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INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE
EPA'S NON-TARGETED ANALYSIS COLLABORATIVE TRIAL (ENTACT)
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How do you test for something
when you don't even know it's
there? EPA researchers are
developing new ways to do just
that in order to protect human
health and the environment.
Chemicals registered for use in
the U.S. number in the tens of
thousands, and there is evidence
of potential environmental and
human exposure to some of these
chemicals. However traditional
analytical chemistry methods that
look for the presence of unknown
chemicals are not sufficient to
monitor for all of these potential
contaminants. Therefore. EPA
has developed non-targeted
analysis methods to rapidly
assess for chemical exposures.
The objective of non-targeted
analysis methods is to identify
unknown chemicals 111 water, soil
and other types of samples,
without having a preconceived
idea of what chemicals are
present.
EPA scientists are leading a
multi-phase project to evaluate
the ability of non-targeted
analysis methods to consistently
and correctly identify unknown
chemicals in samples. EPA's
Non-Targeted Analysis
Collaborative Trial (ENTACT)
was formed in late 2015 and
includes nearly 30 academic,
government and industry
laboratories.
ENTACT samples
Scientists used about 1,200
chemical substances from
EPA's ToxCast library to
make 10 liquid mixtures
containing 100 to 400
compounds each.
Three types of samples were
also used in the study: house
dust, human serum and
silicone wristbands. These
samples were each spiked with
one of the 10 liquid mixtures.
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Ten mixtures made from 1,200
ToxCast chemicals. Each
mixture contains about 100-
400 chemicals.
The dust and serum samples were
purchased from the National
Institute of Standards and
Technology (NIST) and are
certified standard reference
materials. Oregon State
University prepared the
wristbands by uniformly
exposing them to outdoor air to
allow them to absorb airborne
environmental pollutants.
Phase 1: Blinded analysis
In Phase 1 of ENTACT, the
sixteen total samples were sent to
approximately 25 analytical labs.
Those labs were instructed to use
their own non-targeted methods
to analyze the samples, and to
report back to EPA what
chemicals they detected in the
samples. This phase of ENTACT
began in September 2016 and is
expected to be completed by
August 2018.
Each lab received:
•	10 liquid mixtures (each
containing 100 to 400
ToxCast chemical
substances);
•	Dust, serum, and wristband
extract, each spiked with one
of the 10 ToxCast mixtures
prior to extraction; and
•	Dust, serum, and wristband
extract not spiked.
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U.S. Environmental Protection Agency
Office of Research and Development

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The labs send their results to
EPA using a standardized format
that allows comparison between
the labs.
world use non-targeted analysis
methods to screen for substances
that are included in the ToxCast
library of chemical substances,
they can compare their own
results with those in the database.
EPA's 2018 ENTACT
Workshop:
http://bit.lv/Entact2018
EPA's ToxCast Library:
https: //www .epa. gov/chemi cal-
research/toxicitv-forecasting
National Institute of Standards
and Technology:
www.nist.gov
Silicone wristbands prepared by
Oregon State University.
Phase 2: Unblinded analysis
For Phase 2 of ENTACT, as the
labs report their analytical results
from Phase I. EPA scientists will
reveal what chemicals were
added to the samples they
analyzed. This will allow the
participating labs to evaluate
what they correctly or incorrectly
identified, and what they failed to
detect
Phase 2 of ENTACT started in
June 2017 and has been
completed by several labs.
Phase 3: Analysis of individual
chemical substances
In the ongoing Phase 3 of
ENTACT, the team shared the
entire EPA ToxCast library of
chemical substances (about
4,700) with five participating lab
instrument vendors. Those
vendors are analyzing each
substance separately and creating
a database of how these 4,700
substances look on their
equipment.
Once the database is complete, it
will be made publicly available.
Then, when labs around the
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Organic
Contaminant
House Dust
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A certified sample of
house dust.
Next steps
EPA will host a non-targeted
analysis workshop in August
2018 at its Research Triangle
Park, N.C., facility. There,
researchers will have the
opportunity to discuss the
interpretation of data from
ENTACT, and next steps for the
non-targeted analysis research
community. ENTACT scientists
aim to have completed Phase 1
by the time of the workshop and
to have made good progress on
Phase 2.
Technical Contacts:
Elin Ulrich
Research Chemist
EPA National Exposure
Research Laboratory
ulrich.elin@epa.gov
Jon Sobus
Physical Scientist
EPA National Exposure
Research Laboratory
sobus.ion@epa.gov
Communications Contact:
Emily Smith
EPA National Exposure
Research Laboratory
smith.emilv@epa.gov
April 2018
More information:
Sobus, J.R., Wambaugh. J.F., Isaacs, K.K., Williams, A.J., McEacliran. A.D.,
Richard, A.M., Gmlke, C.N., Ulrich, E.M., Rager, J.E., Strynar, M.J., Newton,
S.R., 2017. Integrating tools for non-targeted analysis research and chemical
safety evaluations at the US EPA. Journal of Exposure Science & Environmental
Epidemiology.
2
U.S. Environmental Protection Agency
Office of Research and Development

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