June 18 2019, 10:54 a.m.
NEW DATA SUGGESTS that
the safety threshold for PFOA in
drinking water should be as low as .1 parts per trillion, according to the
nation’s top toxicologist. Linda Birnbaum, director of the National Institute
for Environmental Health Sciences, cited the figure, which is 700 times lower
than the safety level set by the Environmental Protection Agency, at a conference on
PFAS at Northeastern University last week.
While PFOA has already been
tied to kidney and testicular
cancer, among other diseases, recent research linking PFOA exposure to
pancreatic cancer is the basis for the lower number cited by Birnbaum. The
research was done by the National
Toxicology Program, which is a division of the NIEHS.
“If you look at the data,
pancreatic tumors are present at very, very low concentrations from PFOA,”
Birnbaum told the audience at the conference. “If you use the pancreatic tumors
in the rats in the NTP study to calculate what would really be a virtually safe
dose, you’re getting down at about .1 ppt. Well, that’s really low. And that’s
only for one PFAS.” Birnbaum suggested that regulators might ultimately issue
one drinking water standard for the entire class, which contains thousands of
compounds.
About the EPA’s current water
standard, Birnbaum said, “Many of us would think that is not health
protective.”
According to a summary of
the experiment, male rats exposed to PFOA developed both cancerous and
noncancerous tumors of the pancreas. At the lowest of three doses given in the
experiment, 20 out of 50 rats developed the tumors. At the
higher doses, more than half of the exposed rats developed the tumors.
The summary also shows that
PFOA increased the numbers of cancerous and noncancerous liver tumors in the
two-year rat study. At the conference, Birnbaum mentioned that the recent
experiments also showed that PFAS exposure affected breast development. “There
were clearly impacts on the growth of the mammary gland and problems with
lactation,” she said.
Both the NIEHS,
which conducts scientific research on the effects of the environment on health,
and the EPA,
which is responsible for environmental regulation, have said they are
prioritizing PFAS,
industrial compounds used in firefighting foam, nonstick coatings, and other
products that persist indefinitely in the environment and accumulate in people.
But the new information about their health effects has been emerging very
slowly.
The Japan National Institute
of Health Sciences first asked the
NTP to study the perfluorinated compounds in 1990, noting that in rats the
chemicals induced the presence of a biomarker of DNA damage thought to be
related to cancer. In 2003, the EPA also nominated the
compounds for further study, citing their “presumed widespread human exposure”
and the known toxicity of certain compounds in the class.
The rats in this two-year
study were given their first dose of PFOA almost 10 years ago, in July 2009.
And the NTP released a statistical
analysis of the tumor study in June 2018. Yet more than a year later,
the NIEHS has not published reports of the studies, which regulators
typically need to fully understand the science when setting safety levels.
Asked in March about the delay
in releasing the reports, Robin Arnette, of the NIEHS’s office of
communications and public liaison, wrote in an email to The Intercept that “NTP
routinely releases data tables for completed studies while formal reports are
in preparation” and that reports that go along with the toxicology research on
PFAS “are currently undergoing external peer review. We anticipate their
publication on the NTP website later in 2019.”
A technical report based on
the research “is in preparation and external peer review will take place later
in 2019; the date is not yet set,” according to Arnette’s email, which also
said, “Timelines and prioritization are dynamic. We are actively managing our
usual processes to enable efficient delivery of information for those agents of
growing public concern.”
Although the reports have yet
to be released, some state regulators are already considering the NTP data as
they set safety thresholds for PFAS. The Minnesota Department of Health cited
the NTP tables in its April health-based
guideline for PFHxS. And in March, California regulators
set interim safety levels of 14 and 13 ppt for PFOA and PFOS, while citing “new
cancer data recently released by the National Toxicology Program” and noting
that safety levels “and the health effects on which they are based may change.”
The amount of these chemicals
deemed safe to ingest in drinking water has been dropping quickly over the past
several years, as is often the case as scientists learn more about how
chemicals affect health. Between 2009 and 2016, the EPA’s official safety
threshold for PFOA was 400 ppt. In 2016, the agency lowered the number to 70
ppt. Several states have since calculated lower limits. Vermont set
drinking water health advisory limits of 20 ppt for PFOA. And, in April, New Jersey proposed
drinking water standards of 14 ppt for PFOA and 13 ppt for the closely related
chemical PFOS.
Update: June 20, 2019
After publication,
the National Institute of Environmental Health Sciences provided the
following statement from Linda Birnbaum:
The NIEHS has undertaken an
extensive PFAS research program, which involves many studies, hundreds of
chemicals, and partnerships across federal government. There are almost 5,000
PFAS chemicals in use today. Right now, we don’t know enough about the uses and
potential hazards of exposure to PFAS, but if our research results for PFAS are
similar to what we’ve seen with other biologically active chemicals such as
lead, arsenic, and asbestos, I would not be surprised if the safe level of PFAS
for humans is as low as 1.0-0.1 PPT. That’s why this research is so important,
and necessary for protecting public health.
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