Population Exposure Dose Reconstruction for the Urals Region

This presentation describes the first preliminary results of an ongoing joint Russian-US pilot feasibility study. Many people participated in workshops to determine what Russian and United States scientists could do together in the area of dose reconstruction in the Urals population. Most of the results presented here came from a joint work shop in St. Petersburg, Russia (11-13 July 1995). The Russians at the workshop represented the Urals Research Center for Radiation Medicine (URCRM), the Mayak Industrial Association, and Branch One of the Moscow Biophysics Institute. The US Collaborators were Dr. Anspaugh of LLNL, Dr. Nippier of PNL, and Dr. Bouville of the National Cancer Institute. The objective of the first year of collaboration was to look at the source term and levels of radiation contamination, the historical data available, and the results of previous work carried out by Russian scientists, and to determine a conceptual model for dose reconstruction

Experimental system to displace radioisotopes from upper to deeper soil layers: chemical research

BACKGROUND: Radioisotopes are introduced into the environment following nuclear power plant accidents or nuclear weapons tests. The immobility of these radioactive elements in uppermost soil layers represents a problem for human health, since they can easily be incorporated in the food chain. Preventing their assimilation by plants may be a first step towards the total recovery of contaminated areas. METHODS: The possibility of displacing radionuclides from the most superficial soil layers and their subsequent stabilisation at lower levels were investigated in laboratory trials. An experimental system reproducing the environmental conditions of contaminated areas was designed in plastic columns. A radiopolluted soil sample was treated with solutions containing ions normally used in fertilisation (NO(3)(-), NH(4)(+), PO(4)(--- )and K(+)). RESULTS: Contaminated soils treated with an acid solution of ions NO(3)(-), PO(4)(--- )and K(+), undergo a reduction of radioactivity up to 35%, after a series of washes which simulate one year's rainfall. The capacity of the deepest soil layers to immobilize the radionuclides percolated from the superficial layers was also confirmed. CONCLUSION: The migration of radionuclides towards deeper soil layers, following chemical treatments, and their subsequent stabilization reduces bioavailability in the uppermost soil horizon, preventing at the same time their transfer into the water-bearing stratum

Radioecological studies related to the BANEBERRY event

On December 18, 1970, at 7:30 a.m., PST, a venting occurred at the Nevada Test Site in conjunction with the Baneberry test. The Lawrence Radiation Laboratory (LRL) Bio-Medical Research Division and the University of Utah responded to this event by activating their jointly operated air-sampling network and by gathering forage, milk, and animal samples. These data are used to calculate the dose to humans from inhalation, submersion, and food-chain contamination; food-chain contamination calculations are limited to the cow-milk pathway, but included bovine inhalation. The question of food-chain contamination is explored under both the actual situation that dairy cows were fed stored feed and under the hypothetical situation that dairy cows were fed fresh feed. Our results show that {sup 131}I was the significant radionuclide emitted by the event and that the strongest dose was received by the thyroid glands of both foraging animals and humans. The integrated concentrations of {sup 131}I were higher in the northern part of Utah; the maximum value of 1100 pCi h m{sup {minus}3} was recorded at Draper (near Salt Lake City). For conservative results, we calculated the dose to a child rather than an adult. For the actual conditions following the venting, we estimate on the basis of measurements of baled hay and or milk that the dose to an infant's thyroid via the cow-milk pathway was between 0.0065 and 0.012 rad at Draper. If cows had been continuously on fresh pasture, we estimate that the dose to the infant thyroid for the same integrated air concentration would have been 1.3 rad for dry deposition and up to 100 rad for wet deposition. 24 refs., 3 figs., 13 tabs

