Firefighters are exposed to numerous hazards every day! Fires in homes especially newer homes there there is treated wood, dry wall with god knows what is actually in it! Plastic articles like PVC pipe! And a whole host of items that any and most respirators do not filter out! Even if they are on supplied air lines as opposed to SCBA, Self Composed Breathing Apperatae. Fumes from various burning items can and will breach the equipment as no equipment is 100% safe at any given time! Plus filters must be frequently changed out and there are a lot of cities and municipalities around the country that have cut fire budgets and layed off a good portion of their fire departments. Does anyone think that these cities will buy all the needed filters that their departments require! Now then let's go to fire retardant gear! The outer canvas fire retardant suit that most firefighters wear have carcenigenics (sorry misspell) in the fabric of those suits! As well as the t-shirts and trousers that they wear underneath! That has been known for years! Cancer in fire fighters has been around for a long time! Throat cancer is common! Also skin cancer! It's the nature of the beast! Now then if the Feds need to gather data then go to all the doctors and hospitals where fire fighters have been treated for these ailments also look at autopsy reports upon the death of retired fire fighters! They can gather all there info there and make their conclusions! I also failed to mention that burning paints are a big hazard and no respirator is 100% effective! NONE! Also they have been exposed to a lot of asbestos in older buildings! Does that answer your question? Also if I may! The 9/11 attack of the twin towers of the World Trade Center! Remember seeing all that dust? What do most of you think it was? Asbestos!!! That's right! It was sprayed on everything! And the whole city and a large part of that region was breathing it in for weeks and perhaps months! Asbestos has a latency period of 30 to 40 years before the first signs of cancer show up! How many of you had respirators with P100 filter on them! That stuff went to the upper atmosphere and what goes up comes down! Think about it!