Models for Risk Assessments of Nanoparticles - Biointeractions of Nanomaterials - page 389

In vitro toxicity
studies

Epidemiological
studies

Aminal toxicity
studies

QSAR

Adverse health
effect

Interactions
with
macromolecule Pharmaco-

kinetic
modeling

Effect
qualification

Biologically
relevant dose

Exposure
modeling

Risk
assessment

Human
exposure
modeling

Human
exposure

Environmental
modeling

Environmental
considerations

Environmental
media
monitoring

Exposure
qualification

Production
emmision
factors

Pollutant
emissions

FIGURE 19.3 General environmental health framework for risk assessment. (From Gross MK et al. Journal
of Nanoparticle Research . 2007;9:137-56. With permission.)

monitoring to measure tissue burden and thereby estimate the dose. The estimation of a biologically
relevant dose from exposure information is, however, often very difficult and requires fairly detailed
knowledge of the toxicokinetics of the pollutant in the human body. The lower portion of the dia-
gram relates to the estimation of the health effects of the exposure and the biologically relevant
dose. Information regarding the effects can come from in vitro and in vivo studies, quantitative
structure-activity relationship (QSAR) modeling [50], and epidemiological studies. The quantifica-
tion of exposures and effects allows the quantification of risk that, in turn, allows the proper alloca-
tion of resources to manage the risk. For example, risk assessment might allow the identification of
populations or individuals at greater risk because their exposures are greater than some threshold
identified in epidemiological studies.

19.5 STRUCTURE FOR RISK ASSESSMENT
Recent studies on nanoscale substances along with relevant research on UFPs from air pollution,
metal fume, and mineral fibers provide an initial basis for evaluating the primary issues in a risk
assessment framework of nanomaterials [5] (Figure 19.4).