Michael H. Dong MPH, DrPA, PhD readings Epidemiology and Risk Assessment (4th of 10 Lectures on...
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Transcript of Michael H. Dong MPH, DrPA, PhD readings Epidemiology and Risk Assessment (4th of 10 Lectures on...
Michael H. DongMPH, DrPA, PhD
readings
Epidemiology andRisk Assessment
(4th of 10 Lectures onToxicologic Epidemiology)
Taken in the early ’90s, when desktop computers were still a luxury.
Learning Objectives• Appreciate the recent advances in
epidemiology pertinent to health risk assessment (RA).
• Study the epidemiologic approaches to human exposure assessment.
• Learn about the biomarkers used in epidemiology as well as in RA.
Performance Objectives• Able to list and describe the recent
advances in epidemiology pertinent to health risk assessment (RA).
• To describe the epidemiologic approaches to exposure assessment.
• To discuss the strengths and limitations of the use of biomarkers in epidemiology and in RA.
Health Statutes & Regulations
Toxicity Studies/Data
Research Developments
Recent Advances in Epidemiology
• Branching out from general epidemiology.
• Specialty disciplines now including: psychosocial; pharmaco-; occupational; environmental; nutritional; genetic; molecular; cancer epidemiology; and more.
Psychosocial Epidemiology
• Determinants of disease: social; psychological; behavioral factors.
• Not directly of regulatory concern.
• But offering valuable information for health risk assessment.
Pharmacoepidemiology
• Studying the use, efficacy, and safety of pharmaceuticals.
• Beginning to flourish in 1980s.
• Adding a new twist to the regular course of health risk assessment.
Nutritional Epidemiology
• Studying the role of nutrition/ diet in the etiology of disease.
• Nutritional epidemiologists conducted the first clinical trials.
• Human and social factors affect dietary intake.
Genetic and Molecular Epidemiology
• Actually two separate branches.• Molecular: studying with known
genes.• Genetic: studying with unknown
genes.• Useful in flagging preclinical effects
of exposure.
Cancer Epidemiology• Related closely to molecular and
genetic epidemiology.
• Now more into identifying and quantifying nutritional and other environmental carcinogens.
• Epidemiology on cancer effects becoming more available for health risk assessment.
Environmental & Occu- pational Epidemiology
• Actually two separate branches.• But both are linked together due to
studying exposures to common toxic agents which are relatively more preventable.
• Occupational epidemiology tends to use biomarkers more.
Clinical Trials• Were conducted as early as 1537.
• Sometimes referred to as human intervention trials.
• Used to test not only treatment but also adverse (side) effects.
• A simplified or special version of health risk assessment.
Phases of Regulatory Clinical Trials
• Preclinical: a series of laboratory or animal studies.
• Trial Phases: (I) testing for human safety; (II) testing for efficacy; (III) overall trial assessment.
• Postlicensing surveillance.• Ideally should follow a double-
blind randomization design.
Meta-Analysis of Clinical Trial Data
• First used around 1976.• Uses routine statistical methods on
data pooled from various trials typically not following the same study protocol.
• A controversial technique unacceptable to some statisticians.
Basic Epidemiologic Study Designs
•Using primarily observational data.•Descriptive studies.•Cohort studies.•Case-control studies.•Cross-sectional studies.•Ecological studies.
Guidance for Epidemiology Studies
•Epidemiologic study designs can be used to assess human exposures.
•Good epidemiology practices by: International Society for Pharmaco-epidemiology; International Epidemiological Association; and World Health Organization.
Human Exposure: Basic Definition
• Human exposure to a toxic agent is defined as the (level of) contact of a person with the toxicant.
• Human exposures can be categorized by route of entry; exposure source; and exposure duration.
Human Exposure: Methods and Advances
• Methods: direct monitoring of individuals; and from measurement of environmental levels.
• Advances: Social Readjustment Rating Scale; Stress Process Model; geographic information system; biomarkers, etc.
Use of Biomarkers
• Limitations: low detection levels; compliance with sample collection.
• Related to biological monitoring.
• Types of biomarkers: for exposure; adverse response; susceptibility.
• Best estimate for aggregate dose.
Criteria of Selection of Biomarkers
•Criteria: availability; specificity; invasiveness; persistence; time-to-appearance; intra- and interperson variability.
•Multiple factors causing biological variation in dose-response.
Biomarkers: Legal and Ethical Considerations
•Legal authority as barrier; privacy act.
•Ethical implications concerning the subject’s right-to-know.
•These considerations making biomarkers useful at a slow pace.
Overview of Next Lecture Toxicologic Side of
Epidemiology•Illustrating this side through use of historical cases.
•Epidemiologic activities might have initiated/dominated in these cases.
•But the toxicologic side was also there and critical.