Dioxin migrates out of milk cartons.

Dioxin migrates out of milk cartons

Throughout the industrialized world, people are accumulating a low-level body burden of toxic dioxins and furans, including the highly toxic TCDD (SN:7/13/85, p.26). A Canadian government scientist has found one potential source in the food supply: cardboard cartons used to package cow's milk.

John J. Ryan, an environmental chemist with Health and Welfare Canada in Ottawa, examined milk samples as part of a large study to identify dietary sources of dioxin. While all samples showed low levels of highly chlorinated dioxins -- those having 5 to 8 chlorine atoms per molecule -- only a few contained the 4-chlorinated dioxin, TCDD, and a somewhat less toxic 4-chlorinated furan, TCDF. Quantities of both were low--0.04 parts per trillion (ppt) TCDD and 1.0 ppt TCDF -- and appeared only in milk from plastic-coated cardboard cartons. Milk packaged in plastic or glass showed none.

Ryan noticed a similarity between the TCDD:TCDF ratio in his milk and a TCDD:TCDF ratio reported a year ago by U.S. Environmental Protection Agency scientists studying pulp-paper mills. The EPA study showed that mills using chlorine to bleach their wood pulp create dioxins and furans that can end up in the paper. When Ryan analyzed his cardboard milk cartons, he found TCDD and TCDF. He presented preliminary findings at an August symposium in Umea, Sweden.

If all milk were contaminated with the levels Ryan found, "there'd be an immediate concern," says dioxin toxicologist Stephen Safet at Texas A&N University in College Station. As it is, he says, this constitutes a problem and should be eliminated. Michael Farrar, vice president for Environment and Health with the New York City-based American Paper Institute, says, "We had been trying to do [paper-dioxin] migration work, but had trouble" measuring the trace levels involved. About two weeks ago, one of the institute's researchers met with Ryan to discuss his analytical techniques and findings. On the basis of that meeting, Farrar says, the institute now expects to begin its own study of the potential problem.