Biodegradability
This chart presents the results of two tests that measure biodegradability. It includes six types of esters along with mineral oil.
Source: Synthetic Lubricants and High-Performance Functional Fluids, 2nd Ed. L.R. Rudnick, R. L. Shubkin, Ed. Chapter 3, P 80. Additionally, mineral oil data from Biodegradation Test Methods and PAOs report, Lawrence K. Low, EMBSI, August 2005.