As you can see in the skin diagram, many structures are embedded in the dermis including:
Exposure to bifenthrin can be achieved either by skin contact or ingestion. Skin contact is not toxic, apart from a slight tingling sensation on the specific location of contact. Ingestion is toxic, although only slightly. Commercially available bifenthrin (Ortho Home Defense Max, for example), however, can induce toxic effects in those concentrations, because the added chemicals which improve the sustainability either potentiate bifenthrin or are toxic on their own. Symptoms of excessive exposure are nausea, headaches, hypersensitivity for touch and sound, and irritation of the skin and the eyes.