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1000 bananas = 1 micromort of risk (Source: Thamizppartithi Maari/Wikimedia Commons/CC BY-SA 3.0)

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Life’s little risks all add up

Tuesday 29th September 2015 1:26 pm

We all know that your weight is measured with the ‘unit’ called kilograms, and that your height is measured in the units of metres or centimetres.

But only a few people have heard of the unit called the ‘mort’ or the ‘micromort’ — and they mostly work in insurance. The mort and the micromort measure ‘risk’.

The word ‘risk’ has many definitions — situations involving danger, the chance that something bad will happen, and of course, the possibility of a financial loss. The word came from 17th century French and Italian roots referring to ‘danger’.

For example, if you jump off a cliff, your risk of sudden death is one ‘mort’ — you will almost certainly die. (By the way, ‘mort’ is related to ‘mortality’, or death.)

But most of our daily activities are much less dangerous than jumping off a cliff, so risk assessors generally use a much smaller unit called a ‘micromort’ — or a millionth of a mort. A micromort implies that you have a one in a million chance of dying, as a result of that activity.

Professor Ronald A Howard, from Stanford University, introduced the concept of the ‘micromort’ in 1980. He helped found the field of ‘decision analysis’.

Decisions are involved in investment planning, hurricane seeding, choice of a partner, road design and nuclear waste disposal. Making a decision involves certainities, uncertainities, emotions, risks, etc.

The universe is a dangerous place, and everything carries risk — you just want to minimise overall risk, while still having fun.

There’s a whole bunch of different activities that will expose you to one micromort. They include drinking half a litre of wine, smoking 1.4 cigarettes, spending one hour in a coal mine, and living for two days in New York or Boston (that’s because of the air pollution).

Food-related activites that expose you to one micromort of risk start with eating 1000 bananas. Yep, bananas are very slightly radioactive, thanks to their potassium 40. So are brazil nuts. Brazil nut trees have a very extensive underground root system, which very effectively absorbs any radium in the soil.

If you eat 100 charcoal-broiled steaks, you get your one micromort risk of dying via a circuitous pathway. As you charcoal-broil the steaks, you create a chemical called benzopyrene from the cooking process, and this chemical increases your risk of dying from a cancer.

Also, if you eat 40 tablespoons of peanut butter, you pick up one micromort of risk of dying from liver cancer. This is due to a chemical called aflatoxin, that a fungus sometimes manufactures in peanuts.

But let’s leave the relatively safe land of one micromort, and look at bigger risks.

Each skydiving jump, or hang-gliding flight, exposes you to eight micromorts. In other words you have an eight in one million chance of sudden death each time you skydive or hang-glide.

You get seven micromorts for each marathon you run, and five micromorts for each bout of scuba diving.

BASE-jumping is more dangerous — each event exposes you to 430 micromorts. However, trying to climb Mt Everest gives you 40,000 micromorts in one ascent — that’s a 4 per cent chance of dying.

Even getting out of bed is risky (and so is staying there.) Travelling as well exposes you to the risk of sudden death.

When I was studying obstetrics and gynaecology, my professors told me the most dangerous journey you ever took in your whole life (in terms of injuries and death per kilometre) was the 10 centimetre journey down your mother’s birth canal. And this truism is partly backed up by the risk assessors, who have figured that on your first day of life, your chances of dying are 430 per million (430 micromorts).

With land travel, the safest transport is the train — needing 9700 kilometres to give you a one in a million chance of dying (one micromort). But on the road, to get one micromort, you need to ride just 11 kilometres on a motorbike or 32 kilometres on a bicycle, or drive 480 kilometres in a car. But besides your mode of transport on the road, you also need to factor in the type of road.

The average multi-lane divided expressway is pretty safe — you have to drive 1600 kilometres to pick up one micromort. But the rural two-lane blacktop is about six times more dangerous – driving just 250 kilometres will give the same risk of dying, one micromort.

Currently, the GPS/sat nav in your car will give you the option of the quickest or cheapest paths to destination. Maybe future sat navs will incorporate risk factors and become safe navs, reducing micromorts as you travel?

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This blog first appeared on Dr Karl's Great Moments in Science

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  1. Todd Stoehr says:

    Hello Dr. Karl:
    During the long search for the missing Flt. 370 in the southern Indian Ocean huge amounts of sonar scans have been made of the ocean floor in the search areas. What is being done with all this data? Where is it being archived? When will it be made available to researchers and scientists?

    Best regards.

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