British Polythene Industries forecast first half results ahead of last year's despite losses in North America.BPI said the upbeat performance would come in the face of a loss in the group's North American operation, which took a hit from a delay in delivery and installation of a replacement extrusion line.Volumes in its farming film markets were similar to last year after a slow start caused by floods in southern England and volumes in other products increased modestly, leading to an expected slight improvement in overall volumes.Raw material input costs eased very slightly in the last few months, but were rising in July as polymer producers' feed-stock costs firmed in Western Europe."The first half result underpins our confidence in current market expectations for the full year," it said in a trading update ahead of first half results on August 29th.Shares were flat at 652p in early trading in London.PW