The EPA, FDA, and others well, pretty much name your ABC's agency out there test food and drink for toxicants and contamination.
For your initial post, Using an actual DOCUMENTATED test by one of the ABC agencies, comment on:
1) What Toxicant they test for.
2) How they test for the given toxicant?
3) What do the RESULTS mean? (Is there a healthy range vs. a dangerous range the testing can determine)
4) What these agencies will do or suggest doing to limit or lower contamination LEVELS.