It's not, but it's close. For example, if you go to buy a brass valve for some plumbing work, you will see two things: 1. A label that states "LEAD FREE", pos

It's not, but it's close. For example, if you go to buy a brass valve for some plumbing work, you will see two things: 1. A label that states "LEAD FREE", possibly stamped into the metal surface of the valve body itself. 2. A Prop 65 warning to California residents that the valve contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. We can only assume that this is because "lead-free" does not actually mean that the item contains absolutely zero atoms of lead; it has a specific technical definition (NSF 61G) that is intended to prevent or greatly limit the likelihood that lead will be leached out of the fitting into potable water. According to California, that's not good enough, so you get a helpful stamp telling you that your fitting is lead-free and also a warning from California about (one assumes) the fitting's lead content. Umm... so is the fitting suitable for potable water system use or not? Thanks, California! (Example, if you're feeling lazy: http://www.homedepot.com/p/Everbilt-1-2-in-Brass-C-x-C-Full-Port-Ball-Valve-107-453EB/205821852 http://www.homedepot.com/p/Everbilt-1-2-in-Brass-C-x-C-Full-...). Prop 65 is basically useless, in that it requires you to be informed that a product, building, room, etc. contains one of a few basic classes of harmful substances, but it doesn't require that you be told what those substances are or anything else about them (like whether they're in a form that can harm you, how to avoid them, etc). Even worse are the countless manufacturers who have seemingly taken to labeling every product with something like "Prop 65 warning to California residents: this product may contain chemicals known to the State of California to cause {cancer, birth defects or other reproductive harm}" (emphasis mine). If you want to know whether it actually does, what those chemicals are, or the concentrations or forms in which they are present, I hope you work in a materials testing lab. And, oh yeah... the "Safe Drinking Water and Toxic Enforcement Act" and Prop 65 are one and the same, in case you weren't aware (see http://oehha.ca.gov/prop65/law/P65law72003.html http://oehha.ca.gov/prop65/law/P65law72003.html). None of this means that Soylent doesn't contain heavy metals in dangerous concentrations. It does mean that we can't really rely on a Prop 65 label, or a violation of Prop 65's labeling requirements, to tell us whether it does. If you want to know that, you don't need California law books, you need a mass spectrometer and related lab equipment. Personally, I'll stick to eating things that I grew myself. They might have heavy metals in them, too, but at least I don't have to worry about whether some Chinese supplier snuck a little something extra into some random "food" manufacturer's supply chain and neglected to tell anyone about it. But your life, your choice. Just don't expect the label to give you any guidance.