Wednesday, August 15, 2007

How Many Licks Does It Take

You know it's a slow day at the office when VUBOQ resorts to doing math problems.

As some of you know, I used to work for the National Lead Information Center. Thus, the recent recall of some toys has piqued my interest. The question that I (and I'm sure YOU) have been dying to know is:

How many toy cars does a child need to eat to become lead poisoned?

First, a few fun lead facts:

Lead-based paint is defined as being 0.5% lead by weight. This converts to .... 5000 micrograms/gram (ug/g).

The Consumer Product Safety Commission (CPSC) has since decreed that no paint shall contain more that 0.06% lead by weight, or 600 ug/g.

The Centers for Disease Control and Prevention (CDC) has set the blood-lead level of concern for children at 10 ug/dL (micrograms/deciliter).

A persistent blood-lead level as low as 10 ug/dL can be associated with subtle learning and behavior problems. There can also be negative impacts on hearing and growth. Children with blood-lead levels under 10 ug/dL are not considered lead poisoned.

According to a fun and fact-filled FDA article, Lead Threat Lessens, But Mugs Pose Problems (April 1993), for every microgram (ug) of lead a child intakes per day, his (or her!) blood-lead level increases by 0.16 ug/dL.

Now, the math portion of our program ...

Since the toy car recall notice only stated that the level of lead in the paint used was "in excess of federal standards," we know that it was above 600 ug/g (0.06%). More than likely (although I'm not entirely sure), it was probably lower than 5000 ug/g (0.5%).

To make the math a little easier, let's make the following assumptions:

1. The level of lead in the paint was 1000 ug/g (0.1%), and
2. The amount of paint used on the cars was 1 g.

Thus, using the fun little crossy-outy math thingy, we can determine that each car contains 1000 ug of lead.

Remember, for every 1 ug of lead ingested, the child's blood-level increases 0.16 ug/dL.

So, if a child swallows one car (and a doctor doesn't remove it, and the child's stomach acids strip off all the paint, and all that paint is absorbed into the bloodstream), the child's blood-lead level will be:

Hm ...

1000 ug x 0.16 ug/dL = 160 ug/dL!

Congratulations, the kid had seizures and died (Severe seizures and sometimes death can occur at blood-lead levels over 70 ug/dL).

OMG! Mass Hysteria!

Of course, more than likely, a child will not swallow an entire 2.5 inch model car. If anything, he (or she!) may ingest a tiny paint chip ... which might constitute, let's say, 1% of the paint used on the car.

So, 1% of 1000 ug = 10 ug.

10 ug x 0.16 ug/dL = 1.6 ug/dL.

Congratulations, the kid probably doesn't even notice his blood-lead level increased. Maybe his (or her!) IQ dropped half a point or something. Say goodbye to your dreams of him (or her!) attending Harvard.

This concludes the math lesson. My head hurts.


  1. lol that made my head hurt too. I swallowed a plastic othello piece once (while trying to see how many I could fit in my mouth ((shut up)) and the doc told me to verify it's exit (I'll spare you the 'tails) But I wonder if any lead leached out of it. That would explain ALOT, lol.

  2. /singing

    Nobody likes me,
    everybody hates me,
    I'm gonna eat some

    /end singing

  3. Some rarely wise person appeared on TV last night and said that people should not worry, the children of Canada are not dying from lead-poisoning. As a matter of fact, the toy-related lead poisoning is zero.

    I'm now thinking that this hoo la la was created by some conspiracy inside those complicated layers of toy making business. What ya reckon?

  4. Thanks for doing the math -- I had actually wondered about the real level of "threat." Still, there are some kids out there who will make their throat the international speedway for their toy cars.

  5. yea sounds like overkill. I remember when my kids were little they slobbered all over their toys constantly. It's possible over time, they could ingest a lot of the paint.

    eh... better to be safe I guess


  6. That's got to be the only context in which anyone uses a deciliter.

    Dood. Math is boring. I guess lead poisoning is kind of interesting tho.

  7. Thanks for doing the math for me! My baby does chew on his little cars although he hasn't actually ever swallowed one. Still though, it was enough to make me gather them all up to return to the store today.