Search Results
You are looking at 1 - 10 of 13 items for
- Author or Editor: U. Mishra x
- Refine by Access: All Content x
Abstract
Studies on radioactive fallout from atmospheric nuclear weapons tests have been carried out at this laboratory since the mid-fifties. The data thus generated on the levels and composition of radioactive fallout in India has been published periodically. Consequent to the Chernobyl reactor accident in the USSR in April 1986, similar studies were carried out. A number of fairly active samples were collected from commercial aircraft which had flown over the USSR soon after the accident. Even though the levels of fallout from the Chernobyl reactor accident observed in India were not significant from a health hazard view point, the studies provided detailed information on differences in the composition of fallout from the accident and long term radiation exposures likely to accrue from the Chernobyl fallout as opposed to global fallout from atmospheric nuclear weapons tests. This paper presents the results and their interpretation on the above aspects.
Abstract
Lung cancer and smoking are associated. Epidemiological studies show that not only lung cancer but other chest diseases have causative relationship with smoking. Cigarette tobacco and smoke contains many carcinogens. Inorganic and metallic constituents of cigarette tobacco and smoke have not been studied as extensively as the organic compounds. Since some of the metals are highly toxic and also carcinogenic, authors have attempted to measure the levels of some of the trace elements of Indian tobacco by instrumental neutron activation analysis, and compared the results with the tobacco of America, Germany, Iran and New Zealand.
Abstract
Trace elements present in Indian cigarette tobacco and cigarette smoke have been reported earlier. This paper presents trace element concentrations in chewing and snuff tobaccos determined by Instrumental Neutron Activation Analysis. The levels of Br, Co, Cr, Fe, Mn, Zn, etc., present in different brands of chewing and snuff tobaccos are compared in two types of tobacco as well as with similar data from other countries.
Abstract
Trace elements play an important role in the metabolism of the human body. Some of the trace elements are essential, whereas others are toxic and even carcinogenic. Cigarette smoke contains many of these hazardous trace elements. Tobacco samples have been analyzed by the authors for their trace element contents and the results have been reported earlier. This paper presents results on the trace element content analyzed in cigarette smoke using an automatic smoking machine developed in this laboratory to simulate actual smoking pattern. The trace element levels in the total particulate matter samples of the cigarette smoke collected on filter papers were measured and compared with those of cigarette smoke condensate reported in the literature. Both methods of collection give comparable results.
Abstract
Samples of coastal marine sediments of the East Coast of India were leached with a saturated solution of ammonium carbonate for the extraction of uranium from the sediment particle surface without attacking the mineral core of the particles. All the sediment samples were found to exhibit a234U/238U activity ratio in the range of 1.07 to 1.14. On removal of surface organic matter, the234U/238U activity ratio is close to 1.00, indicating that the anomaly between238U and234U exists only on the labile surface layer. However, no such variations are observed in235U/238U activity ratios. These ratios are close to 0.045 which is the same as that of natural uranium.
Abstract
Trace elements in tobacco and tobacco smoke of a large number of commonly available brands of cigarettes were analyzed by energy dispersive X-ray fluorescence. This work supplements the data on same samples gathered by INAA and reported earlier. Data on some toxic elements like Pb, Cu and Ni that could not be measured by INAA are presented here. A number of chewing and snuff tobacco samples were also analyzed. The concentrations of Ca, K, Cl, Br, Cu, Fe, Ni, Pb, Rb, Sr, Ti and Zn in all these samples are presented and their relative hazards are discussed.
Abstract
The blood serum is the fluid medium through which most of the minerals are absorbed into the human body and get metabolized. The concentrations of Th in blood serum is in equilibrium with the content of Th in human body and therefore could reflect its content in the body. The daily intake (ingestion and inhalation) and the corresponding concentration of Th in blood serum of a group of subjects living in the high-background (monazite) area of Kerala State were measured and compared with the daily intake and corresponding blood serum concentrations of Th in three other groups of subjects namely: (1) those living in normal background area, (2) administrative staff working in Thorium Plant but not directly exposed to Th and its compounds, and (3) the occupational workers from Thorium Plant working for a time period in the range15–30 years. The Th concentration in the blood serum of subjects from high background area were found to be only marginally higher in comparison to the similar data from normalbackground area, which indicated that internal exposure due to Th to the subjects living in high background is quite low.
Abstract
Radioactive elements like 232Th and 238U along with their daughter products, form part of all environmental matrices and are getting transferred to living beings by different pathways, leading to a continuous radiation exposure and need to be monitored. This paper presents an analytical methodology, highlighting the need to separate interfering beta- and gamma-emitters from the analytes, when neutron activation analysis is employed for the determination of traces of uranium and thorium in soil and plant materials. The method has been applied to the soil and plant materials from selected regions of India, along with standard reference materials to verify the validity of the proposed separation scheme. The overall reproducibility of the procedure was 2–10%. The concentration values of uranium and thorium so obtained, have been used to calculate transfer factors from soil to various parts of wheat plant.
Abstract
Toxic trace metals like mercury, arsenic and cadmium have been determined in widely used Indian chewing tobacco and cigarette tobacco by neutron activation followed by sequential radiochemical separation (RNAA). Differential Pulse Anodic Stripping Voltammetry (DPASV) has been used for the estimation of lead, cadmium and copper in cigarette tobacco and its smoke aerosols. The reliability of the data has been assured by analyzing standard reference materials, bovine liver (NBS-1577) and orchard leaves (NBS-1571), and intercomparison of the Pb, Cd and Cu values by three techniques, namely, RNAA, DPASV and Energy Dispersive X-ray Flourescence technique (EDXRF). The levels of Hg, Cd, As, Pb and Cu in cigarette and chewing tobacco and the estimated intake of Cd, Cu and Pb to the smoker are presented and discussed.
Abstract
High activities of radium were observed in the spring waters of Tuwa in Panchamahal district of Gujarat state. These determinations have led to further studies on geochemical behaviour of uranium in the surface sediments of this region. Labile uranium from the surface of the sediment particles is leached with saturated solution of ammonium carbonate. Uranium is chemically separated from the leachates by cellulose column chromatography. Unusually high activity ratios of234U/238U in the range of 2.3 to 2.77 were observed on the surface of the particles. The core of the particles exhibited a ratio of 1.00 indicating soluble234U fraction has migrated.