SHILLONG: The government slogan that "Let's Make Meghalaya Clean and Green" may end up being an empty rhetoric if urgent steps are not taken to deal with the problem of thermocole pieces or styrofoam dumped by fish-loaded Shillong-bound trucks on the National Highway 40. Mounds of this non-biodegradable pollutant seen on various stretches of highway are not just an eyesore to tourists visiting Meghalaya. They are a potential threat to the environment and human health as well.