Environmental Risk Assessment Reports - Chapter 11 pptx

Sampling and analytical procedures should be matched tothe level of risk assessment rigor that is needed to sufficiently understand the natureand extent of contamination and its potentia

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Analytical Quality Assurance/ Quality Control for Environmental Samples Used in Risk Assessment

Wayne Mattsfield and David A Belluck

CONTENTS

I Introduction 277

II Effective Use of Analytical QA/QC for Risk Assessment 279

III The Role of Analytical QA/QC in Risk Assessment Preparation, Review, and Management 279

A Project Description 281

B From Sampling to Data Analysis 282

C Blanks 287

D Choosing Laboratory Analytical Methods 296

E Where Analytical QA/QC is Used in Risk Assessment Reports 296

F Quality Assurance Project Plans (QAPPS) 297

IV Effect of Data Quality on Data Usability in Risk Assessment 297

V Conclusion 298

References 299

I INTRODUCTION

Risk assessments are designed to calculate site, activity, or facility risks for individual chemicals and chemical mixtures When environmental releases of chemicals or exposures are known or suspected to have occurred, environmental samples can be collected and chemically analyzed to identify and quantitate sample contaminant residue levels Regardless of where or how an environmental sample is taken and

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278 A PRACTICAL GUIDE TO ENVIRONMENTAL RISK ASSESSMENT REPORTS

its chemical composition analyzed, it must meet defined quality parameters or itsusefulness is questionable Sufficient data of known quality must be used in a riskassessment to ensure that risk assessments properly reflect site, activity, or facilityrisks Environmental sample quality assurance and quality control is a major focus

of chemists and risk assessors during the planning and early phases of the riskassessment process U.S EPA recognized the importance of data quality for riskassessment by noting that its quality assurance program goal is to ensure that alldata be scientifically valid, defensible, and of known precision and accuracy towithstand scientific and legal challenge relative to the use for which the data areobtained

Environmental sampling and analytical chemistry work should proceed after a riskassessment team has thoroughly considered why the data is needed, how much data

is needed, what kinds of data are needed, how good the data need to be, and who willuse and review the data Sampling and analytical procedures should be matched tothe level of risk assessment rigor that is needed to sufficiently understand the natureand extent of contamination and its potential human health or ecological risks.Several mechanisms have been devised to provide step by step procedures towalk project managers, scientists, risk assessors, and others through the process ofdesigning sampling and analytical plans which provide data of known quantity andquality Several of these processes have been formalized by the EPA and are recog-nized by their acronyms: Data Quality Objectives (DQOs), Quality Assurance ProjectPlans (QAPPs), and Sampling and Analysis Plans (SAPs)

These processes are used to ensure integration of risk assessment data generationactivities This includes design of the work plan or sampling plan, communicationwith all parties involved in the process, utilization of appropriate sample collection,sample preparation and analytical methods, and validation and assessment of ana-lytical data This primer provides the basic concepts of QA and QC in field samplecollection and laboratory analysis

Anyone who is about to review environmental data for the purpose of riskassessment is faced with some fundamental questions about its application to theprocess, such as, how do you differentiate “good” analytical results from “poor”results? Risk assessors are often faced with using data collected prior to theirinvolvement in a case that may not have been produced for their use, and which wasobtained and analyzed over time using different sampling, analytical chemistry, andQA/QC protocols How can this data be appropriately evaluated and combined withother data sets, and can it be combined with new data specifically produced for arisk assessment? As this primer will show, when data is properly collected, analyzed,and reported, data of known quality can be properly considered for use alone or incombination with other data sets of known quality

Data collected and analyzed for a risk assessment should be collected afterseveral important planning steps have been completed Before environmental sam-pling and analysis occurs to supplement historical data, or prior to the first thoroughinvestigation of a site, data quality goals should be clearly defined for collection ofanalytical data in terms of precision, accuracy, representativeness, comparability andcompleteness (or PARCC), and DQOs Failure to use these planning tools may result

in collection of data that fails to meet all the needs of risk assessors

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ANALYTICAL QUALITY ASSURANCE/QUALITY CONTROL 279

Consultants performing a QA/QC function should be technically trained inphysical and chemical sciences and experienced in the design, collection, and inter-pretation of environmental data Useful experience includes participation in scopingdifferent environmental investigations, and preparation of SAPs and QAPPs, as well

as in data review and validation for these activities Consultants should thoroughlyunderstand applicable federal and state regulations for risk assessment QA/QC and

be able to provide previous work products and reporting formats; a list of laboratoriesthe consultant uses for risk assessment projects (include laboratory audits and rele-vant certifications); and a summary of the qualifications and experience of the firmand persons proposed to work on the project If the consultant has their own ana-lytical laboratory, they should provide a prospective client with relevant certifica-tions, approvals, and records of laboratory audits

