Is Food Safety Based on Science?
March 23, 2011
You might think that scientific evidence would constitute the "last word" when food safety rules are made, but in fact it's only the beginning. Policymakers take many other factors into consideration, including tradition, cultural trends, political expediency and pressure from industry. This approach sometimes imposes arbitrary and scientifically indefensible restrictions that limit food choices, confuse the public and prevent cooks from preparing the highest-quality meals, says Scientific American.
To complicate matters, some guesswork and compromise are inevitable in setting safety standards. Take, for example, the way in which health officials decide how much the pathogen count should be reduced when heating food.
- Killing 90 percent of the pathogens within a specific food, for example, is called a 1D reduction (where D stands for "decimal," or factor of 10).
- Killing 99 percent of the pathogens is referred to as a 2D reduction, killing 99.99 percent is termed a 4D reduction, and so forth.
- Cooks achieve these reductions by maintaining food at a given temperature for a corresponding length of time.
- The practical impact of an elevated D level is a longer cooking time at a particular temperature.
What D level should regulators choose to ensure food safety? If the food contains no pathogens to begin with, then it's not necessary to kill pathogens to any D level. Highly contaminated food, on the other hand, might need processing to reach a very high D level. Right away, you can see that decisions about pathogen-reduction levels are inherently arbitrary because they require guessing the initial level of contamination. That guess can be supported by the results of scientific studies measuring the number of foodborne pathogens present under the various conditions that cooks encounter. But it's still a guess.
All food safety standards deal in probabilities. Reaching a higher standard (i.e., cooking food longer or at a higher temperature) will make the food less likely to be unsafe, and targeting a lower standard will make it a bit more likely. But there are no guarantees and no absolutes, says Scientific American.
Source: Nathan Myhrvold, Chris Young and Maxime Bilet, "The Complex Origins of Food Safety Rules --Yes, You Are Overcooking Your Food," Scientific American, March 13, 2011.
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