Costs And Benefits Of Mitigating Radon In Drinking Water
The Environmental Protection Agency (EPA) is considering regulating radon, a naturally occurring soil gas dissolved in drinking water, because it poses a lung cancer risk. Benefits and costs of compliance are estimated for 29 water systems with radon above the proposed maximum contaminant level. The estimated cancer risk is three times higher than assumed by EPA, making it likely that a national regulatory standard of 300 picocuries per liter of water would pass a cost-benefit test. Site specific estimates of compliance costs are also substantially greater than EPA estimates. Nevertheless, the estimated cost per avoided death is only about $1 million.
Expected indoor 222Rn levels in counties with very high and very low lung cancer rates.
Counties in the U.S. with high lung cancer rates should have higher average 222Rn levels than counties with low lung cancer rates, assuming the average 222Rn level in a county is not correlated with other factors that cause lung cancer. The magnitude of this effect was calculated, using the absolute risk model, the relative risk model, and an intermediate model, for females who died in 1950-1969. The results were similar for all three models. We concluded that, ignoring migration, the average Rn level in the highest lung cancer counties should be about three times higher than in the lowest lung cancer counties according to the theory. Preliminary data are presented indicating that the situation is quite the opposite: The average Rn level in the highest lung cancer counties was only about one-half that in the lowest lung cancer counties.
Computer simulations and theory of oceanographic fluorescence lidar signals: effect of sea surface structure.
A 3-D computer simulation model has been developed using geometrical optics suitable for analyzing the effect of sea surface structure on oceanographic fluorescence lidar signals. Depth-resolved and depth-integrated signals reveal a considerable dependence on the surface structure. The results obtained by simulation are confirmed by a theoretical approach based on the transformation of solid angles by curved boundaries. Using statistical assumptions about the distribution of curvatures of the ocean surface, a general expression for this influence is found.