New Analytical Methods to Assess Aggregate and Cumulative Risk

1
New Analytical Methods to Assess Aggregate and
Cumulative Risk James Starr1, Karen Bradham1,
Andy Lindstrom1, Elin Ulrich1, Mark Strynar1,
Sharon Harper1, Jeanette Van Emon1, Mark
Mason2 U.S. Environmental Protection Agency,
Office of Research and Development, 1 NERL 2 NRMRL
Results/Conclusions
Science Question
Immunoassays
Methods/Approach

• Fluoro-telomer alcohol concentrations in CTEPP
  house dusts have been found to be on the order of
  0.1 to 4.98 mg fluoro-telomer alcohol per gram of
  house dust. These are in similar to
  concentrations of pesticides/PAH (Lewis et al.,
  1999) and PFOS/PFOA (Moriwaki et al., 2003) found
  in vacuum cleaner bag collected house dust.
• Automated extraction and cleanup methods save
  time, solvent, energy, while GC/MS and LC/MS
  instruments produce accurate reproducible, and
  reliable pesticide data that is used to fill data
  gaps in exposure analysis.
• Good correlation between ELISA and GC/MS data
  (3,5,6-TCP) in dust, soil, food, and urine with
  applications to monitoring.

Metals/toxic Element Bioavailability Research
Perfluorinated Compounds
How can uncertainties and data gaps be reduced so
information inputted into models provides a
better understanding of human aggregate and
cumulative exposures? To help answer questions
regarding contributions to aggregate exposures,
new analytical methods are developed and applied.

Chlorpyrifos is a commonly used OP pesticide
found in various environmental and biological
matrices. The urinary metabolite of chlorpyrifos
is 3,5,6-TCP, which has also been found in air,
dust, soil, surface and dermal wipes and food.
There is a continuing need for rapid,
cost-effective, and reliable analytical methods
for human exposure assessment and environmental
monitoring studies. This work evaluates
cost-effective immunochemical methods that are
being developed by ORD to measure contaminants in
both indoor and outdoor environments, as well as
to determine urinary biomarkers of exposure.
Faster and more cost-effective field screening
and monitoring methods can help improve human
exposure assessment and environmental monitoring
studies by increasing the amount of information
available concerning the location and
concentration of target analytes that might
impact human health and the environment. This
research provided direct support to the CTEPP
project, and the Agricultural Health Study.
Pesticides
This task focuses on the development/improvement
of traditional methods for measuring toxic
elements as well as developing bioavailability
techniques to better characterize human and
ecological exposure from various sources and
pathways. Research is needed to produce data
under varying environmental conditions to help
establish relationships between total
concentrations and bioavailable concentrations to
yield a better understanding of the absorbed dose
of toxic elements. The objective of this task is
to develop state-of-the-science methods for
evaluating toxic elements. These methods will
include measuring bioavailable concentrations of
toxic elements as well as enhanced traditional
methods. ORD (NERL) is using these methods in
collaboration with OPPT and the U.S. Department
of Housing and Urban Development in the American
Healthy Homes Survey (AHHS), to provide data from
a national cross-section of residential soils
collected near Chromated Copper Arsenate (CCA)
treated wood. ORD (NERL/NRMRL) scientists are
also evaluating the effectiveness of coatings in
reducing dislodgeable arsenic from CCA-treated
wood.
Analytical methods for Perfluorinated Compounds
(PFC's) including perflurooctane sulfonate and
perflourooctanoic acid in environmental and
biological matrices have also been developed.
Prior to this work, methods were not available or
lacked the requisite reproducibility. The methods
will support research in a number of high
priority programs including AHHS, which will
provide the first population-based assessment of
perfluorinated compounds the Children's Total
Exposure to Pesticides and Persistent Pollutants
(CTEPP) program, where the first assessment of
the volatile telomer alcohols has been completed
and animal research studies conducted to support
priority research identified by the Office of
Prevention, Pesticides, and Toxic Substances
(OPPTS). This work provides a means to evaluate
exposures to the PFCs, helps to establish risks
associated with these exposures, and ultimately
may support an assessment of the effectiveness of
any mitigation strategies that may be put in
place to control exposures deemed hazardous.
Extraction, cleanup, Gas Chromatograph/Mass
Spectrometry (GC/MS), and Liquid
Chromatography/Tandem Mass Spectrometry methods
have been developed to accommodate requirements
of the Children's Health Environmental Exposure
Research Study. The goal for this research is to
improve analytical sensitivity and specificity
for new and emerging pesticides commonly used
indoors. Methods to measure trace levels of
pesticides on sampling devices, food, and
environmental media have been developed. These
methods are applied to pilot-scale aggregate and
cumulative exposure studies. The results from
these small sample sets will increase research
efficiency by early identification of problem
areas and selecting target analytes before
embarking on larger studies.
Impact and Outcomes
The developed methods will be used by OPPTS to
reduce uncertainty of total concentration
analyses, which may over estimate health hazard,
provide inaccurate risk assessments, and lead to
inappropriate risk-reduction expenses. These
methods will be used in ORD field studies (see
Egeghy et al. poster) to fill data gaps
identified in the aggregate/cumulative exposure
and risk research area of the Human Health Risk
Assessment research plan.

