Mutagenic activity of chlorinated surface waters and humic acid solutions

The mutagenicity of the chlorination by‐products in water supplies of the Venetian region (Italy) and in humic acid solutions were analysed. The samples were concentrated with XAD‐2 resin and tested for mutagenic activity on Salmonella typhimurium TA98 and TA100 strains. Significant mutagenic activity on TA98 strain in the presence (raw water) or absence (chlorinated water) of metabolic activation was observed only for the Po river. All other raw and chlorinated water samples did not induce significant mutagenic effects under the test conditions. The absence of mutagenic activity in almost all the raw water samples suggests very low concentrations of genotoxic pollutants. However, the low values of natural organic carbon and the appropriate treatment conditions used in the local water plants could well explain the negative results obtained for chlorinated waters. In comparison with water samples, the extracts of chlorinated humic‐rich solutions gave highly toxic and mutagenic effects on both the Salmonella strains, with and without metabolic activation. The addition of H₂O₂ at different times from the start of the chlorination greatly influenced the level of the observed mutagenic effects.     

官厅水库/永定河水中有机污染物致突变性的初步研究

1999年 7月在官厅水库和永定河下游三家店河段设 4个采样点 ,应用Ames实验对所采集水样中经XAD 2树脂富集后的有机污染物进行了致突变性检验。研究结果表明 ,对于TA98( S9)实验 ,八号桥和雁翅样品在 0 8L plate以下呈现阳性结果 ,表明样品中含有移码型直接致突变物 ,尤其是八号桥样品有很强致突变性。上述状况在加入体外代谢活化物S9后消失 ,说明样品中不含间接致突变性物质。在碱基置换型直接致突变性检验中 ,八号桥样品在 0 4L plate剂量条件下即呈直接致突变阳性 ,加入S9后在 0 8L plate剂量条件呈可疑阳性。上述结果表明在采样期间 ,该水体已受到致突变性物质的污染 ,从检验结果还可以看出 ,相对于静止水体 (水库大坝、三家店 )而言 ,流动水体 (八号桥、雁翅 )具有更强的致突变性 ,而以上游的八号桥点致突变性最高。说明致突变性物质可能来自洋河或桑干河     

Personal dust exposures at a food processing facility

A field study was performed to quantify personal dust exposures at a food processing facility. A review of the literature shows very little exposure information in the food processing industry. The processing area consisted of a series of four rooms, connected by a closed-loop ventilation system, housed within a larger warehouse-type facility. Workers were exposed to various fruit and vegetable dusts during the grinding, sieving, mixing and packaging of freeze-dried or air-dried products. Eight two-hour periods were monitored over two days. Personal total suspended particulate samples were collected on 37 mm PVC filters with 5 microm pore size according to National Institute for Occupational Safety and Health (NIOSH) Method 0500. The filters were analyzed gravimetrically. The two-hour task sampling personal dust exposures ranged from 0.33-103 mg/m3. For each worker, an eight-hour time weighted average (TWA) concentration was calculated, and these ranged from 3.08-59.8 mg/m3. Although there are no directly appropriate occupational exposure limits that may be used for comparison, we selected the Threshold Limit Value (TLV) for particulates not otherwise classified (PNOC) of 10 mg/m3 for inhalable particles. Neglecting the respiratory protection used, five out of eight of the worker time-weighted averages exceeded the TLV. It should be noted that the TLV is based on the inhalable fraction and in this study total suspended particulate was measured; additionally, the TLV is applicable for dusts that are insoluble or poorly soluble, and have low toxicity, which may have limited protective ability in this case due to the irritant nature of certain dusts (e.g., jalapeno peppers, aloe vera). Sieving resulted in significantly higher exposure than grinding and blending. Measuring area concentrations alone in this environment is not a sufficient method of estimating personal exposures due to work practices for some operations.     

Mutagenic properties of inland waters and sediments in northern Poland

Mutagenic properties of inland waters in northern Poland were evaluated using the Ames test. The tested surface waters were characterised by low mutagenic impact, while the majority of bottom sediment samples turned out to be highly mutagenic. The mutagenic rates (MR) of sediments ranged from 2 to 169 and depended on pollution of aquatic environment by organic substances and bacteria Escherichia coli. The most polluted sites of the studied rivers and lakes were indicated (MR=158, 169). This information should be useful for local governments as well as habitants.     

Mortality among workers at a nuclear fuels production facility

A retrospective cohort mortality study was conducted in a population of workers employed at a facility with the primary task of production of nuclear fuels and other materials. Data for hourly and salaried employees were analyzed separately by time period of first employment and length of employment. The hourly (N = 6,687 with 728 deaths) and salaried (N = 2,745 with 294 deaths) employees had a mortality experience comparable to that of the United States and, in fact, exhibited significant fewer deaths in many categories of diseases that are traditionally associated with the healthy worker effect. Specifically, fewer deaths were noted in the categories of all causes, all cancers, cancer of the digestive organs, lung cancer, brain cancer (hourly workers only), diabetes, all diseases of the circulatory system, all respiratory diseases, all digestive system diseases, all diseases of the genitourinary system (hourly only), and all external causes of death. A statistically significant, and as yet unexplained increase in leukemia mortality (6 observed vs. 2.18 expected) appeared among a subset of the hourly employees, first hired before 1955, and employed between 5-15 years.     

Atmospheric deposition, resuspension, and root uptake of Pu in corn and other grain-producing agroecosystems near a nuclear fuel facility

Plutonium released to the environment may contribute to dose to humans through inhalation or ingestion of contaminated foodstuffs. Plutonium contamination of agricultural plants may result from interception and retention of atmospheric deposition, resuspension of Pu-bearing soil particles to plant surfaces, and root uptake. Plutonium on vegetation surfaces may be transferred to grain surfaces during mechanical harvesting. Data obtained from corn grown near the U.S. Department of Energy's H-Area nuclear fuel chemical separations facility on the Savannah River Site were used to estimate parameters of a simple model of Pu transport in agroecosystems. The parameter estimates for corn were compared to those previously obtained for wheat and soybeans. Despite some differences in parameter estimates among crops, the relative importances of atmospheric deposition, resuspension, and root uptake were similar among crops. For even small deposition rates, the relative importances of processes for Pu contamination of corn grain should be: transfer of atmospheric deposition from vegetation surfaces to grain surfaces during combining greater than resuspension of soil to grain surfaces greater than root uptake. Approximately 3.9 X 10(-5) of a year's atmospheric deposition is transferred to grain. Approximately 6.2 X 10(-9) of the Pu inventory in the soil is resuspended to corn grain, and a further 7.3 X 10(-10) of the soil Pu inventory is absorbed and translocated to grains.     

某核设施安全关闭的辐射防护实践

目的 通过科学合理的辐射防护措施保障某核设施安全关闭工程中的辐射安全。方法 在该核设施安全关闭前期,对其放射性源项进行了辐射监测,根据监测结果对施工过程进行辐射风险分析,设计了安全关闭的施工流程,制定了科学合理的辐射防护方案并实施。结果 通过辐射监测结果可知,该核设施主要污染核素为¹³⁷Cs、⁹⁰Sr、²⁴¹Am,建筑物、设备及工器具等的放射性表面污染面积较大且污染严重,人员工作区域存在较高水平的γ辐射及放射性气溶胶;根据监测结果对工程的辐射风险进行了安全分析,采取了合理的施工流程和科学合理的辐射防护措施,确保了本工程的辐射安全。结论 本次辐射防护工作满足了本工程的辐射防护要求,为从事核设施退役相关工作的科研人员和管理部门提供参考。