Impact/Purpose:

The objective of this task is to identify, develop, and evaluate simple, cost effective monitoring methods that can be used to develop exposure classifications for the proposed Longitudinal Cohort Study. Methods once evaluated should be applicable to other epidemiological studies. This project will be conducted as four concurrent subprojects.

(1) demonstrating field performance and developing uptake rates of a semipermeable membrane devise (SMPD) to collect long-term integrated samples for semivolatile organics in air,

(2) developing simple rapid methods for analyzing the SMPDs,

(3) developing rapid field or near field methods for analyzing chemical metabolites in urine,

(4) review literature to identify available but not currently used techniques for long-term integrated exposure measurements.

Description:

Accurate exposure classification tools are required to link exposure with health effects in epidemiological studies. Exposure classification for occupational studies is relatively easy compared to predicting residential childhood exposures. Recent NHEXAS (Maryland) study articles reveal that population distributions of exposure are relatively constant; however, for the majority of individuals within the study population exposures vary dramatically over time (62 subjects sampled six times during a one-year period - air, food, water, dust, and urine). Long-term, time-integrated exposure measurements would help address the problem of developing appropriate residential childhood exposure classifications. This task will investigate/or evaluate measurement methods classifying exposure, both long term integrated and screening for exposures to short half life contaminants.

Although long-term integrated exposure measurements are a critical component of exposure assessment, the ability to include these measurements into epidemiological studies is often limited by time, budget, and compliance issues. Another problem which arises when determining the sources, routes, and pathways of exposure to pesticides and other chemicals is the lag time between collection of a sample and the receipt of the results. Current methods which use laboratory analysis may take 30-60 days, or longer, to obtain results. This means that the source of exposure may be gone by the time it is discovered that the child has been exposed, given the relatively short half-lives of many compounds. Screening techniques could direct attention to the most highly exposed (to particular indicator compounds) population of children for which multiroute, multimedia monitoring would be of value. In addition, stratification of the study population (i.e., the majority of the environmental/biological samples collected from the "highly exposed population" of children) often is required, given the expense of multiroute, multimedia monitoring (numerous non-detect results are counterproductive in determining sources).

Record Details:

Record Type:PROJECT

Start Date:10/01/2000

Projected Completion Date:09/01/2006

Record ID: 56202

Show Additional Record Data

Project Information:

Progress :A literature review of has been completed in FY03 that identifies long-term, integrated exposure measurement techniques that are currently available or will be available in the near future. Techniques found were primarily passive and active air monitoring methods for a variety of analytes. This information can be used to either select techniques for use in the NCS or identify gaps where additional methods development or validation is needed.

The SPMD work has demonstrated that they are an effective air sampling device for semivolatile organic compounds. The recent work has involved developing uptake rates to permit the estimation of air concentrations from levels found in SPMDs. During FY02, an exposure device was invented and uptake rates were developed for 26 chemicals which included polycyclic aromatic hydrocarbons, organophosphate pesticides, organochlorine pesticides and pyrethroid pesticides. Uptake rate studies are continuing with another set of 26 chemicals in FY 05.

Screening methods have been developed for determining anticholinesterase compounds (organophosphate and carbamate pesticides) in SPMDs. These methods would be useful for the NCS in providing low cost screening of SPMDs to limit complete analyses to those containing significant amounts of cholinesterase inhibiting compounds. This would reduce costs.

-Report -- Development and Application of Techniques for Sampling Bioavailable Airborne Organic Contaminants (9/13/99)

-Report -- Development and Application of Techniques for Sampling Bioavailable Airborne Organic Contaminants-Tentatively Identified Compounds By Gas Chromatography/Mass Spectrometry 3/01/01

-Report -- Calibration of Lipid-Containing Semipermeable Membrane Devices (SPMDS) for Vapor Phase Airbourne Contaminants 10/16/02

-Report -- Identification of Time-Integrated Sampling and Measurement Techniques to Support Human Exposure Studies 10/01/02

--Book Chapter--Mishra, N.N., Pedersen, J.A. exposure assessments. The results of this work will be published in EPA reports and journal articles.



Clients :National Children's Study (NCS) Interagency Coordinating Committee (Peter Scheidt, Carole Kimmel, James Quackenboss), NCS Workgroup on Exposure to Chemical Agents (Robin Whyatt, Larry Needham, Haluk Ozkaynak), Office of Children Health Protection (Mi

Project IDs:

ID Code :8819

Project type :OMIS
Relevance :This work directly supports the proposed interagency Longitudinal Cohort Initiative by developing low cost and burden methods that will increase the feasibility of collecting good exposure data. The methods developed will also be useful in other human exposure studies and investigations. This research supports the science outlined in the Presidential Task Force . It also directly supports the high priority research defined in FY 06 APM422 to provide new or refined methods to the Agency and scientific community for measuring pollutant concentrations in environmental samples that will be used in field studies to provide high quality data for cumulative exposure assessments. The results of this work will be published in EPA reports and journal articles.



Clients :National Children's Study (NCS) Interagency Coordinating Committee (Peter Scheidt, Carole Kimmel, James Quackenboss), NCS Workgroup on Exposure to Chemical Agents (Robin Whyatt, Larry Needham, Haluk Ozkaynak), Office of Children Health Protection (Mi

Project IDs:

ID Code :8819

Project type :OMIS