Most of the time toxins accumulate in the Fat and liver cells. Different types of Substances that gather in the fat cells are removed permanently. Caffeine could be an example of this type of toxin. Of course, avoid future exposure if you want to stay toxin-free. Substances such as tobacco smoke accumulate primarily in the fat cells. Traces of these types of toxins can remain in your body for up to 6 months. Even exposure to secondhand smoke can cause detectable levels to accumulate in your body.