• This research focuses on developing
  bioavailability techniques to better characterize
  human and ecological exposures and provide
  information on absorbed doses.
• Traditionally, total metal/toxic element
  concentrations have been used to assess metal
  exposure, which may result in over estimation of
  health hazards and unnecessary risk reduction
  expenses
• Specific advantages
• more accurate means of assessing exposure as
  bioavailable concentrations provide more accurate
  information on the absorbed dose of toxic
  elements
• reduce uncertainty of the exposure assessments
  by providing absorbed dose of toxic element,
  which traditional technologies cannot provide
• incorporate cumulative and aggregate exposures
• improve default values in models
• improve risk assessments and hazard
  identification
• reduce risk reduction expenses because
  technology is based on bioavailable
  concentrations and not total toxic element
  concentrations

Future Directions
These methods will continue to be developed,
tested and validated to strengthen field studies
that support the reduction of uncertainties and
refine the risk assessments for childrens
exposure to residential pesticides. The continued
development of these methods will provide the
requisite analytical techniques that are
sensitive, specific, and robust to more precisely
assess aggregate and cumulative exposures.
Research Goals
Office of Research and Development (ORD) methods
development researchers apply their knowledge to
high priority agency needs for data to perform
risk assessments and make decisions. The methods
provide a scientific foundation to characterize
and reduce human risks resulting from exposures
to multiple environmental stressors and to
further understanding of aggregate and cumulative
exposures.
References
Bradham, K., Harper, S.L., and Coppedge, E.A.
Bioavailability of metals in contaminated soil
and dust. Presented at 19th Annual Regional Risk
Assessors Meeting, Boston, MA, May 3-7,
2004. Chuang, J.C., Van Emon, J.M., Reed, A.W.,
and Junod, N. Comparison of immunoassay and gas
chromatography/mass spectrometry methods for
measuring 3,5,6-trichloro-2pyridinol in multiple
sample media. Analytica Chimica Acta 517
(1-2)177-185 (2004). EPA/600/J-04/254. Logan,
M.N., Thibodeaux, J.R., Hanson, R.G., Strynar,
M.J., Lindstrom, A.B. and Lau, C. Effects of
Perfluorooctane Sulfonate (PFOS) on Thyroid
Hormone Status in Adult and Neonatal Rats.
Presented at 43rd Annual Meeting and Toxexpo of
the Society of Toxicology, Baltimore, MD. March
21-25, 2004. Morrison, C., Starr, J., Ulrich,
E.M. Analysis of selected pyrethroid pesticides
using reverse phase high pressure liquid
chromatography/UV. Presented at Joint Carolinas
and Southeast SETAC Chapter Meeting March 2004,
Kennesaw, GA. Van Emon, J.M., and Chuang, J.C.
"Immunoassay methods for measuring atrazine and
3,5,6-trichloro-2-pyridinol in foods." Pesticide
Analysis Methods and Protocols, Vol 1 Analysis
for Human Exposure, Jose Luis Martinez Vidal, ed.
2004.

This Chromatogram shows that LC/MS reduces the
need for temporal separation of analytes