Word derivation Middle English, so not a racial slur of any sort:

(from dictionary.com)

pol-li-wog   /ˈpɒliˌwɒg/ Show Spelled Pronunciation [pol-ee-wog]

–noun; a tadpole.

Also, pollywog.


Origin:
1400–50; var. of polliwig, earlier polwigge, late ME polwygle. See poll 1, wiggle