Perfluoroalkyl compounds (PFCs) are a class of chemicals whose unique atomic properties have been exploited to make numerous everyday products more convenient. Most notably PFCs make up the nonstick coating on cookware, provide water-, oil-, and stain-repellant surfaces for fabrics and carpeting, and are used to make grease-proof packaging for greasy foods. Yet, like so many ‘miracle’ chemicals discovered or created in the 20th century, PFCs have some seriously sinister effects that we have only recently begun to document and understand.

A growing pile of evidence has already quite convincingly established that PFCs may harm the human reproductive system by interfering with hormone signaling, and in the latest – and definitely most tangible – investigation into the chemicals’ impact, a team from the University of Padua, Italy, has found that young men who grew up in an area with PFC-contaminated drinking water have significantly smaller penises and less mobile sperm than those who grew up with clean water.

Taking the study one step further, first author Andrea Di Nisio and his colleagues used a series of lab-based cellular experiments to provide the first direct evidence that two of the most common PFCs, compounds called PFOA and PFOS, will readily bind to the testosterone receptor and block its activation. Their full results are published in the Journal of Clinical Endocrinology & Metabolism.

“This study documents that PFCs have a substantial impact on human male health as they directly interfere with hormonal pathways potentially leading to male infertility,” they wrote. “We found that increased levels of PFCs in plasma and seminal fluid positively correlate with circulating testosterone and with a reduction of semen quality, testicular volume, penile length, and AGD [anogenital distance].” (Shortened AGD is a marker of abnormal male reproductive tract development.)

The Veneto region, which contains the province of Padua, is one of four locations in the world known to be heavily polluted with PFCs. The other members of this depressing club are the Dordrecht area of the Netherlands, the Shandong district in China, and the Mid-Ohio Valley of West Virginia, where a DuPont plant dumped a bunch of waste into a river (while covering up evidence of PFCs’ danger).

“As the first report on water contamination of PFCs goes back to 1977, the magnitude of the problem is alarming as it affects an entire generation of young individuals, from 1978 onwards,” the researchers wrote. To make it even worse, all the PFCs that have been introduced into the environment continue to pose a threat – scientists estimate that these extremely stable chemicals will outlast human life on Earth.

So, what can we do to keep ourselves safe? Di Nisio believes the next priority is figuring out how to safely remove PFCs from the blood. Until we can do so, and until more PFCs are banned or phased out, the outlook is far from sunny.

“At least here in Italy, it is very difficult to know if a product contains these chemicals,” he told IFLScience. “In the case of a product where it is explicitly stated ‘PFOA-free’, I do not feel safe anyway, because PFOA is only one of hundreds of possible PFC compounds, and they can all be dangerous… therefore it is very hard to avoid any contact with any PFC.”

[H/T: The Intercept – for an excellent summary of PFCs’ known effects and how the chemical industry has tried to sweep such findings under the rug, check out their investigative series]