Chinese e-commerce giants AliExpress and Shein have been found to sell children's accessories tainted with high levels of toxic metals, exceeding permitted levels, the Seoul Metropolitan Government announced Thursday.

According to chemical safety tests conducted by the Korea Conformity Laboratories on seven children's products sold on AliExpress and Shein, two accessories -- a children's watch listed on Shein and a children's necklace from AliExpress -- contained hazardous chemicals above the acceptable national standards.

The watch's crown contained lead levels 278 times above the permitted limit, while the back of the watch had chromium levels 3.4 times higher and nickel levels 4.4 times higher than allowed. The pendant of the necklace contained lead levels 1.2 times above the standard.

High levels of lead can potentially disrupt the reproductive system and increase cancer risks. Chromium is associated with dermatological toxicities and respiratory irritation, while nickel is linked to allergies and cardiovascular diseases, among other health issues.

The city government is conducting a series of safety tests on items sold on major Chinese e-commerce platforms AliExpress, Temu and Shein, where domestic consumers frequently make purchases as cross-border shopping increases, Seoul officials said. The results from its latest examinations will be relayed to the platforms so that appropriate action can be taken.

The city aims to complete additional tests on children's leather goods, such as shoes and bags, by the end of this month. It will include various products like food containers and hygiene products in its testing list next month, city officials added.