The extent to which a bacterial cocktail containing equal numbers of Pseudomonas fragi NCTC 10689, Listeria monocytogenes BL5/2, Salmonella Typhimurium LT2, and Escherichia coli JM 109 attached to loin surface cuts (7 by 5 cm) derived from steam-pasteurized beef carcasses has been evaluated. The extent of attachment was categorized as loosely attached (removed by rinsing), firmly attached (released by stomaching), and irreversibly bound. No significant difference (P > 0.10) in the attachment of bacteria to steam-pasteurized carcasses was found compared with control loin samples that had received no treatment. No significant difference (P > 0.05) was also found in the attachment strength between the different bacterial species tested. Most bacteria inoculated onto the loin cuts were reversibly bound, since they had been removed by rinsing and stomaching. The irreversible attachment of bacteria to loin cuts was found to vary significantly (P < 0.01) among the different carcass sets used but was independent of whether the carcass had undergone steam pasteurization treatment. Use of a bioluminescent strain of E. coli showed that cells bound preferentially to cut edges and convoluted areas on the loin surface and could not be removed by rinsing. The possible mechanisms of bacterial attachment and the suitability of steam pasteurization to remove contamination incurred during slaughter are discussed.
It has been shown that the weight average molecular weight determined from light scattering measurements for freshly prepared solutions of an ionic surface active agent in toluene is much greater than the number average molecular weight determined from vapour pressure measurements. This discrepancy is caused by small quantities of water solubilized by the surface active agent. The water initially forms a relatively small number of very large aggregates which disintegrate as the solution ages until at equilibrium the weight average and number average molecular weights are in agreement. It is suggested that similar discrepancies observed for non-ionic surface active materials in non-aqueous media are also caused by solubilized impurities.
The Interagency Steering Committee on Radiation Standards (ISCORS) has recently completed a study of the occurrence within the United States of radioactive materials in sewage sludge and sewage incineration ash. One component of that effort was an examination of the possible transport of radioactivity from sludge into the local environment and the subsequent exposure of humans. A stochastic environmental pathway model was applied separately to seven hypothetical, generic sludge-release scenarios, leading to the creation of seven tables of Dose-to-Source Ratios (DSR), which can be used in translating from specific activity in sludge into dose to an individual. These DSR values were then combined with the results of an ISCORS survey of sludge and ash at more than 300 publicly owned treatment works, to explore the potential for radiation exposure of sludge workers and members of the public. This paper provides a brief overview of the pathway modeling methodology employed in the exposure and dose assessments and discusses technical aspects of the results obtained.
In order to encourage the timely and efficient cleanup of sites contaminated with radioactive materials, the New Jersey Department of Environmental Protection revised its Sampling Procedures Manual to follow the MARSSIM (NRC 2000) methodology. This was done concurrently with the proposal and subsequent adoption of its Soil Remediation Standards for Radioactive Materials (New Jersey Administrative Code Title 7, Department of Environmental Protection, Chapter 28 Radiation Protection Programs, Subchapter 12, Soil Remediation Standards for Radioactive Materials).
past experience, there have been concerns that radioactive materials could concentrate in sewage sludge and The Nuclear Regulatory Commission (NRC) announced the availash and pose a threat to the health and safety of POTW ability of three new documents concerning radioactive materials in sewage sludge and ash from publicly owned treatment works (POTW). workers or the general public. One of the documents is a report presenting the results of a volunteer As a result of interest from the U.S. Congress, the survey of sewage sludge and ash samples provided by 313 POTWs. Interagency Steering Committee on Radiation Standards The second document is a dose modeling document, using multiple (ISCORS) conducted a survey of radioactive material in exposure pathway modeling focused on a series of generic scenarios, sewage sludge and ash. The committee also performed to track possible exposure of POTW workers and members of the dose modeling of the survey results to address radiation general public to radioactivity from the sewage sludge or ash. The concerns and to estimate typical levels of radioactive third document is a guidance report providing recommendations on materials in POTWs around the country. The committee the management of radioactivity in sewage sludge and ash for POTW then provided recommendations on the management of owners and operators. This paper explains how radioactive materials radioactivity in sewage sludge and ash for POTW ownenter POTWs, provides criteria for evaluating levels of radioactive material in sludge and ash, and gives a summary of the results of the ers and operators, including guidance on evaluating survey and dose modeling efforts. Average Typical range Radiation source exposure of variability Sv yr Ϫ1 ‡ WHY IS THERE RADIOACTIVE Natural sources MATERIAL IN SEWAGE AND Terrestrial 300 100-800 SEWAGE SLUDGE? Radon 2000 300-8 200 Cosmic 300 300-800 Radioactive materials are an ever-present component Internal 400 200-1 000 of the natural environment and are also produced through Man-made sources some human activities. Generally, the presence of radio-Medical 500 active materials is a concern only when concentrations Consumer products 100 Other (nuclear fuel cycle 10 become sufficiently elevated above background levels and occupational) (Table 1) to potentially pose a health risk, or in cases Total where the ability of a POTW to use or dispose of the 3600 900-10 800 sewage sludge or ash is limited. † Sources: National Council on Radiation Protection and Measurements Publicly owned treatment works can receive naturally (1987a) for average exposure values, Huffert et al. (1994) and Fisher occurring radioactive material (NORM) or man-made (personal communication, 2003) for ranges of variability. ‡ 1 microsievert (1 Sv) ϭ 0.1 milliroentgens (0.1 mrem).
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