Science Record

SCIENCE RECORD New Ser. Vol. III, No. 1, 1959

BIOPHYSICS

COSMIC RADIATION AND TUBERCULOSIS

II. ACTION OF COSMIC RADIATION ON TUBERCLE BACILLI*

S. G, One (=22798)** (Institute of Epidemiology, Academy of Medical Sciences, Peking)

1. In a preliminary experiment it has been shown that tubercle bacilli exposed to cosmic radiation at Jungfraujoch (3,457 m) with or without screen showed a significant difference in virulence when injected into mice. In fact, the virulence decreased in the following order of treatments:

. Treatments Mean times of survival in days Under 30 m of rock 2... 20.5 Under 2 cm of lead ......... 20.0 79.9 Direct cosmic radiation .......................... 116.0 Under 10 cm of lead .................. (Tubercle bacilli killed)

The objection to this experiment and to all other experiments on the biological action of cosmic radiation is that the action of radio-active radiation from the environment is not eliminated.

2. We repeated the above experiment by enclosing the tubercle bacilli in a lead box of 1 cm thickness so that most of the radio-active rays were eliminated. Fig. 1 shows the dimensions of the box. By inserting lead plates of approximately 1 cm thickness between the tubes, numbered 1—20, different thicknesses of lead can be obtained. The box was placed in an incubator maintained at 37°C on the roof of the laboratory (63 m above sea-level). On the top of the box were placed two unscreened control tubes with tubercle bacilli being thus exposed to the direct action of cosmic radiation. After 53 days the tubercle bacilli from the various tubes were injected into mice. For each pair of tubes 20 mice were injected intravenously with 0.4 mg of tubercle bacilli. However, in groups 3, 4 and 5 the quantity of tubercle bacilli was not sufficient, therefore 15, 19 and 19 mice were used respectively.

*Received Nov, 22, 1958. *“Member of Academia Sinica,