Health Effects
Ionizing radiation is generally harmful and potentially lethal to living things but can have health benefits in radiation therapy for the treatment of cancer and thyrotoxicosis. Its most common impact is the induction of cancer with a latent period of years or decades after exposure. High doses can cause visually dramatic radiation burns, and/or rapid fatality through acute radiation syndrome. Controlled doses are used for medical imaging and radiotherapy. Some scientists suspect that low doses may have a mild hormetic effect that can improve health.
Some effects of ionizing radiation on human health are stochastic, meaning that their probability of occurrence increases with dose, while the severity is independent of dose. Radiation-induced cancer, teratogenesis, cognitive decline, and heart disease are all examples of stochastic effects. Other conditions such as radiation burns, acute radiation syndrome, chronic radiation syndrome, and radiation-induced thyroiditis are deterministic, meaning they reliably occur above a threshold dose, and their severity increases with dose. Deterministic effects are not necessarily more or less serious than stochastic effects; either can ultimately lead to a temporary nuisance or a fatality.
Other effects include radiation-induced lung injury, cataracts, and infertility.
Quantitative data on the effects of ionizing radiation on human health is relatively limited compared to other medical conditions because of the low number of cases to date, and because of the stochastic nature of some of the effects. Stochastic effects can only be measured through large epidemiological studies where enough data has been collected to remove confounding factors such as smoking habits and other lifestyle factors. The richest source of high-quality data comes from the study of Japanese atomic bomb survivors. In vitro and animal experiments are informative, but radioresistance varies greatly across species.
The consensus of the nuclear industry, regulators and governments regarding radiation health effects is expressed by the International Commission on Radiological Protection. (ICRP) Other important organizations studying the topic include
- International Commission on Radiation Units and Measurements (ICRU)
- United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)
- US National Council on Radiation Protection and Measurements (NCRP)
- UK National Radiological Protection Board (NRPB)
- US National Academy of Sciences (NAS through the BEIR studies)
- French Institut de radioprotection et de sûreté nucléaire (IRSN)
- European Committee on Radiation Risk (ECRR)
Read more about this topic: Radiobiology
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