PROP 65 is a California proposition that requires food makers to test their ingredients and foods with certain chemicals. For our LEAN boost, we test the product for traces of certain chemicals in a list that you can find here: http://oehha.ca.gov/proposition-65/proposition-65-list. The chemicals that we test for naturally occur in the environment like the soil and the water. The detection levels to warrants this label is low at 0.5 microgram or .00000005g. The ingredients we source do not naturally have the chemicals but because they are grown in soil and watered by sources that are beyond our control, the item is detected with a low-level of these chemicals.