I've always wondered what these warning labels meant: 

"WARNING: This product contains a chemical known to the State of California to cause cancer and birth defects or other reproductive harm."

Since this is on sooo many everyday products, is it something I should be worried about?  Why does only California know about it?  Why doesn't any other state know?  If it was a legitimate issue, wouldn't the product be outlawed?  Maybe Californians are extra cautious about cancer? 

It turns out it has something to do with a law passed in California in 1986 called the Safe Drinking Water and Toxic Enforcement Act of 1986, or Proposition 65.  This law requires the state to annually update a list of 700+ chemicals that are known to cause health problems.  A group of scientists and industry experts determines which chemicals are added and occasionally removed from the list.  The general qualification for a chemical that causes cancer is that if 100,000 people are exposed to it for 70 years, more than one person would get cancer.  Whether that's a fair qualification or not, I have no idea. 

In my "research" for this post, two things stood out to me:  (1) This information was surprisingly hard to find.  I would think it would be in everyone's best interest for someone to make an easy-to-find, easy-to-understand website with simple yet thorough information about a warning label that shows up on billions of products around the country.  (2) There's no answer as to why California is the only state that created such a list, or why the federal government hasn't adopted a similar list.  This leaves me with two possible conclusions.  Either California is full of extremely smart people who know a lot of stuff about a lot of things and have decided that certain chemicals can cause certain health problems in certain doses and certain situations, or exactly the opposite; i.e. California is full of fruits and nuts.  I'm sure both conclusions are true, but the second one doesn't have much effect on me getting cancer.