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Are skin care products really useful?

November 10, 2017

WechatIMG101There is a saying that everyone can be a beauty and it seems true more than ever in today’s world. Nowadays, both boys and girls are taking skin care more seriously to make their skin smooth and to look young and pretty. A recent study showed that skin texture plays a significant role in the judgment of female facial beauty. [1] Thus, it is not surprising that a girl can accumulate tons of bottles of skin-care products on her dressing table. Even boys at least have one facial cleanser. In my own experience, I use a various of skin-care products because my face gets oily and grow pimples and acne easily. I need to be extra careful since my skin is so sensitive that if I don’t choose the right products, it turns red and itchy. I do worry about if there are some side-effects and whether these countless skin-care products that come from different regions all over the planet are useful or not.

Let’s look at our skin structure first. There are three layers called the epidermis, the dermis and hypodermics in our skin. The layer skin-care products contact most is the epidermis, which it the outermost layer of skin, providing a waterproof barrier and creating our skin tone. What’s more, there are two layers of epidermis, the living basal layer, which is next to the external stratum corneum, or horny layer, which is composed of dead, keratin-filled cells that have migrated outward from the basal layer. Most of the exfoliators and cleanse products are dealing with the stratum corneum layer.

Thus what skin care products actually can do is basic moisturizing, which is a totally physical function rather than chemical. Looking at the ingredients of moisturizing products, it is not hard to find  mineral oils, synthetic oils, plant oils in order to soften and moisten skin. Glycerine and propylene glycol are used for moisture absorption. These ingredients help skin to stay smooth by preventing the loss of water and oxidization.

Another important skin product is sunscreen and cream for isolating the UV and atmosphere pollution or dust. Krysta Biniek, a researcher in Stanford University wrote that “Although the ubiquitous presence of solar UV radiation in human life is essential for vitamin D production, it leads to skin photoaging, damage, and malignancies solar UV radiation poses a double threat to skin by both increasing the biomechanical driving force for damage while simultaneously decreasing the skin’s natural ability to resist, compromising the critical barrier function of the skin”[2] .

Products like skin whiteners have some serious side-effects. There is one study that showed that skin-lightening creams contained higher concentration of the studied metals than the moisturizing creams. Also, people who use skin-lightening creams are potentially exposed to higher concentration of metals. Last but not least, chromium was found at concentrations that can induce allergenic contact dermatitis in pre-sensitized individuals.[3]  Based on this finding, the ingredient of skin whitening products become extremely crucial. So next time when you go shopping, remember to take a look at ingredient list. Natural sources are  much better than chemicals. There is also a scientific analysis that discusses advantages of natural sources. It says that  “Although a number of hypopigmenting products have been developed, those from natural sources are preferred and will predominate in the cosmetics market. More active compounds such as phenols, flavonoids, coumarins and other derivatives have been identified from natural sources. This article summarized natural skin whitening products involving tyrosinase blockers like phenols and polyphenols, and non-tyrosinase blockers like α-MSH, melanosome transferase and cytokine inhibitors.”[4] All in all,don’t forget to take a look at ingredients of skin whitening products when you are shopping. 

Generally if you want to have a glowing skin, the easiest way is try to get a nice DNA at the very beginning of your life. Just kidding! Don’t be fooled by flowery words in advertisements and stay away from those products which have impossible crazy functions. You can surely earn a great skin by choosing suitable skin product and clean, moist and put sun cream everyday. So I guess the magic to have a nice skin is your perseverance.

[1]Fink, Bernhard, Karl Grammer, and Randy Thornhill. “Human (Homo sapiens) facial attractiveness in relation to skin texture and color.” Journal of Comparative Psychology 115.1 (2001): 92.

http://dx.doi.org/10.1037/0735-7036.115.1.92

[2]Biniek, Krysta, Kemal Levi, and Reinhold H. Dauskardt. “Solar UV radiation reduces the barrier function of human skin.” Proceedings of the National Academy of Sciences 109.42 (2012): 17111-17116.

http://www.pnas.org/content/109/42/17111.short

[3]Iwegbue, Chukwujindu MA, et al. “Safety evaluation of metal exposure from commonly used moisturizing and skin-lightening creams in Nigeria.” Regulatory Toxicology and Pharmacology 71.3 (2015): 484-490.

http://www.sciencedirect.com/science/article/pii/S0273230015000173

[4]Lin, Jen-Wen, et al. “Natural products with skin-whitening effects.” Journal of food and drug analysis 16.2 (2008).

https://search.proquest.com/docview/1282142799?pq-origsite=gscholar

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Eileen Zhu
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Eileen is currently second year ISYE student at Georgia Tech. She is interested in math, art and sports.

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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.