Monthly Archives: January 2017

bicycle helmets kill

There is rarely a silver lining that does not come with a cloud, and often the cloud is bigger than the lining. A fine example is bicycle helmets. They provide such an obvious good that, at first glance, you’d think everyone would wear one, even without a law mandating it. Why would anyone risk their skull in a bicycle accident if injury were prevented by merely wearing a particular hat? Yet half the people ride without, even when there are laws and fines. There are some down-side to helmets, but they are so small that even mentioning them seems small. Helmets are inconvenient, and this causes people to ride a little less, so what?

hospital admissions for bicycle related head injuries, red, left; and bicycle related, non-head injuries, blue, right. Victoria Australia.

Hospital admissions for bicycle-related, head injuries, red, left scale, and bicycle-related, non-head injuries, blue, right scale. The ratio is 1:2 before and after the helmet law suggesting that helmet law did nothing but reduce ridership.

As to turns out, helmets hardly stop accidental injury, yet cause people to ride a lot less, and this lack of exercise causes all sorts of problems — far more than the benefits. In virtually every city where it was studied, bicycle ridership dropped by 30-40% when helmets were required, and as often as not, those who still rode, rode unhelmeted. There was a 30-40% decrease in head-trauma injuries, but it appears that this was just the result of 30-40% less ridership. You’d expect a larger decrease if the helmet helped, as such.

Take the experience of Victoria, Australia; head and non-head bicycle injury data plotted above. Victoria required bicycle helmets in January 1990. Before then, in the peak summer months, hospital records show some 50 bicycle-related head injuries per month, and 100 bicycle-related, non-head injuries — a 1:2 proportion. Later, after the law went into effect, each summer month saw about 35 bicycle-related, head injuries, and 70 bicycle-related, non head injuries. This proportion, 1:2, remained the same suggesting the only effect of the helmet law was to reduce ridership, with no increase in safety. The same 30% decrease was seen by direct count of riders on major streets, though now a greater proportion of those still riding were flaunting the law, and not wearing helmets.

One reason that helmets don’t help much is that the skull is already a very good helmet. As things stand, the main injury in a bicycle flip does not come from your skull cracking, it comes from your brain hitting the inside of your skull, and a second helmet doesn’t help stop that. There’s no increase in safety, and perhaps a decrease as the helmet appears to decrease vision. In a study of bicycle-injury-related highway deaths, Piet de Jong found that countries with the highest helmet use had the highest highway death rates. The country with the highest helmet use (the USA, 38% helmeted) had the highest cyclist death rate, 44 deaths per 1,000,000,000 km. By comparison, the nation with the least helmet use (Holland, 1% helmeted) had among the lowest death rates, only 10.7 deaths per 1,000,000,000 km. There are many explanations for this finding, one sense is that the helmets hurt vision making all types of injury and death more likely.

An hour or three of exercise per week adds years to your life -- especially among the middle aged.

From the national cancer institute. An hour or three of exercise per week adds years to your life — especially among the middle aged. Note these are healthy weight individuals. 

Worse than the effect on visibility, may be the effect on exercise. Exercise is tremendously beneficial, especially for middle-aged people in a sedentary population like the US. The lack of exercise is a lot more deadly, it turns out, than any likelihood of flying over the handlebars. How do I know? From studies like the National Cancer institute, shown at right. To calculate the cost/benefit of a little riding, less say you ride 3 hours per week at 10 mph (slow roll). The chart at right suggests a middle-aged person will add 3.4 years to your life, or about 10% life extension. Now consider the risks. This person will ride 30 miles per week, or 2400 km per year. Over 35 years the chance of death is only 0.36%. In order to get a 10% chance of death, you’d have to ride, over 2.3 million km, or 1000 years. Clearly the life extension benefit far outweighs the risk from fatal accident.

But life extension isn’t the total benefit of exercise. Exercise is shown to improve metal health, reducing depression and ADD in children, and likely in adults. Exercise also helps with weight loss, and that is another big health benefit (the chart above was for healthy body weight riders). So my first suggestion is get rid of bicycle helmet laws. I would not go so far as to ban helmets, but see clear disadvantages to the current laws.

The other suggestion: invent a better helmet. While most helmets are vented, and reasonably cool while you ride. They become uncomfortably hot when you stop. And they look funny in a store or restaurant. You can’t easily take them off, either: Restaurants no longer have hat racks, and stores never had them. What’s needed is a lighter, cooler helmet. Without that, and with helmet laws in place, people in the US tend to drive rather than ride a bicycle — and the lack of exercise is killing them.

Robert Buxbaum, January 19, 2017. One of my favorite writing subjects is the counter-intuitiveness of health science. See, eg. on radiation, or e-cigarettes, or sunshine, or health food. Here is a general overview of how to do science; I picked all the quotes from Sherlock Holmes.

