Final answer:
The risk of low dose radiation rates in humans is traditionally assessed through the linear hypothesis, which posits a direct proportionality to higher dose effects. The unit of measurement for dose rates is the Sievert, with 1 Sv equal to 100 rem. Background radiation and concepts like hormesis play a role in understanding the effects of low-level radiation exposure.
Step-by-step explanation:
The estimation of risk related to low dose rates of radiation in humans is a crucial aspect of radiological protection. According to the linear hypothesis, the risk of radiation-induced effects, such as cancer or genetic defects, is considered to be directly proportional to the dose, even at low levels. The standard measurement of radiation dose is the Sievert (Sv), where 1 Sv equals 100 rem.
Commonly, whole-body single-exposure doses of 0.1 Sv or less are categorized as low doses, doses from 0.1 to 1 Sv are moderate, and those over 1 Sv are high doses. For an individual receiving a dose of 1 rem, the annual risk of dying from radiation-induced cancer is estimated at 10 in a million, which over a lifetime (approximately 30 years) amounts to a risk of 0.03 percent. In the grander scale of demography, where about 20 percent of all deaths worldwide are due to cancer, such an increase in risk is statistically indiscernible. However, a dose of 100 rem, which is equivalent to the average dose received by Hiroshima and Nagasaki survivors, results in a 3 percent increase in cancer risk, which is discernible against the background rate of natural cancer incidence.
Overall, the average person is not typically exposed to large amounts of radiation. Background radiation from natural sources, such as cosmic rays, averages about 0.40 mSv per year globally. Certain studies and theories, such as hormesis, even suggest that low doses of radiation may evoke a positive biological response by activating repair mechanisms or helping cells adapt to small amounts of radiation. Yet, these effects are still subject to scientific debate and research.