ENVIRONMENTAL RISK ASSESSMENT Use of Risk Assessment as

ENVIRONMENTAL RISK ASSESSMENT Use of Risk Assessment as a Management Tool for Contaminated Sites Scott Steer, R. P. Bio. , CSAP scott. steer@steerenvironmental. com

Outline • • What is environmental risk assessment? Regulatory context The Conceptual Exposure Model Estimating Exposure Estimating Adverse Effects Risk Characterization Case Studies

Risk Assessment of Chemical Agents A systematic process to quantify potential adverse health effects to humans, plants and animals from exposure to chemicals in the environment Basis for water, soil, air, and food quality standards Safety of food additives, pharmaceuticals, pesticides 3

Where Does Risk Assessment Fit Into Contaminated Sites Process? Site Profile PHASE & Stage 1 PSI I Desktop Risk Assessment & Remediation Confirmation Field Investigation Remediation/ Management Verification Intrusive Sampling Investigation Physical Testing ↓ CSM Contaminant Destruction, Removal or Risk Control Verification Sampling to Confirm Estimates Management Plan Stage 2 PSI PHASE II & DSI ESA Option 1: Remediate contamination to numerical standards Option 2: Conduct risk assessment and manage excess risk 4

Option 1 - Remediation § Remove contamination § Advantages: § Eliminates liabilities § § 5 More efficient for simple sites Disadvantages: § Expensive § Sometimes not feasible

Option 2 – Risk Assessment / Management § Determine risks and reduce excess risk to comply with risk-based standards § Typically involves management in place but could include some remediation § Advantages: § Cost-effective § Disadvantages: § Environmental liabilities remain § Land use restrictions § Ongoing monitoring and maintenance § Stigma 6

Guidance

Standard Risk Assessment Framework INVESTIGATION Conceptual Site Model Problem Formulation Who is exposed and how? RISK ASSESSMENT Exposure Assessment How much exposure? Effects Assessment How much exposure is safe? Any adverse effects? Risk Characterization Is there a risk? RISK MANAGEMENT 8

Types of Environmental Risk Assessments § Screening Level Risk Assessment § Detailed Risk Assessment § Simple exposure pathway evaluation § No further risk assessment required if no exposure pathways § Example § Sites with operable exposure pathways § Full quantitative analysis § Hazard Quotients or Weight of Evidence § Example § Deep soil contamination 9 § Shallow/exposed soil contamination

Key Concepts Risk Assessment Paradigm “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy. - Paracelsus (1493 -1541) Hazard Quotient = Estimated Exposure Safe Exposure 10

Problem Formulation INVESTIGATION Conceptual Site Model Problem Formulation Who is exposed and how? RISK ASSESSMENT Exposure Assessment Effects Assessment Risk Characterization RISK MANAGEMENT 11

Conceptual Exposure Model § Extension of the Conceptual Site Model § Graphical summary of: § Contamination sources § Exposure pathways § Receptors § Emphasis on interaction between contaminants and receptors 12

Conceptual Exposure Model – Pictorial/Animation 13

Conceptual Exposure Model – Flow Chart PRIMARY SOURCE SECONDARY SOURCE RELEASE MECHANISM EXPOSURE MEDIUM EXPOSURE ROUTE RECEPTOR TERR INVERTS PLANTS WILDLIFE* CONTACT HISTORICAL SITE OPERATIONS SOIL BIOACCUMULATION SOIL INGESTION TISSUES INGESTION SOIL COCs Phenol VOLATILIZATION GROUNDWATER COCs Ammonia Nitrate Nitrite Copper Lead Naphthalene Fluoranthene Pyrene Total Non-chlorinated Phenols PATHWAY OPERABLE PATHWAY INOPERABLE SOIL VAPOUR INHALATION LEACHING GROUNDWATER CONTACT DISCHARGE FRASER RIVER POREWATER (SED)/ SURFACE WATER CONTACT/INGESTION ADSORPTION FRASER RIVER SEDIMENT CONTACT/INGESTION BIOACCUMULATION (From Sed/Porewater/ Surface Water) TISSUES INGESTION PATHWAY OPERABILITY NOT FULLY DETERMINED *Includes reptiles, amphibians, terrestrial/aquatic birds, and mammals EXPOSURE PATHWAY POTENTIALLY COMPLETE EXPOSURE PATHWAY INCOMPLETE/LIKELY INSIGNIFICANT AQUATIC INVERTS PLANTS FISH

Identifying Contaminants § What substances should be considered? § 15 Often policy-driven § Exceed applicable guidelines/standards § Exceed natural background levels § Non-regulated substances if they are hazardous

Identifying Receptors - Ecological § Which ecological groups should be considered? § Starting Point: Land use-based policy § Filter out irrelevant groups based on site characteristics MOST RISK ASSESSMENTS FOCUS ON LOWER TROPHIC LEVEL RECEPTORS 16

