Is There More Fluoride In a Pea-Sized Amount of Toothpaste or a Liter of Water?
Jake (whom I assume is a dentist) left an interesting comment about fluoride on Sunday. He said:
I had an anti-fluoride patient the other day that was saying he read somewhere that a pea-sized amount of toothpaste contains the same amount of fluoride in 1 liter of tap water (1 ppm). His argument was that the toothpaste labels says to call poison control if more than a pea-sized amount is swallowed (which it doesn't), and the same amount is in 1 liter of water. So he was wondering if he should call poison control every time he drinks more than a liter of water. It sounded ludicrous, but how much fluoride is actually in a pea-sized amount of toothpaste in comparison to 1 liter of water?
I enjoy talking about water fluoridation. Looking back, I've actually written 15 different posts about fluoride!
Jake's comment really got me wondering about how the fluoride levels compare between fluoridated water and toothpaste.
Do Toothpastes Contain a Warning Telling You to Call Poison Control?
First, let's take a look at the common anti-fluoride claim that fluoride is poison. I took a picture of the back of three different brands of toothpastes: Colgate, Aquafresh, and Crest. If you click on the picture, you can view a large size that will let you read the warning. Each tube has a similar warning. The back of the Colgate Total toothpaste box states:
If more than used for brushing is accidentally swallowed, get medical help or contact a Poison Control Center right away.
But how much do people really use for brushing? There's the ultra-conservative pea size, and then there's the large stripe that toothpaste manufacturers want us to use so that we buy lots of toothpaste!
I decided to find out how much toothpaste is in a large stripe by conducting a two-part experiment.
My Toothpaste Experiment
On the back of the toothpaste tube, it states that you should call the poison control center if you swallow more than is used for brushing. This is what the toothpaste manufacturers write. I took the liberty of assuming that a normal amount of toothpaste for them is a thick stripe on a manual toothbrush (like they show in their commercials).
I decided to find out exactly how much toothpaste is in a big stripe so that I could figure out how much fluoride it has. I got carried away and tried two different brands.
Here's the large stripe of Colgate Total that I put on my wife's toothbrush (are your toothbrush bristles as straight as hers? If not, it may be time to get a new toothbrush):
I measured the toothpaste and found that it filled the 1/4 teaspoon - giving us 1.25 ml of toothpaste:
Out of curiosity (and because it seemed like a fun idea after taking two finals over the past 36 hours), I measured the Crest Toothpaste as well. I was able to get a slightly bigger stripe on the brush this time. Unfortunately, the stripe I created just wasn't as good looking as it is on the toothpaste commercials! However, if you want to practice making a beautiful stripe of toothpaste on your brush, I have to recommend the Crest since it is much thicker.
This large stripe of Crest ended up overflowing the 1/4 teaspoon, giving us about 1.75 ml of toothpaste:
I decided to take the average of my two "large stripes" to use as the baseline amount of toothpaste you can swallow and still be safe (according to the toothpaste manufacturers) - which appears to be 1.5 ml from my unscientific experiment.
Contrast this with a pea-size amount of toothpaste which is only 0.2 ml. Who would've guessed that the average pea only takes up a volume of 0.2 ml?
Now that we know how much toothpaste we use, we can figure out how much fluoride we would ingest if we swallowed a large stripe of toothpaste.
How Much Fluoride is in Toothpaste?
A majority of toothpastes on the market contain about 0.15% fluoride ion, which comes out to 1500 ppm (parts per million.)
In 1.5 ml of toothpaste (the large stripe pictured above) you would find 2.25 mg of fluoride.
In a pea sized amount of toothpaste, you would only find 0.3 mg of fluoride.
How Much Fluoride is in Fluoridated Water?
Most fluoridated water contains about 1.0 ppm. That means that in 1 liter of water, you would find about 1 mg of fluoride.
Not sure how much fluoride is in your water? Then find out how much fluoride is in your tap water!
Comparing the Amount of Fluoride In Water with the Amount of Fluoride in Toothpaste
As you can see, you would have to drink over 2 liters of water to get the same amount of fluoride that you would get by swallowing a large stripe of toothpaste. You would only have to drink 300 ml of water (a little less than a 12 oz. can of soda) to get the same amount of fluoride you would get by swallowing a pea size amount of toothpaste.
You Don't Need to Call Poison Control When You Drink Fluoridated Water!
I'm sure Jake's patient was just trying to make a point. Point taken! However, according to the American Dental Association (Page 31 in their Fluoridation Facts PDF), it would take 5-10 grams of fluoride to cause fluoride toxicity in an average 155-pound man. That means that a 155-pound man would need to drink 5,000 liters of water (over 1300 gallons!) in order to get a toxic dose of fluoride.
The water would kill you (as this tragic story illustrates) long before the fluoride would have any toxic effect.
Interestingly, there is more fluoride in a liter of water than in a pea-sized amount of toothpaste, but more fluoride in a large stripe of toothpaste than in a liter of water. Here's what I found:
- In a pea size amount of toothpaste, there's 0.3 mg of fluoride.
- In a large stripe of toothpaste, there's 2.25 mg of fluoride.
- In one liter of fluoridated water, you'll find 1 mg of fluoride.
Although fluoride is great for your teeth, too much of it during development of the teeth can cause dental fluorosis.
Do you have any questions about toothpaste fluoride content or water fluoride content? I'd love to hear what you have to say in the comments section below. Thanks for reading!
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