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Measuring vs counting

While listening to talk radio a few years ago I heard press release from an environmental group. They said a study had concluded that washing fruits and vegetables did not reduce their number of pollutants.

This seemed so odd that I made it a point to listen to the next broadcast to be sure I heard correctly. How could this be? Washing surely removes most surface contaminants. Than I realized that this was a case of measuring vs counting.

Suppose a fruit is tested for the presence of one hundred different pollutants and ten are found. Modern analytical equipment is so sensitive that it can almost detect single molecules so unless washing removes absolutely all of a chemical it will probably still be detected. Removing 99.999% will still leave a detectable amount so when the fruit is washed and tested again the same ten chemicals will still be found. Ten equals ten so washing does not reduce the number of pollutants.

The overwhelming majority of people will not understand that the study said nothing about the effect on your health of washing fruits and vegetables; they will hear that it doesn't do any good. Some people, especially children, will stop washing their fruits and vegetables because they heard on the radio that it was pointless. They will consume more toxic chemicals than if the announcement had never been made.

Why would an environmental group presumably trying to reduce the poisoning of people issue a press release certain to mislead people, especially children, into consuming more poisons? Anything that goofy must have its roots in politics.

The lesson for all of us is that there is a difference between counting and measuring, a difference between number and amount, and sometimes it is important.