Identifying Receptors - Human § Consider all groups of people that could occur § Exposure Intensive Groups: § Toddlers § Aboriginal communities § Construction, utility workers Farm HUMANS - PROTECT INDIVIDUALS ECOLOGICAL – PROTECT POPULATIONS AND COMMUNITIES 17

Exposure Pathways - Ecological § Wildlife – Oral intake from food, water, soil, sediment § Fish – Oral intake from food, water, sediment; absorption across gill § Invertebrates – Dermal absorption, ingestion § Vegetation – Uptake from soil, sediment, water 18 DERMAL ABSORPTION AND INHALATION BY WILDLIFE NOT TYPICALLY CONSIDERED

Exposure Pathways - Human 19

Case Study Site: Park and Playground Built on a Former Landfill Park and Playground

Conceptual Exposure Model – Ecological Raptors Plants Reptiles Songbirds Herb. Mammals Insect. Mammals Carnivore Game Birds Soil Invertebrates Contaminated Soil CSM: Soil Contamination: Metals, Methylmercury, PAHs, PHCs Groundwater not contaminated Soil vapours with respect to outdoor air not contaminated 21

Conceptual Exposure Model – Human Inhalation Ingestion Dermal Soil Contamination: Metals, PAHs, PCBs, VOCs What human receptors should be considered at this site? Receptors – Public (local residents) Pathways - Ingestion (soil/berries), Dust Inhalation and 22 Dermal

Conceptual Exposure Model – Future Commercial Development Pavement Vapours Receptors: Workers, public, no ecological receptors Pathways (Public/Commercial Workers): Indoor Air Inhalation Pathways (Construction/Utility Workers): Soil Ingestion, Dust 23 Inhalation and Soil Dermal Contact, Soil Vapour Inhalation

Exposure Assessment INVESTIGATION Conceptual Site Model Problem Formulation Who is exposed and how? RISK ASSESSMENT Exposure Assessment Effects Assessment How much exposure? Risk Characterization RISK MANAGEMENT 24

Human Exposure Estimation - Dose Where, C= IR = RAF = ET = BW = 25 contaminant concentration (mg/kg, mg/L) intake rate (kg/day, L/day) relative absorption factor (unitless) exposure term or fraction of time exposed (unitless) body weight (kg)

Human Exposure Estimation – Air Concentration Air Exposure Concentration = C x RAF x ET Where, C= contaminant concentration (mg/m 3) RAF = relative absorption factor (unitless) ET = exposure term or fraction of time exposed (unitless) 26

Estimating Human Exposure 1. 2. 3. 4. STEPS Determine Exposure Concentrations (C) Determine receptor characteristics (IR, ET, BW) Determine bioavailability factors (RAF) Calculate exposure Air Exposure Concentration = C x RAF x ET 27

Example – Human Exposure Estimation A site contaminated with arsenic in soil and groundwater is being used for residential purposes. Drinking water for the residence is obtained from an on-site water well. Estimated Exposure Concentrations: Cs = 50 mg/kg in shallow soil Cgw = 0. 025 mg/L in groundwater 28

Example Calculation – Exposure to Arsenic via Soil Ingestion (Toddler) 29

Example Calculation – Exposure to Arsenic via Dermal Soil Contact (Toddler) 30

Example Calculation – Exposure to Arsenic via Drinking Water Ingestion (Toddler) 31

Arsenic Exposure Estimates Summary - Toddler Exposure Pathway Daily Dose of Arsenic (mg/kg/day) Soil Ingestion 0. 00024 Dermal Soil Contact 0. 0000063 Drinking Water Consumption 0. 00091 Total Daily Dose of Arsenic 0. 0012 32

Arsenic Exposure Estimates Summary - Adult Exposure Pathway Lifetime Average Dose (mg/kg/day) Soil Ingestion 0. 000014 Dermal Soil Contact 0. 0000036 Drinking Water Consumption 0. 00053 Total Lifetime Average Dose of Arsenic 0. 00055 33

Estimating Exposure - Ecological 1. External Media § 2. Internal Media § 3. Soil, sediment, water, food items Tissues within receptor Dose Estimation § Food chain modelling 34

Estimating Exposure Using External Media Arsenic Exposure by Soil Invertebrates 35 Surface soil data available for 21 samples Maximum – 225 mg/kg 95% UCL of Mean – 150 mg/kg

Estimating Exposure Using Internal Media Arsenic Exposure by Vegetation 18 grass tissue samples collected Maximum – 26. 5 mg/kg ww 95% UCL of Mean – 14 mg/kg ww 36

Food Chain Modelling - Wildlife Shrew Analogous to human daily intake estimation § Total daily intake of contaminant from all exposure pathways § Invertebrates Soil Water Most common exposure metric for wildlife § 37

