I know that less than 20 ppm of gluten is considered “gluten-free,” but I really have no idea how much that is. What is this proportion in terms I can understand?
In this case, parts per million means 20 weight units of gluten per million weight units of all components of the food or the product.
Here are some comparisons to illustrate 20 ppm:
- 1 second in approximately 14 hours
- 1 penny in $500
- 1 teaspoon in approximately 65 gallons of water