Lecture 13 Env Risk assessment.pdf

Environmental Risk Assessment (ERA)  Environmental Risk Assessment (ERA) It is a process of predicting whether there may be a risk of adverse effects on the environment caused by a chemical substance, action of project etc. It a generic term for a series of tools and tech...

Environmental Risk Assessment (ERA)  Environmental Risk Assessment (ERA) It is a process of predicting whether there may be a risk of adverse effects on the environment caused by a chemical substance, action of project etc. It a generic term for a series of tools and techniques concerned with the structured gathering of available information about Environmental Risks, and then the formation of a judgment about them. Risk Probability of occurring any adverse effect. 1. Risk/ Hazard identification The process of determining whether exposure to an agent can increase the incidence of a health condition 2. Dose-response assessment The process of characterizing the relation between the dose of an agent administered or received and the incidence of an adverse health effect in exposed populations; it expresses incidence as a function of exposure to the agent. 3. Exposure assessment: The process of measuring or estimating the intensity, frequency, and duration of human exposures to an existing agent or of estimating hypothetical exposures that might arise from the release of new chemicals into the environment. 4. Risk characterization The process of estimating the incidence of a health effect under the various conditions of human exposure described in the exposure assessment 1. Risk/ Hazard identification Risk Identification: Is the process of determining risks that could potentially prevent the program, enterprise, or investment from achieving its objectives. It includes documenting and communicating the concern. For a hazard to result in harm there must be a way in which it can be affect a “Receptor”. Or as some specialists use the term “Source (Hazard)– pathway–receptor”. Is one element of a comprehensive approach to safety and health. To be effective, risk recognition should be implemented along with the other key elements of safety and health management For example in Flood Defense Project might be: -How likely is it that the scheme will over-topped with flood water? (Hazard) -How might people living on the neighboring floodplain be exposed? (Pathway) -What effects might be experienced by an exposed individual? (Receptor) 2. Exposure Assessment. Examine the potential consequences associated with exposure to a hazardous event. Ex-(Chemical Spell). By taking account for these considerations: I- A clear definition of the hazard. II- the characteristic of the local environment. III- the behavior of the Hazard. IV- the specific “Dose-Response” relationships that might be known for particular species or environmental feature. Exposure Assessment How much of a pollutant do people inhale/ ingest ? In what period of time? How many people will be exposed? To what? Or which (e.g. PCB)? From what source(s)? With what interaction(s) (e.g. smoking) Model the exposure (using for example wind speed) Determine the source(s) Find out anything “special” about the population Determining the 1st factor is relatively straightforward process , but to determine the other 3 is difficult & complex. (Example of a various levels of consequences) Very High Risk: Ecosystem Irreversibly altered, no recovery, over 100Km2affected. High Risk: Ecosystem altered, but not irreversibly, recover may take long as 50 years, 50-100 Km2 affected. Moderate Risk: only one component of the ecosystem affected, 10 years of recovery period. Low Risk: Temporary alternation, less than 0.5Km2, less than 5 years of recovery period. Very Low Risk: Temporary alternation, very localized, and minor consequences. Grading of Risk Grade 1- Low risk Grade 2- Low to medium risk Grade 3- Medium to high risk Grade 4- High risk 3. Risk Estimation Risk can be determined by combining the result of hazard and consequences analysis. The simplest form of Risk Estimation is “matrix”. Such matrices designed to be simple or complex as appropriate. Approaches to complete these matrices can be qualitative, quantitative, or a combination for both. Such approaches that considered more complex or more controversial, the use of “Multi-Criteria Analysis”. In Risk Estimations , sometimes it is possible to present risk results in Numerical Terms. Example: There is a 20% chance that the use of pesticide will lead to the loss of 50% of butterfly in a certain ecosystem. 4. Risk characterization  Risk characterization is the process of estimating the incidence of a health effect under the various conditions of human exposure described in the exposure assessment The results of risk characterization are used to identify potential options that are then evaluated in terms of expected public health, economic, social, and political consequences Quantitative risk characterization: Involves the calculation of a simple risk ratio (PEC/PNEC). That is, the predicted environmental concentration is compared to the predicted concentration at which no effects on organisms in the compartment will occur. Qualitative risk characterization It is not always possible to undertake a quantitative characterization of risk. In these instances, such as when assessing the risks to remote marine areas or where PECs or PNECs cannot be calculated, the risk characterization will need to be performed qualitatively.  Low risk Rare, occurs less than 0.1% of the time/cases Low to medium May happen, occurs between 0.1% and 1% of the time/cases Medium to high Quite often, occurs between 1% and 10% of the time/cases High risk Very often, occurs more frequently than 10% of the time/cases