Lindsey St Mary in her toxicology lab

Lindsey St. Mary is an Environmental Toxicologist studying for a PhD at Heriot-Watt University. She works as part of a team of researchers from across Europe studying a group of chemicals called polycyclic aromatic hydrocarbons, or PAHs for short. These chemicals are found both on earth and in space, however their perspective and effects are very different in each location!

Where do PAHs come from?

They are formed through the incomplete combustion of organic material. Essentially this means they’re created by anything that results in a fire; such as wood burning, smoking, car exhaust fumes, volcanic eruptions, etc.

What are you and your team trying to understand about PAHs?

We already know that they are toxic so, as a toxicologist, I view PAHs as an environmental contaminant. I’m interested in identifying and understanding their toxicity and potential to harm human and animal life here on earth. Our team of 16 is multi-disciplinary and includes engineers, chemists, astronomers, physicists, experimental physicists, theoretical chemists and a social scientist. Other researchers in the team are looking at reactions and effects of PAHs in space.

Why is it important to understand more about PAHs?

PAHs were around long before humans, created through natural processes like volcanic eruptions and forest fires. Since the global increase of industrial processes, the production of PAHs has dramatically increased so we are being bombarded by PAH exposures daily. Over time our bodies have evolved ways to metabolise and get rid of PAHs after exposure. Part of the way our bodies try to rid themselves of PAHs is to ‘activate’ them with various enzymes. Unfortunately, this can create toxic by-products called reactive oxygen species. Antioxidants play a part in ridding the body of these by-products, which is why we are often encouraged to consume products containing antioxidants. Activated PAHs can sometimes bind directly to DNA causing a mutation which could possibly be the first step along the pathway leading to cancer.

So that’s the effect PAHs have on Earth, but you also mentioned they exist in space?

Yes, in space PAHs play an important part in understanding the creation of stars, meteors and solar system bodies, so astronomers and astrophysicists can actually use PAHs as a way of figuring out what’s happening in space. By understanding how these chemical reactions occur and contribute to the formation of stars and solar system bodies, like comets and asteroids, it may lead to an understanding of how our own planet was formed.

To find out more about Lindsey’s research, visit the project website.

Lindsey is part of the Heriot-Watt Year of Health team who are running science activities for children at Party at the Palace in Linlithgow on Saturday 10th and Sunday 11th August 2019.