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Radiation and health: How big is the difference between rem and millirem?
Radiation is a ubiquitous presence in our daily lives, whether it comes from the universe, the soil, or medical examinations. For the correlation between the dose of radiation and human health, the scientific community has special measurement units to annotate it. This article will explore the differences between the two dosage units of “rem” and “mirem” and their impact on health risk assessment.
What are rem and millirem?
The rem is a unit used to describe the potential health effects of ionizing radiation on the human body, and is particularly used to assess the risk of cancer caused by radiation. A millirem (mrem) is one-thousandth of a rem and is typically used for radiation doses from daily exposure, such as medical X-rays or background radiation.
The rem is defined since 1976 as 0.01 sievert (Sv), which is the more commonly used unit internationally.
Rem’s historical background
The concept of REM first appeared in literature in 1945, and was initially defined in 1947. The definition at that time was "any dose of ionizing radiation that induces biological effects, equivalent to the dose of a high-voltage X-ray." Over time, the usage and definition of Rem went through many changes and adjustments, eventually becoming the current standard.
Correlation between health effects and dose
Ionizing radiation may cause both deterministic and stochastic health effects. Examples of deterministic effects include acute radiation syndrome (ARS), the occurrence of which often requires high doses of radiation (>10 rad). Stochastic effects, including radiation-induced cancer, may be the result of cumulative doses. Scientific consensus states that the incidence of cancer associated with ionizing radiation increases at a rate of approximately 0.055% per rem.
The risks from radiation are generally higher for babies and fetuses than for adults, and for women, the risk is higher than for men.
Industrial and Public Health Standards
According to the recommendations of the International Commission on Radiological Protection (ICRP), annual public doses of artificial radiation should be limited to 100 millirem (1 millisievert), excluding medical and occupational exposure. For radiation workers, the U.S. Nuclear Regulatory Commission (NRC) stipulates that the upper limit of total body radiation dose allowed during the year is 5,000 millirem. This protects workers' health to a certain extent and promotes workplace safety.
Usage scenarios of rem and millirem
In the United States, rem and millirem are the most common dosage units, while in other countries the sievert (Sv) is the standard. Although NIST recommends the use of SI units for labeling radiation doses, both units are still widely used in some industrial and government settings.
"The unit of radiation dose reflects the potential impact of the dose on human health, and it is very important to choose the appropriate unit."
Conclusion
With the advancement of science and technology, the assessment of the impact of radiation on health has become more and more precise, and the use of rem and millirem is crucial in this process. Understanding these units and their significance as indicators of health risk can help us better protect the health of ourselves and others. Faced with such an important issue, do you fully understand the limits of your safe exposure to radiation?
