Health Risk Assessment

Document Sample
Health Risk Assessment Powered By Docstoc
					Health Risk Assessment
HRA and Decision Making

     Scientific Research     Impact Assessment                   Risk Management


     • Epidemiology           • Hazard
     • Clinical Studies       • Dose-Response
     • Animal Toxicology      • Exposure           • Economic      D    • No Action
     • In vitro Studies       • Risk                 • Ethical     E    • Ban
     • Computation methods
                                Characterisation      • Legal      C    • Emissions
     • Monitoring/                                    • Moral      I    • Standards
       Surveillance                                • Political     S    • Incentives
     • Social sciences                               • Social
     • Psychology                                                  I    • Education
                                            • Technological        O    • Control
                                                       • RA        N      devices

                                                                   S

35
                                  HRA
   The World Health Organization’s principles for “environmental health
    impact analysis” are:
   • Health should be one of the fundamental considerations in the approval
    of projects, policies and plans;

   • Greater consideration should be given to the health consequences of
    projects, policies and plans in EA;

   • EA should provide the best factual information on the health
    consequences of projects, policies and plans; and

   • Information on health impacts should be available to the public.

(World Health Organization, 1987)
           Objective of HRA

 “The  primary objective of risk
 assessment is to estimate the likelihood (or
  probability) and
 the severity of harm to human health and the
  environment occurring from exposure to a risk
  agent.
HIA in EIA
        Health Risk Assessment

 What     is it?
HRA is defined as the scientific process of evaluating the toxic properties of
a hazard And the conditions of human exposure to the hazard in order to:

1. As certain the likelihood that the exposed humans will be adversely affected
2. To characterize the nature of the effects they may experience
                                    source: Environmental Toxicology, 1996



The characterization of probability of potentially adverse effects from human
Exposures to environmental hazards.
                                   source: National Academy of Sciences
           What is it?....Continue

HRA is a methodological approach in which the toxicities of a chemical
 are identified, Characterized, analyzed for dose response relationships,
and the data generated are applied to a mathematical model to produce
 a numeric estimate representing a guideline or decision concerning
allowable exposure
                                source: Industrial Toxicology, 1985




EHRA
Involves the analysis of environmental hazard exposure ………………
   Evidence for HRA
 “The  Credibility of RA depends,
 to large extent, on the strength of
 the scientific evidence on which
 it is based” WHO
Evidence for HRA
 Human   studies
  – Extrapolation of high
    level exposure
 Toxicological   evidence
  – Based on animal studies
  – Extrapolation across
    species
  – Apply the uncertainty
    factor
  – Available for large
    number of pollutants
             Mixture of air pollutants:
               The Joint Toxicities
Joint                               three categories of
toxicity refers                     joint toxicity are:
                                    greater than additive
to the outcome                      (synergism and
of two or more                      potentiation);
chemicals                           additive (no
                                    interaction); and less
acting together                     than additive
                                    (antagonism and
                                    inhibition).

                                    Additivity is
                                    the default assumption
                                    for evaluating health
                                    effects of multiple
                                    chemicals.
        Key Concept for HRA of
         Mixture of pollutants




             Professional Training On Urban Air Quality Management
Policy and Tool for Integrated Assessment, 27-29 March 2007, Kuala Lumpur, Malaysia
          Appropriate method?

 Non   Cancer effect
  –   Dose Addition Method
  –   Three methods of dose addition;
  –   the relative potency factor (RPF),
  –   the toxic equivalency factor (TEF), and
  –   the hazard index (HI).
 Cancer   Effect
        Response   Addition Method
       Mixture of pollutants




             Professional Training On Urban Air Quality Management
Policy and Tool for Integrated Assessment, 27-29 March 2007, Kuala Lumpur, Malaysia
Major steps in HRA

   Hazard  Identification
   Dose-response
    relationship
   Exposure assessment
   Risk Characterization
             Hazard Identification
   This stage of HRA is critical         Review the available studies
    – Determine the hazards                / evidence
    – Determine the selection of           – Provide a list of health
                                             endpoints for each pollutants
      health endpoints
                                           – Type of effect
    – Determine Dose-response
                                           – Acute or chronic
      data to be used
                                           – Nature of effect
    – Determine the air quality data
                                           – Irritation/systemic
      required during exposure
                                             effect/cancer
      assessment
                                           – Target organ affected
    – Selection of Health endpoint
      depends on the objective of
      HRA
 Health Endpoints
Non cancer effects
                             Health Endpoints
                             Non Cancer Effect
Chemical of         Chronic RfC   Primary Target   Type of critical effect for   Source of
   concern          (mg/m3)           Organ            development of               Toxicity
                                                       threshold dose               data
                                                                                    (date*)
SO2                 ND*           URT              URT Irritation
NO2                 ND*           URT              URT irritation
HCL                 2x10-2        URT              URT irritation                IRIS
                                                                                     (20/05/06)
Dioxin/Furan        4.E-05        Development      Systemic effect               OEHHA,2005
    (ITEQ)
(as 2,3,7,8-TCDD)
Arsenic             0.03          skin             Systemic effect               OEHHA,2005
Cadmium             0.02          Kidney           Systemic effect               OEHHA,2005
Lead                NA            NA               NA                            NA
Chromium IV         1x10-4        Respiratory      Systemic effect               IRIS
                                     toxicity                                        (20/05/06)
Mercury             NA            Nervous                                        IRIS
                                      system                                         (20/05/06)
                    Cancer effects
Criteria for Carcinogens


Qualitative assessment:
how likely an agent is a human carcinogen?

