I'm really concerned that i'm allergic to the root canal materials. how would i know and what would the symptoms be?

Cannot Be "Allergic": You cannot be allergic to a root canal. You can be allergic to one, or some, of the medications used for the procedure. If you have concerns, please speak with your dentist and tell them what you are allergic to, if unsure have an allergen test done for a complete panel of potential allergens. The dentist will then inform you if any of your allergens are used in the root canal procedure.

Other issue?: What would lead to believe that you are allergic to a root canal therapy procedure? That's a very remote possibility. We need much more information to even try to begin guessing what you are experiencing and why. Either repost your question with symptoms and why you believe that, or better yet ask a dentist who can actually take your medical and dental history and then examine you.

Rare, but possible: Some people do have sensitivities to materials used in dentistry. There are a myriad of ingredients used, from the latex rubber in the dam, chlorine in the irrigants, materials in the sealers or fillers. The best way to know is to have an allergen test. Most materials are very safe for the vast majority of the population, so it would the rare but not unheard of.