And almost never is. To quote your source:
“Chromium (VI) however is harmful to health and occasionally exists in leather. It can come about due to mistakes in production or can emerge later in the manufactured leather. There is a risk of an allergic reaction to the end user.”
That risk was 0.2 to 0.6%. OMG how can we let children touch this stuff? Danger Will Robinson, Danger!
“These substances do not necessarily exist in chrome tanning processes, although they may arise depending on the method and the materials used.”
Except for the highly allergic
“The remaining allergy risk is almost irrelevant in everyday use of leather.”
Of course there is this:
“Many reports of chromium VI exceeding safe limits have been published in the press. However, none of the reports provide any details of damages or allergies caused.”
Of course, no product grown, made, treated or transported can be guaranteed to be free from contaminants or measurable amounts of unsafe or dangerous substances. Most people would be amazed at what is allowed to be in the water they suck out of plastic bottles (or their own tap) every single day. Or the cigarettes they’re puffing away on while worrying about hexavalent chromium exposure.
My point is not that there is no risk with any of this, but that dire warnings of toxicity and the scaremongering that results, especially for people new to lasers is irresponsible. Especially when the science says exactly the opposite.
Every class I teach has someone who is scared to death because they read something or heard someone say something that led them to believe this stuff is incredibly dangerous to themselves or the machine. They’re so focused on the danger they’re scared of doing anything. We see that in the forum all the time - people afraid to laser anything but PG, scared they’re going to break something. Unless we stop the misinformation they’re likely to go find some other “safer” hobby.
Personally I don’t give a rodent’s patootie if someone chooses not to use some perfectly good materials due to fear. It’s their creativity that gets limited. What I care about are definitive statements by perceived experts that are not backed by facts. And it really trips my trigger when the warnings cross the death & danger line.
Which you won’t be doing even in incredibly small trace amounts ** with a properly vented ** machine.