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Epidemiology and

Risk Assessment

(4th of 10 Lectures on Toxicologic Epidemiology)

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.

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.

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.

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.

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.

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.

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.