Thursday, February 27, 2014

In the news: Uplifting stories III

In the last few months, I've read a number of inspiring stories in the news. Here is a quick recap (with links) of what I've learned.

The BBC does a great job of reporting environmental news that is truly newsworthy -- personal, prompt, and prominent. Here are some recent articles that caught my attention.

Apple to use ethically sourced materials -- yeah! Read it here.

The city's impact on wildlife is not as bad as we thought. Endemic species still manage to survive. Find the article here.

Logging laws can be hard to enforce. A new application allows tree loss to be detected in near real time. The system uses both satellite imagery as well as citizen reports to update a map showing tree cover. Indigenous peoples of the Brazilian rainforest are already using smartphones to flag illegal logging. This is the next step in citizen reporting! Again, from the BBC.

Chicago to eat the Asian carp into extinction. Finally, an invasive species gets what is coming to it. Read more over here.

Why is the weather so horrible all of a sudden? This great article from the BBC explains it in lay terms.

Poorly designed cities are bad for your health. Read it here, then go support local green space initiatives near you!

Distant planet terrified it may one day be infested by humans. Okay, this one is just for laughs. From the Onion.

Saturday, February 22, 2014

Is fluoride safe?

The Question

A friend of mine asked me to check out this article:
"I am wondering how different the amount China's environment has compared to toothpaste...or US fluorinated water..." 

In other words, should we be worried about drinking fluoridated water or using regular toothpaste?

The Short Answer

There are two types of risk to consider here: acute fluoride poisoning and long term exposure to fluoride.

1. Acute: Most people in the United States are not at risk for acute fluoride poisoning. High levels of fluoride can cause brain damage in children similar to mercury or lead. If you have a young child, use fluoride-free toothpaste until you are sure your child can spit out the toothpaste.

2. Long term: this type of exposure to moderate levels of fluoride may cause teeth and bones to weaken. The risk is real, but small. Some areas of the country do not even bother to fluoridate water, so check with your local water district before starting to worry. If the levels of fluoride in your local tap water are higher than 2ppm and you drink a lot of tap water (versus juice, sparkling water, etc), consider reducing your exposure to fluoride by switching to fluoride-free toothpaste. 

The Long Answer

First of all, let's cover some basics. How does fluoride work and why do we bother with it?
Remember back to chemistry class when your teacher taught you that nature works towards equilibrium? For example, salt will cross a membrane until the solution on both sides is equally salty. The same thing happens with teeth and bones. If there is a lot of acid in your mouth (from sugar or plaque) your teeth will start to lose minerals. If you eat lots of mineral dense food and water, minerals like fluoride and calcium will sink back into the teeth. If there is too much, though, teeth can be hypermineralized meaning there is not enough collagen in the tooth matrix to keep it strong. This can make teeth or bones too brittle and more likely to break.
This hypermineralization from overexposure to fluoride is called fluorosis, and, again, children are more susceptible to this risk than are adults because their teeth and bones are still developing. Children under 6 years of age should not use toothpaste or mouthwash with fluoride [WebMD on fluorosis]. However most adults do not need to worry about this unless they live in an area where there is too much fluoride in the water.
What about the article your friend mentioned? The article is a meta-analysis of epidemiological studies conducted in China where there are high levels of naturally occurring fluoride in the water. Elevated levels of fluoride were linked to small problems in brain development, similar to what is seen with exposure to mercury or lead. The article does not mention specifics, but it seems like they are dealing with cases that are closer to acute toxicity than to what we might see in the USA with long-term damage from lower levels.
The article also seems to skip a lot of other details that would be useful to know when trying to draw conclusions. For example, what other factors might also explain the phenomenon? Water with high levels of naturally occurring fluoride might also have elevated levels of lead or mercury. Also, the study does not discuss what type of fluoride occurs in the water -- there are many different types of fluoride isotopes, and this naturally occurring fluoride may not be equivalent to what is typically added in toothpaste or public drinking water. In other words, natural fluoride might be more chemically reactive and therefore more dangerous.

So what other information do we have? A study from the National Academy of Science sheds a little more light on the topic. Their brief states that the EPA level of max 4ppm of fluoride in water is too high for people who drink fluoridated water over their lifetime. But again, the risk here is long term exposure to low levels. No mention is made of problems with brain development for children. The report also estimates how much fluoride exposure comes from water and how much comes from toothpaste and mouthwash. From what I've read, it looks like switching to fluoride-free toothpaste could reduce your ingestion of fluoride from anywhere between 10 and 40%.

Peeps in San Mateo and Santa Clara counties. You have no need to worry. Santa Clara county water district started fluoridating their water in 2011 [see their website], but levels are at 2 mg/lt (milligrams per litter which is nearly equivalent to parts per million) [see their Jan'14 report]. San Mateo's 2012 water quality report showed 0.17 ppm of fluoride.

Will my Brita water filter remove fluoride?
Nope. Only distillation and reverse osmosis will remove fluoride. But, again, check with your local water district's water quality report before deciding if you need to make any changes.