In situ monitoring with Tradescantia around nuclear power plants.

Highly sensitive mutational responses of the stamen-hair system of some Tradescantia clones heterozygous for flower color (blue/pink, the blue being dominant) to low-level radiation and chemical mutagens, as demonstrated in the last decade, seem to endorse this system to be the most promising biological tester for detecting the genetic effects of mutagens at low levels. Two triploid (thus sterile) clones, KU 7 and KU 9, have been established as those suitable for in situ monitoring of environmental mutagens. In situ monitoring with such Tradescantia clones was first tried in 1974 around a nuclear power plant in Japan, then has been repeated until 1979 around more nuclear plants. About 260,000 to 1,570,000 stamen hairs were observed per year per nuclear plant (about 12-million hairs in total), and the data of pink mutation frequency were analyzed statistically. Significantly increased mutation frequencies were observed and were correlated to the operation periods of the nuclear facilities and to predominant wind direction, but not to other environmental factors. Considering physical monitoring data of radiation dose in the air, internal exposure due to incorporation and concentration of man-made radioactive nuclides seems to be of a greater importance in increasing mutation incidence.