By Douglas Main

Bioplastics, often considered a safer alternative to synthetic plastics, may in some cases be toxic to soil organisms, a worrisome finding that indicates a need for more thorough testing, according to a new study.

The work adds to a growing body of research suggesting that bioplastics, which are derived from plant materials or other biological feedstocks, are not necessarily safer than plastics that come from petroleum.

The new study, published on Nov. 5 in Environmental Science and Technology, found that two types of bioplastic fibers were more toxic to earthworms than were bits of conventional polyester.

While promoted as “environmentally friendly,” the alternative materials actually