Sensitization demonstration

As discussed in the introduction to Section 2.1, there are a number of limitations in the human database for most health effects, the data are inadequate to assess the potential for humans having a particular effect. Because the human data are incomplete, hazard and risk must be extrapolated across species. A large number of adverse effects have been observed in animals, and most have been observed in every experimental animal species tested, if the appropriate dose is administered. This is illustrated in Table 2-8 for 8 major effects associated with CDD toxicity (acute lethality, hepatotoxicity, wasting syndrome, chloracne, immunotoxicity, reproductive toxicity, developmental toxicity, and cancer). With the exception of acute lethality in humans, positive responses have been observed in each tested species, when a response has been investigated. Despite the similarities in hazard response between different species, large species differences in sensitivity have been observed. Comparisons of species sensitivity demonstrate that no species is consistently sensitive or refractory for all effects and, for some effects,... 

Fig. 7.3 shows the second-derivative spectra of control caeruloplasmin and of caeruloplasmin (20 mg/ml) treated with hydroxyl radicals generated from 0.5 mM Cu(II) and 5 mM hydrogen peroxide. These spectra were obtained for samples in 2H20. Control caeruloplasmin has bands near 1637 cm-1 indicating -structure with a relatively weaker band near 1652 cm-1 due to a small amount of a-helix/random coil structure. On exposure of caeruloplasmin to the hydroxyl radical-generating system, this band shifts to 1656 cm-1, indicative of a transition to the disordered conformation, with no major shift in the original band indicative of the -structure. Thus FTIR-spectroscopy allows sensitive demonstration of the loss of the small amount of a-... 

Table 2 shows that the induction times determined by pNMR were the longest, while those determined by the image analysis technique were the shortest. Therefore, with the image analysis approach, we were able to detect some early crystallization events beyond the sensitivity of the other methods. The higher sensitivity demonstrated allowed for the detection of early crystallization events, possibly in the vicinity of the true nucleation events. 

Standard methods of analysis employ schemes to capture volatile compounds, concentrate them, separate them, and quantify them. Recent reviews of sample preparation for volatiles analysis include foods in general (1), cereals (2), and dairy products (3). Recent advances in analytical instrumentation and methodology have approached the threshold of selectivity and sensitivity demonstrated by the human nose. In this chapter, we describe new methodology employed to measure some of the key odorants in rice. The effective collection and analysis of volatile compounds can now be accomplished using solid-phase microextraction (SPME). A pictorial outline of the procedure is depicted in Fig. 1. 

---