I have received many messages on the subject matter of taking CBD and drug testing at work. Here is the information and research I have come across:

Full spectrum CBD oil contains other cannabinoids as well as terpenes. These are all chemical compounds within cannabis plants which have shown to have health benefits, especially when working together. Research is showing that these work very well together because of their synergistic effect on the body. They state that with all the extra cannabinoids and terpenes working simultaneously the CBD oil works with better results. It is sometimes referred to as the entourage effect.
Full spectrum has small amounts of other cannabinoids such as THC, CBG, and see me in. The amount of THC is usually very low down to 0.3% which is very negligible. However it can still trigger a drug test positive.

Broad spectrum CBD oil extracts all the THC out of the oil but leaves the other cannabinoids and terpenes within. You must be careful with this if having 0% THC is important to you. Due diligence and research on the extraction process of the company you use is highly recommended. You may have to do more research on the lab and the lab processes the company uses.

Isolate CBD claims that all of the THC, other cannabinoid, and terpenes have been extracted. They usually state that it is 100% pure CBD hemp plant that is used. With Isolate compounds it should not be a problem for drug testing since only CBD is present. Again, check and research the labs used. I only recommend products that I have seen work well with patients. Many of them have started CBD on their own and have not had issues with work testing. Just make sure you research before you start.

These are the three types and definitions of each. So you can rest your mind when choosing the product you need. Hope this helps!