Risk Characterisation

Chemical risks are measured by comparing the predicted or measured exposure to the DNEL or PNEC. In risk assessment, the extent to which an exposure exceeds a DNEL or PNEC determines if a risk is deemed high or very high . If an exposure is considerably less than the no-effect level (e.g., a factor of 1000 when compared with a NOEL), the risk is generally considered insignificant (see [146]). 

Risk assessment is primarily limited by costs rather than science. The cost of meeting the highest-level of risk assessment testing for a single 

21 The term margin of safety is sometimes used to compare exposure levels to NO(A) EL and then this margin is compared with assessment factors. DNEL already include these assessment factors in the equation, so this thesis uses the term level of safety . 

22 For non-threshold effects, the term margin of exposure rather than margin of safety is sometimes used if assessment factors are excluded from the assessment and a unit descriptor system used to characterise the effect. 

23 Risk management must also account for how to manage exposure levels when there is no DNEL, DMEL or PNEC available, how to manage exposure levels based on underlying assumptions made in the risk assessment, and how to prioritise management activities. 

The results of the quantitative exposure assessment are taken forward to the risk characterisation where they are combined with the results of the effects assessment. 

For occupational risk characterisation, this should be conducted, in the first instance, without the incorporation of Personal Protective Equipment (PPE) or Respiratory Protective Equipment (RPE). If required, the protective effects of PPE and/or RPE can be used to refine the risk characterisation for appropriate exposure scenarios. If the use of PPE and/or RPE is necessary to reduce the risk to an acceptable level then this would form part of the decision-making process and the appropriate PPE and RPE would have to be included onto the product label. 

For use by the general public, where the recommended use of PPE cannot be guaranteed, the incorporation of PPE and/or RPE into a risk characterisation is deemed inappropriate. 

In a quantitative human health risk characterisation, the exposure data for relevant use situations is compared to the pivotal NO(A)EL to determine either that the derived Margin of Safety (MOS) is exceeded or that the ratio of the level of exposure/AOEL does not exceed 1. If this is the case, the risk characterisation of the biocidal product should be acceptable. 

If the risk characterisation of the biocidal product is not acceptable, based on realistic worst case estimates, then the characterisation must be re-calculated and based on more typical exposures and a review of the likelihood of the occurrence and the severity of adverse effects. 

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For these substances, the waste life stage of the substance needs to be covered by suitable exposure scenarios, the corresponding exposure estimation and the related risk characterisation. The conditions ensuring control of risk in the waste life stage of the substance need to be documented in the chemical safety report (CSR) and also communicated in the supply chain by means of the extended safety data sheet. [19]. 

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 ... 

Risk characterisation of non-ionic surfactants including their metabolites... 

No effect concentrations (NEC) for risk characterisation. Several countries and agencies have performed risk assessments for alkylphe-nols (AP) and APEO based on the approaches outlined above. Perhaps the most elaborate has been the assessment carried out by Environment... 

Mixture toxicities. As is obvious from Chapters 2 and 6, APEO and their degradation products occur in the environment as complex mixtures. In risk characterisation studies of AP and APEO, the toxicity of individual constituents of such mixtures, whether assayed in acute and chronic toxicity, or in estrogenicity tests (Chapter 7), is being considered to occur, for each separate endpoint, through the same separate mode of action, and consequently to be additive. Thus, relative potencies can be established for each individual... 

Aquatic toxicity NEC values of NP, NPEO and NPEC proposed for risk characterisation by Environment Canada [8]... 

The relative potency can now be derived from this equation. The risk characterisation then proceeds by calculating the total concentration (Ctotai) of the sample (expressed in equivalents of NP) as follows (Eq. (7.4.2)) ... 

Fort the risk characterisation of PFGS and PFGA, the currently available information is inadequate to characterise dietary exposure in the different regions in the European Union. 

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. 

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. 

USEPA, 2001. Exposure and human health reassessment of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related compounds (Draft Final Report, EPA/600/P-00/001Bc), Exposure Assessment and Risk Characterisation Group, National Center for Environmental Assessment, Office of Research and Development Washington DC. September 2001. 

Renwick AG, Barlow SM, Hertz-Picciotto I, Boobis AR, Dybing E, Edler L, Eisenbrand G, Greig JB, Kleiner J, Lambe J, Muller DJ, Smith MR, Tritscher A, Tuijtelaars S, van den Brandt PA, Walker R, Kroes R (2003) Risk characterisation of chemicals in food and diet. Food Chem Toxicol, 41(9) 1211-1271. 

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. 

On risk reduction, the RC-GC commits signatories to utilise clean and safe technology, establish partnership across the value chain, minimise waste, and assess product stewardship practices, whilst GPS recommends measures to complete risk characterisations and risk management recommendations for chemicals in commerce, establish global product stewardship guidelines and develop a management system approach for implementation. 

Since the last case includes both issues of the other two, the process of judging the tolerability and acceptability of a risk can be structured into two distinct components risk characterisation and risk evaluation. The first step, risk characterisation, determines the evidence-based component for making the necessary judgement on the tolerability and/or acceptability of a risk the step risk evaluation determines the value-based component for making this judgement. 

Identifying a hazard is only a small part of the risk assessment process. Hazard must be differentiated from risk. Assessing risk involves an analysis of the likelihood that adverse effects to human health or the environment after exposure to a chemical may occur. For risk management, exposure assessments therefore play equal (if not more) important parts as evaluations of hazard. The following sections discuss how toxicology, exposure assessments, and risk characterisations contribute to the central scientific definition of risk as probability versus consequence [93-95]. 

Type IV Risk characterisation - Lack of data exists on the level of compliance, compliance monitoring and enforcement for a high level risk that requires specific safety measures to ensure adequate protection. - Insufficient monitoring or modelling data exists to determine the extent of trans-boundary pollution caused by emissions to environment. - Exposure data of ecosystems and humans via the environment primarily depend on emissions from incorrectly disposed products. 

Any Member State(s) experiencing the results of the transboundary pollution would be responsible for preparing the risk characterisation section of the Annex XV dossier (unless located outside the EU). 

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