Exposure Pathways: How Substances Enter the Body
Substances enter the body through four main routes: the air you breathe, the water you drink, the food you eat, and through contact with products and surfaces. These pathways determine how toxic substances such as PFAS, heavy metals like lead and mercury, and VOCs from everyday products get into the body.
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Each pathway affects how substances enter the body and how often that exposure occurs.
Why Exposure Pathways Matter
Most contact with toxic substances does not come from a single event. It happens through everyday activities such as breathing indoor air, drinking tap water, eating food, and using personal care or household products.
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These sources may seem routine, but they determine what the body comes into contact with on a daily basis. Understanding how substances enter the body is the first step before looking at what happens once they are inside.
How These Pathways Show Up in Daily Life
Air
Cleaning sprays • fragrances • VOCs • pollution
Water
Tap water • pipes • treatment chemicals like chlorine byproducts and heavy metals
Food
Pesticides • packaging chemicals like BPA and phthalates • food processing
Skin
Lotions • cosmetics • sunscreens • cleaning products
What Happens After Exposure
Once substances enter the body, what happens next depends on how often that contact occurs and how the body processes them. Over time, this can begin to influence processes like chronic inflammation and oxidative stress, and connects directly to cumulative exposure.
How Pathways Overlap in Real Life
The same toxic substances, such as PFAS, heavy metals like lead, and VOCs, can show up across multiple pathways including air, water, food, and everyday products.​
Because daily life involves constant interaction with these sources, the body is often exposed through multiple routes at the same time.