Exposure

Environmental

I
S
S
U
E
S

Model

• Hypothesis or problem statement clearly defined
• Scientific plausibility (e.g.,toxicity, biokinetics, relationship between time of exposure and time of assessment)
• Motives and desired results

• application of scientific methods to research theoretical questions
• application of available scientific knowledge to provide answers to questions from the public

Public health criteria and study design

• Selected parameters to be measured are valid with respect to the model
• Interpretation possible (e.g., dose-response relationship, population norms, intra- and interindividual variability)
• Relevance of interpretation to the problem statement (e.g., prevention possible) or to questions from the public (e.g., predictive value, risk communication)
• Feasibility (technical feasibility and cost feasibility)
• Timeliness
• Ethics

Collection
and handling

• Contamination
• Stability during transport or storage
• Preparation methods (e.g., cleaning, digestion)

Laboratory
methods

• Validity, reliability, accuracy, precision, sensitivity, specificity
• Quality control (proficiency tests, coefficient of variation)