Ecologically Appropriate Xenobiotics Induce Cytochrome P450s in Apis mellifera

BACKGROUND: Honey bees are exposed to phytochemicals through the nectar, pollen and propolis consumed to sustain the colony. They may also encounter mycotoxins produced by Aspergillus fungi infesting pollen in beebread. Moreover, bees are exposed to agricultural pesticides, particularly in-hive acaricides used against the parasite Varroa destructor. They cope with these and other xenobiotics primarily through enzymatic detoxificative processes, but the regulation of detoxificative enzymes in honey bees remains largely unexplored. METHODOLOGY/PRINCIPAL FINDINGS: We used several approaches to ascertain effects of dietary toxins on bee susceptibility to synthetic and natural xenobiotics, including the acaricide tau-fluvalinate, the agricultural pesticide imidacloprid, and the naturally occurring mycotoxin aflatoxin. We administered potential inducers of cytochrome P450 enzymes, the principal biochemical system for Phase 1 detoxification in insects, to investigate how detoxification is regulated. The drug phenobarbital induces P450s in many insects, yet feeding bees with phenobarbital had no effect on the toxicity of tau-fluvalinate, a pesticide known to be detoxified by bee P450s. Similarly, no P450 induction, as measured by tau-fluvalinate tolerance, occurred in bees fed xanthotoxin, salicylic acid, or indole-3-carbinol, all of which induce P450s in other insects. Only quercetin, a common pollen and honey constituent, reduced tau-fluvalinate toxicity. In microarray comparisons no change in detoxificative gene expression was detected in phenobarbital-treated bees. However, northern blot analyses of guts of bees fed extracts of honey, pollen and propolis showed elevated expression of three CYP6AS P450 genes. Diet did not influence tau-fluvalinate or imidacloprid toxicity in bioassays; however, aflatoxin toxicity was higher in bees consuming sucrose or high-fructose corn syrup than in bees consuming honey. CONCLUSIONS/SIGNIFICANCE: These results suggest that regulation of honey bee P450s is tuned to chemicals occurring naturally in the hive environment and that, in terms of toxicological capacity, a diet of sugar is not equivalent to a diet of honey

A Knowledge Assessment Following Nutrition and Food Labeling Instruction with College Students

DESIGN A pre-post-post- test design was used to evaluate differences in students\u27 knowledge before and after instruction. SUBJECTS A sample of 84 students who were present for all lectures regarding nutrition and food labeling and tests were selected from a total of 223 students enrolled in a mandatory wellness class in a major Southeastern U.S.A. urban university. INTERVENTION The pre-test was followed by three one hour nutrition lectures, one of which was devoted to a study of food labeling. A post-test followed the third lecture, and a second post-test was given six weeks later. STATISTICAL ANALYSES Knowledge test scores were analyzed by using repeated measures analysis of variance. Demographic information was analyzed by using the chi-squared statistics. The SPSS computer program was used for data analysis. RESULTS The sample group had a fair knowledge of the food label prior to the study as indicated by the pre-test scores. Significant changes in knowledge occurred following instruction although knowledge was not retained for six weeks. The only variable to be related to significant change in knowledge was race. CONCLUSION Although students had knowledge of food labeling prior to instruction, limitations were present. More than a one-hour educational lecture may be needed to increase knowledge. © 1995 American Dietetic Association

Consequences of the Chernobyl accident for the natural and human environments

In the ten years since the Chernobyl accident, an enormous amount of work has been done to assess the consequences to the natural and human environment. Although it is difficult to summarize such a large and varied field, some general conclusions can be drawn. This background paper includes the main findings concerning the direct impacts of radiation on the flora and fauna; the general advances of knowledge in the cycling of radionuclides in natural, seminatural and agricultural environments; some evaluation of countermeasures that were used; and a summary of the human radiation doses resulting from the environmental contamination. although open questions still remain, it can be concluded that: (1) at high radiation levels, the natural environment has shown short term impacts but any significant long term impacts remain to be seen; (2) effective countermeasures can be taken to reduce the transfer of contamination from the environment to humans but these are highly site specific and must be evaluated in terms of practicality as well as population does reduction; (3) the majority of the doses have already been received by the human population. If agricultural countermeasures are appropriately taken, the main source of future doses will be the gathering of food and recreational activities in natural and seminatural ecosystems

Estimated long-term health effects

Apart from the dramatic increase in thyroid cancer in those exposed as children, there is no evidence to date of a major public health impact of the radiation exposure from the Chernobyl accident in the three most affected countries. Although some increases in the frequency of cancer in exposed populations have been reported, these results are difficult to interpret, mainly because of differences in the intensity and method of follow-up between exposed populations and the general population to which they are compared. If the experience of atomic bomb survivors and of other exposed populations is applicable, the major radiological impact of the accident will be cancer and the total lifetime numbers of excess cancers will be greatest among the liquidators and among the residents of contaminated territories, of the order of 2,000 to 2,500. These increases would be difficult to detect epidemiologically against an expected background number of 41,500 and 433,000 respectively (size of the exposed populations: 200,000 and 3,700,000, respectively). It is noted, however, that the exposures received by populations exposed as a result of Chernobyl are different (in type and pattern) from those of atomic bomb survivors. Predictions derived from these populations are therefore uncertain. Indeed, the extent of the increase in thyroid cancer incidence in persons exposed as children was not foreseen. In addition, only ten years have passed since the accident. It is essential therefore that monitoring of the health of the population be continued in order to assess the public health impact of the accident, even if, apart from leukemia among liquidators, little detectable increase of cancers due to radiation from the Chernobyl accident is expected