When cows get hungry for news

Science News, March 13, 1993

When cows get hungry for news

Looking for more and more creative ways to cope with old newspapers, some recyclers have proposed using them as bedding in cow barns. But when Bossie gets a hankering for a snack, she might eat yesterday's news, and that concerned a team of scientists headed by Barbara S. Shane at Louisiana State University in Baton Rouge. The researchers realized that newsprint "contains a galaxy of chemical compounds, including whiteners and fillers . . . dioxins which can be formed in the bleaching process [SN: 2/18/89, p.104], naphthenic oils used to solubilize the inks, and the inks themselves." Because many of these contaminants accumulate in fat, they may be shed into cows' milk and consumed by children.

Shane's team of environmental, veterinary and toxicological scientists decided to investigate how much risk that might pose by conducting mutagenicity assays on the milk from four Holsteins before and after the cows ate a diet containing 10 percent newsprint for two weeks.

A finding of newsprint-derived mutagens in two milk samples suggests the chemicals "were transferred through the food chain," the researchers report in the February Journal of Agricultural and Food Chemistry. Their assays also detected dioxins, though none of the most toxic forms, such as TCDD. Overall, however, the team found mutagens sporadically and then in low concentrations. As a result, Shane's group concludes, drinking a glass of milk from these newsprint-noshing cows poses less of a health risk than drinking coffee or tea.

Nevertheless, the researchers resist sanctioning newsprint for dairy-cow bedding. Many of the chemicals that can end up in newsprint have never undergone testing for human toxicity, they note. Even if the animals excreted such chemicals completely, they point out, the toxicants might still pose an environmental hazard if they were transferred to soil through manure. Finally, recyclers don't always reject soiled papers or those with inks known to contain toxic heavy metals. Indeed, the researchers report witnessing one commercial operator who was shredding a rat-poison box for use in cattle bedding.