The size of a molecule influences its ability to penetrate biological membranes and reach target sites within the body. Smaller molecules can often diffuse more easily through cellular barriers, while larger molecules may require specific transport mechanisms. This size-dependent permeability can impact the potency of a toxicant. Additionally, the size of a particle can determine its deposition in the respiratory tract. For instance, nanoparticles can penetrate deep into the lungs, potentially leading to adverse health effects.
