Human Toxicology and Effects of Nanoparticles - Environmental and Human Health Impacts of Nanotechnology - page 354

Physico-chemical
characteristics

Behaviour of particles in
the biological systems

Behaviour of particles in
the environment

Exposure routes and
concentrations

Hazard in biological
systems

Risk

Figure 9.1 Understanding Risk. Risk is estimated from a combination of the exposure and
hazard (toxicity) of a substance. The physico-chemical characteristics of nanoparticles infl u-
ence how they behave in the environment and, therefore, what the route and quantity of
exposure might be, as well as their toxicity.

e.g. fibre shape
effects clearance

Entry route and
efficiency

Inherent toxicity
e.g. low TiO 2
high Cd

SHAPE

Translocation

SIZE/
SURFACE
AREA

COMPOSITION

Electrochemical
gradients

NANOPARTICLE
Physico-chemical
characteristics

Molecular
interactions

ELECTRICAL
CONDUCTANCE

CHARGE

Membrane
potential

CRYSTAL
STRUCTURE

STRENGTH

Durability

e.g. crystalline silica
vs. amorphous silica

SOLUBILITY

Biopersistence

Clearance

Biopersistence
Release of toxic
components

Clearance

Figure 9.2 Linking the physico-chemical characteristics of particles to their biological activ-
ity. These properties include published information for particles (quartz, asbestos, air pollu-
tion) and nanoparticles, as well as purely hypothetical ideas (e.g. electrical conductance).