Circumstantial Factors

Human exposure to PFCs is likely to occur via a number of vectors and routes, for example food, drinking water, the ingestion of non-food materials, dermal contact and inhalation. Circumstantial factors such as place of residence, age, nature of PFCs vector, may also influence exposure. For example, according to Tittlemier et al. [27], food seems to represent the major intake pathway of PFAS in adult Canadians however, house dust, solution-treated carpeting and treated apparel might contribute a non-negligible 40% to the overall exposure. 

Thus far, sound has been discussed. So whaf is noise An all-encompassing definifion would be fhaf noise is any undesirable sound. By saying fhis, fhe concepf is introduced that what is considered to be noise is somewhat relative and depends on several temporal and circumstantial factors. 

Table 3.18. The correlation between nitrogen burial fluxes and various circumstantial factors...

Sampling can occur when the effect of time and other circumstantial factors can be controlled ... 

Cloth and climate circumstantial factors such as age of the cloth, temperature, and humidity of the surroundings may affect color uptake and appearance. 

Figure 4.18 also expresses how the probability of the circumstantial factor is influenced by three gradients expressing temperature... 

The cause of MS is not known, but most evidence points to an immunologically mediated disease with important genetic and environmental risk factors [ 1,2,7,8]. The evidence for an autoimmune process is largely circumstantial... 

Body iron level and iron depletion play an important role in the gender differences seen in death from cardiac disease. There is a better correlation with heart disease mortality in iron levels compared with levels of cholesterol (5). It was found that risk of coronary heart disease (6) and carotid atherosclerosis (7) is associated with increased iron stores. However, impaired endothelium-derived nitric oxide activity may be without overt atherosclerosis in patients with risk factors and may be associated with the presence of atherosclerosis (4). Thus, endothelial dysfunction related to iron activity not only may be an early marker for cardiovascular risk but also may contribute to the pathogenesis of atherosclerosis (2) by the stimulation of low-density lipoproteins (LDL) and membrane lipid peroxidation (I) and may be a key to the understanding of early mechanism in the development of atheroma (7,8). Nakayama et al. (9) showed the role of heme oxygenase induction in the modulation of macrophage activation in atherosclerosis. However, Howes et al. (10) concludes that at the moment, the available evidence on iron hypothesis remains circumstantial. Moreover, Kiechl et al. (7) showed that the adverse effect of iron is hypercholesterolemia, In patients... 

A differentiation between natural and anthropogenic heavy metal loads into the Baltic is not possible because metals are also natural components of the earth s crust. Taking into consideration that the HELCOM database is stiU incomplete, a general reduction of the total metal load was calculated for Hg ( 74%), Pb (< 66%), Cd ( 62%), and Zn ( 9%) between 1990 and 1995. For Cu, an increase of 13% was estimated. With the addition of the trace metal input data from the fourth pollution load compilation, the situation changed drastically. Compared to 1995 (HELCOM, 1998), the total heavy metal loads increased by a factor of -3 for Cd, 4 for Pb, and 9 for Hg in 2000 (HELCOM, 2004,2005), while for Cu (0.7) and Zn (0.8) a decrease of the river loads was estimated. The heavy metal export into the North Sea is of circumstantial relevance in relation to the total metal load entering the Baltic Sea (Dippner and Pohl, 2004). 

Work done on the measurement of corticotropin in the fetus has so far not provided direct information on its use for steroid production control, but adrenals, normal for the newborn in size and morphology, have been produced in anencephalic monsters by corticotropin stimulation (L2), and the administration of corticoids to pregnant women before and during delivery leads to a decrease of DHA and 16 -OH-DHA in cord plasma (S22). This circumstantial evidence indicates that corticotropin may be involved as a controlling factor. This question is further discussed in Section 12. 

In this article we propose to survey the role of iron as a conformational determinant in polypeptides and in non-haem proteins. This aspect of iron coordination research has been either ignored or only sporadically dealt with in reviews concerned with metalloproteins. By stressing this often circumstantial aspect of iron biochemistry it is our hope that the relevance of metals in general as fundamental structural factors in biomolecules will be brought into proper perspective. 

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