Quantitative risk assessments usually measure human exposure through all of the following except:

Quantitative risk assessments are designed to estimate the likelihood and severity of adverse health effects resulting from exposure to environmental hazards. This process typically involves measuring human exposure through a variety of methods, each offering unique insights into how individuals or populations interact with potential risks.

When considering the options, personal surveys, blood or urine analyses, and toxicological analyses serve as direct methods of assessing actual or potential human exposure to substances. Personal surveys can gather data regarding behaviors and environmental interactions, while biological analyses, such as blood and urine tests, provide concrete evidence of exposure by measuring the concentration of substances directly within the human body. Toxicological analyses further assess how these substances may impact health based on their properties and interactions within biological systems.

On the other hand, computer models are generally used for simulations and predictions rather than direct measurement of exposure. They help estimate potential exposure levels based on various assumptions and data inputs but do not directly measure actual human exposure. Thus, they serve more as tools for risk assessment rather than direct assessment methods.

In summary, the correct choice reflects the fact that while computer models can aid in the risk assessment process, they do not directly measure human exposure in the way that the other methods do.