Exposure-related parameters assessments

DoseLinearity/Proportionality typically is assessed, based on exposure-related PK-parameters measured... 

The Remedial Action Priority System (RAPS) and Multimedia Environmental Pollutant Assessment System (MEPAS) are different names for an objective exposure pathway evaluation system developed by Pacific Northwest Laboratory to rank chemical and radioactive releases according to their potential human health impacts. Constituent migration and impact are simulated using air, groundwater, overland, surface water, and exposure components based on standard assessment principles and techniques. A shell allows interactive description of the environmental problem to be evaluated, defines required data in the form of problem-specific worksheets, and allows data input. The assessment methodology uses an extensive constituent database as a consistent source of chemical, physical, and health-related parameters. 

Two types of parameters have to be considered in assessments of chemical contaminants in the environment exposure-related factors that determine the spatial and temporal abundance of the contaminants, and effects-related endpoints that indicate the potential toxicity. The observed interactions and effects are assumed to be related directly to the concentration of the compounds at the site of action. By appropriate combination of the respective information, a probability of negative impacts can be obtained - risk assessment (Chapter 9). The most toxic agents are not necessarily the most dangerous ones. The statement by Paracelsus that sola dosis facit venenum still holds true (Aliens, Mutschler and Simonis, 1978) any substance, xenobiotic or biogenetic, will be toxic if applied in a sufficiently high dose. 

Risk Assessment. This model successfully described the disposition of chloroform in rats, mice and humans following various exposure scenarios and developed dose surrogates more closely related to toxicity response. With regard to target tissue dosimetry, the Corley model predicts the relative order of susceptibility to chloroform toxicity consequent to binding to macromolecules (MMB) to be mouse > rat > human. Linking the pharmacokinetic parameters of this model to the pharmacodynamic cancer model of Reitz et al. (1990) provides a biologically based risk assessment model for chloroform. 

Clearly, environmental chamber studies are very useful tools in examining the chemical relationships between emissions and air quality and for carrying out related (e.g., exposure) studies. Use of these chambers has permitted the systematic variation of individual parameters under controlled conditions, unlike ambient air studies, where the continuous injection of pollutants and the effects of meteorology are often difficult to assess and to quantitatively incorporate into the data analysis. Chamber studies have also provided the basis for the validation of computer kinetic models. Finally, they have provided important kinetic and mechanistic information on some of the individual reactions occurring during photochemical smog formation. 

Numerous diagnostic methods have been developed to evaluate female reproductive dysfunction. Although these methods have rarely been used for occupational or environmental toxicological evaluations, they may be helpful in defining biological parameters and mechanisms related to female reproductive toxicity. If clinical observations link exposure to the reproductive effect of concern, these data will aid the assessment of adverse female reproductive toxicity. The following clinical observations include end-points that may be reported in case reports or epidemiological research studies. 

The model or set of models to be used in the exposure assessment to relate the presence of a substance to human exposure/absorbed dose should be stated. The model s general description should provide enough detail so that the user or reviewer understands the input variables, underlying mathematical algorithms and data transformations and output/results, such that the model can be easily compared to other alternatives. The basis for each model, whether deterministic, empirical or statistical, should be described. The statement of the model should include which variables are measured and which are assumed. A description should be provided of how uncertainties in the parameters and the model itself are to be evaluated and treated. 

THERdbASE contains two major modules, namely a Database Module and a Model Base Module. The Database Module relates information from exposure, dose and risk-related data files, and contains information about the following population distributions, location/activity patterns, food-consumption patterns, agent properties, agent sources (use patterns), environmental agent concentrations, food contamination, physiological parameters, risk parameters and miscellaneous data files. The Model Base Module provides access to exposure dose and risk-related models. The specific models included with the software are as follows Model 101, subsetting activity pattern data Model 102, location patterns (simulated) Model 103, source (time application) Model 104, source (instantaneous application) Model 105, indoor air (two zones) Model 106, indoor air (n zones) Model 107, inhalation exposure (BEAM) Model 108, inhalation exposure (multiple chemicals) Model 109, dermal dose (film thickness) Model 110, dose scenario (inhalation/dermal) Model 201, soil exposure (dose assessment). 

Effective dose was a parameter used to assess biological risk related to radiation exposure, from dual-energy X-ray absorptiometry (DXA). Children are a worst case estimate because they absorb higher doses than adults. With the exception of the hip scans in 1- and 5-year-old children, the effective doses were below the negligible individual dose limit of 1 mrem per year (Thomas et al, 2005). 

The so-called Occupational Exposure Level (OEL) is a key parameter for people responsible for the safety issues in pharmaceutical and chemical industries. " The assessment and the application of the OEL are particularly important also for hazardous pharmaceuticals that are routinely handled within the pharmaceutical companies. There are different approaches to determine the OEL of a certain chemical and its relation to the handling/use of the substance. We are oriented to applying a tiered approach, which assesses all possible parameters that compose the hazard evaluation of a chemical substance. 

The TVOC has been used as an indicator for lAQ as well as a label parameter for building products. It has even been used to evaluate the lAQ. However, the latest research indicates that the TVOC is an indicator for the presence of VOC indoors, but it can be used in relation to exposure characterisation and source identifications for VOCs only [63]. The TVOC cannot be used as an indicator for the presence of other pollutants and it cannot be used for normal regulatory risk assessment. 

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