A team at the NIEHS-funded Duke University Superfund Research Program (SRP) Center created a simple, interactive experiment to teach children about the health effects of heavy metals like cadmium. Led by Javier Huayta, Ph.D., a postdoctoral fellow at the Duke SRP Center, the approach uses a microscopic, transparent worm called Caenorhabditis elegans and a do-it-yourself fluorescence microscopy setup to show the effects of metal exposure at a genetic level.
“We see a lot of potential for this experiment in classrooms or informal education spaces,” said Chiara Klein, a program coordinator at the center’s community engagement core. “Beyond the materials needed for setup, all that is needed is a willing institution and a great facilitator.”
C. elegans transparent bodies as seen through a microscope. (Photo courtesy of Chiara Klein)
Making worms glow
The idea for the experiment came after Duke SRP Center scientists discovered high levels of heavy metals — including lead, cadmium, and antimony — in soils near homes and parks in Durham, North Carolina. Even in small amounts, exposure to heavy metals can lead to health problems like cancer, lung and kidney disease, and neurological disorders.
To set up the experiment, the team first exposed C. elegans to cadmium for 24 hours in the lab, triggering an increase in production of mtl-2, a gene that helps detoxify cadmium. Next, the scientists tagged this gene with a green fluorescence protein, which glows under blue light.
Using a “do-it-yourself” fluorescence kit, researchers shined a blue LED light on the worms to highlight their transparent bodies. In response, cadmium-exposed worms glowed as the green fluorescence protein in their cells was activated. To confirm that cadmium was the cause, the team compared microscopic images of exposed and unexposed worms and measured how much light the worms emitted, finding that cadmium-exposed worms shined brighter.
These images show the experiment setup and images of glowing worms. Orange arrows in the bottom right box point to fluorescence from tagged mtl-2 genes. (Image adapted from Shahid et al. 2025)
Brighter kids ahead
To show their experiment to a student audience, the researchers hosted a hands-on demonstration at the Museum of Life and Science in Durham. Using blue LED light, kids and their parents observed differences in cadmium-exposed and unexposed worms.
The experiment sparked curiosity in kids, with many asking if cadmium could harm the worms and if the same could happen to humans. The team used this opportunity to explain how harmful metals build up in the body and ways to reduce exposure to them.
“By making heavy metal toxicity visible, we start a dialogue with participants who might not otherwise know about these risks,” explained Klein. “Through experiments like this, we hope to inspire future scientists while teaching people how to protect their health.”
Citations:
Schaefer MA, Nelson HN, Butrum JL, Gronseth JR, Hines JH. 2023. A low-cost smartphone fluorescence microscope for research, life science education, and STEM outreach. Sci Rep 9;13(1):2722.
Shahid S, Klein Chiara, Meyer JN, Huayta. 2025. Glowing worms: a low-cost fluorescence kit for toxicological education using Caenorhabditis elegans. MicroPubl Biol; online 4 Feb doi: 2025:10.17912.
Wang Z, Wade AM, Richter DD, Stapleton HM, Kaste JM, Vengosh A. 2022. Legacy of anthropogenic lead in urban soils: co-occurrence with metal(loids) and fallout radionuclides, isotopic fingerprinting, and in vitro bioaccessibility. Sci Total Environ 806(Pt 3):151276.
(Isaac Conrad is a communication specialist at MDB, Inc., a contractor for the NIEHS Division of Extramural Research and Training.)
