To calculate the environmental lifetimes of the drinking straws, we fit our mass loss measurements to a phenomenological surface erosion model. The model defines the relative mass loss in terms of the straw's shrinking initial dimensions due to a specific surface degradation rate (𝑘 𝑑 ), an environmentally dependent material property. This approach recognizes that the intrinsic properties of a material and extrinsic properties of an item control a plastic item's degradation rate. Values of 𝑘 𝑑 were 7710 µm/yr for the CDA straw, 1259 µm/yr and 1279 µm/yr for the two PHA straws, Phade and Beyond Green, respectively, and 30836 µm/yr and 29638 µm/yr for the uncoated and coated paper straws, respectively. Our values of 𝑘 𝑑 for CDA and PHA straws agreed with those previously reported (Figure , Table ).