Lecture 2 Introduction to Exposure Assessment Eric Amster MD MPH

Overview Basic Concepts in Exposure Assessment Exposure Assessment Hierarchy 3 Stories of Exposure Assessment gone wrong Types of Exposures

Overview Basic Concepts in Exposure Assessment Exposure Assessment Hierarchy 3 Stories of Exposure Assessment gone wrong Types of Exposures

Epidemiology in a nutshell Exposure Outcome Confounding Nutrition: High fat diet  Obesity Social: High stress  Cancer Occupational: Shift work  Depression Environmental: Air pollution  CV Disease

Epidemiology in a nutshell Exposure Outcome Confounding Outcome Assessment has clear clinical definition   Fairly straightforward. Diabetes: fasting plasma glucose level >126 mg/dl (7.0 mmol/l) or a casual plasma glucose >200 mg/dl (11.1 mmol/l) PTSD : Traumatic event, avoidance, hypervigilance, >1month

Epidemiology in a nutshell Exposure Outcome Confounding 4 things to think about Multiple levels of Exposure Assessment Technical methodologies Non-static Varying degrees of biological significance/plausibility

Epidemiology in a nutshell Exposure Outcome Confounding It’s complicated! Understanding exposure assessment can  avoid confounding by co-exposure,  refine Exposure  Outcome association,  Clarify significance of results

BMI > 30 Exposure is McDonalds in neighborhood… course exposure assessment Ecological study  Ecological Fallacy Are the obese kids the ones eating at McDonalds? What are they eating at McDonalds? What is the fat content of their food at McDonalds?

BMI > 30 It could be something totally different… Low SES Latino Race Epigenetics

Exposure vs Dose Exposure does not = dose We care about actual dose Exposure metric: what we actually measure Dose: The portion of the exposure that effects the body

Exposure  Dose… depends on Chemical half-life (i.e., persistence of chemical in blood or urine); Route of exposure; Genetic susceptibility; Demographic characteristics (e.g., age or gender); Health status and nutrition(e.g., reduced kidney function, iron deficiency); Lifestyle or behavioral factors (e.g., smoker versus non- smoker, or occupation); and Geography (e.g., proximity to environmental chemical sources, or climate).

Overview Basic Concepts in Exposure Assessment Exposure Assessment Hierarchy 3 Stories of Exposure Assessment gone wrong Types of Exposures

Exposure Hierarchy Molecular Internal Exposure Community Exposure Individual Exposure

Exposure Hierarchy Env/Occ Epi Personal Exposure Bioactive Dose Internal Dose Ambient Exposure

Personal Exposure Bioactive Dose Internal Dose Ambient Exposure Exposure Hierarchy Env/Occ Epi

Personal Exposure Bioactive Dose Internal Dose Ambient Exposure Exposure Hierarchy Env/Occ Epi

Overview Basic Concepts in Exposure Assessment Exposure Assessment Hierarchy 3 Stories of Exposure Assessment gone wrong Types of Exposures

What do these children do for work? Children who are chimney sweepers are 12 times more likely to have Scrotal Cancer

Exposure Hierarchy Personal Exposure Bioactive Dose Internal Dose Ambient Exposure Occupation: Chimney Sweep Research was repeated in US. No association was found in chimney sweeps. Why?

Exposure Assessment 1. Higher up on the exposure pyramid, the better the exposure assessment. But the better exposure assessment is more expensive

PM2.5 “The IQR (4.1 mg/m3) of birth year PM2.5 was associated with a significantly increased risk of asthma (OR 3.1, 95% CI 1.3 to 7.4) and with “ to increased risk of bronchial hyper-reactivity OZONE

PM2.5 PM2.5 is a co-exposure which confounds the association. If you don’t measure and incorporate co-exposures into model  confounding OZONE

Exposure Assessment 1. Higher up on the exposure pyramid, the better the exposure assessment. 2. Co-exposures can confound results. They need to be measured and incorporated into the model.

Env Health Pers ? [As] 90% of kelp samples had high As levels Two types of arsenic: organic and inorganic. Organic non-toxic What we measured did not represent biological reality

Mercury Example Autism?

Mercury Example Personal Exposure Bioactive Dose Internal Dose Ambient Exposure Urine and blood Mercury Levels Ingested inorganic mercury is not bio-available and not toxic.

Exposure Assessment 1. Higher up on the exposure pyramid, the better the exposure assessment. 2. Co-exposures can confound results. They need to be measured and incorporated into the model. 3. Understand biological significance of exposure

Overview Basic Concepts in Exposure Assessment Exposure Assessment Hierarchy 3 Stories of Exposure Assessment gone wrong Types of Exposures

Environmental Exposures What do we mean by environment?  It is the point of interaction between you and the world around you How do we define it?  Medium of environment  Type of environment  Location of environment

Environmental Exposures Medium of Exposure  The environmental medium by which we are exposed to the world around us. It’s the classical way of thinking about pollution.  Air pollution: the air we breath  Water pollution: the water we drink  Soil pollution: the food we eat But to truly quantify exposure, look deeper

Environmental Exposures Type of Environment  Chemical Environment  Physical Environment

Environmental Exposures Types of Environments  Chemical Environment

Environmental Exposures Types of Environments  Physical Environment  Ionizing Radiation  UV Radiation  Noise  Heat

Environmental Exposures Location of Environment  Ambient Environment  Work Environment  Residential Environment

Environmental Exposures Location of Environment  Ambient Environment  The environment we are exposed to just by being outside

Environmental Exposures Location of Environment  Work Environment  The environment you are exposed to at work

Environmental Exposures Location of Environment  Residential Environment  The environment we are exposed in your home  Means something different depending where you live.  Which has the worst exposure?

Environmental Exposures: pop quiz Type of Exposure: Location of Exposure:

Environmental Exposures: pop quiz Type of Exposure: Chemical Location of Exposure: Work Environment

Environmental Exposures: pop quiz Type of Exposure: Physical Location of Exposure: Work and Ambient

Environmental Exposures: pop quiz What is this?? Type of Exposure: Location of Exposure:

Environmental Exposures: pop quiz What is this?? Cell phone tower Type of Exposure: Physical Location of Exposure: Ambient

Environmental Exposures: pop quiz What is this?? Type of Exposure: Location of Exposure:

Environmental Exposures: pop quiz What is this?? Mould Type of Exposure: Chemical Location of Exposure: Residential

Measuring exposures in the environment Depends on medium of exposure Depends on location of exposure Depends on type of exposure Depends on duration of exposure. Air, water, soil Ambient, area, personal Chemical, physical Cross-sectional, time- averaged

Measuring exposures in the environment Depends on medium of exposure Depends on location of exposure Depends on type of exposure Depends on duration of exposure. Air Personal Chemical Cross-sectional

Measuring exposures in the environment Depends on medium of exposure Depends on location of exposure Depends on type of exposure Depends on duration of exposure. Air Personal Physical Time-averaged

Measuring exposures in the environment Depends on medium of exposure Depends on location of exposure Depends on type of exposure Depends on duration of exposure. Air Area Chemical Time-averaged

Measuring exposures in the environment Depends on medium of exposure Depends on location of exposure Depends on type of exposure Depends on duration of exposure. Air Personal physical Time-averaged and cross-sectional