Question
I NEED TO USE SCOTTS GRUB MIX EVERY SPRING.ITS VERY EFFECTIVE IN CONTROLLING GRUBS. BUT, WHAT ARE POTENTIAL HARMFUL SIDE EFFECTS TO ANIMALS,SUCH AS SQUIRRELS,BIRDS,WORMS,PETS. THE BAG IS NOT REAL SPECIFIC.

Answer
My standard reply is, "There are no safe chemicals; only safe ways of using chemicals".
I am not sure what is the active ingredient in the product (look for it on the label) but if it is so effective against grubs then it must have a significant residual effect. An indication of the potential danger of a chemical is the 'signal word' CAUTION, WARNING or DANGER. Again, on the label, there must be a statement about environmental impacts (fresh water contamination, wildlife etc.) You will find more information in the 're-entry statement' and  'in case of emergency' statement.
Also, I would question why I need to use the same product against the same pest every year. I would have to conclude that something is not working.