from the bench
Iowa’s State Hygienic Laboratory
Tackles Radioanalytical
Challenges for Lead-210
by Dustin May, radiochemistry supervisor and graduate researcher,
State Hygienic Laboratory at the University of Iowa
Even though lead’s adverse health
impact on human health is commonly
recognized, the health impacts of
radioactive lead isotopes are often ignored
and overlooked. Lead-210 ( 210 Pb) is a
radioactive form of lead that can be found
naturally in earth sediments, rocks that
contain natural uranium, ground-derived
water and in air as a decay product of
radon gas. Radon is a cancer causing gas
and is the second leading cause for lung
cancer according to the American Cancer
Association. Adverse health impacts of
210
Pb include the carcinogenic effects of its
beta particle emission, as well the alpha
particle emission of its decay product,
Polonium-210 ( 210 Po), which is extremely
hazardous when inhaled or ingested. It
is, therefore, helpful to actively monitor
for the environmental contaminant
Pb. However, the determination of
Pb in complex aqueous solutions,
such as hydraulic fracturing flowback
fluid, is a common radioanalytical
challenge in environmental science.
210
210
Researchers at the State Hygienic
Laboratory (SHL) and University of
Iowa have developed a new alternative
method to measure 210 Pb by using the
electron-capture, gamma-emitting
isotope Lead-203 ( 203 Pb) as a yield tracer.
The new method takes advantage of
the relatively short half-life (52 hours)
of the 203 Pb isotope and its pure gamma
emission to circumvent interferences
from stable lead and alkaline earth metals
in the chemical separation and enables
the accurate measurement of 210 Pb in
environmental samples at trace levels.
Laboratory supervisor Dustin May analyzes drinking water for gross alpha particles as part of community water system regulatory
compliance. Photo: University of Iowa
As with all science, and especially with environmental science, we must
actively ask questions and do the work to determine the potential impacts of
contaminants in the environment. Research on these potentially important
environmental hazards is critical to developing evidence-based, common
sense regulation to protect public health.”
Alpha-emitting radionuclides are co-precipitated with iron
hydroxide using a color indicator, bromocresol purple, and a
strong base, ammonium hydroxide. Photo: University of Iowa
Traditionally, yield for 210 Pb measurements
is determined utilizing the recovered
mass of a stable lead carrier. This
approach, while very simple, is susceptible
to interferences from endogenous stable
lead and high levels of alkaline earth
metals such as barium and strontium.
Additionally, mass-based yield approaches
limit the counting methodology to
gas-flow proportional counting or
require the use of inductively-coupled
plasma-mass spectrometry (ICP-MS)
analysis for yield determination. The new
method developed at SHL eliminates the
need for a stable lead carrier entirely,
while allowing for the use of variable
counting methodologies, including liquid
scintillation counting. This additional
flexibility can allow for simpler calibration
and counting procedures utilizing
liquid scintillation counting (LSC).
Besides offering the full spectrum of
radioanalytical testing services to support
the public health community, the SHL’s
radiochemistry department is leading
research efforts to answer important
questions such as hydraulic fracturing’s
impact on our environment, as well as the
potential impact of less well-understood
radioactive isotopes (such as 210 Pb and
210
Po) on public health in public and
private drinking water. These radioactive
isotopes are not routinely monitored
in drinking water, and their prevalence
in public and private drinking water
has not been widely studied; SHL and
the University of Iowa researchers are
currently undertaking several studies
examining the distribution of these
radioactive materials in drinking water. n
—Dustin May, radiochemistry supervisor and lead for research projects
16
LAB MATTERS Summer 2017
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