the risK estimate for some tumors by a factor of at least two. The method of analysis (e.g., relative vs. absolute risk model) can alter the risk estimate by an additional factor of three. Choosing different age and sex distributions can further change tne estimate by another factor of up to three. When decisions have been made about the selection of SPS workers, the precise influence of age and sex distribution can be included in risk estimates. However, the choice of dose-respose relationship and projection models at present is a matter of opinion and will not be resolved scientifically for quite some time. CONCLUSIONS The conclusions of the committee based on the findings above are: a. The risk of excess cancer deaths is assumed to be closer to the lower limit estimated above because the major exposure will be from the low dose rate, low-LET irradiation. This being the case, we consider a reasonable estimate to be one excess death per 10,000 workers per rem of exposure. If this level of risk is applied to the worst case reference system exposure level, namely 40 rem, there would be 400 excess cancer deaths in a work force of 10,000 completing ten missions (accumulative dose equivalent of 400 rem). b. The potential genetic consequences could be of significance, but at the present time, sufficient information on the age and sex distribution of the worker population is lacking for precise estimation of risk. c. The potential teratogenic consequences resulting from radiation are considered significant. Radiation exposure of a pregnant worker could result in developmental abnormalities. d. Based on the Reference System, dose to space workers from low- LET bremstrahlung approaches the cataratogenic level for man. The appropriate quality factor for the HZE particle portion of the dose is unknown at this time. If its Q is greater than 20, the cataract hazard may be significant. More information is needed regarding this hazard. e. In tne absence of a radiation accident or some other unexpected situations (e.g., nuclear detonation) and with adequate shielding to protect against the increased radiation levels during solar particle events, there will be no early or acute radiation health effects occurring in the SPS worker population. f. No other radiation health effects are considered to be of sufficient consequence to be important for risk estimation.
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