Measurement body fat

Ultrasound, measuring body fat, 383 Units of energy, 274-276 Unsaturated fatty acids, 320, 746-747 Untranslaled regions (UTKsl, 37 Upper body fai, 385... 

Degree of overweight/obesity measures body fat and muscle mass... 

Differences among individuals can partially explain the differences in the before workshift and end of workshift levels of trichloroethylene and its metabolites. Increased respiration rate during a workday, induced by physical workload, has been shown to affect levels of unchanged trichloroethylene more than its metabolites, while the amount of body fat influences the levels of the solvent and its metabolites in breath, blood, and urine samples before workshift exposure (Sato 1993). Additionally, liver function affects measurements of exhaled solvent at the end of workshift increased metabolism of trichloroethylene will tend to decrease the amount exhaled after a workshift. Increased renal function would affect levels of TCA and trichloroethanol in blood before a workshift in the same way, but it probably would not affect urine values between the begiiming and the end of the workshift because of the slow excretion rate of TCA. 

Correlations of exposure with other measures of body burden are often difficult and their results are consequently less conclusive. For example, trichloroethylene was present at unspecified levels in eight of eight samples of mother s milk from four urban areas in the United States (Pellizzari et al. 1982). Whole-blood specimens from 121 men and 129 women with no known exposure to trichloroethylene had levels from nondetectable to 1.5 ppb (Antoine et al. 1986). Post-mortem analyses of human tissue revealed body fat... 

One of the main determinants of the number of subjects required to reach the desired statistical power is the precision of the measurement tool utilized. More precise measurements will reduce the number of subjects required. As an example, if a study is being conducted to assess the influence of a dietary supplement on body fat, several measurement tools could be used to assess this outcome. These tools range from low levels of cost and precision (e.g. skinfold measurements) to moderate levels (e.g. bioelectrical impedance) to high levels of cost and precision (dual x-ray absorptiometry - DXA). A study that uses skinfold measurements to measure the outcome will require many more subjects than one which employs DXA. Therefore, it is often less expensive in total to utilize a more expensive measurement tool, because the more precise tool will allow the study to have sufficient power with a smaller number of subjects. 

Both hexachloroethane and its lipophilic metabolites can distribute to body fat. Only hexachloroethane can be used to confirm compound exposure by way of a fat biopsy, since some of its metabolites are also produced from other chlorinated hydrocarbons or are present as contaminants in the environment. Based on one worker occupationally exposed to hexachloroethane, Selden et al. (1993) estimated that the plasma half-life in humans was several days, but less than one week. A clearance half-life in rats of 2.5 days was reported for hexachloroethane absorbed from the diet (Gorzinski et al. 1985). Therefore, similar to measurement of hexachloroethane in blood, urine, and feces, hexachloroethane in body fat is representative of current exposures rather than exposures that occurred weeks or months before testing. 

Disulfoton and its breakdown products can be measured in the blood, urine, feces, liver, kidney, or body fat of exposed people. In cases of occupational or accidental exposure to disulfoton, the breakdown products are often measured in the urine. The breakdown products are relatively specific for disulfoton and a few other similar organophosphate pesticides and can be detected in urine for up to one week after people were last exposed. Because disulfoton inhibits cholinesterase in blood and in blood cells, inhibition of this enzyme activity may also suggest exposure to disulfoton. Cholinesterase activity in blood and in blood cells may remain inhibited for as long as 1-2 weeks after the last exposure. Because other organophosphate pesticides also inhibit cholinesterase activity in blood and blood cells, this test is not specific for disulfoton. The measurement of cholinesterase in blood and blood cells and the amount of disulfoton breakdown products in the urine cannot always predict how much disulfoton you were exposed to. Your doctor can send samples of your blood or urine to special laboratories that perform these tests. Chapters 2 and 6 provide more information about medical tests. 

Disulfoton and its metabolites have been measured in various tissues and body fluids (blood, urine, feces, liver, kidney, and body fat) from humans or animals exposed to disulfoton (Brokopp et al. 

