CRI听力: Fluorescent Whitening Agent Detected in Mushroom

Mushrooms have long been considered healthy and nutritious food. But recently, a primary school student in Beijing's Xicheng District says the experiments he did show that about 90 percent of the mushrooms on Beijing's market have been contaminated by a fluorescent whitening agent, which a chemical element that poses a danger to our health.

Is the student's experiment reliable? And do fluorescent whitening agents really harm our health? Our reporter Li Dong has the details.

ZhangHao, a primary school student, is a member of the "science inquiry class" at the Xicheng District Youth Science and Technology Museum.

His experiment was done at China Agricultural University's microbiology laboratory. He employed a commonly used method of detecting fluorescent whitening agents: using ultraviolet radiation in darkrooms to detect fluorescence.

Zhu Yi, an associate professor at the Nutrition Engineering Institute at China Agricultural University, says the process and method of Zhanghao's experiment can be scientifically reliable. And the experiment may be perfect should he perform another migration test.

"We use migration tests to determine whether the fluorescence is carried by the mushroom itself rather than added by people. You can use a piece of fluorescence-free gauze to touch the mushroom. If fluorescence can be found on the gauze, it means, the fluorescence whitening agent is added by people."

ZhangHao chose 16 kinds mushroom samples from the market. The samples were collected from supermarkets, shopping centers, as well as some large wholesale markets.

Fluorescent whitening agents are a kind of dye which improves the whiteness of clothing and decoration materials. Zhuyi says according to related laws and regulations, this whitening agent is forbidden for use even on the wrapping materials for food, not to mention on food itself.

However, she also admits the study on the harmful effects of fluorescent whitening agents still lacks solid research.

"So far, with the data we have at hand, the poison of fluorescence whitening agent is not serious or still unknown. Research has not indicated that if you have eaten it, your health will be seriously affected. But it's not edible. We should avoid eating it."

Zhuyi says even if some farmers use it to whiten their mushrooms, they won't use too much and consumers can avoid buying contaminated mushrooms by using the following tips:

"Don't buy mushrooms that look like they've been dipped in water, and if you find there is big color difference between the broken parts and other parts of the mushroom, don't buy it. It may be contaminated by a whitening agent. Choose mushrooms which are comparatively dry."

Zhuyi adds that consumers' attitude may affect mushroom grower's actions. If people don't believe that the whiter, the cleaner; the whiter, the healthier; mushroom growers won't use fluorescent whitening agents.

For CRI, I am Li Dong.