关键词: 转基因作物, 低水平混杂, 无意混杂, 阈值

Abstract: Over the last two decades,the land area under cultivation with genetically modified organisms（GMOs）has been growing steadily,and the amount and speed of circulation of many GM products in international trade tend to be rising. The issue that low content of GMO in non-GM product occurred in different countries and regions,i.e.,low level presence（LLP）of transgenic components has been increasingly serious. Considering this issue,this article expounds the definitions of LLP in seven different countries and regions（organizations）,and analyzes the common characteristics;then summarizes the current policies in every country,the threshold of LLP,and the effects of LLP on import and export trade. This study would provide the basic information for the relevant policies and detection standards for China.

Key words: genetically modified crops, low level presence, adventitious presence, threshold