I personally have never believed that Simple Green is non-toxic. The smell alone is headache inducing and the color makes one wonder just how "simple" it is.

From an article on Environmental Working Group titled "Natural Doesn't Always Mean Safe" comes this snippet on some testing that was done on Simple Green.

"Simple Green is a popular household cleaner marketed to environmentally concerned consumers. It's green, smells lightly of sassafras, and the product claims to be "nontoxic" and "the safer alternative" to other cleaners. If a consumer wants to know what is in the "green cleaner," the company offers a phone number to call for a complete ingredient list.

A key ingredient of Simple Green is butyl cellosolve, a substance considered toxic by the federal Agency for Toxic Substances and Disease Registry. In lab tests, the liquid has destroyed red blood cells and caused minor birth defects in animals. When absorbed through the skin or inhaled, it has caused irritation around the eyes and noses of humans and headaches."

Years ago Simple Green was one of the only seemingly non-toxic cleaner on grocery store shelves. Now there are so many better, less toxic choices out there. I'd personally stear clear of Simple Green.