Food Chain Modelling Equation Food Item A Proportion of Diet Total Daily Oral Dose of Contaminant Food Ingestion Rate of Receptor Food Item B Chemical Concentration TDOD = EA/HR x (PA(IR x CA) + PB(IR x CB)) + …. . Contaminant Exposure Area Home Range of Receptor Food Item A Chemical Concentration Food Item B Proportion of Diet http: //www. federalcontaminatedsites. gc. ca/B 15 E 990 AC 0 A 8 -4780 -9124 -07650 F 3 A 68 EA/13 -049 -EC-ID 541 -Module 3 -ENG. pdf 38

Food Chain Modelling Example Herbivorous Mammal VOLE TDOD = EA/HR x (PSoil(IR x CSoil) + PVeg(IR x CVeg)) 39 Exposure Area (EA) = 1 hectare Home Range (HR) = 0. 007 ha Psoil = 2% Pveg = 98% Ingestion Rate (IR) = 0. 33 kg ww food/kg BW/day Ingestion Rate (IR) = 0. 066 kg dw food/kg BW/day Csoil = 150 mg/kg dw Cveg = 14 mg/kg ww

Food Chain Modelling - Example § Total daily oral dose of arsenic by a vole (herbivorous mammal): • • Exposure Area (EA) = 1 hectare Home Range (HR) = 0. 007 ha Psoil = 2% Pveg = 98% Ingestion Rate (IR) = 0. 33 kg ww food/kg BW/day; 0. 066 kg dw food/kg BW/day Csoil = 150 mg/kg dw Cveg = 14 mg/kg ww DODSoil = 1 x 0. 02 x (0. 066 kg/kg BW/d x 150 mg/kg) = 0. 2 mg/kg bw/d DODVeg = 1 x 0. 98 x (0. 33 kg/kg BW/d x 14 mg/kg) = 4. 5 mg/kg bw/d TDOD = 0. 2 mg/kg bw/d + 4. 5 mg/kg bw/d TDOD = 4. 7 mg/kg bw/d 40

Effects Assessment INVESTIGATION Conceptual Site Model Problem Formulation Who is exposed and how? RISK ASSESSMENT Exposure Assessment Effects Assessment How much exposure? How much exposure is safe? Any adverse effects? Risk Characterization RISK MANAGEMENT 41

Key Points It’s the dose that makes the poison. § E. g. even common table salt can be toxic § Essential for controlling balance, function of muscles and nerves § Chronic: WHO recommended adult intake: < 3 -5 g/day or < 1 tsp/day § Acute: lethal toxicity of adult (70 kg) possible at < 230 g/dose or ~40 tsp/dose 42

Threshold Chemicals (Non-Carcinogens) § Threshold chemicals exhibit non-linear dose-response curve (i. e. , NOAEL): 43

Threshold Chemicals (Non-Carcinogens) § There are dose levels that are considered to be acceptable or “safe”. § Dose rates used by health agencies to develop TRVs § TRVs are used in risk assessment and to set numeric criteria for: § Soil § Drinking water § Air 44 Examples § Tolerable daily intake (TDI) § Tolerable concentration (TC) § Reference dose (Rf. D) § Reference concentration (Rf. C)

Non-Threshold Chemicals (Carcinogens) § Non-threshold chemicals do not exhibit clear threshold dose (e. g. , carcinogens) § Any dose other than zero is believed to have some potential for producing a toxic effect § Slope factor(mg/kg/day)-1 § Unit Risk(mg/m 3)-1 45

Sources of Human Toxicity Reference Values 46

Methods of Predicting and Measuring Ecological Effect 1. Toxicity Reference Values 2. Toxicity Testing 3. Biological Surveys 47

Predicting Ecological Effect Using Toxicity Reference Values − Threshold at which maximum acceptable effect occurs for given contaminant – receptor combination § 48 Soil/sediment(mg chemical/kg dw) Concentrationbased (external) § Water(mg chemical/L) § Tissue(mg chemical/kg ww) Concentrationbased (internal) § Wildlife dose(mg/kg bw/day) Dose-based

Sources of Ecological TRVs − Where are Eco. TRVs obtained? § Secondary literature - compilations and databases § Derived from primary literature (de novo derivation) § Derived from bioassays on site media 49

Risk Characterization INVESTIGATION Conceptual Site Model Problem Formulation Who is exposed and how? RISK ASSESSMENT Exposure Assessment Effects Assessment How much exposure? How much exposure is safe? Any adverse effects? Risk Characterization Is there a risk? RISK MANAGEMENT 50

3 Steps of Risk Characterization 1. RISK ESTIMATON 2. UNCERTAINTY ANALYSIS 3. RISK DESCRIPTION 51

Risk Estimation - Humans Health Canada Guideline: HQ ≤ 0. 2 ILCR ≤ 1. 0× 10 -5, or 1 in 100, 000 52

