Escaping the cult of sunscreen

Intelligent choices come from comparing the costs vs. benefits of all known alternatives, and choosing the one alternative with the best cost/benefit ratio.

Unfortunately, Americans often try instead to avoid any risk, no matter how small, at any cost, no matter how high.  This is why our healthcare is so expensive.  It’s also why we receive nutty proposals like the one I got today from the local high school.

Today, our child’s high school sent a bulletin recommending all parents force their children to wear sunscreen at all times during school hours, to prevent skin cancer.  Is that smart?  Let’s examine the costs and benefits, and compare them to alternatives.

  • For practical purposes, melanoma is the skin cancer that kills you, and hence the one worth focusing on.
  • Over 95% of melanomas occur in people with blue or green eyes.  Our high school is majority Asian;  less than 5% of students, or fewer than 175 people, have blue/green eyes.
  • Annual incidence of melanoma among non-Caucasians is less than 1 in 25,000.
  • Incidents usually occur after decades of exposure, but let’s say 10 years.
  • Skin cancer is proportional to sun exposure, occurring mostly in people who spend hours a day outdoors with no protection.
  • Our students spend between 0.5 and 1.5 school hours outdoors, depending on whether they have physical education class.  Students take an average of 2 years of PE, so over their four years, average daily exposure per student, per school day is about 1 hour.
  • Skin cancer is far more associated with episodes of sunburn than with long-term, low-level exposure.  Almost no one, other than blue-eyed people, can become sunburned by 1 hour of incidental sun exposure.
  • Sunscreen costs $15 a bottle.  Bottles last no more than two weeks if you use them every day, reapplying as directed.  Suppose all 3500 students followed the school’s advice.  They would use 91,000 bottles of sunscreen a year, costing almost $1.4 million.
  • Nearly all store-bought sunscreens rely on oxybenzone, homosalate, and similar chemicals, which are suspected hormone disruptors, and which have not been reviewed by FDA since the 1970s.
  • The developed world suffers from an epidemic of Vitamin D deficiency, primary caused by a lack of sun exposure.

Conclusion:  by following the school’s advice, at a cost of $1.4 million a year, we might save at most one hundredth (1/100) of a student life per year, and probably far less — while causing unknown harm due to vitamin deficiency and hormone disruption.  Minimum cost per life saved:  $140 million.

Those who don’t think rationally about cost/benefit will protest here.  Life is precious!  If we could save just one life, maybe it’s worth $140 million.  Well, maybe.  But let’s first compare alternative ways of saving lives at the same venue, and choose the cheapest.

For example, for $50k a year, the school could hire a full-time suicide counselor.  The school has a suicide every few years.  If a counselor saved just one fourth of them, say one student every 10 years, the cost would be $500k per life saved — about 250 times more effective than ubiquitous sunscreen.

That’s cost benefit analysis.  It’s not an exact science.  It doesn’t need to be exact, when the difference in effectiveness is so stark.


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