Mr. Steinman got the information regarding the hazardous ingredients from Simple Green itself, through a request of a type that industry uses to find out what the full ingredients of products are, because of the potentially dangerous interactions with other dangerous chemicals, or just the interactions of certain chemicals in different products which can be toxic.
The level of danger of mixing chemicals and the interactions of different products in industry is at a far more potentially dangerous level than the avarage consumer uses, and so that is why the hiding of certain ingredients from consumer labels is justified, whereas the revealing of the complete ingredient list to industries is deemed as neccessary.
He basically pretended to be a company that would be using the products that the various manufacturers of products like Simple Green produced in his inquiries to Simple Green, for example. They thus gave him the info. Had they known beforehand that he was using the info to write a book, they wouldn't had given it to him.
He then researched the health effects of this more EXTENSIVE listing of ingredients, and found that the product contains neurotoxins.
As an aside, a lot of cosmetic companies have carcinogens in their ingredients, but none of them reveal this fact, nor are they required to, because the cosmetics aren't intended for internal use.
