Exposure factors physiological

Although the positive effects of ERT have been well established, it has been shown that the cell proliferative actions of estrogen can increase the incidence of breast cancer in some patients. In addition, duration of exposure to physiological levels of unopposed estrogens is an established risk factor for breast, uterine, and ovarian cancer. In an effort to attain pharmaceutical agents that oppose the carcinogenic... 

Abstract Delivery of nicotine in the most desirable form is critical in maintaining people s use of tobacco products. Interpretation of results by tobacco industry scientists, studies that measure free-base nicotine directly in tobacco smoke, and the variability of free-base nicotine in smokeless tobacco products all indicate that the form of nicotine delivered to the tobacco user, in addition to the total amount, is an important factor in whether people continue to use the product following their initial exposure. The physiological impact of nicotine varies with the fraction that is in the free-base form and this leads to continued exposure to other toxic tobacco contents... 

When the project was started in 2002, European exposure factor data were scattered within numerous national and international institutions. ExpoFacts has created no new data, but instead compiled the existing data into one Internet database, where it can be easily found, screened, and downloaded from. Data were collected from the EU countries, candidate countries to EU, and EFTA countries. As a result, the ExpoFacts database contains data from 30 European countries. In addition to the population time use patterns and exposure route information, e.g., dietary statistics, the database contains socio-demographic and physiologic information to enable database use as a tool for population-wide exposure modeling and risk assessment. 

For each of the exposure pathways, a relationship between soil concentration and exposure of the human receptor can be developed. Developing this relationship for each of the exposure possibilities allows the land use planner to assess how the choices for land use may influence the exposure relationships. Once the relationships between soil concentration and exposure are established, the relationships can be presented graphically, as shown in Figure 5.6. The relationships shown in this diagram are hypothetical and would ultimately depend on several chemical, physiological, and exposure factors. 

Table 10.3 Adult physiological exposure factors developed by the NAFTA Technical Working Group... 

Where defensible, harmonization of exposure factors, including physiological, pesticide usage and lifestyle factors. 

Exposure factors The inputs used to translate unit exposure values (p-g/kg a.i. handled) to estimates of an individual s daily exposure (pg/kg b.wt./d), which can then be compared to no effect levels in mammalian toxicology studies or acceptable operator exposure levels (AOELs). Exposure factors can be categorized as (i) physiological (inhalation rates, body weights and lifespan), (ii) pesticide usage (dmation of activity, acreage Peated per day, etc.) and (iii) lifestyle (activity patterns and co-occurrence information) (Norman, Ch. 10). 

Health and Safety Factors. Sulfur hexafluoride is a nonflammable, relatively unreactive gas that has been described as physiologically inert (54). The current OSHA standard maximum allowable concentration for human exposure in air is 6000 mg/m (1000 ppm) TWA (55). The Underwriters Laboratories classification is Toxicity Group VI. It should be noted, however, that breakdown products of SF, produced by electrical decomposition of the gas, are toxic. If SF is exposed to electrical arcing, provision should be made to absorb the toxic components by passing the gas over activated alumina, soda-lime, or molecular sieves (qv) (56). 

Subsequently, individual data on exposure are converted to dose by using conversion factors (OECD/NEA, 1983). The choice of the appropriate numerical value depends on physiological parameters (e.g. respiratory minute volume) as well as physical characteristics of the inhaled aerosol (e.g. particle size). Mean values range typically from about 5 mSv/WLM (non-occupational exposure) to about 10 mSv/WLM (occupational exposure). 

Due to the superposition of various other biological, physiological and physical parameters used in modelling, the published exposure-dose conversion factors range from 2 to 120 mGy per WLM. However, a sensitivity analysis indicated that for most indoor exposure situations compensatory effects can reduce this range to about 5 to 10 mGy/WLM for the indoor situations occurring most frequently (OECD/NEA, 1983). 

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