I did a search on it, this is what I found.
From
http://www.short-hair-style.com/keratin-hair-treatment.html
The October issue of Allure magazine in US includes an investigation into the Brazilian Keratin hair treatment also known as "escova progressiva" treatments, which cost as much as $600 and claim to
turn dry, frizzy hair into smooth, silky hair for months. Stylists and
clients often wear gas masks or other protective equipment and still may feel the ill effects of this potentially fatal gas.
Many customers and stylists do not know that this Brazilian treatment often
contains high concentrations of formaldehyde, a cancer-causing chemical.
The magazine found that many of the most popular treatments on the market contain at least
ten times more formaldehyde than the .2 percent considered safe by the Cosmetic Ingredient Review Expert Panel. The Food and Drug Administration does not regulate cosmetics but now is looking into the "escova progressiva" treatments.
Some salon owners and stylists believed that their Brazilian keratin treatment solution contained 2 percent and not .2 percent formaldehyde and that is actually approved by the FDA. But that statement is false according to FDA's spokeswoman Veronica Castero.
Most stylists using this treatment said they use safe measure, like wearing latex gloves and working near ventilation hood or windows, but that might not be enough.
Most interesting part is that this product claim smooth silky hair using Keratin, but it seems keratin has nothing to do with hair straightening and does NOT change the structure of the hair and it's really the formaldehyde that makes the treatment work. According to Allure Magazine
"It's doubtful that keratin does anything except provide a good marketing story. It's window dressing."
Many hair salons are started to suspend this kind of treatments and others offering their own alternative to unsafe popular Brazilian Keratin treatment. Yellow Strawberry Salon in Florida has developed its own
Caribbean Dream treatment.
"Caribbean Dream requires no gas masks, no extreme or unorthodox safety equipment and stylists can use this product without worrying about endangering their clients or themselves, confident that this hair treatment will give women the same, sought-after look as escova progressiva," Says the owner Jesse Briggs.