A new study has linked exposure to two common perfluorinated chemicals (PFCs) with osteoarthritis.
The study - published in Environmental Health Perspectives - looked at the associations between perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), and osteoarthritis in a U.S. study. Data was analyzed from six years of the National Health and Nutrition Examination Survey (NHANES, 2003-2008), and accounted for factors such as age, income, and race and ethnicity.
They found that PFOA and PFOS exposures are associated with a higher prevalence of osteoarthritis, particularly in women. As a group, women are disproportionately impacted by this chronic disease. When they looked at men and women separately, they found clear, strong associations for women, but not men. Women in the highest 25 percent of exposure to PFOA had about two times the odds of having osteoarthritis compared to those in the lowest 25 percent of exposure.
Reasons for differences in the associations between men and women, if confirmed, need further exploration. Better understanding the health effects of these chemicals and identifying any susceptible subpopulations could help to inform public health policies aimed at reducing exposures or associated health impacts
PFCs are used in more than 200 industrial processes and consumer products including certain stain and water-resistant fabrics, grease-proof paper food containers, and personal care products. Because of their persistence, PFCs have become ubiquitous contaminants of humans and wildlife.
Perfluorooctanoic acid (PFOA), also known as C8 and perfluorooctanoate, is a synthetic perfluorinated carboxylic acid and fluorosurfactant. One industrial application is as a surfactant in the emulsion polymerization of fluoropolymers. It has been used in the manufacture of such prominent consumer goods as Teflon and Gore-Tex.
PFOA persists indefinitely in the environment. It is a toxicant and carcinogen in animals. PFOA has been detected in the blood of more than 98 percent of the general U.S. population in the low and sub-parts per billion range, and levels are higher in chemical plant employees and surrounding subpopulations.
Exposure has been associated with increased cholesterol and uric acid levels, and recently higher serum levels of PFOA were found to be associated with increased risk of chronic kidney disease in the general United States population, consistent with earlier animal studies, according to the American Journal of Epidemiology study Perfluoroalkyl Chemicals and Chronic Kidney Disease in U.S. Adults.
Perfluorooctanesulfonic acid or perfluorooctane sulfonate (PFOS), is a man-made fluorosurfactant and global pollutant. PFOS was the key ingredient in Scotchgard, a fabric protector made by 3M, and numerous stain repellents. Perfluorooctanesulfonic acid is usually used as the sodium or potassium salts.
PFOS, together with PFOA, has also been used to make aqueous film forming foam, a component of fire-fighting foams, and alcohol-type concentrate foams. PFOS compounds can also be found in some impregnation agents for textiles, paper, and leather; in wax, polishes, paints, varnishes, and cleaning products for general use; and in metal surfaces and carpets.
In the semiconductor industry, PFOS is used in multiple photolithographic chemicals including photoacid generators and anti-reflective coatings. It has been phased out in the European Union semiconductor industry due to health concerns.
In animal studies PFOS also causes cancer, physical development delays, endocrine disruption, and neonatal mortality. Neonatal mortality might be the most dramatic result of laboratory animal tests with PFOS, as noted in the paper: Perfluoroalkyl Acids: What is the Evidence Telling Us? Female mice with blood levels of PFOS within ranges found in wildlife and humans demonstrated higher mortality when infected with influenza A.
Although production and usage of PFOA and PFOS have declined due to safety concerns, human and environmental exposure to these chemicals remains widespread. Future studies are needed to establish temporality and shed light on possible biological mechanisms.
The research study was authored by Sarah Uhl, Michelle L. Bell, Yale Professor; and Tamarra James-Todd, an epidemiologist at the Harvard medical School and Brigham and Womens Hospital as the focus of Uhls Masters of Environmental Science Program at the Yale School of Forestry and Environmental Studies.
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