Food safety has once again drawn negative attention amid claims that many flavoring ingredients served in popular hotpot dishes at restaurants contain harmful chemical additives, according to insiders.

A typical hotpot is served at a restaurant in Shanghai.

"Eighty percent of hotpots served at (restaurants) contain such chemical additives," said Wang, a chef who recently quit from a hotpot restaurant due to guilty feelings over the practice, the Anhui Business Daily reported Tuesday.

A restaurant owner named Xu made a damning claim, saying he never eats hotpots at his restaurant because boiling the chemical additives for a long time can increase their harmful effects on health.

Such additives mostly contain chemicals simulating flavored powder, concentrated spicy liquids and even poppy traces, insiders said.

The concentrated base could contain heavy metals, such as arsenic and lead, risking damage to the nervous and digestive systems and could lead to mental disorders and cancer.

Some restaurants even eschew natural ingredients such as Sichuan pepper or cinnamon since chemical additives are much cheaper, reports said.

"It's almost an open secret that chemical additives are added in hotpots," Sang Liwei, a lawyer specializing in food safety, told the Global Times Wednesday. "However, there lacks an explicit standard governing what ingredients can be used in what quantity."

"Inspections on restaurants are only limited to checks on the sanitary conditions of kitchens, dining halls or cutlery. There is no check targeting the quality of raw materials or ingredients," Sang said.

"However, the industry in some local areas has been left without any supervision due to the food and drug administrations not having the man power to cover them," he added.

The Anhui Business Daily gave the example of a company that provides training for chefs, which teaches them to make a hotpot soup base with chemical additives with materials costing only 0.5 yuan per kilogram.

A hotpot restaurant owner in Nanjing told the Yangtze Evening Post Wednesday that when using natural materials, a soup base would cost at least 26 yuan per hotpot serving.

Wang Kai, an official from Jiangsu's provincial Dining Industry Association, said that it is "high time" for authorities to regulate the misuse of additives.

"It seemed that media organizations are the forerunners of uncovering food-safety scandals, and the watchdogs are lagging behind," said Sang.

In March, the State Food and Drug Administration issued an emergency notice, indicating an overhaul of the catering industry.

Food scandals have wracked China of late, with reports shedding light on restaurants using highly carcinogenic recycled oil with a toxicity 100 times stronger than arsenic.

Yu Xiaodong, director of the Center for Public Nutrition and Development at the National Development and Reform Commission, agreed that tracing the origins of cooking ingredients would help improve safety concerns.

"Most restaurants never reveal the source of their raw materials or ingredients, with many restaurants, especially smaller ones, using low-quality materials that present health risks in order to save costs," Yu told the Global Times Wednesday.

Relevant departments should formulate a strict standard governing the safety of food ingredients, including measures to require restaurants to provide nutrition or safety labels on the meals they offer instead of relying on media exposure of individual food safety scandals, Yu added.