Rethinking fluoride in drinking water

Fluoride is a poison, toxic tor a small child in doses of 500 mg, and toxic to an adult in doses of a few thousand mg. It is a commonly used rat poison that kills by robbing the brain of the ability to absorb oxygen. In the form of hydrofluoric acid, it is responsible for the deaths of more famous chemists than any other single compound: Humphrey Davy died trying to isolate fluorine; Paul Louyet and Jerome Nickles, too. Thomas Knox nearly died, and Henri Moissan’s life was shortened. Louis-Joseph Gay Lussac, George Knox, and Louis- Jacques Thenard suffered burns and similar, George Knox was bedridden for three years. Among the symptoms of fluoride poisoning is severe joint pain and that your brain turns blue.

In low doses, though, fluoride is thought to be safe and beneficial. This is a phenomenon known as hormesis. Many things that are toxic at high doses are beneficial at low. Most drugs fall into this category, and chemotherapy works this way. Diseased cells are usually less-heartythan healthy ones. Fluoride is associated with strong teeth, and few cavities. It is found at ppm levels many well water systems, and has shown no sign of toxicity, either for humans or animals at these ppm levels. Following guidelines set by the AMA, we’ve been putting fluoride in drinking water since the 1960s at concentrations between 0.7 and 1.2 ppm. We have seen no deaths or clear evidence of any injury from this, but there has been controversy. Much of the controversy stems from a Chinese study that links fluoride to diminished brain function, and passivity (Anti-fluoriders falsely attribute this finding to a Harvard researcher, but the Harvard study merely cites the Chinese). The American dental association strongly maintains that worries based on this study are groundless, and that the advantage in lower cavities more than off-sets any other risks. Notwithstanding, I thought I’d take another look. The typical US adult consumes 1-3 mg/day the result of drinking 1-3 liters of fluoridated water (1 ppm = 1 mg/liter). This < 1/1000 the toxic dose,

While there is no evidence that people who drink high-fluoride well water are any less-healthy than those who drink city water, or distilled / filtered water, that does not mean that our city levels are ideal. Two months ago, while running for water commissioner, I was asked about fluoride, and said I would look into it. Things have changed since the 1960s: our nutrition has changed, we have vitamin D milk, and our toothpastes now contain fluoride. My sense is we can reduce the water concentration. One indication that this concentration could be reduced is shown below. Many industrial countries that don’t add fluoride have similar tooth decay rates to the US.

World Health Organization data on tooth decay and fluoridation.

World Health Organization data on tooth decay and fluoridation.

This chart should not be read to suggest that fluoride doesn’t help; all the countries shown use fluoride toothpaste, and some give out fluoride pills, too. And some countries that don’t add fluoride have higher levels of cavities. Norway and Japan, for example, don’t add fluoride and have 50% more cavities than we do. Germany doesn’t add fluoride, and has fewer cavities, but they hand out fluoride pills, To me, the chart suggests that our levels should go down, though not to zero. In 2015, the Department of Health recommend lowering the fluoride level to 0.7 ppm, the lower end of the previous range, but my sense from the experience of Europe is that we should go lower still. If I were to pick, I’d choose 1/2 the original dose: 0.6 to 0.35 ppm. I’d then revisit in another 15 years.

Having picked my target fluoride concentration, I checked to see the levels in use in Oakland county, MI, the county I was running in. I was happy to discover that most of the water the county drinks, that provided by Detroit Water and Sewage, NOCWA and SOCWA already have decreased levels of 0.43-0.55 ppm. These are just in the range I would have picked, Fluoride concentrations are higher in towns that use well water, about  0.65-0.85 ppm. I do not know if this is because the well water comes from the ground with these fluoride concentrations or if the towns add, aiming at the Department of Health target. In either case, I don’t find these levels alarming. If you live none of these town, or outside of Oakland county, check your fluoride levels. If they seem high, write to your water commissioner. You can also try switching from fluoride toothpaste to non-fluoride, or baking soda. In any case, remember to brush. That does make a difference, and it’s completely non-toxic.

Robert Buxbaum, January 9, 2017. I discuss chloride addition a bit in this essay. As a side issue, a main mechanism of sewer pipe decay seems related to tooth decay. That is the roofs of pipe attract acid-producing, cavity causing bacteria that live off of the foul sewer gas. The remedies for pipe erosion include cleaning your pipes regularly, having them checked by a professional once per year, and repairing cavities early. Here too, it seems high fluoride cement resists cavities better.

math jokes and cartoons

uo3wgcxeParallel lines have so much in common.

It’s a shame they never get to meet.



sometimes education is the removal of false notions.

sometimes education is the removal of false notions.

pi therapy

pi therapy

Robert E. Buxbaum, January 4, 2017. Aside from the beauty of math itself, I’ve previously noted that, if your child is interested in science, the best route for development is math. I’ve also noted that Einstein did not fail at math, and that calculus is taught wrong, and probably is.