United States. The average exposure from medical uses in those countries is equal to about 80 percent of what the world’s population receives from natural sources, the committee reported.

Between 1980 and 2006 in the United States, medical exposure grew to levels comparable with natural background exposure, the report said. Computed tomography scans were the major contributor, with additional exposure accruing from diagnostic x-rays, interventional procedures and nuclear medicine.

“In several countries this has meant that medical exposure has displaced exposure due to natural sources of radiation as the largest overall component,” the report stated.

The committee defined four levels of health care, with the highest, level one, based on the number of physicians per capita in the population. Working with this criteria, the committee found that medical x-ray examinations in the United States are 65 times more frequent than in level three and four countries with the lowest ratio of physicians per capita. However, the report noted that as medical imaging techniques developed and their use widened, medical uses of radiation continued to increase irrespective of the level of health care being delivered.

The additional 2 percent of artificial exposure sources include the atmospheric testing of nuclear weapons that decreases as testing wanes; occupational exposure, with the highest population of exposures among mine workers exposed to radon; exposures at nuclear power plants, which are falling steadily; the declining effects of the Chernobyl nuclear plant accident in 1986; and the nuclear fuel cycle of mining, power generation and waste disposal.

The UNSCEAR findings on exposure from medical radiation are contained in the first of two volumes, with the second covering exposures of the public and workers from various sources of radiation. A press release on these studies can be accessed on the U.N. News Centre website at http://www.un.org/apps/news/.