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I just received my own message from Radsafe.
The table did not come out well. I put the info directly in the body
of the message.
Mark, Mike Ford
and Radsafe friends
(I tested sending this message to myself, with the table. It came out OK. I hope it does to everyone. If not, please e-mail me directly, I will send things by fax) For those interested, here is a summary of stats on the 11 cohorts subject to Jay Lubin's et al. joint analysis (NIH publ. No. 94-3644, 1994) One can note the wide disparity in number of Rn or Rn progeny measurements between cohorts. Also worth noting is the wide range of duration of employment at the facility in which the exposure used to calculate the risk was acquired. Miners are a highly mobile bunch, particularly in North America. It is no mystery that, at Beaverlodge for example, the company (Eldorado) hired preferentially local miners (there were several other U and Rn mines in the region), who therefore left a Rn mine to join Eldorado and went to other local mines when they left Beaverlodge. Exposures accumulated in other mines are not taken into account in risk calculations, hence a systematic overestimation of Rn risk (how big is it ?). Perhaps the question of '' other mine doses '' is worth looking at in the cohorts who have a mean duration of employment of less than 10 years. In some mines considered in the 11 cohorts, no measurements at all. exposures were ''reconstructed'', extrapolated, assigned from values obtained in nearby mines, .... Furthermore, the excess lung cancer incidence is attributed to radiation, then the excess of lung cancers is due to the sum of all lung doses, from all radiation sources, not that from Rn progeny alone. For the curious mind, calculating non-radon doses and comparing them to Rn doses is quite interesting ! Another source of systematic overestimation. NOTE: In all the cohorts, there is no excess of cancer for organs other than lung, except liver in Czech miners (alcohol consumption) and buccal cavity in French miners (alcohol + cigarette) - see BEIR VI, table 4.3, p. 123). To Mark, re iron Swedish miners: hematite (iron ore) is a known lung carcinogen. Silica is another one listed as such by IARC. The incidence of lung cancer in French iron miners is 3 to 5 (Anthoine, D., Lamy, P., De Ren G., Braun, P., Cervoni, P., Petiet, G., Schwartz, P., Zuck, P. and Lamaze, R. Le cancer bronchique des mineurs de fer de Lorraine, Arch. Mal. Prof., 40, no. 2, 48-51, (1979). It is up to 15 in Czech iron miners (Isco , J and Szollosova, M. Incidence of Lung cancer in Iron ore miners, Proceedings of the International Conference on Low Dose Irradiation and Biological Defense Mechanisms, Kyoto, Japan, 103-106, (1992). What are the respective contributions of radon, silica, hematite in the excess lung cancer in Swedish iron miners ? (to reassure some of you, I spent ten years in radiation studies among miners in French underground and open pit U mines, worked a few more years in Elliot Lake in U mine dosimetry and did rad prot studies in high grade mines in Saskatchewan) Summary data
for the eleven cohorts of underground miners exposed to
radon progeny (Radsafers can make their own mind from real numbers). Cohort :
Chinese tin miners
Number of measurements (Rn or Rn decay products) : 26500 Number of workers in the cohort : 13649 Number of measurements per worker : 1.94 Number of person.y : 17607 Average number of years of exposure : 1.3 Number of lung cancer cases : 936 ERR/WLM : 0.16 (0.1-0.2) Cohort : Colorado uranium miners Number of measurements (Rn or Rn decay products) : 43000 Number of
workers in the cohort : 3347
Number of measurements per worker : 12.85 Number of
person.y : 16735
Average number of years of exposure : 5.0 Number of lung cancer cases : 327 ERR/WLM : 0.42 (0.3-0.7) Cohort : Czech
uranium miners
Number of
measurements (Rn or Rn decay products) : 120000
Number of
workers in the cohort : 4284
Number of
measurements per worker : 28.01
Number of
person.y : 31273
Average number
of years of exposure : 7.3
Number of lung
cancer cases : 656
ERR/WLM : 0.34 (0.2-0.6) Cohort : French
uranium miners
Number of
measurements (Rn or Rn decay products) : 1 200 000
Number of
workers in the cohort : 1769
Number of
measurements per worker : 678.35
Number of
person.y : 25882
Average number
of years of exposure : 14.6
Number of lung
cancer cases : 45 ERR/WLM : 0.36 (0.0-1.3) Cohort : New
Mexico uranium miners
Number of
measurements (Rn or Rn decay products) : 92 000
Number of
workers in the cohort : 3457
Number of
measurements per worker : 26.61
Number of
person.y : 25581
Average number
of years of exposure : 7.4
Number of lung
cancer cases : 68
ERR/WLM : 1.72 (0.6-6.7) Cohort :
Newfounland fluorspar miners
Number of
measurements (Rn or Rn decay products) : 80
Number of
workers in the cohort : 1751
Number of
measurements per worker : 0.05
Number of
person.y : 8405
Average number
of years of exposure : 4.8
Number of lung
cancer cases : 112 ERR/WLM : 0.76 (0.4-1.3) Cohort :
Ontario uranium miners
Number of
measurements (Rn or Rn decay products) : 131 000
Number of
workers in the cohort : 21346
Number of
measurements per worker : 6.14
Number of
person.y : 64048
Average number
of years of exposure : 3
Number of lung
cancer cases : 282 ERR/WLM : 0.89 (0.5-1.5) Cohort : Port
Radium uranium miners
Number of
measurements (Rn or Rn decay products) : 261
Number of
workers in the cohort : 1420
Number of
measurements per worker : 0.18
Number of
person.y : 4544
Average number
of years of exposure : 3.2
Number of lung
cancer cases : 39 ERR/WLM : 0.19 (0.1-0.6) Cohort : Radium
Hill uranium miners
Number of
measurements (Rn or Rn decay products) : 721
Number of
workers in the cohort : 1457
Number of
measurements per worker : 0.49
Number of
person.y : 1602
Average number
of years of exposure : 1.1
Number of lung
cancer cases : 32
ERR/WLM : 5.06 (1.0-12.2) Cohort :
Swedish iron miners
Number of
measurements (Rn or Rn decay products) : 80
Number of
workers in the cohort : 1294
Number of
measurements per worker : 0.06
Number of
person.y : 23033
Average number
of years of exposure : 17.8
Number of lung
cancer cases : 79 ERR/WLM : 0.95 (0.1-4.1) Cohort :
Beaverlodge uranium miners
Number of
measurements (Rn or Rn decay products) : 6900
Number of
workers in the cohort : 6895
Number of
measurements per worker : 1.00
Number of
person.y : 13101
Average number
of years of exposure : 1.9
Number of lung
cancer cases : 58 ERR/WLM : 2.21 (0.9-5.6) Philippe Duport
International Centre for Low Dose Radiation Research University of Ottawa 555 King Edward Ave. Ottawa, ON, Canada, K1N 6N5 Tel: (613) 562 5800, ext. 1270 pduport@uottawa.ca |