Hair Products popular with Black Women may contain harmful chemicals

Thus saith UnScientific American on their website.  They go on at some length, listing a whole bunch of organic chemicals that I am unfamiliar with.  I never took organic chem.  On the other hand, they failed to mention, anywhere, ever, just HOW MUCH of these allegedly harmful chemicals were present in the hair products.  Modern chemical analysis is so sensitive that it can detect small amounts of anything, just about anywhere.  The article failed to let us readers know if these harmful chemicals  were present in just tiny trace amounts, or in amounts large enough to matter.