1. DIRECT

1. Biologic monitoring of body fluids for the compound and/or its metabolites—quantitative (e.g., blood level)

1. Identifies exposed individuals

2. Provides measure of body burden for some agents (e.g., metals)

3. Measures absorption of compound from all routes of entry—respiratory, cutaneous, and oral

4. Gives information about prior exposure

1. Many methods still in developmental stages and lack validation

2. May be expensive due to need for specially trained personnel and sophisticated equipment

3. May require concurrent air sampling if exposures are not constant

4. Interpretation may be influenced by variation in uptake with physical exertion and interference from diet and drugs

5. Requires careful timing of specimen collection, especially for blood samples

6. Subject consent required to obtain specimens

7. Lack of population reference values

2. Personal industrial hygiene or ambient monitoring, single and multiple—quantitative

1. Estimates exposure for individual employees

2. Can be performed easily by the employer

3. Exposure to multiple compounds can be assessed simultaneously

1. Requires cooperation of worker or study subjects to wear monitoring equipment

2. Does not measure body burden

3. Limited ability to assess multiple routes of exposure

4. Gives no information about prior exposures

5. May not correspond with results of area sampling

6. Samples may not reflect “average” work day; taking of measurements should consider shifts, production, seasons, etc.