The product is a thin sheet of edible rice paper printed to resemble a Chinese textbook, exercise book, exam paper or a certificate of merit.

It became popular at the start of the autumn term, sold online with slogans such as “stress reliever” and “eat knowledge into your stomach,” and quickly spread among primary and secondary pupils.

The State Administration for Market Regulation said its monitoring uncovered serious food‑safety hazards across the category, including the use of food additives that are not allowed for starch products, production methods that fall short of national standards, and a small number of items that contain non‑food raw materials.

Voice of China reporters identified two items that were both labelled as starch products. One listed the colourings tartrazine, brilliant blue and allura red; the other listed beetroot red and gardenia blue. China’s national standard does not permit any of these colourings in the starch‑product category, although they may be used in candy.

Market regulators in Guangzhou’s Zengcheng District, in Karamay in the Xinjiang Uyghur Autonomous Region and in Lintao County in Gansu Province each issued food‑safety alerts, urging parents not to buy the snacks out of curiosity.

Because the sheets are cheap, some workshops may print them with non‑food‑grade or even industrial ink. Wu Wenbin, deputy director of the spleen and stomach department at the Guangdong Provincial Hospital of Chinese Medicine’s Dade Road branch, told Voice of China that such ink can exceed heavy‑metal limits and may harm children’s liver and kidneys.

Regulators also note that pupils often handle the sheets as toys before eating them, and that this handling can lead to abdominal pain and diarrhoea.

Guangzhou’s Nansha street market supervision office has made illegal sales of edible homework products a priority in its term‑opening enforcement campaign, warning merchants that refusing to clear non‑compliant stock will result in penalties and public disclosure.