An estimated 200 tons of herbal chrysanthemums contaminated by a banned toxic chemical has entered the market, cnr.cn reported Thursday.

The herbal flower, which is often used by Chinese in tea and medicine, is believed to have been dried with sulfur dioxide, a prohibited preservative that can cause sickness.

Dubbed China's herbal town, Yangma County in Jiangsu province produces 2,000 tons of chrysanthemums each year. It is suspected 200 tons of the herb are contaminated.

Using the chemical, which was banned in 2005, in the drying process makes the herb sour and weakens its effect which could lead to poisoning.

"Farmers using sulfur-drying methods can make more profit, saving the cost of electricity and coal as much as 4,000 yuan ($595) to 5000 yuan per ton," a unnamed manager of a chrysanthemum processing company said.

The manager added that sulfur-dried chrysanthemums sold well because it can not be detected and claimed the sulfur flavor of the chrysanthemums will fade away in a month if stored in a ventilated room.

However, the quality watchdog said the sulfur remained in the herb and will harm people's health even if the smell has gone, the report said.