Our complicated relationship with chemicals

Nina Sarmiento, Binghamton University

Chemicals found all around us that have been altered, mimicked, and synthesized to be added to our products, are behind the success of our modern society. They have made our plastics strong, our crops prosperous, and our medicines effective. But I have always wondered about the toxicity of these chemicals.  When you look at their biological activity, a chemical might possess the potential to do harm, like interfere with biological processes. The safety of a potentially harmful chemical is based on exposure and dose. It is important to know if we are touching it, eating it, or breathing it in, and for what period of time. The study of evaluating the harmful effects of substances on exposed organisms is what toxicology is all about. They have such an important job because their findings influence what we know is safe and unsafe, for us and organisms all around us.

I learned early on from pursuing biology that we are exposed to many things we are unaware of. Not only are we exposed to potentially harmful chemicals, but we facilitate exposure to other living organisms that may more sensitive. Take dogs for simple example. The toxic dose of something like chocolate for humans is very high, whereas leaving a small amount of chocolate out for a dog to eat could easily kill it.  Rachel Carson is someone I greatly admire, whose work on the pesticide DDT also exemplifies this reality. Food crops were the target for DDT, but birds were indirectly ingesting it, explaining the decline in the Bald Eagle population.  She is one of the people that sparked my interest in ecotoxicology, looking at the effects of harmful substances on ecology, not just humans.

unnamedThis is an example of some of the questions ecotoxicologists ask when there is a potentially harmful substance found in the environment. Photo credit: globe.setac.org.

Here is a chemical product you may not suspect as a threat, sunscreen. In sunscreens, UV filters protect you from getting burned, but also can act as endocrine disruptors, altering hormones and growth (1). Sunscreens are only meant for human skin, however they end up in our lakes, rivers and oceans through swimming or through waste water treatment effluent (2). Unintentionally, many more organisms become exposed.

Toxic-Sunscreen

Photo credit: thesleuthjournal.com

In my project I will be using sea urchins as a model organism to study the effects sunscreens might be having on coral reefs.  I am learning how to preform toxicity tests on sea urchin sperm and embryos which involve an exposure period with sunscreen formulations and then evaluation of effects. I hope to investigate if the chemicals from sunscreens in the water can have negative impacts on coral reproduction.  My work can potentially help create understanding of how humans are contributing to coral reef decline, and influence others to take action to protect them.

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This is a picture of sunscreen water accomodated fractions (WAFs) I am making. They are a mix of sunscreen and seawater and I will be exposing the sea urchin embryos to each solution!

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This is me in the lab with a microscope I use to look at sea urchin sperm and embryos! Photo by Bob Podolsky

My research is funded by the National Science Foundation and College of Charleston partnered with National Oceanic and Atmospheric Administration

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Works cited:

1 Krause M.,, Klit A., Jensen M., Soeborg T., Fredrickson H., Schlumpf M., Litchensteiger W., Skakkebaek N E., Drzewieck K T. 2012. Sunscreens: are they beneficial for health? An overview of endocrine disrupting properties of UV-filters. International journal of andrology. 35 424-436.

2Kyungho C., Kim  S. 2014. Occurances, toxicities, and ecological risks of benzophenone-3, a common component of organic sunscreen products: a mini review. Environment International. 70 143-157.

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