Difference between revisions of "Team:SF Bay Area DIYBio/Practices"

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Human Practices

Why was PABA banned (at least from sunscreens) in the EU?
Para Aminobenzoic Acid (PABA) is a once-common ingredient in sunscreen, now avoided due to allergic dermatitis and photosensitivity (1A). Research indicates PABA has carcinogenic potential in rodents(1B). PABA derivatives are now more commonly used, but these too may have health concerns (Figure 1). Additionally, beyond the damage possible through exposure to one of these compounds, there is the possibility of additive effects with multiple chemical sources and also the time dependant and environment dependant effects.

Figure 1 (PABA derivatives) - 4-Aminobenzoic acid; aminobenzoic acid; P-aminobenzoic acid; P-carboxaniline; 4-aminobenzoic acid; 4-carboxaniline; amben; aminobenzoic acid; anticanitic vitamin; P-aminobenzoic acid; pcarboxyaniline

PABA’s use as a sunscreen component is intended to protect skin DNA from mutagenic effects of UV light. However, concerns have arisen following studies that indicated PABA induces its own DNA damage when applied to human skin cells in vitro and exposed to UV light, despite it’s UV protection of the skin cells from incident UV rays (1C). To quote the paper directly, “Human cells irradiated with a sunlamp in buffer containing PABA have a frequency of transformation...nearly 10 times higher than that of cells irradiated in buffer alone...the relevance of these in vitro findings to the safety of PABA is not clear. “ To be clear, this study was not done in vivo in humans and there is no evidence that use of PABA has caused any known human disease except benign allergic dermatitis (skin allergies) (1A).

Shortly following the study that showed PABA’s ability to damage human skin cells under UV light, the EU banned it’s use. It was banned for use in cosmetic consumer products due to failure on the cosmetics industry part to supply the Scientific Committee on Consumer Products (SCCP) with additional information that conformed to current standards and guidelines. PABA was subsequently removed from Annex VII I (List of UV filters which cosmetic products may contain) and added to Annex II (List of substances which must not form part of the composition of cosmetic products) It is not banned in all consumer products outright as the effects are only known to occur when used on skin in UV light.

Some sunblock compounds damage corals (big issue with snorkelers)
With the rise in the use of sunscreen, as well as increased human activity near coral reefs, a concern on the impacts humans have near and on these ecosystems has become a growing concern 2A. The decline in the health of coral reefs around the world over the past 50 years prompted the need for a more benign sunscreen 2B. A great deal of attention has become focused on human activity’s impact on these fragile biomes, specifically with respect to the deleterious effects of sunscreen on marine ecosystems. Research has shown damage to coral reefs can occur via multiple pathways associated with chemical effects due to ingredients found within sunscreen. One such compound is benzophenone-2, or BP-2; a UV blocker. The effects of BP-2 on coral are multi-faceted. Low concentrations can kill juvenile or developing corals. Additionally, BP-2 has a bleaching effect, causing a discoloration of the outward appearance of the coral. Furthermore, BP-2 has been linked inducing or increasing the mutation rate of corals by damaging DNA. BP-2 is also a known endocrine disruptor and a weak genotoxicant 2C.A second method of coral damage can occur via a trojan attack on the symbiotic algae that live in healthy coral tissue. The algae provide nutrients to the coral through photosynthesis, the coral provide a protective living space for the algae. Several compounds have detrimental effects on the algae including, but not limited to paraben, cinnamate, benzophenone, and camphor derivatives. These compounds have been found to stimulate dormant viral infections in the algae. This has a domino effect by causing a viral outbreak once a virally weakened algae population explodes into the surrounding coral community 2D. “The [negative] effect of sunscreens is due to organic ultraviolet filters, which are able to induce the lytic viral cycle in symbiotic zooxanthellae with latent infections.”
Some sunblock compounds damage corals, this has profound implications for snorkelers, swimmers, or other water seeking recreationalists; natural compounds like mycosporine that come from algae or coral should be much better for coral ecosystems due to their presence in the reef system 2E.

