(AFP) – Women’s accessories sold by some of the world’s most popular online shopping firms contained toxic substances sometimes hundreds of times above acceptable levels, authorities in Seoul said.

Chinese giants including Shein, Temu and AliExpress have skyrocketed in global popularity in recent years, offering a vast selection of clothes and accessories at stunningly low prices that has helped them take on US titan Amazon.

The explosive growth has led to increased scrutiny of their business practices and safety standards, including in the European Union and South Korea, where Seoul officials have been conducting weekly inspections of items sold by online platforms.

In the most recent inspection, 144 products from Shein, AliExpress and Temu were tested, and multiple products from all companies failed to meet legal standards.

Shoes from Shein were found to contain significantly high levels of phthalates — chemicals used to make plastics more flexible — with one pair 229 times above the legal limit.

“Phthalate-based plasticisers affect reproductive functions such as sperm count reduction, and can cause infertility and even premature birth,” an official from Seoul’s environmental health team told AFP.

One such chemical “is classified as a human carcinogen by the International Cancer Institute, so special care should be taken to avoid long-term contact with the human body”, they added.

Formaldehyde, a chemical commonly used in home building products, was detected in Shein’s caps at double the allowable threshold.

Two bottles of nail polish from Shein were found to have dioxane — a possible human carcinogen that can cause liver poisoning — at levels more than 3.6 times the allowed limit and methanol concentrations 1.4 times above the acceptable level.

Shein told AFP that they “work closely with international third-party testing agencies… to regularly carry out risk-based sampling tests to ensure that products provided by suppliers meet Shein’s product safety standards”.

“Our suppliers are required to comply with the controls and standards we have put in place as well as the product safety laws and regulations in the countries we operate in,” the company added.

Seoul authorities found sandals from Temu contained lead in the insoles at levels more than 11 times the permissible limit.

“Upon receiving notice from the Seoul city government, we immediately launched an internal investigation,” a spokesperson from Temu told AFP.

“We have swiftly removed these product listings from our global marketplace and are enhancing our systems and guidance to merchants to ensure they comply with safety standards and local regulations.”

Seoul officials asked for all the products to be removed from sale, according to a government statement.

“Products that exceed the legal limit are products that directly contact the body, such as leather sandals and hats, so citizens should pay special attention,” said Kim Tae-hee, an official in the capital.

“The Seoul Metropolitan Government will continue to conduct safety tests periodically and disclose the results.”

The European Union in April added Shein to its list of digital firms that are big enough to come under stricter safety rules — including measures to protect customers from unsafe products, especially those that could be harmful to minors.