Recently, six branded whitening toothpaste including Colgate (高露洁), Zhonghua (中华), Black girl (黑妹), Crest (佳洁士), Darlie (黑人) and Liby (黑人) were exposed as containing bleaching chemical with long-term health risks. This message not only started the questioning of the functioning of the whitening toothpaste, but also raised the security concern over the toothpaste with other functions.
A media in Guangxi put the six brands of whitening toothpaste under test and the results showed that all the six kinds of toothpaste can make the test agent fade which contained iodine solution, dilute sulfuric acid and starch. And thus it concluded the toothpaste contained some bleaching component, or similar substances.
In response to the report, the China Oral Care Products Industry Association, claimed that test had been done to clarify the matter. Trial was presided over by the director of the Chinese Chemical Society, Professor Ji Ning, who said that the number of active ingredients of toothpaste reached 500, some materials might have reducing characteristics which make the reaction with iodine possible; but it did not necessarily help to conclude that the toothpaste must contain bleaching chemicals.
Dental experts suggested that brushing teeth is friction between the toothbrush and tooth to achieve the cleaning effect, the various whitening toothpaste business advertisements tended to exaggerated such effect. Even the toothpaste really contains some whitening ingredients, since the toothpaste stays in tooth surface for a very short time, the whitening effect is limited.