For example,one advantage of paper cups is that paper is made from a renewable resource(woods and chips),while the polyfoam cup relies on petroleum,a nonrenewable resource.More careful examination,however ,reveals that paper cups actually use more petroleum than polyfoam cups!The reason?Converting wood chips to pulp to paper cups uses energy.Effluents and emissions produced during the products’life cycle are also listed in Exhibit 17-7.Interestingly,the only significant environmental release for polyfoam cups is pentane,a blowing agent.On the other hand,production of paper requires extensive use of inorganic chemicals and large amounts of water effluents .Furthermore,recycling seems to favor polyfoam cups.Finally,ultimate disposal,at least in landfills,tends to favor paper cups because of their biodegradability.Yet, this advantage is called into question by recent studies indication that biodegradable materials in anaerobic landfills remain undegraded over relatively long periods of time.From the viewpoint of a variety of environmental impacts,perhaps polyfoam cups are better than paper cups!