I was just forwarded an e-mail from a friend who’s been having a lot of complicated health problems. She’s nearly exhausted the possibilities of traditional medicine to find a cause, so she’s recently taken to “alternative” or “homeopathic” medicine, and these practitioners claim to have found all kinds of toxins in her body. Her mom then forwarded this e-mail to her asking if this might be a “cause for some of the toxins in your system.”

Cancer update from Johns Hopkins !

NO matter how many times you get this e-mail, you need to send it on!!!! […]

Bottled water after being hot from being transported in hot weather is very dangerous!
On the Ellen show, Sheryl Crow said this is what caused her breast cancer. It has been identified as the most common cause of the high levels of dioxin  in breast cancer tissue.

The e-mail goes on to say that a Doctor from Castle Hospital said the same thing on TV, and that Walter Reed Army Medical Center and John’s Hopkins were saying the same thing. You shouldn’t have hot water in plastic bottles and you shouldn’t freeze water in plastic bottles, etc etc.

A few things about this made me skeptical. First, it doesn’t make sense that both heat + water + plastic = dioxin AND freezing water + plastic would generate the same chemical compound. Also, if this were such a dire health emergency, and it came from such respected authorities, I would have expected to see something about it on the news. Sure enough, this is a hoax. Apparently, it’s been around since 2002 and has been thoroughly refuted. Most tellingly, John’s Hopkins (the alleged source cited in the e-mail), has refuted the claim, and indeed never issued such a press release.

This whole debacle is an example of the classic fallacy, argument from authority (argumentum ad verecundiam). The e-mail cites doctors, health professionals and even celebrities to “prove” that what’s being said is true. Consider the source – if your doctor tells you dioxins are a problem and you can get them from bottled water, it’s reasonable to listen. But if a chain e-mail tells you that “doctors say” (or Sheryl Crow says that her doctor told her) that something is dangerous, but doesn’t actually provide direct links to their source, you should probably be skeptical.