How dangerous is plastic bags for our environment?

Our eco-friendly jute bags are mainly used by developed countries like UK, US, Germany, France, Denmark, Netherlands, Australia, Canada, Belgium etc. But we want it should be used by the whole world. Perhaps people think that jute bags are costly than polythene bags but if we go through a calculation, we can find the actual truth. Suppose a single polythene bag cost is USD0.02, if we use 30 bags per month it costs USD0.06 so for 2 months we expend USD1.20 just to carry our everyday articles. If we use a jute bag it costs USD1.20 and it can be used at least 90 days. Most important thing is jute bags are extremely safer than polythene bags. So if we use jute bags we can save our money as well as the environment.