I'm sure it's known to cause cancer in the state of California but I don't worry about it. I live in Washington.
I'll bet the reminder is on the pellet sack.
Yup the warning is on the lower left hand corner on the back side of your favorite pellets. It has become sort of a joke rather than a warning. Most of those risks are based on statistical manipulation rather than on direct cause and effect. I could convince you of almost anything by statistical analysis.
Example: Let us say that in a big study of 100,000 people exposed to wood ash there were 6 cancer deaths in 5 years. And there were only 4 cancer deaths per/100,000 in those not exposed. They could state that the incidence of Cancer deaths was 50% higher in the wood ash group. And a 50% increase is certainly significant from that viewpoint. What they would not tell you is that the actual risk is .006 % in the exposed group and .004% in the non exposed group. Which is statistically insignificant. That sort of incomplete reporting is used all the time in research to try and market or stop the marketing of a product. Statistical analysis is a great tool, but only if ALL the facts are listed. 
As much as I would like to leave this alone, I hear this type of argument all too often. This is not how science is done. Statistical analysis is much more sophisticated than that. Only non scientists who are either ignorant of how statistics work, or are trying to be deceptive would do what you describe. Statistics, like any tool, can be misused. Legitimate science frequently gets lumped in with the "how to lie with statistics" crowd. Recognize that by the time you see something in the mainstream media most of the rigor has been stripped away in addition to any discussion on the reliability of the findings, which, by the way, is calculated using statistics.
My first exposure to the issue of burnt material being mutagenic was back in the early 80's when I was a graduate student in chemistry. It was brought up by a visiting scientist during one of our regular seminars. He had stated that all burnt materials were mutagens. It was presented as more of an interesting factoid than a true health concern. But then you never know. We used to do experiments where we put various chlorocarbon compounds on our finger so we could feel cooling by evaporation. Now those chemicals are known carcinogens and are no longer in common use.