Other Environmental Effects
Concerns have arisen with other possible environmental effects of sunscreen ingredients with a specific ingredient, Titanium Dioxide (TiO2). TiO2 can react in water to allow compounds such as H2O2 to form which can alter coastal chemistry and have resulting environmental impact. A study published in 2013 analyzed the organic and inorganic compounds that end up in coastal seawater at beaches where tourism is prevalent (3A). They found that phosphate and hydrogen peroxide were found in environmentally relevant concentrations and that this could increase algae growth, and have cascading effects on the local ecosystem. Further research is needed into this area: naturally occurring compounds used in sunscreen (such as mycosporines) may result in reduced environmental impact or unforeseen downstream consequences.

Human toxicity/disease effects
UV-protective mycosporine-like amino acids (MAAs) such as shinorine are not known to be toxic to humans. There are no known studies on toxicity of these compounds, however, based on the human consumption of a variety of organisms that contain and produce these compounds in quantity, we know that they have relative safety 4A.
In fact, many MAAs have simultaneous anti-oxidant properties in addition to their UV absorbing properties and thus may actually be beneficial in certain human conditions and when used for certain applications.
In one mammalian study (mice), were fed a high MAA diet to see if they were able to accumulate the MAAs in their body to offer UV protection, and it was found that MAAs did not accumulate in their tissue to any considerable degree. We can infer some degree of safety from toxic accumulation based on this result.
Marine microorganisms harbor a multitude of secondary metabolites. Among these are toxins of different chemical classes as well as the UV-protective mycosporine-like amino acids (MAAs). The latter form a group of water-soluble, low molecular-weight, that do not bioaccumulate upwards through the food chain.

Public Reception on E. Coli
This is a very good opportunity to combine our fundraising efforts and public discourse. A survey was conducted to see the public's perspective, knowledge, and acceptance of existing sunscreens and genetically engineered sunscreen.

References
1A. Dromgoole SH, Maibach HI. Sunscreening agent intolerance: Contact and photocontact sensitization and contact urticaria. J Am Acad Dermatol. 1990;22(6):1068–1078. doi:http://dx.doi.org/10.1016/0190-9622(90)70154-A.
1B. Gurish MF, Roberts LK, Krueger GG, Daynes RA. The Effect of Various Sunscreen Agents on Skin Damage and the Induction of Tumor Susceptibility in Mice Subjected to Ultraviolet Irradiation. J Investig Dermatol. 1981;76(4):246–251. Available at: http://dx.doi.org/10.1111/1523-1747.ep12526084.
1C. Taylor CR, Stern RS, Leyden JJ, Gilchrest BA. Photoaging/photodamage and photoprotection. J Am Acad Dermatol. 1990;22(1):1–15. doi:http://dx.doi.org/10.1016/0190-9622(90)70001-X.
2A. http://mesfiji.org/resources/environment/threats-to-coral-reefs-human-impacts
2B. http://earthobservatory.nasa.gov/Features/Coral/
2C. Toxicological effects of the sunscreen UV filter, benzophenone-2, on planulae and in vitro cells of the coral, Stylophora pistillata; http://rd.springer.com/article/10.1007/s10646-013-1161-y
2D. Sunscreens Cause Coral Bleaching by Promoting Viral Infections Roberto Danovaro, Lucia Bongiorni, Cinzia Corinaldesi, Donato Giovannelli, Elisabetta Damiani, Paola Astolfi, Lucedio Greci, and Antonio Pusceddu: http://www.ie.unc.edu/enec259/docs/sunscreen_and_coral.pdf
2E. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2291018/#b23-ehp0116-000441/
3A. Tovar-Sánchez A, Sánchez-Quiles D, Basterretxea G, et al. Sunscreen Products as Emerging Pollutants to Coastal Waters. PLoS One. 2013;8(6):e65451. Available at: http://dx.doi.org/10.1371%2Fjournal.pone.0065451.
4A. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2525485/