Susceptible groups

Diseased groups No extrapolations Susceptible groups Long-term, low-level effects Many covariates Minimal dose-response data Association vs. causation... 

Demographic data snch as age distribution, susceptible groups, etc. 

As shown in Table 8, mosquito colonies with KT50 values below 60 min in the 25-m3 semi-field test were classified as susceptible (Group I), those with KT50 of 60-120 min as less susceptible (Group II), and those with KT50 of over 120 min as low susceptible (Group III). 

The 1435 data points selected for use here were divided into three susceptibility groupings on the basis of information from Table VIII in Heck and Brandt and Table 6-6 in Air Quality Criteria for Photochemical OxidantsThese tables were modified on the basis of the analysis of the data used, and are presented in Table 11-23. The three susceptibility groups were sensitive (471 data points), intermediate (373 data points), and resistant (291 data points). The plants (and appropriate references) in each susceptibility group are listed in Table 11-24. In addition, see Index of Plant Names and Reference Numbers, the last section of this chapter. Note that the italicized references in Table 11-24 were not used in compiling the data for the generation of Figure 11-6 and Table 11-25. 

The data developed for each susceptibility group were then analyzed with the equation of Heck and Tingey (Figure 11-6 and Table 11-25). This is not to say that the data generated could not be used to develop a different or more complex model. However, this model presents a better interpretation of data than other simple models that have been used. It should be emphasized that the data presented are pertinent only to pollutant concentrations that produce an acute response in 8 h or less (two data points in the sensitive group were for 12 h). None of the infor-... 

FIGURE 11-6 Ozone concentration vs. duration of exposure required to produce a S% response in three diffinent plant susceptibility groupings. The curves were generated by developing 95% confidence limits around the equations for all plants in each susceptibility grouping from Table 11-25. Qirves a > sensitive plants, b intermediate ants, c > resistant plants. 

TABLE 11-25 Concentration, Time, Response Equations for Three Susceptibility Groups and for Selected Plants or Plant Types with Respect to Ozone ... 

B. Describe the populations that were assessed, including the general population, highly exposed groups and highly susceptible groups. 

The uses and adverse effects of raloxifene have been reviewed (8-12). Current work seems to show an altogether positive effect of raloxifene (for example 60 mg/ day) on bone metabolism and serum lipids in post-meno-pausal women on chronic hemodialysis, without significant adverse effects in the short term. However, even the authors of very promising work in this connection point to the difficulty in assessing the long-term safety of the treatment in such women (13). Longer-term work elsewhere has pointed particularly to the occurrence of thromboembolic disease, but also of hot flushes, influenza-like symptoms, peripheral edema, and leg cramps. With the exception of thromboembolism these are unpleasant rather than serious, but they still need to be recorded and studied in this very susceptible group of users. 

Reference values indicate the upper margin of the current background exposure of the general population and [are used] to identify subjects with an increased level of exposure (Jakubowski and Trzcinka-Ochocka 2005) compared with the background population level. Those values are derived from data on blood, urine, and other tissues collected from population studies (Ewers et al. 1999). Reference values may be derived differently for susceptible groups if physiologic differences are substantial (for example, children vs adults) (Ewers et al. 1999). 

For prevention of disease in the elderly, the pregnant, or other susceptible groups, national fortification of food with vitamin B12 appears sensible and inexpensive but at present is not used and, in the absence of population screening s unlikely to be mandated by governmental edict. In general terms, the hematological manifestations of vitamin B12 deficiency are rapidly and fully correctable, although deficiencies of other micronutrients such as iron, folic acid, pyridoxine, copper, or vitamin C may be unmasked in the process and may limit the bone marrow s response until they are also corrected. 

Withers and Lees (1985) used lethality data from animal and human studies in a probit analysis to estimate concentrations that would be lethal to 50% (LC50) or to 10% (LC10) of a human population. They estimated a 30-min LC50 of 250 ppm for a normal population, 100 ppm for a susceptible population, and 210 ppm for the average population (combining normal and susceptible groups). The estimated LC10 for each population was 125 ppm, 50 ppm, and 80 ppm, respectively. 

Proteins, due to the complexity of their chemical structures, undergo oxidative modifications in subsequent stages which depend both on the presence of oxidation-susceptible groups and on steric availability of these groups for oxidant attacks (S25). Some oxidative structural modifications produced in proteins are common in various oxidants. Some modifications, such as chlorinated and nitrated protein derivatives produced in reactions with hypochlorite, peroxynitrite, and nitric dioxide, are specific for the oxidants employed. Certain oxidative protein modifications, such as interchain or intrachain disulfide bond formation or thiolation, are reversible and may be reduced back to the protein native form when oxidative stress is over (Dl). Other changes, such as sulfone formation, chlorination, and nitration, are irreversible and effect protein denaturation and promote its subsequent degradation. 

Reductions of hydrazones with LAH may, as expected, proceed further if carbonyls or other susceptible groups are present. Thus, A -acyl hydrazones (e.g. 30) give A -alkylhydrazines along with the A -acyl derivative (equation 7), while the phenylosazone (31) gave further rearrangements of the intermediate dihydrazine to afford (32 equation... 

Molecular toxicology has enabled toxicologists to understand events at the molecular level and examine alterations in fundamental biological processes that lead to the manifestation of toxic responses. As a result, toxicologists are examining the mechanisms of action of toxic substances in order to identify molecular changes predictive of exposure to harmful substances. This information can be used to identify susceptible groups within a population or establish... 

Of the many salivary and plaque factors potentially influencing calculus and caries, only oral calcium and inorganic phosphate levels appear to make a significant independent contribution, in the studies reviewed in section 1.5. The lack of discrimination between caries- or calculus-susceptible groups and corresponding non-susceptible groups in many studies of potentially relevant factors, is likely to be because subject numbers were too small. 

In fact, a beneficial effect on the emissions of NO has been attributed to MMT (Lynam etal. 1999). By contrast, several reports have shown that roadside air, soils, plants and animals are contaminated by elevated Mn concentrations (Thibault etal. 2002 Zayed etal. 1999). Consequently, Frumkin and Solomon (1997) concluded that especially susceptible groups of the population (fetuses, infants, children, pregnant and nursing women, the elderly people, individuals with pre-existing neurological... 

---