While I agree with everyone above that it's an extremely wasteful way to smoke spice there's no link between Alzheimer's and aluminum.  This was something that started in the 60s and reemerged in the 90s but there's never been any solid evidence that backs it up.

As to burning plastic, again I don't see how this would happen.  The temp needed to vaporize DMT is so low that you should be holding your heat source well away from the aluminum foil and thus never allowing the plastic to reach a point that it starts to melt.

I also started with this method, having found it on youtube, but only used it once before I started looking for more efficient means.

Currently I use a tire gauge crack pipe and sandwich my spice between two chore boy screens.  It took quite a bit to get the vaporization method down but now I'm fairly confident in the pipe and my technique (I hold it at nearly a vertical angle and draw the heat from the flame into the pipe with my breath without letting the flame even touch the outside screen).

I'm sure a GVG is nice and I'm sure one day I'll pick one up.  For now though, with my limited funds, I'm quite happy with the method I'm using.