In 2015, Stanford University scientists discovered that mealworms could be employed to break down Styrofoam (polystyrene) waste. The insects eat the material and break it down through digestion. Since then, the team has found that the worms do not absorb the toxic substance in the foam (hexabromocyclododecane, aka HBCD) into their bodies. Meaning, the bugs are safe to eat! They can be used to help with the problem of Styrofoam waste and then livestock feed.
In the first study, the researchers showed that mealworms effortlessly consumed the Styrofoam and then excreted it at a ratio of approximately 50% carbon dioxide and 50% biodegradable droppings. They figured that the droppings could be used as crop fertilizer, and the worms as food for farm animals – that is, if they could prove that the insects didn’t have any toxins remaining in their bodies.
Styrofoam typically contains HBCD, which is a highly-toxic flame-retardant chemical. The follow-up study was conducted to examine if this additive accumulated within the bodies of the mealworms when they consumed Styrofoam made with it. Most importantly, they wondered if the HBCD could pass into the farm animals (chicken or fish) if they ate the worms, then into humans if they ate the animals.
So, what they did next was feed HBCD-treated Styrofoam to a group of mealworms. They kept a control group on the side, being fed a regular diet. Within 24 hours, the group being fed HBCD-treated Styrofoam excreted 90% of the HBCD they ate. After 48 hours, they discharged all of it.
The team thinks that the plastic fragments in their gut were responsible for concentrating and then removing the HBCD. When the experiment was over, the team analyzed both groups of worms in terms of their health, and they were equally healthy.
Then, they fed shrimp the worms to see what effect the HBCD worms had over the ones fed a regular diet. They found no difference between the health of the shrimp fed HBCD worms over the normal worms. Meaning, the worms could safely be used as feedstock.
However, the droppings cannot be used as fertilizer because they do contain the toxic chemical. Because the droppings contain the harmful additive, they would have to be disposed of responsibly. The research has been published in the journal Environmental Science and Technology.
The study only tested for HBCD. There may be some other harmful additives in Styrofoam that do not pass through the mealworms so readily. Therefore, the scientists advise to replace toxic Styrofoam with biodegradable or more easily-recyclable alternatives rather than depend on mealworms to break down the waste.
