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Greek yogurt — the thicker and more protein-packed version of yogurt — has been everywhere lately: Greek yogurt for men, Ben & Jerry’s new frozen variety, even New York City pop-up shops. The “crack yogurt” has ignited such a feeding frenzy that in the past five years yogurt plants in New York state have nearly tripled, growing by more than 1 billion lb., according to the New York governor’s office.

But here’s a new dollop of truth that might sour your taste buds: when Greek yogurt gets strained, it leaves a waste product called acid (sour) whey, a liquid substance consisting of water, lactose (sugar), protein and yogurt cultures. Modern Farmer reports that whey acid is so environmentally toxic that it is illegal to dump it: once it gets into the waterways, it consumes so much oxygen that aquatic life significantly die off.

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According to Modern Farmer, there are no industry-wide statistics on where the whey is being disposed. Yogurt manufacturers usually pay nearby farmers to haul it away. The farmers then repurpose the sour whey by blending it into feed or fertilizer. But in an already resource-tight industry — it takes 3 to 4 oz. of milk to make 1 oz. of Greek yogurt — researchers are looking beyond the local level. Dave Barbano, a dairy scientist at Cornell University, tells Modern Farmer that there might be a way to capitalize on the protein in the sour whey by using it in infant formula. This is similar to what cheesemakers are doing: manufactured cheese’s by-product, sweet whey, which has more protein and less acid than sour whey, is now widely incorporated into body-building supplements and used as an ingredient to replace sugar in baked goods.

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Some are also redirecting the caloric energy into kinetic: farmers in New York state are turning lactose, the sugar in the acid whey, into methane, which can then generate electricity for their farms. Unfortunately, these generators are so expensive up front that many are holding out for a quick fix on this toxic asset. At New York state’s Yogurt Summit last year, one producer quoted in Modern Farmer said: “If we can figure out how to handle acid whey, we’ll become a hero.”

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