I have been conditioned (as have, perhaps, most readers) to view hazards as something to be eliminated.The presence of heavy metals like lead and mercury in food is not desirable.Trihalomethanes are not desirable.Pathogens like Salmonella, Listeria monocytogenes, or the Shiga toxin-producing strains of Escherichia coliare not desirable in food.Analytical science has responded with faster and more sensitive tools.We have many tandem instruments—gas chromatography–mass spectrometry (gc-ms), tandem mass spectrometry (ms-ms), etc.We have powerful molecular techniques and instrumentation like polymerase chain reaction (PCR).These tools are not as mind-blowing as they are portrayed to be in television and movies, but we can detect very low levels of most hazards using them.So, what is the problem?
Perhaps an anonymizedcase from the past will illustrate one of the challenges of sensitivity.In 1986, California passed Proposition 65.This proposition requires businesses to provide warnings to Californians about significant exposures to chemicals that cause cancer, birth defects, or other reproductive harms—a noble objective.Lead, as a heavy metal, is a reproductive toxin.It is present in canned foods.If the proposition, as written,were to be applied to canned food, then the tolerance would have defaulted to the detection level.At around this time,however, new tandem instrumentationreduced the detection limit by several orders of magnitude.This detection was so low that a special clean room was required to house the instrument to avoid contamination from the nominally clean laboratory environment.How much below the background level does a detection limit need to be? Fortunately, the detection limit-based tolerance was not applied to canned foods.It was a scary time for the food industry, however.