My company manufactures and sells chemicals. I recently provided a product that I don't usually sell to a company, but they needed it, they're a good customer and they asked for it so I provided it at no cost. A few weeks later a get a call from an angry person in the environmental department that was very upset because I had furnished a product that was not on the approved product list. They needed an MSDS immediately. The product? A bag of gravel. I told them I didn't think there was an MSDS for gravel, but to my surprise, they do exist, and also for sand. What I didn't know is sand is very hazardous. Then it occurred to me that millions of people come into contact with sand and gravel everyday and don't know about the hazards. You see, silica dissolves readily in hydrofluoric acid producing a corrosive gas silicon tetrafluoride. So, next time you're at the beach, please, please, please, don't bring that bottle of hydrofluoric acid. Please forward this info to as many people as possible. Lives are at stake. And next time you see an environmental engineer, say thanks.