An exposure scenario is a set of conditions or assumptions about sources, exposure pathways, amount or concentrations of agent(s) involved, and exposed organism, system or (sub)population (i.e. Numbers, characteristics, habits) and used to aid in the evaluation and quantification of exposure(s) in a given situation. GENERAL PRINCIPLES EXPOSURE EVALUATION The purpose of exposure assessment is to identify the routes by which humans are exposed and the magnitudes of that exposure, including the frequency and duration. Identify the number of exposed people along with either characteristics Exposure may be measured as the amount of the contaminant in various media and an estimate of human intake of these media under different activity patterns Some people may be exposed to more than one media. Total intake must be evaluated.
EXPOSURE ASSESSMENT I Biomarkers Herman Autrup Wednesday, December 7 2011 1 Generel introduction to exposure science Biomarkers pro and con Exposure asessment – use of biomarkers Biomarkers for air pollution Conclusion OUTLINE 2 RISK = HAZARD X EXPOSURE 3 WHAT IS EXPOSURE ASSESSMENT? • EXPOSURE is the contact of a chemical, physical, or biological substance with the outer boundary of an organism • EXPOSURE ASSESSMENT is the determination or estimation of the magnitude, frequency, duration, and route of exposure 4 An exposure scenario is a set of conditions or assumptions about sources, exposure pathways, amount or concentrations of agent(s) involved, and exposed organism, system or (sub)population (i.e. Numbers, characteristics, habits) and used to aid in the evaluation and quantification of exposure(s) in a given situation. IPCS 5 GENERAL PRINCIPLES EXPOSURE EVALUATION The purpose of exposure assessment is to identify the routes by which humans are exposed and the magnitudes of that exposure, including the frequency and duration. Identify the number of exposed people along with either characteristics Exposure may be measured as the amount of the contaminant in various media and an estimate of human intake of these media under different activity patterns Some people may be exposed to more than one media. Total intake must be evaluated. 6 EXPOSURE SCENARIOS Occupational exposures Different function Consumers Release of chemical from product during use Indirect environmental exposures 7 8 AGGREGATE EXPOSURE Exposure for the same compound present in multiple sources and through several routes (i.e. oral, dermal,inhalation ) 9 EXPOSURE ASSESSMENT Ambient Monitoring Biological monitoring external exposure disease internal exposure biochemical effects biological effects chemicals: in air, soil, water hazardous substances, Metabolites in blood, urine protein adducts DNA adducts cytogenetic parameters enzymes, enzyme levels importance for estimating the risk HESI Annual meeting 2006 J. Angerer 10 [...]...ADVANTAGE - BIOMARKERS Demonstrate that exposure has occurred Integrate dose across all routes of exposure Reflect activity pattern Validation of exposure models Relates exposure to dose Do not depend on memory/records Characterization of individual exposure- dose Cohort studies relating exposure to early markers/disease outcome 11 BIOMARKERS - LIMITATION • Source... FATE AND ELIMINATION 15 BIOMARKERS -TIME 16 NATIONAL REPORT ON HUMAN EXPOSURE TO ENVIRONMENTAL CHEMICALS What it is: An ongoing (every 2 years) biomonitoring assessment of the exposure of the U.S population to selected environmental chemicals Matrices monitored: Urine; blood and its components 17 CHEMICALS IN 4TH REPORT ~265 chemicals Exposure biomarkers for: • Metals • Polychlorinated biphenyls, dioxins... population • Identifies prevalence of persons with elevated levels • Identifies population groups with elevated levels • Monitors changes in exposure over time • Assesses effectiveness of public health efforts to reduce exposures • Provides exposure data for risk assessment • Helps set priorities for human health effects research 34 BIOMARKERS - WILDLIFE To assess environmental burden of toxic compounds... ACTION VALUE above which there is an increased risk for adverse health effects 22 MERCURY (1999) Mercury in urine (exposure to inorganic mercury) Hg (u) [µg/l] increased risk of adverse health effects 25 a HBM-II alert, control range 7a HBM-I no risk of adverse health effects reference value exposure general population 1.4 b a rule out neurotoxic and nephrotoxic effects b for children and adults without... and MN in buccal cells 29 AIR POLLUTION EXPOSURE BENZENE Benzene in exhaled air Metabolites in urine muconic acids S-phenylmercapturic acid (S-PMA) Reaction products with proteins Early biological effects Comet assay, 30 PMA as BIOMARKER FOR BENZENE Cotonou, Benin 1.5 Ln(PMA/creatinine) 0.5 -0.5 -1.5 -2.5 -3.5 -4.5 -5.5 Rural Suburban Cityroad Taxidrivers 31 PAH EXPOSURE – BANGKOK 1-hydroxypyrene 32... back calculation • Biological variability • Participant burden •Specificity/sensitivity •Lack of normative values for comparison • Exposure – effect relationship 12 BIOMARKERS Efficacy of use • Lower burden than traditional monitoring • More practical - children • Route of exposure • Sampling device after behaviour 13 VALIDATION OF BIOMARKERS Sample collection and sample stability • Transport and storage... • Perfluorinated chemicals • Brominated flame retardants • VOCs • Perchlorate • Bisphenol A & Alkylated phenols • Triclosan • Sunscreen agent • Speciated arsenic Acrylamide • • Persistent www.cdc.gov/exposurereport Update: July 2010 Percentage of children 1-5 years old in the US with elevated blood lead levels (≥ 10 µg/dl) 100 88.2 Percent 80 60 40 20 8.6 4.4 1.6 1991-1994 1999-2002 0 1976-1980 1988-1991... urine Children and adults 220 - - 5oxo-MEHP urine Children and adults 150 - - Σ 5OH-MEHP, 5oxo-MEHP urine Children Female adults Male adults - 500 300 750 - 25 BIOLOGICAL MONITORING OF METALS Metal Media Exposure Health effects Aluminum B,U ++ (++) Arsenic U ++ ++ Cadmium B,U +++ +++ Lead (inorg) B +++ +++ Lead (org) U +++ ++ Nickel U,B ++ ? 26 BIOMARKERS - LEAD 27 BLOOD LEAD LEVEL IN CHILDREN MINING TOWN... provide an ”early warning” or indication of possible effects on humans To provide an economically effective way of ranking human health questions by indicating the type of responses To assess whether exposure was from chemical passing through food chains or by other routes – e.g inhalation 35 . Conclusion OUTLINE 2 RISK = HAZARD X EXPOSURE 3 WHAT IS EXPOSURE ASSESSMENT? • EXPOSURE is the contact of a chemical, physical, or biological substance with the outer boundary of an organism • EXPOSURE ASSESSMENT is. evaluated. 6 EXPOSURE SCENARIOS Occupational exposures Different function Consumers Release of chemical from product during use Indirect environmental exposures 7 8 AGGREGATE EXPOSURE Exposure for. in the evaluation and quantification of exposure( s) in a given situation. IPCS 5 GENERAL PRINCIPLES EXPOSURE EVALUATION The purpose of exposure assessment is to identify the routes by which