It is the external environment that contributes most to the load of toxins that the liver has to detoxify. Today, the burden on the liver is heavier than ever before in history. Additionally, nutritional deficiencies and imbalances from unhealthy eating habits add to the production of toxins, as do alcohol and many prescription drugs, further increasing stress on the liver and requiring a strong detoxification capacity. Surprisingly, even unprocessed organic foods can have naturally occurring toxic components that require an effective detoxification system.
Toxic chemicals are found in the food we eat, in the water we drink, and in the air we breathe, both outdoors and indoors. In a study by the Environmental Protection Agency (EPA), chemicals such as p-xylene, tetrachloroethylene, ethylbenzene, and benzene were documented as "everywhere present" in the air (Wallace et al. 1989). Listed as "often present" were chloroform, carbon tetrachloride, styrene, and p-dichlorobenzene. A customary trip to a gas station or a dry cleaner (as well as smoking) results in elevated levels of inhaled toxins.
The Food and Drug Administration (FDA) has found an alarming level of chlorinated pesticides in food. Dichlorodiphenyldichloroethylene (DDE) was found in 63% or more of 42 food samples, even though the use of dichlorodiphenyltrichloroethane (DDT) and DDE has been banned in the United States since 1972. DDE is a breakdown product of DDT. Unfortunately, carried by the winds, toxic chemicals used anywhere in the world can move easily around the globe. There is enough evidence of a connection between chemical exposure and chronic health problems for us to be aware that herbicides, pesticides, household chemicals, food additives, etc. pose serious health concerns.
So what happens when the liver's detoxification system is overloaded? The answer is simple. When the liver does not function properly, toxins that we are exposed to accumulate in the body. These toxins affect us in numerous ways, and have damaging effects on many body functions, particularly the immune system, causing chronic health problems. It is not surprising that an overburdened and undernourished liver can be a root cause of many chronic diseases.
Cancers are also thought to be a result of the effects of environmental carcinogens (e.g., cigarette smoke, chemical fumes, toxic exhaust, and airborne particulates), particularly if combined with deficiencies of nutrients required for optimal functioning of the detoxification and immune systems. In a study of chemical plant workers in Turin, Italy, Vineis et al. (1985) analyzed the association of bladder cancer according to occupation (i.e., textiles, leather, printing, dyestuffs, tire and rubber goods production). Highest risks were for the leather, dyestuffs, and tire production industries. An association was found for cancer and the aromatic amines, with the risk being estimated at 10% for those occupations consistently associated with bladder cancer. Vineis et al. (1984) also found that there was a multiplicative effect of relative risks for persons in high-risk occupations who also smoked cigarettes.