Hazard characterisation

In practice, while hazard identification forms the basis of hazard assessment, hazard characterisation serves in analysing data when establishing whether a substance is dangerous or... 

After hazard identification, hazard characterisation is undertaken, and this is normally based on dose-response relationships in the range of toxicological studies summarized in Section 2.5.1. It is assumed that a threshold dose for response can be identified, where the NOEL is the highest dose that causes no (adverse) detectable effect in the most sensitive animal species or strain. Other approaches have been used, however, such as determination of a benchmark... 

The rapid progress in DNA sequentiation (genomic), in gene expression (transcriptomic) and the development of techniques which allow one to analyse changes in proteins expressed (proteomic), together with the availability of databases and libraries, presents a great potential for hazard characterisation and for biomarker development. 

Risk assessment is a scientific procedure consisting of the following steps (i) hazard identification (ii) hazard characterisation (ui) exposure assessment (iv) risk characterisation. 

At present the approach to assessing the potential risks of exposure to a chemical in the diet involves the application of a standardised risk assessment approach consisting of three main elements - hazard identification and characterisation and exposure assessment. 

Table 3 describes the main parts of an environmental risk assessment (ERA) that are based on the two major elements characterisation of exposure and characterisation of effects [27, 51]. ERA uses a combination of exposure and effects data as a basis for assessing the likelihood and severity of adverse effects (risks) and feeds this into the decision-making process for managing risks. The process of assessing risk ranges from the simple calculation of hazard ratios to complex utilisation of probabilistic methods based on models and/or measured data sets. Setting of thresholds such as EQS and quality norms (QN) [27] relies primarily on... 

Risk characterisation Comparison of information on hazardous properties and effective dose levels/ concentrations with exposure levels in order to characterise the degree of risk posed by the substance to human health or to the environment ... 

The papers presented quantified and characterised dust from pig and poultry buildings. They also described the hazards to livestock and workers health due to the carriage of micro-organisms, smell and reactive chemical agents. 

The characterisation of health hazards of food contaminants, the assessment of the occurrence of undesirable compounds in food and the estimation of the dietary intake are key issues in the risk assessment. In 2000, the European Commission published a White Paper on Food Safety, which underlined the importance of ensuring the highest possible standards of food safety and proposed a new approach to achieve them. Recently, PFCs have gained increased scientific and socioeconomic interest as emerging environmental contaminants due to the unique combination of persistence, toxicity and environmental prevalence. Risk assessment of the dietary exposure to PFCs, however, is hampered by the lack of sufficient data about the occurrence of these contaminants in food. 

Besides the dangers originating from hazardous substances and the conflicting interests of the involved parties, the discussion surrounding chemicals policy is also characterised by problems of comprehension, e.g. between corporate practitioners and proponents of regulation theories and/or between experts and the public. We thus present some definitions at the start of this chapter, at least for the sake of improved terminological clarity ... 

The criteria and procedural methods for characterising substances with regard to their hazardous characteristics and risk characterisation are harmonised in Europe. There also exists a common European system for the classification and labelhng of hazardous substances and for safety data sheets. Officially harmonised classifications also exist for around 3000 substances. The individual elements of the current system as well as its weaknesses are to be explained in the following section. 

Many measures in the areas of employee protection and environmental protection are not initiated until a substance or a preparation is classified and/or characterised as being hazardous. If existing data are not adequate to assess a substance, this initially has no consequences. This means that the present system leads to completely inappropriate and initially inconsequential gaps in knowledge for existing substances. It rewards the substance manufacturer, who does not invest in collecting substance data, structurally. 

The individual waste facilities are characterised so that a Hazard number is developed. This is then modified by the Likelihood of release and Receptor factors for each Pathway. Once the final score for the mine site is obtained it is assigned to one of the following groups (Table 1)... 

Guidance to date supports the risk assessment principles for general chemical substances already published by the Commission (1996). Consequently, the risk characterisation simply involves a quantitative comparison of the outcome of the hazard/effects assessment with the exposure assessment. For human risk this involves the calculation of the TER (Toxicity Exposure Ratio) and comparing it with the MOS (Margin Of Safety). For environmental risk the PEC/PNEC ratio (Predicted Environmental Concentration versus the Predicted No-Effect Concentration) for the various environmental compartments. 

These are indolent neoplasms characterised by uncontrolled expansion in the erythron where additional hazards are added by the thrombocytosis and, to a lesser extent, leucocytosis. There is a specific point mutation in the Janus Kinase 2 or JAK 2 gene that better defines these cases. 

Once potential hazards have been identified the nature of the hazard must be characterised. Initially the nature of any toxicological damage should be identified. For example, cadmium, which can be present at high levels in certain soils and sediments, can cause damage to the kidneys, whereas polycyclic... 

In recent years it has become increasingly apparent that for chemical contaminants that are abundant in the environment a more sophisticated approach to dose-response characterisation is required. There is increasing evidence that small but significant sub-populations are exposed to intakes that exceed PTWIs and most people are exposed to potential carcinogens through their diet. In such cases the PTWI concept is redundant because it is necessary to assess the actual levels of risk to which individuals are exposed in order to introduce proportionate control measures. Simply knowing that the hazard exists is not sufficient. 

In the concept proposed in 1983 in the US, risk assessment comprised of four steps, namely, hazard identification, dose-response analysis, exposure analysis, and risk characterisation. In a simplified procedure of risk assessment, only three types of information is needed, namely, physico-chemical characteristics, toxicology, the behavior of the chemical at the use situation. The physicochemical data is supposed to show some sense of toxicity and behaviour of the chemical. The toxicology data shows the kind of symptoms to be elucidated, the target organism, and the amount of chemicals needed for showing the symptoms. Behaviour data would show the extent the receptor - here, humans or other natural organisms - is contacted by the chemical at the use situation. The risk assessment is simply to compare the extent the receptor is contacted and the amount of the chemicals needed to show the symptom. 

It is quite clear that traditional risk assessment and risk management approaches are not working sufficiently well in the field of chemicals policy, in particular not in cases of high uncertainty. The traditional approach could hardly deal with the early chemical problems, characterised by evident impacts such as acute effects, and is even less effective in the present situation, with globalised flows of articles that contain hazardous chemicals and the resulting complex chemical cocktail, which may cause diffuse but significant adverse effects on human health and the environment. 

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