II EFFECTIVE USE OF ANALYTICAL QA/QC FOR RISK ASSESSMENT

Effective use of QA/QC tools results in efficient data collection and chemical analysis

of environmental samples and allows for smooth integration of sampling data intothe risk assessment Precious time and money are saved when a properly constitutedsampling and analysis plan is followed, because there will then be little need toreturn to the field to collect and analyze additional samples for the same or supple-mental chemical substances not previously sought or analyzed Effective risk assess-ment sampling and analysis programs can engender a public perception of thoseinvolved as competent, cooperative, and accountable professionals

III THE ROLE OF ANALYTICAL QA/QC IN RISK ASSESSMENT

PREPARATION, REVIEW, AND MANAGEMENT

Planning the risk assessment must include environmental sampling and analyticalQA/QC plans Obtaining the right type and amount of analytical data begins in theplanning or scoping process During this process, participants should review anypreviously obtained data and determine the number, location, and media types ofsamples to be collected Sample collection techniques; data quality needs; appropri-ate analytical methods and quantitation limits; QC acceptance criteria for projectsamples; and the extent and format of the data review/validation report, performed

on the analytical data, should also be determined at this time The planning or scopingmeetings can include many parties, but at a minimum should include the projectmanager, risk assessor, hydrologist or geochemist, and chemist/QA manager (see

Tables 1 and 2)

The role of the chemist/QA manager in the planning process is to recommendthe sampling techniques; numbers of investigative samples, analytical methods, andquantitation limits; and numbers of QC samples and data reports (deliverables) whichare necessary to meet the data quality/quantity needs of the risk assessor

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During planning, members of a risk assessment team must evaluate:

• relevant historic data to determine the COPC

• the number and types of samples to obtain

• the analytical methods to use

• project-specific QC requirements

• what laboratory will conduct the chemical analyses

• sampling design, data review, and validation protocols and reviewers, balancing good sample collection and analytical procedures with health concerns

• product, process and performance standards

• deliverables

• program constraints

Table 1 Key Individuals in Risk Assessment Project QA/QC

Project Manager Organizes scoping meeting

Coordinates actions of all individuals in project Oversees preparation of Work Plan, Sampling Analysis Plan

Coordinates field sampling activities Manages subcontractors

Risk Assessor Reviews historical data

Determines chemicals of concern for risk assessment Assists in preparation of Work Plan, Sampling Analysis Plan

Reviews validated data for use in risk assessment Prepares risk assessment

Chemist/Quality Assurance Manager

Assists in preparation of Work Plan, Sampling Analysis Plan; recommends field and analytical methods to achieve project goals

Determines quality control samples needed to achieve data QC goals

Assists project manager in managing field sampling activities; audits field sampling activities

Provides limited oversight of sample analysis by the laboratory

Reviews preliminary data Validates data

Provides risk assessor and project manager with report Geologist /Hydrogeologist Assists in preparation of Work Plan, Sampling Analysis

Plan Reviews preliminary data with respect to representativeness to site

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A Project Description

Project descriptions are the summaries of the project location; history of activities;responsible party and/or regulatory agency investigations and monitoring activities;and documents produced from these activities Project descriptions are used toprovide the reader with an understanding of the physical layout of the site; extent

of contamination and media affected (if known); the written record of past gations; and the field and laboratory data acquired from these endeavors

investi-Project descriptions should be concise and contain several elements investi-Projectdescriptions begin with a statement of the decision to be made or questions to beanswered Following this statement of purpose, a description of the site, activity,facility, operating parameters to be studied, and anticipated uses of sampling andanalysis results, should be provided Additional elements include: anticipated uses

of sampling and analysis results; a list of all measurements to be performed; a projectschedule, indicating when samples are expected to be submitted to the laboratory;and a summary table covering the following for each sampling location — totalnumber of samples (including primary, quality control, and reserve); type of samples(air, water, soil, etc.); analytical techniques employed for each sample; and a list of

Table 2 Project Scoping Checklist — Sampling/Analytical

What types of media will be sampled and analyzed ? _ Air _ Soil _ Surface water _ Groundwater _ Other:

What are the chemicals of concern?

