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Biomedical subjects

U C Mishra

Publications and source records attributed to U C Mishra.

At least 19 recordsLinked to original sources
PubMed2005

Uptake and distribution of natural radioactivity in wheat plants from soil.

The uptake of naturally occurring uranium, thorium, radium and potassium by wheat plant from two morphologically different soils of India was studied under natural field conditions. The soil to wheat grain transfer factors (TF) were calculated and observed to be in the range of 4.0 x 10(-4) to 2.1 x 10(-3) for 238U, 6.0 x 10(-3) to 2.4 x 10(-2) for 232Th, 9.0 x 10(-3) to 1.6 x 10(-2) for 226Ra and 0.14-3.1 for 40K. Observed ratios (OR) of radionuclides with respect to calcium have been calculated to explain nearly comparable TF values in spite of differences in soil concentration of the different fields. They also give an idea about the discrimination exhibited by the plant in uptake of essential and nonessential elements. The availability of calcium and potassium in soil for uptake affects the uranium, thorium and radium content of the plant. The other soil factors such as illite clays of alluvial soil which trap potassium in its crystal lattice and phosphates which form insoluble compounds with thorium are seen to reduce their availability to plants. A major percentage (54-75%) of total 238U, 232Th and 226Ra activity in the plant is concentrated in the roots and only about 1-2% was distributed in the grains, whereas about 57% of 40K activity accumulated in the shoots and 16% in the grains. The intake of radionuclides by consumption of wheat grains from the fields studied contributes a small fraction to the total annual ingestion dose received by man due to naturally existing radioactivity in the environment.

Aluminum Silicates↗
PubMed2004

Environmental impact of coal industry and thermal power plants in India.

Coal is the only natural resource and fossil fuel available in abundance in India. Consequently, it is used widely as a thermal energy source and also as fuel for thermal power plants producing electricity. India has about 90,000 MW installed capacity for electricity generation, of which more than 70% is produced by coal-based thermal power plants. Hydro-electricity contributes about 25%, and the remaining is mostly from nuclear power plants (NPPs). The problems associated with the use of coal are low calorific value and very high ash content. The ash content is as high as 55-60%, with an average value of about 35-40%. Further, most of the coal is located in the eastern parts of the country and requires transportation over long distances, mostly by trains, which run on diesel. About 70% oil is imported and is a big drain on India's hard currency. In the foreseeable future, there is no other option likely to be available, as the nuclear power programme envisages installing 20,000 MWe by the year 2020, when it will still be around 5% of the installed capacity. Hence, attempts are being made to reduce the adverse environmental and ecological impact of coal-fired power plants. The installed electricity generating capacity has to increase very rapidly (at present around 8-10% per annum), as India has one of the lowest per capita electricity consumptions. Therefore, the problems for the future are formidable from ecological, radio-ecological and pollution viewpoints. A similar situation exists in many developing countries of the region, including the People's Republic of China, where coal is used extensively. The paper highlights some of these problems with the data generated in the author's laboratory and gives a brief description of the solutions being attempted. The extent of global warming in this century will be determined by how developing countries like India manage their energy generation plans. Some of the recommendations have been implemented for new plants, and the situation in the new plants is much better. A few coal washeries have also been established. It will be quite some time before the steps to improve the environmental releases are implemented in older plants and several coal mines due to resource constraints.

Carbon↗
PubMed2004

Regulation of nuclear radiation exposures in India.

