March 3 (UPI) -- They have been called "forever chemicals" -- researchers say they earned the nickname for a reason -- and a new study suggests they increase risk for cancer.
An analysis published Tuesday in the International Journal of Environmental Research and Public Health offers insight into the long-term effects the substances have on human health, with researchers suggesting they should be classified as carcinogens and investigated as such.
Researchers affiliated with the Washington, D.C.-based Environmental Working Group show in the analysis how PFAS -- or per- and polyfluoroalkyl substances -- can act like established cancer-causing chemicals by altering DNA, compromising the immune system or encouraging cell proliferation.
"Our analysis shows that there really is a lack of safety data on these chemicals," Alexis Temkin, a toxicologist with the EWG, told UPI. "However, there's a significant amount of evidence that we're being exposed to these chemicals in our environment. Even though many have been phased out or are being phased out, they tend to linger in water and elsewhere."
Earlier research has shown that PFAS, which have been found in drinking water, soil and in food packaging, can accumulate in the human body and persist in the environment -- hence their nickname -- and some studies have linked these chemicals with fertility problems, birth defects, obesity, diabetes and cancer.
Elevated levels of one of the most commonly used and well-studied PFAS, perfluorooctanoic acid, or PFOA, has been associated with an increased risk for non-Hodgkin's lymphoma as well as kidney, testicular, prostate and ovarian cancers among people living in the Ohio Valley region, where the drinking water had been found to be contaminated with the chemical.
In addition, PFOA has been shown to induce tumors an animal studies, while GenX, a chemical used to replace PFOA in Teflon, for example, has been shown to cause the development of tumors in animal studies as well.
To date, however, health and environmental officials have declined to describe PFAS as carcinogens, because research has yet to demonstrate that they cause cancer in humans.
Temkin and her colleagues reviewed existing studies for evidence of carcinogenic traits in animal, cell and human studies of 26 PFAS chemicals, using the Key Characteristics of Carcinogens framework for cancer hazard identification.
They found "strong evidence" that multiple PFAS cause oxidative stress, are immuno-suppressive and modulate receptor-mediated effects, as well as "suggestive evidence" indicating that some PFAS can cause epigenetic alterations and affect cell proliferation.
Not all PFAS are carcinogens, though several Temkin and her team looked at possess at least five of the "key characteristics of carcinogens," Temkin said, while others "have at least one."
Based on the findings, the researchers say existing scientific evidence indicates that several PFAS have at least one key characteristic of carcinogens and that these chemicals should be investigated as such.
According to Temkin, EWG will continue to work with lawmakers at the national and state level to pass legislation designed to protect the public from exposure to these chemicals.
She noted that, in February, the U.S. Environmental Protection Agency announced plans to regulate PFOA and PFOS, another common PFAS, in drinking water, but that this "could take years" to implement.
"Our earlier work has confirmed the presence of six to seven of these chemicals in different drinking water sources," Temkin said. "Certainly, water filtration systems can help, and consumers can also work to limit their exposure to PFAS by limiting their consumption of packaged fast foods, where they can persist in grease, or by foregoing the use of stain treatments on carpets, where PFAS may also be used."