We had a problem with dioxin in
NZ milk for a little while when we changed from (reused) glass bottles to (recyclable) plastic bottles and (rubbish) paper cartons.
The paper cartons were leeching dioxin into the milk from the paper.
Eventually the problem was traced back to the way the paper was made and in particular the chlorine process to make it so white... which produced the dioxin.
The process was then changed and the cartons aren't quite as shiny and white as they once were but the dioxin was gone
The annoying part is that the strange (dioxin) peaks were in the gas chromomatagraph (sp?) results for the milk for about a year before it was considered to be a problem and tracked down
