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The Sweet Science of Honey

By: Sophie D.

Most people think of honey as a type of sweetener, delicious to add to bitter tea or drizzle over crisp apple slices. For the bees that make it, honey is a food source, useful because of its ability to last through winter when plant nectar is no longer available. Honey is certainly also known for its healthy properties beyond food; we can find it in lip balms, lotions, and even soap! What you may not know about honey, though, is its unique ability to measure pollutants. And guess what? It’s pretty sweet.

This past fall, I was tasked with designing a research project for a high school course called AP Capstone. I knew I wanted to research pollution in Chicago, and I was also really interested in urban beekeeping, but I didn’t know quite where to start. When I reached out to the environmental science teacher at my school (who also happens to be a beekeeper), she referred me to studies done around the world that used honey as a bioindicator for pollution. At first, I was a bit hesitant, and frankly, confused. The studies were very complex, detailed with advanced chemistry, statistics, and research techniques that I had never seen before and certainly didn’t know how to replicate. I mean to start, what does “honey as a bioindicator for pollution” even mean? Still, I was intrigued by the concept, and dug into study after study, reading about the pollutants in Syria, Lebanon, Canada, France, Poland, Romania, and so many other countries.

When I was about a dozen studies in, the main idea started to click. Bees interact greatly with their respective environments; if they live in a specific neighborhood, they drink from the natural water sources in that neighborhood, pollinate the vegetation in that neighborhood, fly through the air in that neighborhood, and so on. All of this nonstop action is extremely close to their beehive, because bees only travel up to four kilometers away from their hives. Due to this mega-local bee to neighborhood interaction, if the soil, air, water, or vegetation in a particular neighborhood has a huge concentration of a heavy metal, such as lead, the bees from that neighborhood would be interacting with the lead constantly! All of this is to say, bees are living examples of their neighborhoods’ health. Because of this, some scientists have attempted to study bees to get a better idea of how healthy (or polluted) a particular area is. The problem with that approach is that bees are busy, hardworking organisms, and when bothered, they sting! Not the best participant in your scientific study, right? So, for many scientists, that begs the question: what could we use that would have the same proximity to the environment as bees, but is maybe a little easier to work with? That’s right: honey.

Scientists quickly realized that honey, along with other bee products like propolis and wax, have similar heavy metal concentrations as the soil, air, water, and vegetation of the environments they were made in, due to their busy manufacturers. Because honey contains the same dangerous pollutants that its respective origin contains, we can actually measure the traces of different metals in honey samples to discover how polluted certain areas are. That’s where the whole bioindicator for pollution aspect comes in, as honey is essentially a microcosm for the pollutants in its original neighborhood.

When I understood how honey acted as a bioindicator (many studies into my preliminary research), I made an insightful realization. Although these studies have been performed around the world, there is yet to be one published in the United States. Feeling a little excited, I realized that with some help, I could be the first person in not just Chicago, but all of America, to do this research. After getting my project idea approved by my research teacher, I immediately got to work. I began by collecting honey samples from across the city of Chicago, and even in the suburbs. Every beekeeper I asked was super excited about the project and willing to get on board. All in all, I collected 25 samples from Chicagoland.

Honey samples after dissolving in nitric acid and hydrogen peroxide and incubating for a few hours, ready to go through ICP-MS process

(also you can see I was wearing gloves because lab safety>>)

Tray with all 25 samples, caps were labeled with letters of the alphabet to keep track of what was what!

The next aspect of the project was a little tricky. Having the honey samples is a great start, but serious technical equipment is needed to measure the traces of heavy metals inside of them. A fancy technology, called Inductively Coupled Plasma Mass Spectrometry (or ICP-MS for short), detects the unique weights of different heavy metals, and is the most common way to figure out the concentrations of the metals inside of honey samples. Fortunately, my project mentor Ms. Ang (who gave me the initial idea to look into these types of studies) got in contact with the head of the ICP-MS labs at Northwestern University. They had a special research grant for high schoolers, which allowed me to access their equipment (with adult supervision and management) completely for free. At the lab, I was greeted by a friendly scientist named Rebecca Spoonenberg, who performed many complex or potentially dangerous experiments, and taught me a lot about chemistry. It was an incredible experience, and I walked away with all of the information necessary to analyze the pollution of neighborhoods in Chicago.

Inside of ICP-MS technology before it was turned on

Exterior view of the ICP-MS technology (after being turned on), it was super hot!

Before I analyzed the data, though, I did have to make a hypothesis. The Chicago city government has a map of industrial corridors, or areas designated for industrial development (mining plants, factories, etc.). What makes the industrial corridors problematic is that they are often located in neighborhoods made up of predominantly people of color. While there are claims that these industrial corridors are safe for the residents living in neighborhoods around them, I was a little skeptical. So back to the hypothesis—I predicted that: If Chicago apiaries are located within extreme or high proximity to industrial corridors, then they will contain greater concentrations of heavy metals in their corresponding honey samples. And after weeks of careful analysis, I found that the data mostly supported my initial prediction. Metals that are considered to be extremely toxic in smaller concentrations were abundant around industrial corridors, and not so prominent in honey samples from hives farther away. Even though my hypothesis was generally supported, I did find that there was room for error in a lot of my data, making it all the more important for my study to be replicated. I was surprised by the high concentrations of heavy metals in suburban data, and realized that there were more industrial corridors in the suburbs than I was previously aware of.

Computer updated with live data from ICP-MS

At the end of the day, my project was pretty successful. I submitted my 43 page AP Capstone paper to the College Board, and I am currently working on publishing a shorter version to a high school science journal. Most importantly, I learned a lot about the environment, honey bees, chemistry, and research, and I hope you now have too! And who knows? Maybe honey has more sweet superpowers in store for you to discover next.

Discussion Questions:

  • How important is it to research pollution levels in big cities like Chicago and their suburbs as opposed to rural and agricultural locations?

  • After drawing conclusions about environmental racism, climate health, and more from scientific research, how can we ensure real action is taken to address major problems?


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