Just how much evaporated milk are you chugging?
Our government food watchdogs can't and don't test every ingredient in every food we consume. Instead, they maintain a list of ingredients "generally regarded as safe," which goes by the catchy name of GRAS.
According to the Food and Drug Administration, an ingredient is considered safe if there is a "reasonable certainty in the minds of competent scientists that the substance is not harmful under its intended conditions of use." If the substance does not fall under the GRAS umbrella, it is considered a food additive by the FDA and is subject to a lengthy review and approval process.
Ingredients that were in use before 1958, when the GRAS list was put in effect are presumed to be safe "through experience based on common use in food." Ingredients added to the list since then have had to be recognized as safe through scientific procedures. Recognition is ordinarily based on published studies, which may be corroborated by unpublished studies and other data and information. The FDA says it requires the same level of scientific evidence to bestow GRAS status as is required to obtain approval for the substance as a food additive.
Both ingredients you mention, dipotassium phosphate and carrageenan are on the GRAS list. Dipotassium phosphate is a chemical used as an ingredient in foods to control acidity and prevent coagulation. It is most commonly used in the production of cheeses and non-dairy creamers. Carrageenan is a derivative of Irish moss, a type of seaweed found along the west coast of Ireland and the east coast of North America. It is used as a thickener, emulsifier, and stabilizer in many foods and drinks. It has been used in Ireland for hundreds of years and in the US since 1835.
Not everyone you meet is convinced that everything on the GRAS list deserves to be there or that the GRAS list is all that meaningful. But it's what we have and it has been in use for more than 50 years.
There are many people who want to tell you what to eat and how much and how often (just tune in to the morning television shows almost any day of the week if you need confirmation), but we are not among them. Good food with lots of variety, well prepared, and consumed in moderation is our goal for everyone.
There are brands of evaporated milk on the market that do not include dipotassium phosphate or carageenan. Seek them out if you are still concerned.