ENV 455 Hazardous Waste Management

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Risk Assessment Basic Information ENV 455 Hazardous Waste Management Environmental Risk Assessment Özgür ZEYDAN (Phd.) http://cevre.beun.edu.tr/zeydan/ Hazard: a potential source of harm to a worker.

1 Risk Assessment Basic Information ENV 455 Hazardous Waste Management Environmental Risk Assessment Özgür ZEYDAN (Phd.) Hazard: a potential source of harm to a worker. Risk: the combination of the likelihood of the occurrence of a harm and the severity of that harm. Acids has corrosive effects however, they are only creates risk for people who are exposed to acids. Risk Assessment Quantifying the risk with mathematical equations. Environmental Risk Assessment: Health Risk Assessment Ecological Risk Assessment In the existence of hazardous wastes, determining the risk to humans and ecosystem is the subject of Environmental Risk Assessment. Risk Assessment A risk assessment is a thorough look at your workplace to identify those things, situations, processes, etc. that may cause harm, particularly to people. After identification is made, you analyze and evaluate how likely and severe the risk is. When this determination is made, you can next, decide what measures should be in place to effectively eliminate or control the harm from happening. 1

Risk Characterization Risk Characterization Handbook Purposes of Risk Assessment Identifying the potential problems related with

2 Risk Management Decision Framework Risk Assessment 4 basic steps: 1. Hazard Identification 2. Toxicity Assessment 3. Exposure Assessment 4. Risk Characterization Risk Characterization Handbook Purposes of Risk Assessment Identifying the potential problems related with hazardous wastes Assessment of new Technologies in terms of reducing risk Determination of environmental standards (air quality, drinking water etc.) Determination of industrial hygiene standards 2

3 1. Hazard Identification The process of determining whether exposure to a stressor can cause an increase in the incidence of specific adverse health effects (e.g., cancer, birth defects). It is also whether the adverse health effect is likely to occur in humans. What is the environmental hazard of concern? 2. Toxicity Assessment Paracelsus, a Swiss physician ( ), proposed dose-toxicity relationship all substances are poisons; there is none which is not a poison. The right dose differentiates a poison and remedy. Dose Response relationship is determined. Purity and physical form of toxic substance or waste are important. 2. Toxicity Assessment Studies on effected humans Epidemics Animal tests (in vivo) Cell and tissue tests (in vitro) Organ activity relationship Animal and plant eco toxicological studies Mean Lethal Dose LD 50 (Mean Lethal Dose): the amount of a poisonous compound needed to be lethal to half of the test population. 3

Dose-Response relationship andld 50 LD 50 Values for Rats http://aquaticpath.umd.edu/appliedtox/module1-dose.

4 Dose-Response relationship andld 50 LD 50 Values for Rats Dose-Response relationship Dose-Response relationship NOAEL and LOAEL Acute tests: short term tests, less than 24 hours once. Sub-chronic tests: 1-3 months repeatedly. MTD - Maximum Tolerated Dose is determined. Target organ is determined. Chronic tests: More than 3 months, for all population. LOAEL - Lowest Observable Adverse Effect Level NOAEL - No Observed Adverse Effect Level are determined. 4

5 Reference Dose (RfD) RfD is generally expressed in units of milligrams per kilogram of bodyweight per day (mg/kg.day) RfD = NOAEL/ UF UF: uncertainty factor (generally 10) MF: modification factor 0<MF<10 (generally 1) RfD = NOAEL/ (UF x MF) Some RfD values Chemical RfD(mg/kg.day) As 0.1 Cd Chloroform 0.01 Phenol 0.04 PCB Toluene 0.3 Xylene Exposure Assessment Pathways (recognizing that one or more may be involved): Air, Surface Water, Groundwater, Soil, Solid or Hazardous Waste, Food, Non-food consumer products, pharmaceuticals. Routes (and related human activities that lead to exposure): Ingestion (both food and water), Contact with skin, Inhalation, Nondietary ingestion (for example, "hand-tomouth" behavior) Exposure Pathways 5

6 4. Risk Characterization Intake to exposure to chemical or hazardous waste is calculated. Risk is calculated for carcinogen substances. Hazard index is calculated for noncarcinogen substances. Calculation of Intake C CR EF ED I = BW AT I or CDI : Intake (mg/kg.day) C : Concentration (mg/l, mg/kg) CR : Contact rate (l/day) EFD = EF x ED EF : Exposure frequency (day/year) ED : Exposure time (year) BW : Body weight (kg) AT : Average exposure time (day). If chronic exposure is considered, this value is accepted as average human life (70 years). Standard Contact Rates Risk for Carcinogen Substances Risk = I x PF PF: potential factor for carcinogen substances (1/(mg kg -1 day -1 )) I (CDI): Intake (mg kg -1 day -1 ) If Risk < 10-6 then risk is accepted!!! For sudden and high concentrations: 6

7 Risk for Carcinogen Substances Potential Factors for Some Chemicals If more than one chemical and exposure pathways exist: n = number of chemicals p = number of exposure pathways Risk for Non-carcinogen Substances Hazard index (HI) is calculated for noncarcinogen substances. HI = I / RfD HI: no unit. If HI < 1 then it is accepted!!! Exposure to more than one substances: n: number of substances 7

Hazard, exposure, and risk Thinking about risk Risk assessment processes Risk management A.001 Environmental Engineering 2

1 Hazard, exposure, and risk Thinking about risk Risk assessment processes Risk management 457.210A.001 Environmental Engineering 2 2015 2 Hazard: the inherent properties of a substance, object, or activity