China's primary and middle school children will get a lesson in environmental protection just by opening their text books this academic year.

Text book publishers have begun a trial of new environment-friendly printing standards, the General Administration of Press and Publication (GAPP) announced Tuesday.

Seven publishing houses, 11 printing plants and some suppliers had participated in the trial since May, said Yan Xiaohong, deputy head of the GAPP.

About 14 million text books used by students in the semester starting this month were printed according to the new standards and distributed in the country's 20 provincial divisions, he said.

Under the new standards, the book paper should be recognized by international forest organizations as from sustainable sources. The ink and glues should meet strict environment standards set by the Ministry of Environmental Protection.

"Text books are most frequently touched by children. An eco-friendly text book is not only good for the environment, but also for the safety and health of children," Yan said.

The trial of green text books is part of the effort to update the country's printing industry.

The GAPP signed an agreement with the Environmental Protection Ministry Tuesday to promote "green printing."

China had more than 100,000 printing factories, but most still used traditional and highly polluting technologies, said Wu Xiaoqing, Vice Minister of Environmental Protection, at the signing ceremony.

According to the agreement, the two departments will set up an office to work out new environment standards for the printing industry and jointly push publishers to use eco-friendly technologies and green practices.

Besides text books, the departments also planned to expand green printing to packaging for foods and medicines, Wu said.