Data Views Exclude Ubiquitous Chemicals Activities: 124 Chemicals w/Activities: 21 CSV Excel PDF All Chemicals: 39 Previous12 Show all rows. Paginate rows. Click on column headings to sort table by that column # Activity Chemical Part All Leaf Plant Resin, Exudate, Sap Low PPM High PPM StdDev *Reference 60 60 LIMONENE Leaf 855.0 1197.0 0.81 * *Unless otherwise noted all references are to Duke, James A. 1992. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL. CRC Press.