When you reach for a chocolate bar, you might not think twice.
But scientists say it’s time to reconsider. Some brands of chocolate contain worrying levels of cadmium—a toxic metal that may not just affect your own health, but could also harm your children and even your grandchildren.
Dr. Delia Shelton, a biologist at the University of Miami, studies cadmium’s impact using zebrafish, which share about 74% of their genes with humans.
Cadmium isn’t just found in chocolate—it also appears in foods like rice, tortillas, and shellfish. Long-term exposure to this metal has been linked to serious health issues, especially affecting the heart.
One of cadmium’s most dangerous traits is how long it stays in the body. It has a half-life of 10 to 30 years, meaning it can take decades for your body to get rid of just half the amount you’ve absorbed.
This raised an important question for Shelton: Could cadmium exposure have effects that last across generations?
To find out, she partnered with Dr. Amanda Oehlert from the Rosenstiel School of Marine, Atmospheric, and Earth Science. Together, using advanced lab equipment, they studied zebrafish that were exposed to cadmium.
What they found was striking: the toxic effects didn’t stop with the exposed fish. Their offspring—and even their grandchildren—were also affected.
In other words, the damage didn’t disappear over time. It passed down, affecting future generations who had never been directly exposed. This finding is especially important because it suggests that cadmium could have similar multi-generational effects in humans.
That concern hits close to home in Miami-Dade County, where residents in West Coconut Grove were exposed to cadmium pollution for over four decades from the “Old Smokey” trash incinerator. Now, the University of Miami’s Environmental Justice Clinic is fighting for medical monitoring for those affected. Shelton’s zebrafish research could play a key role in supporting that case.
So, next time you’re choosing a chocolate bar—or any food—it might be wise to think beyond the label. What seems like a harmless treat could carry invisible risks, not only to your own health but to the health of future generations.
Shelton hopes her work sparks greater awareness of how hidden environmental toxins can shape our long-term well-being.
