Katherine Alfredo is an assistant
professor with the University
of South Florida, Department
of Civil and Environmental
Engineering.
Chad Seidel is the president of
Corona Environmental Con-sulting.
Amlan Ghosh is a water pro-cess
engineer with Corona
Environmental Consulting.
www.ca-nv-awwa.org 25
PFAS: HEALTH RISK REDUCTION?
draw into question previous negative
determinations for hexachlorobutadiene,
manganese, and potentially telone
(1,3-dichloropropene).
Our second proposed method (Ap-proach
#2) of calculating meaningful
opportunities for health risk reduction
was to multiply the two quantifiable
components (percent population above
threshold concentration * threshold con-centration
RHI), creating a minimum
threshold value (PopRHI). Approach #2
allowed for creating theoretical scenari-os
where regulators could calculate the
toxicological impact via the RHI metric
and then calculate necessary percent
populations to exceed the threshold for
meaningfulness. Again, the dark shad-ed
box establishes an area of meaning-ful
opportunity based on positive reg-ulatory
determinations for arsenic and
uranium and negative determinations
for the other contaminants. Similar to
Approach #1, the EPA positive regulato-ry
determination of PFOA at the current
concentration of 70 ng/L, six additional
contaminants will fall within this new
bounded region of meaningful, shaded
in light grey.
Does regulating PFAS
represent a meaningful
opportunity for health
risk reduction?
Given historical precedent, PFOA
and PFOS individually regulated do
not currently represent a meaningful
opportunity for health risk reduction
given the toxicological and occurrence data
available. This assessment might change
if a PFAS class regulation is proposed
and substantiated with additional health
relevance and occurrence information.
Many of the comments submitted to EPA in
response to the preliminary determination
for PFOA and PFOS focused on the
uncertainty and expedited regulatory
landscape situation at the individual state
level, which was created in the absence of a
federal MCL.
Comments submitted to the EPA by
professional water organizations have
almost unanimously called for more re-search;
however, a delayed regulation cre-ates
public health protection uncertainty.
At present, the burden of deciding how to
proceed falls to individual states with lim-ited
and unequal capacities and capabilities
to address the uncertainty. We anticipate
our analyses will catalyze a beneficial dis-cussion
calling into question many of the
assumed values integral to the determina-tion
of regulated contaminant thresholds
and urge the regulatory policymakers to
develop and use a comparative metric so
that “meaningful” is quantifiable on a com-parative
scale instead of qualitatively de-fined
on a case-by-case basis. In doing so,
we can best achieve the most meaningful
health risk reduction for all. S
/www.ca-nv-awwa.org
/murraysmith.us
