Someone asked Alice this, on the Columbia University health page.
The the answer is as follows:
In order for coffee to qualify as decaffeinated, it must have at least
97 percent of its caffeine removed. What does that chock up to? An
eight-ounce cup of decaf coffee would have no more than 5 or fewer
milligrams of caffeine (compared to the range of 40 - 180 mg.
typically found in one eight-ounce cup of brewed, dripped, or
Today, most processors use safe methods to remove
caffeine. A few different techniques are available, and understanding
them may help allay your concerns about coffee contaminants. Coffee
beans are decaffeinated by softening the beans with water and using a
substance to extract the caffeine. Water alone cannot be used because
it strips away too much of the flavor. The goal is to extract the
caffeine with minimal loss of flavor. Substances used to remove the
caffeine may directly or indirectly come in contact with the beans,
and so the processes are referred to as direct or indirect
In one process, coffee beans are soaked in water to
soften them and dissolve the caffeine. The water containing the
caffeine (and the flavor from the beans) is treated with a solvent,
heated to remove the solvent and caffeine, and then returned to the
beans. The flavors in the water are reabsorbed by the beans, which are
then dried. This process is referred to as "indirect decaffeination,"
because the beans never touch the solvent themselves. The most widely
used solvent today is ethyl acetate, a substance found in many fruits.
When your coffee label states that the beans are "naturally
decaffeinated," it is referring to this process, specifically using
ethyl acetate. Although it doesn't sound like a natural process, it
can be labeled as such because the solvent occurs in nature. Other
solvents have been used, some of which have been shown to be harmful.
One, methylene chloride, has been alleged to cause cancer in humans
and therefore is not often used. Back in the 1970s, another solvent,
trichloroethylene, was found to be carcinogenic and is no longer used.
Another indirect method soaks the beans in water to soften them and
remove the caffeine, and then runs the liquid through activated
charcoal or carbon filters to decaffeinate it. The flavor containing
fluid is then returned to the beans to be dried. This charcoal or
carbon process is often called "Swiss water process" (developed by a
Your concern over the safety of decaffeinated coffee
probably stems from solvents used in the past. If your coffee is
labeled naturally decaffeinated or Swiss water processed, you can be
assured that no harmful chemicals are used. If you are uncertain, you
can ask or call your coffee processor to learn about the method used.
I think it is safe to say that any decaffeinated coffee purchased in a country that competently regulates food safety is safe to consume