Back in 2015, scientists from Stanford University announced that mealworms could be used to break down Styrofoam waste – by eating it. Now, the researchers have additionally discovered that a toxic substance in that foam is not concentrated in the worms … making them safe to eat.
In the original study, it was found that not only did mealworms readily consume Styrofoam (aka polystyrene), but they excreted it at a ratio of about 50 percent biodegradable droppings and 50 percent carbon dioxide. The droppings could conceivably be used as crop fertilizer.
Often, however, a highly-toxic flame-retardant chemical known as hexabromocyclododecane (HBCD) is added to Styrofoam. The scientists were concerned that if mealworms chowed down on foam containing that additive, the chemical could accumulate within their bodies. If animals such as pet reptiles, farmed fish or chickens – or humans, for that matter – were to eat those worms, then the HBCD could be passed onto them.
With this in mind, a Stanford team recently fed HBCD-treated Styrofoam to one group of mealworms, while keeping a control group on a regular diet. It was found that within 24 hours, the first group excreted 90 percent of the HBCD that they had eaten, passing all of it within 48 hours. It is believed that the plastic fragments in their gut were instrumental in both concentrating and removing the chemical.
The HBCD worms themselves were just as healthy as those in the control group. Additionally, shrimp fed on a diet of those first worms likewise fared just as well as shrimp on a normal diet.
That said, because the droppings do contain the toxic chemical, they couldn't be used as fertilizer, nor could they be casually disposed of. Additionally, other harmful additives may not be so readily passed by the mealworms. The scientists therefore stress that a priority still needs to be placed on developing biodegradable or more easily-recyclable alternatives to Styrofoam.
A paper on the study, which was led by Anja Malawi Brandon and Wei-Min Wu, appeared this week in the journal Environmental Science and Technology.
Source: Stanford University
