By Treven Pyles
Posted on October 31st, 2019
Since the DEA established clear links between per- and poly-fluoroalkyl substances (PFAS) and a series of adverse health effects in 1996, interest in this class of man-made compounds increased significantly. Many scientific organizations have issued warnings that PFAS chemicals have cancer-causing characteristics.
Industry research groups, other government agencies, international health regulatory bodies, and independent environmental watchdogs started compiling available data as well as conducting their own studies to better assess the hazardous potential of the fluorocarbon chemicals that have been used for decades. This is a short and far from an exhaustive summary of some of their conclusions.
Comprised of three leading physicians in their field, Dr. Tony Fletcher of the London School of Tropical Medicine, Dr. David Savitz of Brown University, and Dr. Kyle Steenland of Emory University, the C8 science panel was assembled in 2005 with the primary function of analyzing the data gathered during an extensive epidemiological study conducted on 69.000 mid-Ohio Valley inhabitants who have been exposed to 50 ppt. of PFOA through diet for at least a year.
Using study data as well as a number of other sources, they concluded that there are "probable links" between PFOA exposure and:
Their findings corroborate well with other epidemiological research and with toxicology lab results. Generating dozens of articles in scientific journals, the Ohio Valley study becoming something of an amply-quoted landmark in the field.
The Agency for Toxic Substances and Disease Registry issued an 852 pages draft report regarding the toxicity of PFOS and PFOA in 2018.
One of the most interesting recommendations to be found in its pages is the minimum lifetime health advisory recommendation for PFOS and PFOA.
At only 7 ppt, this is 10 times lower than what the Environmental Protection Agency recommends since 2015. This caused quite a stir with members of the government, worried that a lack of consistency might negatively affect public trust in the federal institutions involved.
Without making any definitive statements an ATSDR fact-sheet intended for wide release summarizes current findings regarding the potential health hazards of PFOA and PFOS thusly:
The Environmental Working Group (EWG) and NRDC, two non-governmental organizations specialized in environment and health-related issues, take a great interest in PFAS and the government's reaction to it since the early 2000s.
Both seem to be of one mind in criticizing the federal agencies' minimum health advisory limits as insufficiently low, suggesting figures of 1ppt to 2 ppt instead. This is based on research showing that children are a lot more susceptible to adverse health effects from the two chemicals than adults. Furthermore, laboratory tests commissioned by the EWG show that PFOA and PFOS can pass through the umbilical cord into fetuses, where they might cause developmental birth defects. EPA toxicology studies on rats showed that at their lowest toxicological limit - the lowest concentration of a substance that can be shown to negatively impact one's health - the two chemicals tend to inhibit mammary gland development. EWG scientist recommends a minimum safe limit of 0.8 ppt to eliminate this potential risk.
In similarly low concentrations PFOS had been found to decrease the vaccine antibody response in a cohort of 431 children. Around the same amount seems to be required for suppressing the immune system, with a New Jersey-founded study placing the target for safety in this instance at 1.3 ppt.
For liver tumors and testicular cancer in rats, a series of 3M studies would justify placing the same figure at 3.3 and 14 ppt respectively, for a one-in-a-million chance of these diseases occurring above background levels.
Fourteen parts per trillion are New Jersey's minimum safety level for PFOA exposure, and also the average concentration of the chemicals an American would ingest daily to reach the blood plasma level recorded by the EPA for the general population.
New Jersey's set target came after an extensive state-sponsored evaluation of potential hazards from PFOA and other related chemicals. This materialized into a 475-page report for which some 54 studies from all over the world were cited. Its conclusions weren't much different than those arrived at by governmental institutions and NGOs, but the authors found it noteworthy that "associations of PFOA with some clinical parameters, including cholesterol, liver enzymes, and uric acid, exhibit a steep dose-response curve in the lower exposure range found in the general population".
This means that increases in dosage seem to have a more noticeable impact on the lower values, with adverse effects even reaching a plateau with higher exposure. Basically, the difference between having 20 ppt or 50 ppt in your blood would seem more significant than between 200 ppt and 500 ppt.
Another state to conduct its own assessment of the PFAS threat was Michigan. The panel of scientists employed by the state, drawing heavily from the C8 finds as well as a number of other studies, found the minimum safe advisory issued by the EPA to be insufficiently cautious, and also noted that most members of the PFAS family should be considered for regulation, despite limited toxicological data.
Per- and poly-fluoroalkyl substances stay in the environment and in the human body for long periods of time. Researchers have demonstrated that short-chain PFAS chemicals that can act like established cancer-causing chemicals. The mechanisms include different ways the human-made chemicals disrupt biological activity, such as by changing DNA, weakening the immune system, inducing chronic inflammation, causing cells to proliferate, or altering normal communication between cells.
Many scientific organizations have issued warnings that PFAS chemicals have cancer-causing characteristics: