Take a moment and imagine a street in Paris in the 18th century, much like this depiction of “Place du Havre, Paris, Rain” by Camille Pissarro. The first things you’ll notice: it’s beautiful, romantic, bustling. But what you might not notice is that is also very, VERY smelly.
Back then, sewer systems were extremely unsophisticated, and the smell of rotten eggs spilled into the streets. Even more, if a person were to go too far below ground, they would likely find themselves dead in minutes. The culprit? Hydrogen sulfide, a gas that smells of rotten eggs and is produced when bacteria breakdown the organic material found in sewage.
Thankfully for us, modern-day sewers have come a long way since the 18th century, but so has our understanding of this smelly, toxic gas. In the last 10-15 years, scientists have found that hydrogen sulfide is important for cell-to-cell communication in our bodies. Additionally, exposure to low levels of hydrogen sulfide has beneficial effects on many different organisms. For example, plants exposed to hydrogen sulfide grow better, and worms grown in hydrogen sulfide are long-lived! Remarkably, in rats and mice, treatment with hydrogen sulfide also protects against damage from devastating injuries including stroke, heart attack, and severe blood loss. With so many recent discoveries highlighting the benefits of hydrogen sulfide, you may be asking yourself:
How can something that is so deadly also be beneficial?
The answer lies in the dosage. While scientists are still working on understanding HOW the gas functions in the body, we do know that hydrogen sulfide has beneficial effects at low levels, but toxic effects at high levels. The importance of dosage on human health is not just specific to smelly hydrogen sulfide. In fact, just about every substance that we come in contact with throughout the day has different effects depending on the dosage: even drinking water can be harmful if you consume too much! (Water intoxication: it’s a real thing! Read about it here.)
An easy way to think about dosage effects is the common saying (and the Kelly Clarkson pop hit):
In other words, exposure to low doses can activate cellular responses that provide protection to the cell, making it “stronger”. However, these cellular responses may be insufficient at higher doses, ultimately resulting in damage and death.
There is a lot to learn about hydrogen sulfide before we begin using it regularly as a therapeutic. For those who work in environments where hydrogen sulfide poses a serious occupational threat, utilizing the gas for medical treatment still sounds extremely dangerous and irresponsible. By improving our understanding of the cellular effects of hydrogen sulfide at different doses, scientists can minimize potential dangers of hydrogen sulfide as a therapeutic. Ultimately, the potential benefits of hydrogen sulfide in agriculture and human health make it an important and exciting research field for the future.
If you’re interested in learning more about hydrogen sulfide, you can visit our lab’s website here!
This blog post originated as an exercise for my SciFund Challenge Outreach course, but I liked it so much that I thought it’d make a great first blog post! Let me know what you think!