Shots Across the Bow

In Monday's post on why I'm getting a gun, I talked a little bit about assessing risks, and I wanted to take a few minutes to expand on it because it's an area that most people know nothing about. In most cases, they tend to proceed by gut reaction, rather than using a dispassionate, analytic view, and that leads them into making flawed decisions, often times with catastrophic results.

Take DDT for example. DDT is a very effective insecticide, once widely used to control mosquitos in an attempt to prevent the spread of malaria. And it was very successful. At the heighth of its use, malaria was all but eliminated. But because widespread overuse of DDT lead to thinning of raptor (eagles, falcons, hawks) eggs, and a resultant decrease in their population, it's use was banned. Currently, mosquitos infect approximately 500 million people with malaria annually, of whom about 3 million die. So our decision was to sacrifice 3 million lives per year, most of them in third world nations, to protect eggshells.

That kind of thinking is hard to fathom, mainly because it isn't thinking at all, but an emotional reaction disguised as thought. And because it's an emotional process, it doesn't yield to logical debate. Even though it is ludicrous to allow 3 million people to die every year, and millions more to suffer with recurring bouts of malaria, we can't even discuss alternatives to the ban, like judicious use of DDT, without being attacked as environmental rapists. So one out of every twenty kids in sub Saharan Africa will continue to die from a disease that we could easily control.

Risk assessment is a three step process. In the first, you analyze the probablity of the risk and the severity of its consequences. Next, you determine preventive actions to minimize each risk. Then you evaluate the remaining risk level and determine if the potential payoff outweighs the consequences of failure. By following this process, you come out with a reasonable course of action. Let's step through the process once to see how it works in a real life situation.

A few months ago, I was turning a bowl on my lathe, and I was finish sanding the interior. It was a deep, closed bowl, more like a vase actually, and I couldn't reach in deep enough to sand the bottom 2 inches. The opening was just wide enough that I could slip my hand inside the bowl to reach the bottom, but I would have to stop the lathe to do it because of the tight fit. Once my hand was inside, I could restart the lathe, sand the inside, stop the lathe, then pull my hand out.

Don't laugh; I've heard much worse.

OK, Phase 1, what are the risks involved? Basically, there are two. Either my hand would wedge in the vase, breaking it off the lathe and sending wood shards everywhere, or my hand would wedge in the vase, causing a spiral fracture of my radius and ulna sending bone shards everywhere.

That would be a bad thing.

Next, we need to catagorize the risks by probability and severity. You don't need actual numbers for this, although they do help; a general idea of each will do. Draw a table with two rows and two columns. Label the rows high prob and low prob, and the columns high severity and low severity. Next, place the risks in the appropriate box. In this case, because I'm a klutz, both risks would have to get high probability. Breaking the vase isn't that big of a deal, so it could get a low severity, but breaking my arm definitely goes into the high severity box.

Now we have three catagories of risk. Catagory A is the high probability/high severity risk; Catagory C, the low probability/low severity risks. And the rest are in Catagory B. Now we're ready for phase 2.

In phase 2, we assign our available resource to minimize the risks we identified in Phase 1. Obviously, we concentrate on Catagory A first, then B then C, and allocate resources until all the risks have been minimized or we run out of resources.

In this case, our Catagory A risk is me getting my arm twisted off. I could minimize the risk by:

1. Reshaping the mouth of the bowl to make it wider.
   
2. Lubricating the bowl and my wrist to prevent it from catching.
   
3. Fastening the bowl loosely in the chuck so it will come loose before my arm breaks.
   
4. Wearing a brace on my wrist to support it if it does catch.

Options 3, and 4 won't work because a loose bowl on a lathe represents it's own risks, and my hand is already too large to go into the bowl; a brace would make matters worse. Option 1 would work, but the bowl needed a narrow mouth, so in this case, it's unacceptible.

Which leaves us with Option 2, grease up that sucker and ram 'er in.

Our catagory B risk, the vase flying off, can be taken care of by tightening the chuck for an extra secure grip.

So, now it's time for Phase 3, risk vs. reward. I've done what I can to minimize the risk involved with sticking my hand into a bowl spinning at 300 rpm. Now I have to ask myself, "Is getting a perfectly smooth interior finish worth having to learn to dress myself with one hand?"

NOPE!

