original: however , this list contains substances which may have synthetic origins .
simplifications: however , the list contains substances which may be synthetic . however , this substances contains have synthetic origins . this list contains substances which could have unnatural sources . however , this lists has things which may have origins that are synthetic . however , this list has man-made substances in it . this list contains substances which may have synthetic origins . however , this list contains substances which may have synthetic origins . but , this list has things that may be man-made .