Health and safety implications of alternative energy technologies. III. Fossil energy
This paper reviews both innovative fossil energy sources (tar sands, oil shale, and unconventional natural gas), and more established technologies that are being considered as suppliers of gaseous and liquid fuels (that is, coal gasification and liquefaction). Potential health and safety issues related to the technologies are discussed, although the absence of commercial-scale facilities in the United States restricts the discussion to health effects information derived from related processes. The available epidemiological and carcinogenic studies give cause for concern. The study of the health and environmental impacts of the emerging fossil fuel technologies will be important for quantification of adverse effects and rectification of problems before commitment to large-scale commercialization occurs.
Morbidity and mortality study of shale oil workers in the United States.
The study of the carcinogenic potential of domestic U. S. shale oil has increased significantly in importance because of the present energy problem and resulting research into alternative sources of fuel. With the increased scope of planned oil shale activity on the Colorado Plateau, it is important that an attempt be made to determine the health effects, if any, of occupational exposure to shale oil. This paper briefly reviews some past work of Soviet and British investigators concerning potential health hazards of shale oil. It reviews the results and conclusions of the 1952-1955 dermatological study of oil shale workers by the U. S. Public Health Service, and it discusses in detail the plans of a NIOSH morbidity and mortality study currently under way.
A quantitative measure of nitrifying bacterial growth.
Nitrifying bacteria convert ammonia (NH3) to nitrate (NO3-) in a nitrification reaction. Methods to quantitatively separate the growth rate of these important bacterial populations from that of the dominant heterotrophic bacteria are important to our understanding of the nitrification process. The changing concentration of ammonia is often used as an indirect measure of nitrification but ammonification processes generate ammonia and confound this approach while heterotrophs remove nitrate via denitrification. Molecular probe methods can tell us what proportion of the microbial community is nitrifying bacteria but not their growth rate. The technique proposed here was able to quantify the growth rate of the nitrifying bacterial populations amidst complex ecological processes. The method incubates [methyl-3H] thymidine with water samples in the presence and absence of an inhibitor of nitrification-thiourea. The radioactively labeled DNA in the growing bacteria was extracted. The rate of incorporation of the label into the dividing bacterial DNA was used to determine bacterial growth rate. Total bacterial community growth rates in full-scale and pilot-scale fixed-film nitrifying reactors and an activated sludge reactor were 2.1 x 10(8), 4.1 x 10(8) and 0.4 x 10(8)cell ml(-1)d(-1), respectively; the growth rate of autotrophic-nitrifying bacteria was 0.7 x 10(8), 2.6 x 10(8) and 0.01 x 10(8)cell ml(-1)d(-1), respectively. Autotrophic-nitrifying bacteria contributed 30% and 60% of the total bacterial community growth rate in the nitrifying reactors whereas only 2% was observed in the activated sludge reactor that was not designed to nitrify. The rates of ammonia loss from the nitrifying reactors corresponded to the rate of growth of the nitrifying bacteria. This method has the potential to more often identify factors that enhance or limit nitrifying processes in both engineered and natural aquatic environments.