Although the palette of green materials has widened in recent years, Organic Monitor finds cosmetic formulators still face many technical and sustainability issues when using natural ingredients. Preservation remains the number one technical hurdle for formulators of natural and organic personal care products. Although many green materials have become available for preservation, no single material is popular because of variations in product composition. Stability is a major issue, with some green preservative systems leading to discoloration and/or odor changes. Green surfactants are another problematic area, partly because certification agencies cannot agree on permissible green chemistry processes.