Well, I found these two different items of interest since I use to work a lot with laser printers.
The first is about toner that laser printers can emit as very fine particles. Unfortunately for me, some of the printers that put out these particles are ones I worked with. It seems that a researcher in Australia was working on a study to determine if laser printers emitted fine dust that might have bad effects on the lungs. Here is the link to the study and the table of printers they tested is near the bottom of the paper.
Hewlett Packard responded saying the findings need more study. Here is a link to their response:
The second item is something I had seen in the past about color laser printer sometimes place color patterns on the pages they print so they can be traced back to the printer. I think this was to help catch counterfeiters. Here is a link to a page that has a list of printers that do that: