Cancer Risk from Radiation

Sources

Something needs to be said about the many ways that people can be (and are being) exposed to radiation. The three major sources of dosage come from cosmic radiation, man-made sources, and natural sources, like radon. The 'natural' dose which a person receives is very low but is almost always present in the background - as is cosmic radiation. Man-made sources are generally regulated materials and are properly shielded, assuming those in possession of the material adhere to proper safety procedures.

The link between cell phones and problematic symptoms of radiation exposure has been studied in great depth.Websites like Xrayrisk.com and Cancer.org help disseminate valuable information on the types and consequences of radiation exposure. For example, statistics on the effects of radiofrequency radiation into tissue by cell phone  use are provided, and many rumors are dispelled (+1 for the nuclear community!). Factors like time of exposure, use of speakerphone or handsfree functionality, phone model, phone traffic in area of usage, and distance to the nearest phone tower can all shape the final exposure. Most people are interested in the effect that x-rays and gamma rays have on them, though. Medical imaging techniques are known to add to annual exposure for individuals who seek such diganostics. This can be problematic for those who have occupational dose limitations, or even for pregnant women. The  risk of second cancer has been evaluated by many groups. Radiation therapy health effects were assessed by studying survivors of the the atomic bomb blasts in Japan.

What role does the EPA play?

The "Blue Book" is a name given to the EPA's Radiogenic Cancer Risk Models and Projections for the U.S. Population document. It is a revision of their methodology for estimating cancer risks from exposure.Calculation methods and risk modeling,are given alongside copious amounts of public epidemiological and radiobiological data. The following is presented at the conclusion of their description of the document: "In general results from these data are consistent with a linear no-threshold (LNT).The assumption that the risk of cancer increases linearly as radiation dose increases. This means, for example, that doubling the dose doubles the risk and that even a small dose could result in a correspondingly small risk. Using current science, it is impossible to know what the actual risks are at very small doses." 

In short, the EPA provides the public with adequate pertinent information concerning cancer risk. This is especially so in the case of EPA 402-R-93-076 'Estimating Radiogenic Cancer Risks' where low-LET radiation is considered. The dose and dose rate effectiveness factor are presented at various conditions. High-LET (alpha - RBE factor of 20) risks are presumed to have a linear proportionality to dose and is independent of dose-rate.

Attempts are made to estimate low dose radiogenic cancer risk (which basically describes the likelihood of cancerous harm from ionizing radiation). Biologically based dose-response (BBDR) models can incorporate data on biological processes at the cellular and molecular level to link external exposure to an adverse effect. Organ-specific risk per unit dose for a stationary population is achieved through the use of these risk models. One model to consider for future blog posts is the atmospheric dispersion model.

Exposure Aftermath

Interestingly, when someone is exposed as a result of a mistake on the part of another party, compensation programs provide monetary help to make up for the saddening and traumatic experience. This and more will be considered at a further time...

References:Radiation Exposure and Cancer

http://www.cancer.org/cancer/cancercauses/radiationexposureandcancer/index

Cellular Phones

http://www.cancer.org/cancer/cancercauses/othercarcinogens/athome/cellular-phones

Radiation Risk From Medical Imaging

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996147/

How Much Do CT Scans Increase the Risk of Cancer

http://www.scientificamerican.com/article/how-much-ct-scans-increase-risk-cancer/

Blue Book: EPA Radiogenic Cancer Risk Models and Projections for the US population

http://www.epa.gov/radiation/blue-book-epa-radiogenic-cancer-risk-models-and-projections-us-population

Estimating Radiogenic Cancer Risks (June 1994)

http://www.epa.gov/sites/production/files/2015-05/documents/402-r-93-076.pdf

Analyis of Cancer Risks in Populations Near Nuclear Facilities: Phase I

http://www.ncbi.nlm.nih.gov/books/NBK201995/

BBDR Models in Estimating Low-Dose Risk

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2866670/

dichloromethane --> could be interesting to learn about