Exposure to natural radiation

Recently my daughter and her husband bought their new home in Maryland. The house has a full, below grade basement, pretty common for that part of the country.

Also common for much of the East Coast and big chunks of Appalachia and the heartland, there is concern about potential radon exposure. Radon is a radioactive gas that can leach out of naturally occurring radioactive material in the ground. Some communities require radon remediation systems (basically a pump in the basement that exchanges stale air for fresh air from the outside, thereby not allowing radon levels to accumulate). Sure enough, my daughter’s new home had a radon remediation system – except that the pump ‘sucked’. Actually, it did not suck, as it is supposed to, and that was the problem. Given my ever present worries about familial CLL I bugged her until she took care of the problem.

Below is a map of the USA color coded for the level of radon risk. Darker areas (Zone 1) are at higher risk.

USA EPA Radon Zone Map

How much is too much?

Day in and day out, we are all exposed to radiation from a variety of sources. Even if your home has a perfectly functioning radon remediation system, you cannot do much about cosmic radiation that sleets down on earth. Live at a high elevation? Cosmic radiation levels are higher since there is a thinner blanket of atmosphere to protect you. Do a lot of airplane travel? Your exposure has just gone up. Every ten days we get exposed to natural radiation that is the equivalent of one chest X-ray.

The most popular unit of measuring radiation is named after Professor Rolf Sievert, 1896-1966, who spent a life time researching radiation exposure. A millisievert (mSv) is a thousandth part of a sievert (Sv). There are other units of measurement (rad, rem, gray, roentgen etc) but we will stick to millisievert (mSv) for the rest of this article. Most of us get an average of 3 mSv radiation exposure every year just by living on earth.

Why the sudden interest in radiation?

A recent article in the NY times caught my eye and I decided to do some digging. Pretty interesting article with some startling quotations, I suggest you click and read the full article.

The Consumer

With Rise in Radiation Exposure, Experts Urge Caution on Tests


Published: June 19, 2007

CT scans and X-rays are revolutionary, but they carry risks, too, a new study suggests.

“This is an absolutely sentinel event, a wake-up call,” said Dr. Fred A. Mettler Jr., principal investigator for the study, by the National Council on Radiation Protection. “Medical exposure now dwarfs that of all other sources.”

Radiation exposure and CLL

Until very recently most CLL experts would have dismissed the notion that exposure to radiation had anything to do with CLL. As the study abstract shown below reports, roughly 300,000 nuclear workers in 15 countries were studied for any increased risk of death due to CLL. As you might expect, these people had larger radiation exposure than the average Joe. But even this very large cohort study failed to prove conclusively that there was any connection between CLL and radiation exposure. But the authors point out that they could not rule out the connection either.

Just when we migth have heaved a sigh of relief and quit worrying about radiation exposure, here come two credible articles that raise the question all over again. Notice the first abstract is authored by none other than Dr. Terry Hamblin.

Leuk Res. 2008 Apr;32(4):523-5. Epub 2007 Oct 29.

Have we been wrong about ionizing radiation and chronic lymphocytic leukemia?

Hamblin, T.J.

It is almost axiomatic that chronic lymphocytic leukemia (CLL) is not caused by ionizing radiation. This assumption has been challenged recently by a critical re-appraisal of existing data. A recent paper implicated radon exposure in Czech uranium miners as a possible cause of CLL and in this issue of Leukemia Research the first paper examining the incidence of CLL among those exposed to radiation from the accident at the nuclear power plant in Chernobyl is published. It suggests that CLL occurring among the clean-up workers was of a more aggressive form than is normally seen in the community.

PMID: 17915317

As most of us are aware, one of the most important prognostic indicators in CLL is the IgVH gene mutation status. People with the mutated form can expect to have a very indolent and comfortable form of CLL while those with unmutated IgVH gene can expect a faster growing variety that needs frequent intervention and less than wonderful response to many of the available therapy options.

The next abstract (below) compared 47 CLL patients that had been exposed to radiation due to the Chernobyl (nuclear reactor in Russia) accident with a control group of 141 CLL patients that did not get exposed. A third group of 19 patients were among the clean-up workers. I would expect these poor people had the highest rates of radiation exposure. Here is the kicker: a whopping 94% of these 19 CLL patients had unmutated IgVH (as well as the most dangerous gene usage) and also had the highest risk of Richter’s transformation. Wow. I can understand why Terry Hamblin has decided to take a second look at the potential connection between radiation exposure and CLL risk factors. Whether or not radiation causes CLL, there seems to be grounds to wonder if it causes the CLL to be of a more aggressive variety.