Quantitative assessment of the cancer rate the agent is likely to cause at
  given levels and exposure.
              Cancer effects
 Classification criteria of IARC and HRA
Weight of   Description                                 HRA
Evidence
Group 1:    Proven human                                Risk estimates
            carcinogens:
Group 2     Probable human carcinogens                  Risk estimates

Group 2A    Limited evidence of carcinogenicity in      Risk estimates
            humans, Sufficient evidence of
            carcinogenicity in animals
Group 2B    Inadequate evidence of carcinogenicity in   Guidelines
            humans                                      based
                                                         on non-cancer
                                                        endpoints
Group 3     Unclassified chemicals                      Guidelines
                                                        based
                                                         on non-cancer
                                                        endpoints
Chemical    URF               Type of cancer   EPA Weight of Evidence/   Source of Toxicity data
   of       (ug/m3)                            Route                     (date*)
   concer
   n
Arsenic     Drinking Water:   Skin             A/oral                    IRIS (20/05/06)
                5x10-5 per
                ug/L


            Air:              Lung             A/Inhalation              OEHHA, 2005
            3.30E-03

Cadmium     4.2x10-3          Lung             B1/inhalation             OEHHA, 2005

Lead        1.20E-05          Not reported     B2                        OEHHA, 2005


Dioxin/F    Air: 1.3          Lung             B2/inhalation             IRIS (20/05/06)
   (TEQ)
 Step 2: Evaluation of Dose-
    response relationship
 All substances are
  poisons
 There is none is not a
  poison. The right dose
  differentiates a poison
  and a remedy

    “Paracelsus (1493-1541)”
                       Xenobiotics
                                        Approximate
                                       Dose-response
                                        relationship

 External Dose         Entry Portals




                                                       Dose-response relationship
                                            Better
  Absorption                           Dose-response
                                        relationship

                         Systemic
Internal Dose
                        Circulation
  Transportation                       most accurate
   Metabolism                          Dose-response
    Excretion                           relationship

Biological Effective
                        Target Sites
       Dose
 Step 2: Evaluation of Dose-
    response relationship
Determination of safe human dose
 What is Safe Human Dose: Threshold Dose
  – All dosages and exposures below the threshold dose
    are considered “safe”


 Synonyms      for Safe Human Dose
         –   Acceptable Daily Intake (ADI)
         –   Reference Dose (RfD) for ingestion exposure
         –   Reference Concentration (RfC) for inhalation exposure
         –   Reference Exposure Limit (REL)
         –   Maximal Residual Limit (MRL)
 Step 2: Evaluation of Dose-
    response relationship
 Non-Threshold        Dose
  – No-Threshold dose concept states that all exposures
    to a substances, no matter how small, entail some
    risks
  – Carcinogen
      Unit Risk Factor (URF) is defined as the excess lifetime
       cancer risk estimated to result from continuous exposure to
       an agent at a concentration of 1 µg/L in water, or 1 µg/m3
       in air.
      the cancer potency slope (potency factor), which
       describes the potential risk of developing cancer per unit of
       average daily dose over a 70-year lifetime.
Concentration-response
     coefficients
Dose response
Exposure Assessment


    Determine exposure pathways
    Determine the concentration
    Determine the population exposed
    Determine the intake
         Exposure Assessment of air
                 pollutants
   Inhalation                   Non-inhalation
    Pathway                       pathways
   Air Toxic                    multiple-pathway
    pollutants                    exposure should be
                                  considered
   Criteria                     for emission of
    pollutant                     PAH, arsenic,
     –   PM                       chromium,
     –   O3                       cadmium, lead,
                                  mercury, dioxin and
     –   SO2
                                  furan.
     –   NO2
                                 (OEHHA, 2000)
     –   CO
Classic Graphical Conceptual
           Model
      Multiple exposure pathways
Hazards of concern       Exposure                    Exposure media               Exposure
                           pathway                                                   route
Dioxin/Furan         Air Emission      Ambient air                              Inhalation
Arsenic
Cadmium
Lead
Mercury (Hg)



PAH, Arsenic,        Deposition to     Eating fresh water fish from pond        Ingestion
   Chromium,            surface
   Cadmium, Lead,       water
   Dioxin/Furan,
                     Deposition to     Accidentally Ingestion of water during
   Mercury as
                        surface            recreational activity in the pond
   (MeHg)
                        water
                     Deposition to     Eating duck meat from duck farm at
                        surface            nearby proposed site
                        water
                     Deposition to     Consume home-grown vegetables
                        surface soil
   Inhalation Route
               Estimating Intake
                    For different route of
                          exposure

