Monday, December 17, 2007

Lead in the Christmas Tree Lights—When Caution Becomes Paranoia

Who would have thought? Lurking there amid the gaily colored balls, the fresh-smelling piney-woods aroma of the Douglas fir, and the brilliant sparks of light twinkling throughout, is the silent enemy: lead. Or at least, something like that must have been going through the reader who wrote in to the Austin American-Statesman after she read a caution tag on her string of Christmas-tree lights. According to her, it said "Handling these lights will expose you to lead, which has been shown to cause birth defects." Panicked, she rushed back to the store where she bought them to see if she could find some lead-free ones, but "ALL of them had labels stating that they were coated in lead! This is terrifying news for a young woman who is planning to start a family!"

The guy who writes the advice column in which this tragic screed appeared said not to worry, but be sure and wash your hands after handling the lights. He based his advice on information from Douglas Borys, who directs something called the Central Texas Poison Center.

In responding to the woman's plight, Mr. Borys faced a problem that engineers have to deal with too: how to talk about risk in a way that is both technically accurate and understandable and usable by the general public. We have to negotiate a careful passage between the rock of purely accurate technological gibberish, and the hard place of telling people there's nothing to worry about at all.

In the case of lead, there is no doubt that enough lead in the system of a child, or the child's mother before it is born, can cause real harm. The question is, how much is "enough"?

Well, going to the technical extreme, the U. S. Centers for Disease Control and Prevention issued a report in 2005 supporting the existing "level of concern" that a child's blood not contain more than 10 micrograms of lead per deciliter (abbreviated as 10 mg/dL). No studies have shown consistent definitive harm to come to children with that low an amount of lead in their system. Just to give you an idea of how low this is, the typical adult in the U. S. has between 1 and 5 mg/dL of lead in their blood, according to a 1994 report. The concern about pregnant (or potentially pregnant) women getting lead in their system is that the fetus is abnormally sensitive to lead compared to older children and adults, although exactly how much isn't clear, since we obviously can't do controlled experiments on pregnant women to find out.

Now if you tried to print the preceding paragraph in a daily paper, or a blog for general consumption, or (perish the thought!) read it on the TV news, you'd probably get fired. Why? Because using phrases like "micrograms per deciliter" has the same effect on most U. S. audiences as a momentary lapse into Farsi. People don't understand it and tune you out. But unfortunately, if you want to talk about scientifically indisputable facts, you have to start with nuts-and-bolts things like how many atoms of lead do you find in a person and where did it come from? These are things that scientists can measure and quantify, but the general public cannot understand them, at least not without a lot of help. So it all has to be interpreted.

So to go to the other extreme of over-interpretation, the expert from the poison center could have said something like, "Aaahh, fuggedaboudit! Do you smoke? Does your house have old lead paint? Do you ever drive without seatbelts, or talk on your cell phone and drive at the same time? Are you significantly overweight? If any of these things is true, you're far more likely to die from one of them than from any possible harm that might come to you or your hypothetical children from handling Christmas-tree lights with a tiny bit of lead at each solder joint, covered up underneath insulation and probably not accessible to the consumer at all under any normal circumstance."

In saying these things, the expert would have been entirely correct, but probably would have come across as less than sympathetic, shall we say. A Time Magazine article back in November 2006 pointed out that because of the way our brains process information, we tend to overreact to certain kinds of hazards and ignore others that we'd be better off paying attention to. Unusual hazards and dangers that take a long time to show their insiduous effects worry us more than things we're used to or things that get us all at once (like heart attacks or car wrecks). The woman's worry fits both of these categories: the last thing she was thinking about as she decorated her Christmas tree was exposing herself to a poisoning hazard, and lead poisoning takes a while to show its effects.

As the expert's advice goes, I'd say he walked a reasonable line between the two extremes. Giving people something to do about a hazard (such as handwashing) always helps psychologically, even though as a matter of fact there wasn't any hazard in the first place. And blowing off the danger altogether is generally regarded as irresponsible, because one of the iron-clad rules of technical discourse is that nothing is entirely "safe."

Well, here's hoping that your thoughts of Christmas and the holiday season will be uncontaminated by worries about lead or any other poison—chemical, mental, or otherwise.

Sources: The column "Question Everything" by Peter Mongillo appeared in the Dec. 17, 2007 edition of the Austin American-Statesman. The online edition of Time Magazine for November 2006 carried the article "How Americans Are Living Dangerously" by Jeffrey Kluger at,9171,1562978-1,00.html
. And the U. S. Centers for Disease Control and Prevention carries numerous technical articles on lead hazards and prevention, including a survey of blood lead levels at

1 comment:

  1. Just a clarification, Xmas tree lights have lead in their PVC insulation (to make them fire retardant and prolong their life outdoors where they are exposed to ozone and other chemicals that degrade PVC). Whatever lead is in the solder joints is not of much concern, as that lead is sealed inside the PVC. Still, point taken that neither source of lead is cause for paranoia.