With specific studies related to cannbis lacking (feds illigalization fault) we have to look to studies done regarding tobacco and middle east hooka studies. As well related to hyperemesis in morning sickness. Welding vapors on copper or alloys containing it can even cause death but extreme temps aren't needed when particles are so small in leaf tissue.
On a side note from hooka studies centering on heavy metals it also dispelled myth that water pipes filter heavy metal combustion, it was negligible reduction. We don't suppliment vitamins or micros via smoke it's done via eating where to much of a good thing (copper ect necesarry) is simply expelled via urine. One study conducted on tobacco smokers found 0 copper in urine, and varried between men and women in concentration. One might think great, but it's opposite.
Tobacco generally takes up about 15% of copper available thus it stacks up in soil something organic farmers should consider as well. Anyrate the copper concentration known in tobacco when smoked goes into tissue and brain and ineffectively pass into urine. Old saying taking to many vitamins makes for expensive urine. Gotta run will post more today