I found an alternate method to sand the inside (applied ashesive backed sandpaper to a short length of garden hose) and sanded the bowl that way.

Now obviously, in this case I didn't go through a step by step process like that because it was so simple, but it serves to show the principles involved, and how a systemized approach to risk assessment can guide you from an irrational response, like never sanding another bowl, to a rational one, like finding a safer way to sand it.

Returning to the DDT case, by evaluating the risk/reward structure you can balance harm to the raptor population against the benefit to the human population, and come to a reasonable position that maximizes the benefits while minimizing the risks.

<blockquote><i>
Take DDT for example. DDT is a very effective insecticide, once widely used to control mosquitos in an attempt to prevent the spread of malaria. And it was very successful. At the heighth of its use, malaria was all but eliminated. But because widespread overuse of DDT lead to thinning of raptor (eagles, falcons, hawks) eggs, and a resultant decrease in their population, it's use was banned. Currently, mosquitos infect approximately 500 million people with malaria annually, of whom about 3 million die. So our decision was to sacrifice 3 million lives per year, most of them in third world nations, to protect eggshells.
</i></blockquote>

While I have no beef with the general idea of your post, your history (and that of the articles cited) of the DDT ban is simplistic and severely lacking. While most anti-environmentalists (and some environmentalists) like to attribute the DDT ban as a result of Rachel Carson's <a href="http://www.amazon.com/exec/obidos/tg/detail/-/0618249060/" rel="nofollow">Silent Spring</a>, the truth is that there was a growing body of evidence that supported a consideration of DDT's danger. This included adverse health effects, including its potentially carcinogenic nature, and its damage to the liver. It also included the potential of insect resistance to DDT which limited the effectiveness of over-use of DDT.

It's precisely the sort of risk/benefit analysis you speak of that led to the ban on DDT, and portraying it as some hare-brained scheme by environmentalists to save eggs is unfair and untrue.

Further, DDT was not abruptly banned, but rather was phased out, and its use continued in many states where emergency containment was necessary -- a further testament to their ongoing risk/benefit analysis. Also, most third-world nations <b>do</b> still use DDT, with varying success.

These days, there has been no real substantial evidence that DDT is carcinogenic in humans -- most of the preliminary findings have now been attributed to metabolic pecularities of rats. However, large doses of inhaled DDT in humans have always been known to have adverse, but reversible (once the exposure ceased) effects on the nervous system.

I believe the WHO, these days, has formulated a recommended mg/L type value for the amount of DDT that is acceptable, based on current knowledge, for human consumption.

Indeed, an ongoing risk/benefit analysis would be desirable in evaluating the costs of DDT versus the costs of malaria. However, I see very little evidence that that process is not going on in the third-world countries where malaria is still a deadly problem. Although there certainly was international pressure to ban DDT, many countries didn't cease its use because of this alone, but rather because of domestic instability and political turmoil. Conversely, South Africa, I think, stopped spraying with DDT in the '90s due to international pressure and saw a drastic increase in malaria cases, and so started again in '99. There have been a wide variety of approaches to malaria, some that involve DDT, and some that don't.

It's a complicated problem. Writing off the ban of DDT as the result of an inability to do a simple cost/benefit analysis is insulting to the entire world that has been doing just that for decades. We have a solution, currently, to fight malaria that involves dumping a chemical by the ton world-wide, without an absolute grasp on the effects it could have on our food supply or our health. To some, that risk is acceptable. To some, it's not. The domestic and international dialogue will continue and hopefully a successful strategy to combat malaria will be achieved, whether or not it involves DDT. I personally am no expert on DDT, but what I've read leads me to believe it's probably not that dangerous, but what I have read also leads me to believe that over the past few decades, there was ample justification for concern.

Whether a reaction is considered hasty is simply a matter of scale, and hindsight is always 20/20. If DDT turns out to be completely harmless, it certainly is easy to criticize opponents of its use as being hasty and reactionary. Conversely, though, if we found out that DDT was indeed carcinogenic, or triggered the mutation of a recessive gene that kills us all, it would be very easy for an opponent of DDT to accuse proponents of being hasty and reactionary for wanting to use something so dangerous to abate something so relatively insignificant as malaria. After all, why couldn't they do a simple cost/benefit analysis?

Thanks for the info, Chris. It looks like I need to find a better example to illustrate my point.