                 Inhalation Ingestion Dermal




              Lifetime average concentration
Equation:-
LAC = C predicted ambient ET x EF x ED
                         AT
Where; CAC = Lifetime average daily concentration
       C predicted ambient = concentration of air contaminant from air modelling (mg/m3)
       ET = exposure time (hr/day): 24 hours
       EF = Exposure frequency (days/year)
       ED = Exposure duration
       AT = Averaging time for lifetime exposure (hours): 613,200 hours
              (i.e 70 years * 365days/year *24hours/day)
Source: U.S EPA, 2004. Example Exposure Scenarios. National Center for Environmental
Assessment, U.S Environmental Protection Agency, Washington, DC 20460
        Intake from non-inhalational routes

                       Estimating Intake
                         For different route of
                               Exposure

                       Inhalation Ingestion Dermal




Ingestion of contaminated food (eg: vegetables)

Intake (mg/kg-day) =    CAP x IR x FI x EF x ED
                              (BW x AT)

CAP = chemical concentration in food (mg/kg)
IR = Ingestion Rate (kg/meal)
FI = Fraction Ingested from contaminated area (0 to 1)
EF = Exposure Frequency (days/year)
ED = Exposure Duration (years)
BW = Body Weight (kg)
AT = Averaging Time (period over which exposure averaged in days)
                        Estimating Intake
                          For different route of
                                exposure

                        Inhalation Ingestion Dermal




Ingestion of contaminated food (eg: vegetables)

Intake (mg/kg-day) =    CAP x CF x SA x AF X EF x ED
                              (BW x AT)

CAP = chemical concentration in soil (mg/kg soil)
CF = Conversion Factor
SA = Skin surface area available for contact (cm2/event)
AF = soil to skin adhere factor
ABS= Absorption Factor ranging from 0 to 1
EF = Exposure Frequency (event/year)
ED = Exposure Duration (years)
BW = Body Weight (kg)
AT = Averaging Time (period over which exposure averaged in days)
Estimate the Number of People Exposed


                    Totalnumber of people
                     Exposed
                    By age group
                    By different areas of
                     concern
           Risk Characterization

 Non  Cancer Effect           Basedon
  (chronic or acute)           epidemiological
  – HQ                         evidence
  – HI                          – % of morbidity or
 Cancer   Effect                 mortality
                                – Attributable fraction
  – Life time excess cancer
    risk                        – Number of cases
                                  attributable to exposure
  – Chance per million
    population
Non cancer inhalation health effect
        chronic or Acute
 For multiple pathway air pollutants
 Determine  the non-
  inhalation HQ for each
  substance
Quantification number of cases attributable to exposure
       (based on epidemiological evidence only)

Dose-Response    Morbidity       Exposure Assessment
     Step       Mortality data          step
Cancer effect

 CalculatingInhalation
  Cancer Risk
 1.


2   lifetime average concentration (ug/m3) x URF (ug/m3)-1) = Cancer Risk

                     Equation:-
                     CAC = C predicted ambient ET x EF x ED
                                              AT
                     Where; CAC = Lifetime average daily concentration
                            C predicted ambient = concentration of air contaminant from air modelling (mg/m3)
                            ET = exposure time (hr/day): 24 hours
                            EF = Exposure frequency (days/year)
                            ED = Exposure duration
                            AT = Averaging time for lifetime exposure (hours): 613,200 hours
                                   (i.e 70 years * 365days/year *24hours/day)
                     Source: U.S EPA, 2004. Example Exposure Scenarios. National Center for Environmental
                     Assessment, U.S Environmental Protection Agency, Washington, DC 20460
Routes             Hazard of     Type of     URF
                   concern       cancer      (ug/m3)
                                                                            LIFETIME CANCER RISK
                                                        A1             A2             A3             A4



Inhalation         Arsenic       Lung        3.30E-03
                                                             9.3E-07        9.3E-07        9.3E-07        9.3E-07
Inhalation         Cadmium       Lung        4.20E-03
                                                             2.2E-05        4.4E-05        1.7E-05        4.8E-06
Inhalation         Lead          Not         1.20E-05
                                 reported
                                                             4.6E-07        2.8E-07        2.6E-07        2.5E-07
Inhalation         Dioxin/F      Lung        1.30E+00
                        (TEQ)
                                                             3.7E-09        3.7E-09        3.7E-09        3.7E-09
Sum of lifetime cancer risk for all carcinogens
                                                             2.5E-05        4.7E-05        2.0E-05        2.4E-05
Number of cases
                                                           3 cancer       5 cancer        2 cancer       3 cancer
                                                             Cases          Cases           Cases          Cases
                                                         Per 100,00    Per 100,000     Per 100,000    Per 100,000
 Thank you
Terima Kasih

				
DOCUMENT INFO
Shared By:
Tags:
Stats:
views:25
posted:1/4/2013
language:
pages:42
Description: Lecture note on Health Risk Assessment (HRA) in EIA