When the Göteborg Posten newspaper sent off two black Björn Borg briefs to be analyzed in a lab, the first pair packed a whopping 860 milligrammes of nonylphenolethoxylate per kilo, while the second pair weighed in at 490 milligrammes.
The forbidden fabric chemical has serious effects on the environment, hence its EU ban. The insidious substance makes its way into the water system when clothes are washed and the chemicals rinse off.
The poisonous chemical causes fish to develop dual sexual organs and lose the ability to procreate. While production of the substance is banned in the EU, there is currently no law against importing foreign ready-made fabric goods containing this "gender-bending" chemical.
However, both the Swedish Society for Nature Conservation (SSNC) and the Swedish Water & Wastewater Association (SWWA) recommend that imported fabrics only have a maximum of between 20-50 milligrammes per kilo, in order to protect the environment.
When the SSNC tested some imported towels and t-shirts they came up with similarly worrying test results. Following their study, Swedish fashion success story Cheap Monday decided to withdraw a t-shirt that contained 940 milligrammes per kilo, which was ten times the company's own maximum.
Although the chemicals are forbidden in Europe any longer, our water supplies are full of it. This is due to the large number of textiles and clothing that is imported from abroad, especially from Asia where nonylphenolethoxylate is still widely in use.
There the poison is used to wash fabrics during production, and when we wash the clothes, towels or curtains at home in Sweden, the poison makes it way into the Swedish water supply.
Torbjörn Synnerdahl, an environmental expert at the chemical analysis company Eurofins, fears that "we are importing a great environmental problem."
The Textile Importer's Association in Sweden has issued guidelines advising a maximum level of 250 milligrammes per kilo.
Åke Weyler, CEO at the Textile Importer's Association believes that individual companies need to act responsibly.
"Companies need to tell their deliverer to find out where goods come from and to eliminate it. A scare like this definitely makes everyone pull their socks up," he told Göteborgs-Posten.
Annacarin Modin, head of production at Björn Borg AB, told the newspaper that the company follows Swedish regulations and that random tests on the black briefs had yielded values of between 120 and 200 milligrammes per kilo.
"I do not know what happened here, but we are taking this extremely seriously. Obviously something is lacking somewhere. Our deliverers carry out tests in the Far East and then we send our own tests to the textile lab."
She promised to perform further tests on the black men's pants in question in a bid to get to the bottom of the issue.
Björn Borg men's underwear is a hugely successful brand among young Swedish males. Although the company was inspired by former tennis ace and 1970s Wimbledon winner Björn Borg, it only retains his name as a brand name. Björn Borg is a Swedish company that owns and develops the Björn Borg brand.
The Swedish Chemicals Agency welcomes the attention regarding nonylphenolethoxylate and is of the opinion that the EU should have stricter regulations.
"We believe it is a problem that seems to be present in a variety of imported textiles. And even if some regulations are not in place, the Swedish textile industry is willing to sort this out. Nobody wants to have environmentally dangerous chemicals making their into our water supply", investigator Christina Rudin Snöbohm told Göteborgs-Posten.
"The best thing would be not to allow them at all", she said.