A year-long investigation from environmental campaign group Greenpeace analysed samples of wastewater discharge from the Youngor garment factory, based on the Yangtze river delta, and the Well Dyeing factory based on a tributary of the Pearl.
Scientists later revealed that the samples included several toxic chemicals, some of which are banned across Europe, as they have been linked to affecting the human immune system and sexual development.
Alkylphenols (including nonylphenol) were found in wastewater samples from both factories, and perfluorinated chemicals were present in the wastewater from the Youngor Textile Complex. This was despite the presence of a modern wastewater treatment plant at the Youngor facility, according to the campaign group.
Samples were also taken at night as it was claimed many well known Chinese factories wait to the evening to discharge toxic substances, to avoid government inspectors patrolling in the day.
While these chemicals were detected in small quantities, they can be transported in oceans, atmosphere and food chains, Greenpeace said.
Further investigation into the 'paper trail' of contracts from the alleged polluted suppliers led to a "long list of multinational brands", including Nike, Adidas and Puma. It said that many of these global suppliers would not be aware of the chemicals being used by their suppliers.
In response, Adidas reportedly said that its relationship with the Youngor plant is for the cutting and sewing of fabrics. "Adidas does not source fabrics from Youngor Group, which would involve the use of dystuffs, chemicals and their associated water treatment processes."
Sports brand Puma, also linked to the pollution, told the Guardian: "Our relationship to Youngor Group is, according to our information, restricted to the ready-made garments factory Youngor Knitting, which is not involved in any discharges into the Fenghua and does not operate any industrial wet processes."
Going forward, Greenpeace has called on the brands to become "champions for a toxic-free future" and to work with suppliers to eliminate the release of hazardous chemicals from across their supply chain and products.