LITTLE ROCK, Ark. (KTHV) -- Americans will spend an estimated $2.1 billion on Halloween candy.

The Little Rock Zoo is urging people to choose environmentally friendly brands.

Because, palm oil industry hurts rain forests' ecosystem, the Zoo is using brands that employ sustainable practices that will not harm the environment.

The Cheyenne Mountain Zoo in Colorado made a list ranking candy manufactures.

Among the "excellent" candy category is Hershey's Mars and Kraft. Nestle and Ghirardelli ranked "good," and Haribo gummy candies ranked "needs improvement."