With roughly 8 million metric tons of plastic ending up in the ocean each year, researchers set out to determine the impact of plastic bottle redemption programs on plastic waste pollution.

Publishing their findings in Marine Policy, researchers determined that redemption programs reduced the amount of beverage container waste off the coastlines of the United States and Australia by 40 percent. Additionally, that number was even greater in locations of lower socio-economic status — where, according to researchers, plastic waste most commonly occurs.

Looking at data concerning the 10 U.S. states that currently participate in plastic bottle redemption programs compared with states that do not, researchers estimated that if all coastal states in the U.S. participated in such programs, there would be roughly 6.6 million fewer plastic beverage containers littering the shoreline each year.

To reach their conclusion, researchers looked at details such as the actual amount of waste in both settings and at the higher container lid ratios in states with redemption programs versus the number of container lids per plastic beverage container in states that do not participate in such programs.

For more on the study, go to Marine Policy.