Natural Environmental Radiation

Studies of human populations exposed to high environmental levels of low-dose-rate ionizing radiation found in high-background radiation areas (HBRAs) are very useful in predicting disease risks from chronic radiation exposures in nuclear and medical workers and in other exposed populations [1]. Significant doses are seen from naturally occurring radi-onuclides, particularly from ⁴⁰K, and ²²⁶Ra and ²²²Rn from uranium decay (Table 3.1). Natural ⁴⁰K provides about 380 million disintegrations per day, mostly as β-particles, in standard man. The average whole-body dose rate from ⁴⁰K is 0.15–0.20 mSv/year, whereas the annual, average equivalent dose rate from inhaled radon is 1.3 mSv [3, 4]. The vast majority of the earth's surface experiences annual background-radiation levels that range from <1 to >100 mSv. About 99% of the world's population receives dose rates of <7 mSv/ year [5]. A few geographical hotspots receive annual doses of >100 mSv/year (Table 3.2) [2]. The global average background radiation dose is 2.4 mSv/year [7]. Residents near Yangjiang in Guangdong province, China, receive an annual background dose of 6.4 mSv [8]. The background-radiation dose in Korea averages 2.5 mSv/year with little variability, whereas the background-radiation dose in the United States averages 2.4 mSv/year but with high variability, ranging from 1.2 to 12 mSv/year.

The disconnect between policy and science causes public confusion and loss of credibility. The LNT makes radiation seem uniquely fearsome and the price we pay is horrendous

(Jim Muckerheide)