. >> reporter: stylist olympia piano is talking about a product called karotin.s called brazilian blowout. tested by the occupational health and safety finds a carcinogen is one of the ingredients. >> it's not harmful if you use it properly. >> reporter: it means having the right ventilation in the salon. some like this one shown in the new york times will only apply the product while the stylist and client are wearing gas masks. >> good afternoon. >> reporter: during my visit to shelton salon and spa, they did crank up the ac because of the fumes. >> you're not flat ironing her hair. >> reporter: the heat may activate the brazilian blowout but the levels of formaldehyde found in the product are within permissible limits, limits they still warn can reach a danger zone. the ceo of brazilian blowout believes the product is safe and he tells us he stands by it. >> this is the area where the law ... >> reporter: dr. monte hall is founder of the center forever aesthetic modernism. he's talking to people who have lost their hair after the brazilian blowout. >> i haven'