Environmental safety issues are discussed using a case study on Glycine soja, a wild ancestral species of the GM crop Glycine max. GM Glycine max is considered a threat to biological diversity in the Far East region. The reliability of a press release reported by the Japanese Agriculture, Forestry and Fishery Ministry in 2008 is questioned, particularly regarding the statistical treatment of the data presented. In this press release, the safety of Glycine max is confirmed, based on results that reported small natural hybridization ratios between Glycine max and Glycine soja of approximately less than one in a thousand. However, this natural hybridization ratio was calculated without removing the number of plants whose flowering period differed from Glycine soja. Thus the re-calculated natural hybridization ratios have been corrected to 0.084 and 0.272 for the tests undertaken in 2005 and 2007, respectively. Considering that the natural mutation ratio is between 10&lt;Minus&gt;5 and 10&lt;Minus&gt;7, those natural hybridization ratios can be considered significantly high. The establishment of reliable technology for assessing levels of hybridization is recommended. Also, monitoring technology for early detection of hybridization effects in wild plants as well as corrective measures in case gene flow does occur into the wild are required.