In the last decade, the exponential development of shale gas activities in United States resulted in a real revolution both in terms of gas prices and energy security. However, next to these positive effects, many risks and impacts for the environment and for human health related to shale gas activities have been identified. Risks of water and soil contamination or air pollution issues related to shale gas activities have been revealed in different recent scientific studies. During the last years, and because of the growing concern of local populations, shale gas became very debated in the media. In the scientific community as well, shale gas is a debated issue but in terms of greenhouse gases (GHG) emissions. This study is a scientific assessment of the environmental impacts related to shale gas extraction trying to synthesize information available from different scientific studies and providing potential mitigation measures. As Poland currently plays the most active role in European shale gas exploration, it has been chosen has the reference location in order to evaluate the different impacts. The results are that potential impacts on both human health and the environment can potentially be important but that an important lack of reliable information exists in order to fully assess most of the potential risks related to shale gas activities. Due to the high sensitivity of this issue among scientists, shale gas GHG emissions have been calculated in this study using a Monte Carlo simulation in order to define potential results based on variable parameters instead of using fixed values. The results show that shale gas GHG emissions could be 28% larger than coal over a 20 year timeframe and identical to coal over a 100 year timeframe. Mitigation measures can however reduce shale gas emission and most of the other impacts. The largest problem in order to currently asses and adequately reduce the risks related to shale gas activities is the current paucity of reliable information. An important uncertainty indeed exists in the evaluation of most of the risks. Many more scientific studies are therefore urgently needed in order to fully assess the potential impacts of shale gas activities and in order to ensure that the development of such activities will be done in Poland in the best possible conditions. In the meantime, the biggest risk would be to not accept our current ignorance and a precautionary approach should therefore be adopted.