No abstract

An instrument has been developed for the in situ determination of lead on painted surfaces. It utilizes, as a source of gamma rays, radioactive cadmium-109 and its daughter silver-109 (metastable) to excite the K series x-rays of lead, and a solid-state, lithium-drifted germanium detector. The device, which is capable of detecting 0.26 milligram of lead per square centimeter of paint [approximately 3 percent (by weight) of lead in a single coat] beneath ten layers of lead-free paint, has been tested in a preliminary survey of several tenement apartments in New York City.

The presence of easily measurable quantities of intermediate-lived fission products in ground level air during the first half of 1963 prompted an investigation of the distribution of gamma emitting nuclides in human lungs. Lungs from five cadavers were dissected, ashed and measured for 95Zr-95Nb, 13'Cs and 40K using a 4 x 4411. NaI well crystal and a multichannel analyzer. Prior measurement of the cadavers in a whole body counter using a 8 x 4-in.NaI crystal positioned over their backs, permitted calibration of a low level in situ method of measuring 95Zr-95Nb in human lungs. Counting efficiencies ran from 3 x to 6 x 10-2 counts/dis. in the full energy peak. The measured lung burdens ranged from 210 to 450 pc at the time of death and were comparable to the values expected from the ICRP model for insoluble materials. The distribution in the lobes was fairly uniform.

A preliminary case-control study of 19 lung cancer cases older than 55 y and 141 age-matched controls was carried out among a group of underground miners in Southern China who were exposed to 222Rn and its decay products. 210Pb activity levels were measured in the skull to estimate radon exposure. Radon exposure was also estimated in working level months, based on work histories and available industrial hygiene data. There was a smooth gradient of lung cancer risk with categories of skeletal 210Pb level at time of last radon exposure; relative risks of 1.0, 2.9, 3.2, and 4.7 for categories < 51.8, 51.8-77.7, 77.8-107.3, and > or = 107.4 Bq (< 1,400, 1,400-2,099, 2,100-2,899, and > or = 2,900 pCi), respectively. Relative risks were unaffected by adjustment for exposure to arsenic in the mine or by adjustment for working level months. Risks also increased with cumulative working level month exposure, but the gradient of risk lessened after adjustment for exposure to arsenic. 210Pb, at the time of last radon exposure (p = 0.13) and at the current 210Pb level (p = 0.01), was not highly correlated with the working level month estimate. Data were sparse but smoking had minimal effect on risk gradient with level of skeletal 210Pb activity. This study suggests measured 210Pb level may be a more precise predictor of lung cancer risk than working level month.