The size of a toxicant can determine how it moves through the body and the extent to which it can cause damage. For instance, nanoparticles, which are particles between 1 and 100 nanometers in size, have unique properties due to their small size. They can easily penetrate biological membranes, including the blood-brain barrier, and reach sites that larger particles cannot. This enhanced penetration can lead to increased toxicity as these particles can interact with cellular components in unprecedented ways. Moreover, the size of particles can impact their surface area to volume ratio, which in turn affects their reactivity. Smaller particles have a larger surface area relative to their volume, which means they can interact more readily with biological tissues and may lead to more severe toxic effects.
