Risk assessment features

Major topics include exposure assessment effects assessment and unconventional ecological risk assessment Features indude compiling documentation consistent with EPA framework, models and conceptual approaches, organizing and conducting an assessment large scale problems, and exotic organisms. 

Huo Z, Giger ML, Wolverton DE, et al (2000) Computerized analysis of mammographic parenchymal patterns for breast cancer risk assessment feature selection. Med Phys 27 4-12... 

Although qualitative and quantitative risk assessment techniques differ in approach, they have some features in common. Regardless of the technique... 

The scope of an exposure and risk assessment may be characterized by a number of key features ... 

Analyze each SCADA device to determine whether security features are present. Additionally, factory default security settings (such as in computer network firewalls) are often set to provide maximum usability, but minimal security. Set all security features to provide the maximum level of security. Allow settings below maximum security only after a thorough risk assessment of the consequences of reducing the security level. 

The linkages between research, risk assessment, and risk management, and the scientific and policy features of each, were first systematically... 

Regulatory officials nevertheless act on the basis of such hypothetical risks ( hypothetical definitely does not mean imaginary it means that the risk estimates are based on certain scientific hypotheses and that they have not been empirically tested). Such actions are in part based on legal requirements (Chapter 11) and in part on the prudence that is a traditional feature of public health policies. The scientific information, assumptions, and extrapolation models upon which risk assessments are based are considered sufficiently revealing on the question of human risk to prompt risk-control measures. To put off such actions until it is seen whether the hypothesized risks are real - to wait for a human body count - is considered to be an unacceptable course. 

The focus of this book is on methods and processes designed to predict drug-like properties, exposure and safety during hit and lead discovery. We do not intend to cover specific cultural considerations and marketing aspects [3]. What we will highlight is the need of a risk aware environment for drug discovery, where data-based integrated risk assessment is part of daily life of the team and drives the projects towards molecules with features fit for the description of an efficacious and safe medicine. 

The widespread detection of phthalate metabolites in human urine has produced questions about public-health risks, especially with regard to antiandrogen effects that can influence male gonadal development (Gray et al. 2000 Parks et al. 2000). The extrapolation from urinary biomonitoring results to exposure and risk assessment has been facilitated by calculations that convert urinary metabolite concentrations to intake dose of the parent phthalate (Koo et al. 2002 Koch et al. 2003 Kohn et al. 2000 David 2000). The parent diester phthalates are rapidly and completely metabolized to the monoester metabolites, which are rapidly cleared by the kidney. Those features allow one to assume that the daily excretion rate of metabolite is equal to the daily intake rate of the parent chemical. Furthermore,... 

As in other risk-assessment approaches (e.g., NRC 1994), scientific uncertainties are a predictable feature of any new biomonitoring-led risk assessments. As shown above and discussed more fully in Chapter 6, identifying and communicating those uncertainties—such as the effect of interindividual variation in elimination rate and limits on extrapolating adult PK data to children—are critical in communicating the risk results. 

Two types of responses from exposure to hazardous substances, called stochastic or deterministic,5 are of concern in risk assessment. The two types of responses are distinguished by the characteristic features of the dose-response relationship, i.e., the relationship between the dose of a hazardous substance and the probability (or frequency) of a response. 

The different models show bias. Concentration addition implies that effects always increase with each additional compound (even when present at extremely low concentrations), and there is clear evidence that this occurs with similarly acting compounds, but it is not yet clarified with dissimilarly acting compounds (see reviews, above). Thus, applying concentration addition to mixtures of dissimilarly acting compounds might overestimate effects and risks, and this may be an undesired feature for various risk assessments (e.g., for retrospective, diagnostic risk assessments). Response addition implies that mixture effects only occur when at least 1 compound induces toxic effects. However, as cited in the review of data (Section 5.3.1), mixtures with... 

The basic features of ecological risk assessment schemes are very similar throughout the world. Usually, one focuses on effects (concentration or dose response information), exposure, and risk characterization. The following paragraphs summarize how extrapolation practices can be developed in such a way that a consistent pattern emerges. 

Risk assessment. The model accounts for most of the major features of chromium(VI) and chromium(III) absorption and kinetics in the rat, and reduction from the chromium(VI) to the chromium(III) valence state, but the bioavailability/absorbability of chromium from environmental sources is mostly unknown, except for bioavailability/absorbability of a few chemically defined salts. Furthermore, the mechanisms by which chromium reserves from bone tissue are released into plasma as well as age, physiological conditions and species variations are important considerations in the refinement of any PBPK model for risk assessment purposes. 

Typically, exposure and risk assessments conducted during regulatory evaluations are performed in a tiered or phased approach. A tiered approach refers to a process in which the exposure or risk assessment progresses systematically from relatively simple to more complex. An important feature of a tiered analysis is that the exposure or risk assessment and the accompanying uncertainty analysis may be refined in successive iterations. 

---