These exotic tropical wood species can be irritating to the skin and repiratory tract. Rosewood is just one species that is toxic in that way; there are many others. I don't know about Lapacho.

Wood dust of any type can irritate skin and lung and eye tissue. Body and respiratory protection should be worn when creating wood dust. Some wood dust is carcinogenic.

So in short (as I see it) a professional "all we do is wood floor" installation company should know enough to be wearing dust masks when they are installing an exotic wood.

If they want to be 'comfortable'...then yes. And, theoretically speaking, nuisance dust masks should be worn when creating any wood dust, however many workers feel that the dust masks are a nuisance...just as did all those recovery and cleanup workers at the WTC building collapse site.

Respiratory protection is cheap and available. If folks choose not to use it, then they have no one other than themselves to blame for any health consequences.

The poison on poison darts comes from poisonous frogs.

Here is a link that might be useful: Poison Dart Frog

Tell the guys it's good for them.

"Lapacho plays a central role in the herbal medicine of several South American indigenous peoples. Lapacho is used by herbalists as a putative treatment for cancer, HIV, and numerous other maladies. Studies by the U.S. National Cancer Institute showed that lapacho may prevent, delay, or treat cancer"

Here is a link that might be useful: Lapacho