Another tissue - fat - can store certain organic chemicals that are highly soluble in this medium. Certain pesticides such as DDT and industrial products such as polychlorinated biphenyls (PCBs) readily dissolve in body fat and can stay there for long periods of time. Most people have measurable amounts of these two once widely used chemicals, and several more as well, in their fat stores. 

In the human studies described below, levels of organochlorine pesticides were measured in various tissues of adults at autopsy in stillborn infants and newborns at autopsy and in body fat, human milk, and serum. With the exception of one study (Stehr-Green et al. 1986), all of the studies are limited by the unknown exposure history of the individuals. 

Measured data in air, water, soil, and food, as well as body burden data (blood, urine, breast milk, and body fat), indicate that the overwhelming majority of people within the state of Michigan who... 

The amount of body fat is difficult to measure directly, and is usually, determined from an indirect measure—the body mass index (BMI)— which has been shown to correlate with the amount of body fat in most individuals. (Notable exceptions are athletes who have large amounts of lean muscle mass.)... 

The body mass index (BMI) is a measure of body fat. It is calculated in both men and women as the (weight in kg)/(height in inches2). Individuals with a BMI between 25.1 and 29 are considered overweight, and those with a BMI greater than 30 are defined as obese. 

Body mass index A measure of body mass relative to height that can approximate total body fat. 

BODY MASS INDEX (BMI) A measurement of body fat based on a person s height and weight. 

Exposure to chlorobenzene can be determined by measuring the chemical or its metabolite in urine, exhaled air, blood, and body fat. Tests are not routinely available at the doctor s office. Specific tests are available that can determine if exposure is currently occurring or has occurred very recently, but not whether exposure occurred in the past. Further, levels in the various media stated above do not predict adverse health effects. Additional information on how chlorobenzene can be measured in exposed humans is given in Chapters 2 and 6. 

As well, HCH isomers, including lindane, occur infrequently in human fats. Levels of up to 2.6 mg kg-1 were reported in 1972 by Siyali (1972). More recently, Quinsey et al. (1995) detected low median levels ( 0.1mg kg-1) of HCH isomers, with a measure of 4.4mg kg-1, in human milk fats for Victorian women. The presence of HCH isomers in all of the milk fats suggests a persistent background level of contamination in body fats consistent with POPs profiles for total HCH. 

Two imaging systems, dual energy X-ray absorptiometry scanning (DEXA) and magnetic resonance imaging (MRI), allow for longitudinal studies of whole body composition. DEXA measures bone mineral density and content, fat content, and lean content in anesthetized mice. Echo MRI from Echo Medical System, Houston, TX, is used to measure whole body composition parameters such as total body fat, lean mass, body fluids, and total body water in live mice without the need for anesthesia or sedation (15). The MRI technology is more rapid, less than a minute to scan one mouse, than DEXA which takes about 5 min per mouse. 

Although pharmacists can receive objective patient data from local laboratories or from physicians, it may be decided that it is more convenient for the patient and pharmacist if a laboratory monitoring/screening service is performed at the point of care. Several types of monitors and equipment can be purchased by pharmacists and integrated into their practices. For example, pharmacists who implement a wellness program may purchase a body-fat analyzer, a weight scale, or a monitor that measures the lipid and glucose levels of... 

Specific tests exist to measure CDD levels in samples of body fat, blood, and breast milk, but these tests are not routinely available. All people now have some levels of CDDs in their body fat and blood. Levels of 2,3,7,8-TCDD on a lipid basis are generally below 10 pg/g of lipid (ppt) in the blood and fatty tissue of the general population of the United States, and usually range from 3 to 7 ppt. Levels higher than these indicate past exposure to above-normal levels of 2,3,7,8-TCDD. Although CDDs stay in the body fat for a long time (see Section 1.4), tests are not used to determine when exposure occurred, but can be used to estimate dose of the exposure if the time of exposure is known. 

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