India has a long-term program of wide spread applications of nuclear radiations and radioactive sources for peaceful applications in medicine, industry, agriculture and research and is already having several thousand places in the country where such sources are being routinely used. These places are mostly outside the Department of Atomic Energy (DAE) installations. DAE supplies such sources. The most important application of nuclear energy in DAE is in electricity generation through nuclear power plants. Fourteen such plants are operating and many new plants are at various stages of construction. In view of the above mentioned wide spread applications, Indian parliament through an Act, called Atomic Energy Act, 1964 created an autonomous body called Atomic Energy Regulatory Board (AERB) with comprehensive authority and powers. This Board issues codes, guides, manuals, etc., to regulate such installations so as to ensure safe use of such sources and personnel engaged in such installations and environment receives radiation exposures within the upper bounds prescribed by them. Periodic reports are submitted to AERB to demonstrate compliance of its directives. Health, Safety and Environment Group of Bhabha Atomic Research Centres, Mumbai carries out necessary surveillance and monitoring of all installations of the DAE on a routine basis and also periodic inspections of other installations using radiation sources. Some of the nuclear fuel cycle plants like nuclear power plants and fuel reprocessing involve large radioactive source inventories and have potential of accidental release of radioactivity into the environment, an Environmental Surveillance Laboratory (ESL) is set up at each such site much before the facility goes into operation. These ESL's collect baseline data and monitor the environment throughout the life of the facilities including the decommissioning stage. The data is provided to AERB and is available to members of the public. In addition, a multi-tier system of AERB permissions is in place to ensure that all aspects of safety have been considered before permission to operate is granted. The stages where permission of AERB is essential are site selection, design data, and several stages during construction and operation. The details required by AERB include provision for treatment and storage of radioactive waste, de-commissioning procedures and provision of costs. In addition to AERB, nuclear power plants have to comply with the requirements of Ministry of Environment and Forests and get their clearance. This is given on the basis of Environmental Impact Assessment Report which should satisfy the authorities that no ecological damage will be caused and the facility will not have adverse effect on the environment. In addition, the State Pollution Control Board where the facility is to be located has to permit the site of the plant for its proposed discharges into the environment. It is largely due to the above comprehensive regulatory controls that none of the plants in India had any accident during the last 34 decades of operation. The type of measurements carried out by the ESL's and results from a few typical ESL's will be presented.

Environment↗
PubMed2001

A study of the technologically modified sources of 222Rn and its environmental impact in an Indian U mineralised belt.

These investigations present qualitative and quantitative assessments of the 222Rn contributing potential of the technologically modified sources, e.g. mine exhausts and tailings piles, arising due to the mining and processing of uraniferous minerals at Jaduguda, India. The overall geometric mean of the 222Rn flux from low-grade uranium (U) mill tailings being 1.19 Bq m-2 s-1, requisite attenuation of 37.8% to the recommended limit of 0.74 Bq m-2 s-1 can be attained by a typical clay coverage of 20 cm. Theoretically, feasible options for selection of overburden materials for stabilisation of the tailings piles are examined. Extrapolation studies with a turbulent diffusion model yield an atmospheric dispersion pattern of 222Rn in reasonable correspondence with the prevailing concentrations, especially for locations beyond a 4 km radius. The overall 222Rn contribution of the U complex to the ambient air is the same as that contributed by the adjoining land mass of 2.75 km radius in this mineralised terrain.

Air Pollutants, Radioactive↗
PubMed1989

Measurement of natural radioactivity levels in Indian foodstuffs by gamma spectrometry.

Measurements of natural radioisotopes present in some of the foodstuffs which form the main components of the composite Indian diet are presented. Assessment of daily intake of these natural radionuclides has been made on the basis of the average daily intake of these food-items by the population of Bombay and its environment. The content of 40K, 226Ra and 228Th radioactivity varies from 45.9 to 649.0 Bq/kg, 0.01 to 1.16 Bq/kg and 0.02 to 1.26 Bq/kg, respectively. The average daily intakes of 40K, 226Ra and 228Th have been estimated as 105.6, 0.17 and 0.18 Bq d(-1), respectively for the period 1970-1982.

Eating↗
PubMed1988

Determination of ethylene and other reactive hydrocarbons in tobacco smoke and evaluation of risk from their inhalation.

The levels of the reactive hydrocarbons ethylene, propene and 1-butene were determined in cigarette and bidi (Indian cigar) smoke. Cigarette and bidi smoke was collected under standard smoking conditions, using an automatic smoking machine. A gas chromatograph equipped with a selective chemiluminescent detector was used for measurements. The range of concentrations of ethylene, propene and 1-butene obtained for cigarette and bidi smoke are compared with values from the literature. An evaluation of the risk due to inhalation of the reactive hydrocarbons in cigarette smoke was made and compared with the risk of inhalation of these present as urban air pollutants.

Air Pollution↗
PubMed1988

Size distribution of atmospheric aerosols in urban sites in India.

Particle size distribution of atmospheric aerosols was measured at different locations in Moradabad and Bombay, India, using an Andersen cascade impactor. The size distributions of lead, cadmium, copper and zinc were found to be bimodal. The respirable fraction of the particulates (less than 4.7 microns) was calculated. The fraction of fine particles was found to be greater in Bombay than in Moradabad. The mass median aerodynamic diameter (MMAD) for lead, cadmium, copper and zinc was calculated. The atmospheric concentrations of these elements were also measured at the two locations. The analysis of samples was carried out by differential pulse anodic stripping voltammetry.