Human Cancer Risk: A Perspective Policy ILCR 1 /100, 000 Developing Cancer 40, 000 /100, 000 Dying of Cancer 14, 500 /100, 000 53 Modified from IDEM Risk Assessment (2014)

Risk Estimation Example – Human (Non-Cancer) 54 Exposure Pathway Estimated Arsenic Dose (mg/kg/day) Safe Arsenic Dose (mg/kg/day) HQ Soil Ingestion 0. 00024 0. 0003 0. 8 Dermal Soil Contact 0. 0000063 0. 0003 0. 02 Drinking Water Consumption 0. 00091 0. 0003 3 Total HQ 3. 8

Risk Estimation Example – Human (Cancer) Exposure Pathway LAD of Arsenic (mg/kg/day) Cancer Potency Factor for Arsenic (mg/kg/day)-1 ILCR Soil Ingestion 0. 000014 1. 5 2 in 100, 000 Dermal Soil Contact 0. 0000036 1. 5 0. 5 in 100, 000 Drinking Water Consumption 0. 00053 1. 5 80 in 100, 000 Total ILCR 82 in 100, 000 55

Risk Estimation - Ecological HQ = Exposure Estimate Safe Exposure HQ<1: Risks negligible HQ>1: Adverse effects could occur 56

Interpreting Ecological Hazard Quotients What do these risk estimates mean? Receptor Contaminant Estimated Exposure Concentration or Dose (mg/kg or mg/kg/d) Plants Arsenic 14 20 0. 7 Herbivorous Mammals Arsenic 4. 7 1. 7 2. 8 57 TRV (mg/kg) or (mg/kg/d) Hazard Quotient

Possible Outcomes of Risk Estimation 1. Risk estimate indicates acceptable risk - HQ<1 No Further Action 2. Risk estimate clearly indicates unacceptable risk - HQ>>1 Risk Management 3. Risk estimate elevated but may be affected by over conservatism Risk Management or Refine Risk Estimate 58

Interpreting Ecological Hazard Quotients What do these risk estimates mean? Receptor Contaminant Estimated Exposure Concentration or Dose (mg/kg or mg/kg/d) Plants Arsenic 14 20 0. 7 Herbivorous Mammals Arsenic 4. 7 1. 7 2. 8 59 TRV (mg/kg) or (mg/kg/d) Hazard Quotient

Options for Refining Risk Estimates 1. 2. 3. Refine the Toxicity Reference Value Measure arsenic concentrations in vole tissues and compare to tissue-based Toxicity Reference Value Include other lines of evidence: - Biological survey 60 Refine Risk Estimate Update Risk Conclusion Risk Acceptable – No Further Action Risk Unacceptable – Remediation or Risk Management

Case Example #1 – Overview Type of RA - Screening Level Location – Vancouver Historical Use - Commercial Current Use – Development Future Use – Mixed commercial/residential Contaminants – Metals in groundwater Receptors Aquatic life in False Creek; public, commercial workers

Case Example #1 – Tools/Outcome - - - Tools – Pathway analysis (SLRA - Protocol 13) SLRA used to show that there are no pathways to receptors Since groundwater contamination not siterelated, site owner not responsible for risks to offsite aquatic life Risks acceptable No restrictions on site use No monitoring or maintenance required

Case Example #2– Overview Type of RA - Detailed Location - Okanagan Historical Use - Rail Current/Future Use – Recreational Trail Contaminants Metals and PAHs in soil Receptors Public Wildlife Soil Invertebrates, Plants Aquatic Life Source: Google Earth

Case Example #2 – Tools/Outcome - - Tools – Soil, veg chemistry, food chain modelling, Site observations Risks acceptable for current and future recreational use Metals and PAH contamination can remain in place No restrictions on site use No monitoring or maintenance required Source: Google Earth

Case Example #3 – Overview Type of RA - Detailed Location – Vancouver Harbour Historical Use – Chemical Manufacturing, Port Facility Current Use – Vacant Future Use – Port Facility Contaminants Metals, PAHs and Pesticides in soil, groundwater and sediment Receptors Workers Aquatic and Terrestrial Wildlife, Invertebrates, Vegetation and fish Source: Google Earth

Case Example #3 – Tools/Outcome - Tools –Soil /sediment /groundwater/ tissue chemistry, toxicity testing, biological survey - Risks posed by sediment unacceptable for benthic invertebrates in most impacted areas of subtidal zone - Copper and pesticides in sediment were risk drivers - Risks posed by soil and groundwater acceptable Source: Google Earth - Sediment remediation for portion of site - Risk-based Approval-in-Principle

THANK YOU!! Scott Steer, R. P. Bio. , CSAP scott. steer@steerenvironmental. com 67