Long-Term Monitoring of Thorium Inhaled by Workers and Assessment of Thorium Lung Burden in China

The establishment of a portable high sensitivity exhaled thoron activity measurement system

“…Since no computer was available at the mine in 1982, a simplified sample counting method, using a calculator, was established which permitted a decrease in counting time. to 200 minutes [3]. Instead of an automatically controlled respirator to change the pulse-like expiration air flow into a stable one, two aluminium single-directional valves combined with a tridirectional instrument connected to the mask was used; the latter was much cheaper.…”

“…Instead of an automatically controlled respirator to change the pulse-like expiration air flow into a stable one, two aluminium single-directional valves combined with a tridirectional instrument connected to the mask was used; the latter was much cheaper. The high negative voltage used by this system was increased from 5.8 kV to 9.0 kV, which was the critical step for increasing the total-efficiency of the measurement system from 50 % to 55% [3]. In addition the whole system was changed from a stationary one to a portable one.…”

Indoor and outdoor 222Rn and 220Rn and their progeny levels surrounding Bayan Obo mine, China

“…The Th content in the soil around the Bayan Obo mining area is twice as high as that in the normal background areas [4]. Studies of lung burden of workers in different workplaces for inhaling thorium-containing dust show that dust-carrying radioactive contamination is an important source of air pollution in some areas of Bayan Obo [5].…”

About the importance of the nuclear recoil in αemission near the DNA

“…It is not discussed here the hazardousness implied by the size of the possible aggregates of atoms or molecules containing radionuclides α emitters. There is anyway a vaste litterature about the solubility of these substances and their distribution in the human body [3,4]. Also the contribution of the low-energy electrons emitted by the recoiling nucleus during his motion must be carefully considered [1], but it cannot be discussed in the present article (which obviously is not including all the observations and the consequences of this effect).…”