Air Pollutants↗
PubMed1987

Levels of lead, cadmium, zinc and copper in the blood of an urban population.

Levels of lead, cadmium, zinc and copper were measured in the blood of normal children and adults of Greater Bombay, India using differential pulse anodic stripping voltammetry. The median concentrations of Pb, Cd, Zn and Cu in the whole blood of children and adults were 11.54, 0.21, 484.2 and 86.2 micrograms dl-1, respectively. The blood lead concentration showed an increase with age. Children living in industrial zones with high vehicular traffic have significantly higher blood lead concentrations than their counterparts living in the cleaner suburban parts of the city. The mean levels of Pb, Cd, Zn and Cu in blood of Bombay children and adults are compared with those from other countries.

Adult↗
PubMed1986

Lead levels in teeth of an urban Indian population.

The lead content of teeth of Bombay residents has been determined using differential pulse anodic stripping voltammetry. The median tooth lead concentrations for adults and children in Bombay are estimated to be 8.31 and 3.01 micrograms/g of tooth, respectively. The data indicate that the lead concentration of a tooth increases with the age of the donor. For children the tooth lead content varies with the type of tooth. Further, children living in industrial areas have a higher tooth lead content than children living in the cleaner suburbs of Greater Bombay.

Adult↗
PubMed1986

Natural radiation environment of the Nasik and Neyveli thermal power stations, India.

The trace quantities of naturally occurring radionuclides present in the coal fuel of thermal power stations (TPS) result in redistribution of these radionuclides in the vicinity of the power stations through the deposition and disposal of ash. Two large size TPSs have been studied for environmental radioactivity and radiation doses in the vicinity of the stations. The stations were selected on the basis of the levels of primordial radionuclides in the fuel used. A minor increase was observed in the radiation levels in the ash-pond areas of the TPSs. A few food samples grown in TPS surroundings showed marginal increases in their natural radioactivity content.

Coal↗
PubMed1986

Trace elements in precipitation over an industrial area of Bombay.

An extensive rainwater sampling program was carried out in the Chembur Trombay industrial belt of Bombay to assess the elemental composition of precipitation. The analytes included Hg, Cr, Sb, Pa, Fe, Sc, Sm, La, Eu, As, Co, Zn, Na, K, Ca, Mg, Br and Cl originating from marine, crustal and industrial sources. For comparison, their concentrations at a non-polluted coastal site (Alibag) were also studied. The elemental excesses were determined by calculating the enrichment factors with respect to Sc in the crust, and their probable sources have been examined.

Air Pollutants↗
PubMed1984

Total particulate matter in cigarette and bidi smoke.

It has been well established that smoking causes lung cancer and many other chest diseases. To study the harmful effects of smoking, an automatic smoking machine was developed in this laboratory. Cigarette smoke contains many known carcinogens. The amounts of various carcinogens are proportional to the total particulate matter. Hence variation in total particulate matter (TPM) of different brands of cigarettes, bidis and cheruts (Indian cigars) was studied for various smoking parameters. An attempt has been made to arrive at some intake values of TPM from cigarettes and bidis smoked by the automatic smoking machine under different simulated smoking conditions.

Coronary Disease↗
PubMed1984

Environmental lead exposure of an urban Indian population.

Environmental lead exposure of the Greater Bombay population has been estimated by measuring lead concentrations in air particulates, water, food and cigarette smoke. Atmospheric lead concentrations in different zones of the city varied between 82 and 605 ng m-3. The dietary intake of lead is estimated to be 245 micrograms day-1 and is calculated from the lead content in different food groups and the amount of that group consumed by an average resident of the city. The uptake by a non-smoker living in the city area is estimated to be 33 micrograms of lead per day, 75% of which comes from food, 15% from air and 10% from water. For a suburban resident 85% of the lead intake comes from food. The blood lead measurements and the contribution of atmospheric lead to the blood lead level are discussed.

Air Pollutants↗
PubMed1979

Multicentric metachronous primary carcinoma of the upper alimentary tract in 'Biri' smokers.

Three Biri smokers with multicentric primary metachronous squamous cell carcinomas of the upper alimentary tract are presented. The susceptibility of the tissues of the upper alimentary tract to multiple malignancies, and the carcinogenic effect of radiation and Biri smoke on these tissues, are discussed. We have tried to assess the role of continuous Biri smoking in the production of a second malignancy of the upper food passages in patients who received radiotherapy for their first tumour.

Adult↗