Herbs of chrysanthemum, often used in tea and medicine, were reportedly dried using sulphur dioxide, a prohibited preservative that can cause sickness, the China Daily reported.
Dubbed the "herbal town", Yangma in Jiangsu province produces around 2,000 tonnes of chrysanthemums each year. Nearly 200 tonnes of the herb produced this year were found to be contaminated, officials said.
Sulphur dioxide was banned in China in 2005.
"Farmers using sulphur-drying methods can make more profit, saving the cost of electricity and coal as much as 4,000 yuan ($600) to 5,000 yuan per tonne," an official said.
The sulphur-dried herbs sold well because they cannot be detected by common people, he said.
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