Leuk Res. 2008 Apr;32(4):535-45. Epub 2007 Sep 25.

Chronic lymphocytic leukemia patients exposed to ionizing radiation due to the Chernobyl NPP accident–with focus on immunoglobulin heavy chain gene analysis.

Abramenko I, Bilous N, Chumak A, Davidova E, Kryachok I, Martina Z, Nechaev S, Dyagil I, Bazyka D, Bebeshko V.

Research Centre for Radiation Medicine, Academy of Medical Sciences of Ukraine, Kyiv, Ukraine.

Clinical data and immunoglobulin variable heavy chain (IgVH) gene configuration were analyzed in 47 CLL patients, exposed to ionizing radiation (IR) due to Chernobyl NPP accident, and 141 non-exposed patients. Clean-up workers of the second quarter of 1986 (n=19) were picked out as separate group with the highest number of unmutated cases (94.4%), increased usage of IgVH1-69 (33.3%) and IgVH3-21 (16.7%) genes, high frequency of secondary solid tumors (6 cases) and Richter transformation (4 cases). These preliminary data suggest that CLL in the most suffered contingent due to Chernobyl NPP accident might have some specific features.

PMID: 17897714

What is your level of exposure?

As I wrote above, all of us are exposed to radiation due to where we live, our lifestyles and the quality of our home construction. If you are curious about your own exposure, here is a link to a questionnaire that might help you determine your risk.

Used to be a medical examination meant a lot of poking and prodding, laying of hands and experienced doctors using their eyes and hands to examine patients. How things have changed! Now most of the “physical contact” stuff is done by nurse practitioners and you are lucky if your doctor so much as shakes hands with you. And for complicated stuff like the status of your spleen and the size of your deep abdominal nodes, it is easier to scribble a prescription for a CT or PET scan. Hey, insurance covers the costs, right?

Well, insurance may pay for some or most of the dollar cost, but you (as in your body) pay for 100% of the radiation exposure. As the New York Times article above points out, we have become a nation of test junkies, the more high-tech the better. The unfortunate silo mentality between different doctors and different specializations means they don’t always talk to each other. Each one prefers to get a new CAT or PET scan done to get whatever information he or she needs, not bothering to check if a prior scan done just weeks ago would suffice. Not all scans are the same or pose the same risk. It is important that we as patients understand how much radiation exposure is involved in many of the common radiology procedures. Here is a short list. You can find a more comprehensive list by clicking on this link.

X-Ray Radiation Exposure

Does this mean you absolutely refuse all CAT & PET scans?

No, it does not. By now you should know life with CLL is a complicated business and there are never easy or simple slam dunk answers. Should you get a scan every other week just because your doctor is a little trigger happy? Common sense suggests that might be foolish and at the very least you should be asking your doctor why the frequent CT scans are necessary and what he hopes to learn from them.

But on the other side of the coin, I have heard from patients who categorically refuse all scans, even when they are needed for making good therapy choices. As we pointed out in a prior article (“To wait or not to wait“) sometimes therapy decisions are based on the status of the disease as determined by the size of deeply buried abdominal nodes that cannot be felt by even the most experienced doctor’s fingers. Is ignorance bliss? Will you be better off by letting the darn buggers percolate untreated, getting larger and meaner over time? Or would you be better served by knowing the size of the enemy and therefore able to make sensible choices on when to initiate therapy and what  would be your best therapy choice?

I cannot overstate the importance of simple garden variety commonsense in many of the decisions we have to make, in consultation with our doctors. If you are looking for easy answers that you can follow with brain-not-in-gear, you will pay a huge price for that lack of attention to detail. None of us would (or should) use CT and PET scans just because. But sometimes CLL puts us between a rock and a hard place. Use your head, ask questions, pay attention and make informed decisions. That advice goes for when and how many scans you get as well.

Please accept my apologies for the long break between articles. I and Radha (she is also our webmaster) needed to take some time off to observe a sad first anniversary of death of a beloved husband and father.