SHANGHAI - Products containing fake edible salt extracted from pesticide residue may have made their way on to dining tables in some areas, police in Anhui province have warned.

The warning follows the arrest of three people who manufactured and sold more than 10,000 tons of the fake salt. They are being held to face a public hearing, a court officer from Fuyang city's Yingquan district, Anhui province, told China Daily on Tuesday.

It is thought that more than 14,000 tons of affected products have been sold to markets in 12 provinces and municipalities on the Chinese mainland since 2009. It was that year when the suspects Xu Jingdong, Tao Xianchu and Liu Wei set up a business in Zhenjiang, Jiangsu province, to purchase waste residues from the production of pesticides by the factory of Zhenjiang Jiangnan Chemical Engineering Co.

"But we didn't know they used the waste solid to produce fake edible salt. The business line of their company was industrial salt," said a manager surnamed Cao from the chemical factory.

Fuyang police discovered the practice last year when they stopped a vehicle loaded with the illegal salt on the highway in Anhui. The inedible salt was to be sold to street vendors and small food processors, police said.

Toxicology tests conducted by China Agricultural University found there was 55 milligrams per kg of the herbicide glyphosate, a chemical used in weed killer, in the fake salt.

Safety standards in the United States and the European Union allow up to 20 mg per kg of the chemical in soybean. In China, the maximum permitted residue in fruit is 0.1 mg per kg.

Although no cases of illness caused by the fake salt have been reported in Anhui, according to police, toxicology experts said the substance posed a threat to health if taken in a comparatively large amount.

"It can trigger diarrhea, digestive tract problems and impair cardiovascular function," said Wang Jianhua, an expert on pesticide residues, at Shandong entry-exit inspection and quarantine bureau.

"But experiments showed the chemical doesn't accumulate in animals' bodies and we haven't found it will cause malformation or cancers," he added.

Police said the three accused bought the waste residue for 10 yuan ($1.58) per kg and sold the edible salt to wholesalers for almost 400 yuan ($63) per kg after processing. The price went as high as 1,400 yuan when sold on to small vendors.

Consumer rights experts have urged government agencies to strengthen regulation of the industrial salt sector through legislation and hand out stiffer punishment to lawbreakers making and trafficking substandard edible salt.

"The authorities and the police should also carry out regular campaigns to crack down on the illegal practice and prevent people from eating dangerous salt products," said Qiu Baochang, head of the lawyers' group of the China Consumers' Association.