Cleaning up

Say a dirty bomb goes off in your city – say contamination is spread over a few billion dollars’ worth of property. Government buildings are contaminated. Parks are contaminated. So are trendy restaurants and gentrifying apartment buildings, subway tracks and cars and busses. Tens of thousands of people are contaminated as well as are many of their pets. At some point – when the smoke clears and the dust settles thoughts are going to turn away from the emergency and towards what needs to be done to get people back home, back to work, and getting the city back in operation. Invariably thoughts will turn towards cleanup standards – to how clean is clean enough. This is the question that the Japanese have been facing for the last year, the question that the neighbors of Chernobyl have been facing for a quarter century, and the question we might someday face if there’s an attack or an accident here. In fact, this could be a trillion-dollar question, depending on the amount and extent of the contamination and the cleanup standards that are decided upon.

As a scientist the question is not simple, but it’s also fairly straight-forward. To start with, calculating radiation dose from a given level of contamination is fairly straight-forward and calculating dose is the first step towards figuring out the risk. Although there is some uncertainty about the risks of exposure to low levels of radiation, we can at least put an upper bound on the risks. So from a scientific standpoint the question is fairly straightforward – how much risk are we willing to accept and what level of contamination corresponds to that risk?

Consider the Japanese example – at the start of their evacuation their screening criterion was 13,000 counts per minute (cpm) and anyone with more than this level of contamination required decontamination (an ordinary Geiger counter such as what the Japanese used normally read less than 100 cpm). Soon after the evacuations started authorities realized that there were going to be lot of people with higher levels of contamination; as a result they upped their limits to 100,000 cpm. As a scientist I can tell you that this level of contamination doesn’t pose much risk to the people who are contaminated. But is this level of contamination acceptable to those who are contaminated? I’m not sure how the Japanese reacted – I haven’t seen that information – but I’ve seen plenty of Americans who have trouble accepting even natural background radiation (depending on the detector this might be anywhere from 50 to a few thousand cpm) let alone 100,000 cpm.

So where do we draw the line? Do we impose limits that are safe (but likely to cause worry and heartache) and that are comparatively easy and inexpensive to achieve, or do we set limits that are as close as possible to natural background radiation levels (which will please – or at least will not worry – the greatest number of people) even those achieving these limits is likely to add little additional public health benefit and will come at exorbitant cost? And just as important – do we continue to clean up contamination that poses no public health risk if the public demands it (consider, for example, that today’s cleanup limits are based on the ability to detect contamination more than on the risk that it poses)? How many billions of dollars do we spend to placate the fears of those who don’t know much about the health effects of radiation?

That last sentence might have sounded unduly harsh, but it is a question that needs to be asked. But before it can be answered here are a few more tidbits to consider.

First, we have to remember that psychosocial issues – and the health effects they engender – have been the most consistent health risk from the Chernobyl accident and it is not unreasonable to think that the same will likely be the same in Fukushima. It is easy to scoff at worries that might not be grounded in science, but these worries are real nevertheless, and they have a long reach. The 330,000 who were forcibly relocated after the Chernobyl accident have experienced elevated levels of depression, substance abuse, and suicide as a result of their experiences. Whether or not they are at risk from radiation is, to some extent immaterial – their fears and anxiety have caused very real problems. Similarly, if we force people to accept contamination levels that, while posing little or no health risk, are alarming to the public it may well be that people will die as a result of the elevated levels of anxiety and depression and the concomitant risks of suicide, depression, and substance abuse. It doesn’t matter if a person is sick from radiation or from anxiety – they are still sick.

We also have to recognize that spending money is – to an extent – risky. Governmental costs that are distributed across society take money out of the pockets of taxpayers. This leaves less money to, say, replace worn tires; less money to pay for doctor’s visits; less money for a healthy diet. So if we are talking about hypothetical lives lost due to depression and other mental health effects then we must also talk about hypothetical lives lost due to the distributed expense of cleanup, not to mention the risks from construction (or deconstruction) activities, excavation, traffic accidents (from transporting rubble), and so forth.

So we still have the question – how far do we clean up if there’s a radiological or nuclear attack? Deaths are deaths, whether caused by radiation exposure, radiation-induced cancer, traffic accidents, worry, or something else. So how do we compare these real and hypothetical risks? And can we compare them well enough to develop – in advance of an accident – a reasonable cleanup recommendation?

Right now there is no clear answer to these questions. State and federal agencies are all carefully dodging the question under the guise of it being a local issue (this one is popular among the federal agencies) while local agencies don’t want to come out with a number today that might be fought and argued over for years to come.

It would be easy for me (or any other health physicist) to calculate a number that would try to balance all of these risks and to pontificate about how any other number would be unreasonable. But the fact is that I don’t have any more of an answer than anyone else. There is more to this topic than pure science – I might be qualified to crunch numbers, but I’m out of my depth when it comes to the political, psychological, and social matters. But it might behoove us to let scientists work directly with politicians and members of the public today to at least get a start on figuring out what level of contamination might be considered acceptable should we have a radiological or nuclear emergency – the more work we can do today to figure out what might be acceptable (both scientifically and socially) the more quickly we can decide how much cleanup we will need to perform.

2 Responses to “Cleaning up”

  1. Steve May 24, 2012 at 2:32 PM #

    “So where do we draw the line?” I think is the point of the article and a great question?

    “Tens of thousands of people are contaminated as well as are many of their pets.” This was used to set the stage for the article. I have a hard time imagining what dirty bomb scenario could cause this extent of radiation release. Nuclear weapon detonation -yes. Dirty bomb scenario – really?

  2. Dr Y May 24, 2012 at 3:47 PM #

    Actually, there are plausible cases in which 10,000 is fairly plausible. Consider, for example, the number of people we cram into sports arenas (over 100,000 in some football stadiums and a few tens of thousands for indoor facilities). Or the crowds in Times Square for New Year’s Eve, not to mention the hundreds of thousands on the National Mall for the 4th of July.

    The bottom line is that there are occasions in which there are a LOT of people in a relatively small area. In addition, there have been papers published in the scientific and technical literature reporting that significant levels of contamination can spread up to a kilometer downwind in a plume that is up to 200 meters across. This is certainly a large enough to encompass tens of thousands of people in some of the locations I mentioned above.

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