Past population-based studies have suggested that higher serum levels of perfluorooctanoic acid (PFOA, or C8) and perfluorooctanesulfonate (PFOS, or C8S) are associated with increased risk of having greater amounts of “bad” cholesterol and uric acid in the blood. More research has determined that both these substances could increase the risk of kidney disease. Anoop Shankar, M.D., Ph.D., epidemiologist in the WVU Department of Community Medicine, said the most recent study was a logical extension of the previous studies.
“To date, no previous study had directly examined the association between PFOA and PFOS levels and chronic kidney disease,” Dr. Shankar said. “Given the emerging circumstantial evidence suggesting a role for C8 exposure in kidney disease, we thought it was important to address this question.”
Shankar and his colleagues analyzed a large sampling of existing blood PFC measurements and kidney function data collected in the National Health and Nutritional Examination Survey. The results suggested that among average Americans with relatively low exposures to the chemicals, people with higher amounts of PFOA and PFOS have a higher likelihood of developing chronic kidney disease.
“Therefore our findings have implications even for people who are not living in contaminated areas,” Shankar said.
Humans and wildlife are exposed to PFOA and PFOS through environmental sources such as drinking water, dust, food packaging, air, breast milk, umbilical cord blood and many other sources. National survey results have shown that these manmade chemicals are present in the blood of more than 98 percent of the United States’ population. Though it is practically impossible to avoid contact with these common chemicals, Shankar believes more study could lead to the development of drugs that could reduce their presence in the blood.
“There is some evidence in medical literature to suggest that a group of drugs used to treat high cholesterol which acts by binding to bile acids and prevents their reabsorption from the gut may also be useful in lowering levels of these chemicals in the blood, but much more research needs to be done,” Shankar said. “C8 and other PFCs were once considered to be ‘neutral to health’ and therefore not investigated much in medical research before. With more studies like ours, I believe it is possible to come up with new drugs that can help clear C8 from our bodies.”
“I also believe that on a long-term basis, it is possible to eliminate PFCs from our manufacturing processes,” he continued. “For example, 3M has moved toward stopping the production of PFOS in our country.”
As the study was performed using a cross-section of the general population’s blood samples, it did not explain whether these chemicals cause kidney disease or if impaired renal function leads to higher C8 levels in the blood. Shankar’s team is planning a future study to clarify the relationship between C8/C8S and chronic kidney disease.
The study is being published in the “American Journal of Epidemiology” and advance access is currently available online at http://aje.oxfordjournals.org/content/early/2011/08/26/aje.kwr171.full.
For more information: Leigh Limerick, HSC News Service, 304-293-7087