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Rethinking Radiation

May 3, 2021

In 1896, the French scientist Henri Becquerel observed spontaneous emissions from uranium and called this phenomenon radiation. The first recorded radiation treatment occurred the same year. Early successful uses of radiation to treat various illnesses and ailments captured the public imagination—everyone hoped their bodily problems could be cured with these seemingly limitless materials.

Marie Curie’s discovery of radium in 1898 also fascinated the public. Its radioluminescence gave it a magical quality, and companies were quick to churn out radium-infused health and wellness products including toothpastes, soaps, beauty creams, and radium pads that could be placed on afflicted body parts. Liquid sunshine cocktails, or radium-infused beverages, became a health fad in the early 1900s. Upper-class consumers in cities around the world were eager to get their hands on these energizing elixirs which were advertised as all-purpose cures.

The public’s love affair with radium fizzled out as reports rolled in of painful diseases and deaths associated with radiation poisoning. One of the most famous examples was the 1920s Radium Girls case. Many women working at clock factories developed osteonecrosis (bone tissue death) and osteosarcomas (bone tumors) around their jaws along with other painful conditions. Over a dozen of the women died. Investigators discovered that the women were interacting with toxic levels of radium by constantly pointing brushes on their lips—the brushes being covered in glow-in-the-dark radium paint, of course.

Eventually, the FDA and FTC (and health officials in other countries) cracked down on the use of radium in consumer products as awareness of radiation poisoning grew. The dangers of radioactive materials overtook the public consciousness in 1945 when the devastation of America’s atomic bombs was revealed. Subsequent studies on radiation and nuclear accidents Three Mile Island (1979) and Chernobyl (1986) further solidified fears of radiation and hindered the development of nuclear medicine.

This is because we are operating under the linear no-threshold (LNT) radiation paradigm, which is based on the ideas that all radiation exposure levels are harmful and each increment of exposure adds to the overall risk of negative health effects. However, a different paradigm emerged in the 1990s. Radiation hormesis, which is still very controversial, is based on the ideas that low levels of radiation exposure produce different effects than high-level exposure. In fact, small doses of radiation may improve health! 

Some scientists believe in this paradigm because the body has already evolved to protect DNA against low-level radiation that occurs naturally. Free radical scavengers are a type of radioprotector molecule that can repair the loss of electrons or hydrogen atoms. This naturally occurs in cellular molecules due to metabolic processes but is also caused by radiation exposure. Free radical scavengers can repair this low-level radiation damage. Another concern with radiation is DNA mutation. It is estimated that 10,000 genetic modifications already happen every hour in your body! Whether the cause is a natural error or low-level radiation exposure, enzymes are constantly checking and repairing DNA. Low-level radiation exposure can also cause cell death during reproduction and interphase. Instead of viewing this as a harmful effect, radiation hormesis interprets this as a positive strategy for the body to prevent damaged cells from reproducing.

This controversial framework is supported by several studies. Among atomic bomb survivors, those exposed to low levels of radiation experience a lower rate of leukemia than average people. This is contrasted by the higher rate of leukemia among survivors exposed to high levels of radiation. Under the LNT paradigm, we expect the leukemia rate to be higher than average even among survivors exposed to low levels of radiation, which is not the case. 

Other experimental studies demonstrate health benefits from low doses of radiation including reducing the likelihood of neoplastic transformation (when cells begin to grow abnormally or excessively, which can be benign or cancerous), activating enzymes and mechanisms that protect and repair DNA, and stimulating the immune system. Again, the LNT paradigm leads us to expect the opposite results, that even low-level radiation would negatively impact these areas of health.

So what does radiation hormesis really tell us? Is it okay to guzzle liquid sunshine cocktails again if the radium dose is small enough? Let’s hold off on that…in the meantime, we can take inspiration from the radiation hormesis framework and curb our knee-jerk negative reaction to anything involving radiation. Who knows what will be discovered if we open our minds to the possibilities of nuclear medicine and nuclear energy! 

(Reminder: refrain from immediately ingesting any new discoveries…)

Holcomb, W. F. (1999). Humanity and radiation: The good, the bad, and the unusual. Military Medicine, 164(7), 520-5. Retrieved from https://go.openathens.net/redirector/gatech.edu?url=https://search.proquest.com/scholarly-journals/humanity-radiation-good-bad-unusual/docview/217055431/se-2?accountid=11107

Jolly, D., & Meyer, J. (2009). A brief review of radiation hormesis. Australasian Physical & Engineering Sciences in Medicine, 32(4), 180-7. Retrieved from https://go.openathens.net/redirector/gatech.edu?url=https://search.proquest.com/scholarly-journals/brief-review-radiation-hormesis/docview/204630213/se-2?accountid=11107

Prekeges, J. L. (2003). Radiation hormesis, or, could all that radiation be good for us? Journal of Nuclear Medicine Technology, 31(2), 11-7. Retrieved from https://go.openathens.net/redirector/gatech.edu?url=https://search.proquest.com/scholarly-journals/radiation-hormesis-could-all-that-be-good-us/docview/218635974/se-2?accountid=11107

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Sabrina is a fourth year student studying Computational Media and Industrial Design at Georgia Tech. She enjoys writing about the fantastic and strange, mindlessly scrolling through memes, and drinking a lot of tea.

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.