Epidemiologic studies evaluation

A number of clinical trials and epidemiological studies evaluating the use of ginger in morning sickness have been completed. A systematic review of randomized controlled... 

The relationship of Pb exposure and anemia in terms of dose—response relationships and thresholds indexed by various exposure markers has been recorded. In children, the thresholds in the older literature for onset of Pb-derived anemia with reference to Hb reduction are lower, i.e., <40 pg/dl than it is in adults, s40—50 p-g/dl. At levels above these thresholds, studies typically identified an inverse relationship with PbB levels in children (Pueschel et al., 1972) and Pb workers (Baker et al., 1979). Several Pb worker epidemiological studies evaluated the percentage population response for a selected Hb reduction at varying levels of PbB. In the U.S. study of smelter workers by Baker et al. (1979), employing an Hb level <14.0 g/dl, 5% of workers had a Hb reduction at 40—59 pg/dl PbB, 14% at 60—79 pg/dl PbB, and 36% at s80 p-g/dl PbB. A similar analysis by Grandjean (1979), however, showed much higher frequencies at a somewhat different Hb cutoff of <14.4 g/dl 17% showed an Hb reduction at <25 pg/dl PbB, 26% at... 

The lack of epidemiological studies evaluating the effects of cadmium on the immune system make it difficult to assess its effects in humans. Reports of cadmium immunotoxicity in rodents after long-term exposure would argue for the need for human clinical studies (for reviews, see Roller 1980 Descotes 1992). Mice chronically exposed to cadmium exhibit an immunosuppressive effect on the humoral immune response, i.e., a decreased antibody response (Roller et al. 1975) however, conflicting results demonstrate an elevated antibody response or no response. An immunosuppressive effect of cadmium on cell-mediated immunity, i.e., a decrease in delayed-type hypersensitivity, has also been reported in mice (Muller et al. 1979). Cadmium has been shown to decrease phagocytosis in peritoneal macro-... 

Epidemiological studies evaluating adverse effects of nosocomial infections indicate that pneumonia is the leading cause of death from infections acquired during the hospital stay. Table 3 summarizes six studies that have reported crude mortality rates of ventilator-associated pneumonia ranging from 33% to 71% (20). 

In most studies, phytoestrogen intake has been estimated by direct methods that evaluate food intake either by recall (food-frequency questionnaires -FFQs) or by record (food diary), and subsequently by composition databases based on information of this kind. Food-frequency questionnaires are widely administered to subjects involved in epidemiological studies. Their validity and reproducibility is considered sufficient when statistically correlated to data obtained from dietary records (a properly-completed and comprehensive food diary) and from analysis of blood and urine samples (Kirk et ah, 1999 Huang et al, 2000 Yamamoto et al, 2001 Verkasalo et al, 2001). FFQs can be repeated several times a year and may be administered to large populations. Such an approach provides an easy and low-cost method of assessing the... 

WILD 0 p ANDERSSON 0, o brien n m, WILSON L and WOODS J A (2001) A critical evaluation of the application of biomarkers in epidemiological studies on diet and health. Br JNutr 86 (Suppl 1) S37-S53. 

The question whether lutein and zeaxanthin can contribute to lowering the risk for AMD cannot be answered unequivocally by epidemiological studies. Only randomized controlled trials (RCTs) during the course of which xanthophylls are supplemented in a double-blind, placebo-controlled, and randomized manner, and in which results are evaluated according to clear predefined efficacy criteria (Seddon and Hennekens 1994) have the potential to provide definitive answers. The specific long-term time-course and intricate nature of AMD make the design of such studies difficult, however. 

Human studies including case reports, epidemiological studies, and, in some cases, direct human studies (with volunteers). The advantages of these studies are that toxic effects are evaluated in humans and no interspecies extrapolation is... 

A number of epidemiological studies have been conducted to evaluate the association between lung cancer and occupational exposure to acrylonitrile (Collins et al. 1989 Delzell and Monson 1982 Kiesselbach et al. 1979 O Berg 1980 O Berg et al. 1985). Flowever, many of the studies suffer from deficiencies such as an insufficient quantification of exposure, short follow-up, small and relatively youthful cohorts or lack of consideration of the effects of smoking, and the results of the studies are often inconsistent. 

Biagini, R.E., Epidemiology studies in immunotoxicity evaluations, Toxicology, 129, 37, 1998. 

Let us assume that enough information is available regarding the levels of benzene in Mr. Z s well, the number of years he consumed the water, and even his water consumption rate, to derive a reasonably accurate estimate of his cumulative exposure from this source. The epidemiologists and biostatisticians carefully evaluate the dose-response data from the published epidemiology studies used as the basis for classifying benzene as a cause of leukemia. Further assume that we learn from this evaluation that Mr. Z incurred a cumulative benzene exposure approximately equivalent to the cumulative exposure that was found to cause a three-fold excess risk of leukemia in the occupational studies of benzene exposure. A relative risk of three. 

The effects of chronic oral exposure to chloroform, as a by-product of the chlorination of drinking water, were evaluated in four epidemiology studies (Alavanja et al. 1978 Cantor et al. 1978 Saurez-Varela et al. 1994 Young et al. 1981). The association between the incidence of gastrointestinal cancer in humans and the chlorination of drinking water is discussed in Section 2.2.2.8. The data from these studies should be viewed with caution as many other known or suspected carcinogens are known to exist in chlorinated drinking water. 

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