Are the methods appropriate for risk assessment?

Will special quality control limits be necessary?

What laboratory will conduct the analyses?

Should analyses be performed by a mobile laboratory, fixed-base laboratory, or both? _ mobile laboratory _ fixed-base laboratory _ both

What sampling design is appropriate?

What type of data review is required? Who will perform data review?

How does the data need to be reported? (Data deliverables)

How many background samples are needed? _

What constraints (budgetary, political) may affect data collection?

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all measurements to be performed, differentiating, where applicable, the criticalmeasurements (those necessary to achieve project objectives) from the noncriticalmeasurements

B From Sampling to Data Analysis

Adhering to proper sample collection procedures is arguably the most importantfactor in the process leading to the generation of acceptable data Collection ofenvironmental samples should be carried out after a SAP or Work Plan and QAPPhave been developed Typical contents of a SAP include: a project description (e.g.,project purpose, site description and site history, media to be sampled, COC), DQOs(e.g., precision, accuracy, representativeness, comparability, and completeness);sample collection procedures (e.g., standard operating procedures for collecting,handling, and shipping samples); sample shipment and chain of custody; field andlaboratory instrument calibration; field and laboratory analytical methods; datareduction, validation, and reporting; and internal quality control checks

The correct number of samples (e.g., single grab samples, duplicate samples,time sequence samples, or several grab samples to make up a composite sample);depth intervals (soil samples); matrix type and other relevant factors can dictate thetype of sampling devices and techniques which will result in the most representativesample for laboratory analysis Sample collection procedures can range from sitespecific to those mandated by a given regulatory program Regardless of the origin

of the sampling procedures, they must take into account the type of environmentalmatrix and substances to be measured For example, when collecting soil samplescontaining volatile or quickly degraded substances, special care must be taken toensure that the chemical will still be in the sample when it reaches an analyticallaboratory

Once a sample is collected, it must be properly labeled, inventoried, and shipped

to an appropriate laboratory for analysis Samples must be stored in a way thatminimal loss or change in chemical composition will occur Proper documentationmust be maintained from sample point to laboratory bench to ensure that a samplewill not be misidentified These factors are very important in cases where governmentenforcement actions or litigation is a possibility

1 Extraction Methods

Assuming that all sampling, shipping, recipient sample tracking, and storage dures are adequately followed, the sample can now be analyzed for chemical content.Numerous kinds of methods are used to remove chemicals that are in solution,absorbed, or adsorbed to an environmental matrix Some of the most commonmethods used to extract organic chemicals from environmental matrices are dis-cussed below

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a Purge and Trap

In purge and trap an inert gas is bubbled though an aqueous sample, transferringpurgable compounds (organic compounds with boiling points less than 200°C) fromthe aqueous phase to a vapor phase Purgeables are trapped on a sorbent materialwhich is heated and back-flushed with a gas to carry the purgables into a chromato-graphic column for separation

b Solvent Extraction

Organic compounds are separated from the aqueous or solid phase of the sample bymixing the sample and organic solvent together, or passing the organic solventthrough the sample; in general the solvent has more affinity for the organic com-pounds in the sample than does the sample matrix An aliquot of this solvent phase(now containing the organic compounds) is injected directly into the instrument foranalysis

c Solid Phase Extraction (SPE)

In SPE, an aqueous sample is filtered through or mixed with a solid absorbant thatseparates the organic chemicals from the sample matrix After extraction, the organ-ics are eluted or flushed off the solid phase, concentrated, and directly injected intothe analytical instrument

d Supercritical Fluid Extraction (SFE)

SFE is a low temperature extraction using a gaseous solvent to separate organiccompounds from sample matrices, over a short extraction period, with reduceddestruction of heat labile compounds

Metals can be found in aqueous solutions as dissolved ions precipitated out ofsolution in the form of hydroxides or salts, or bound in organometallic complexes.Water samples that contain relatively few solids (such as drinking waters) may notrequire sample preparation prior to analysis; water samples with significant solidscontent typically are digested with an inorganic acid and heat, to free metal ionsfrom precipitates and organometallic complexes Especially oily samples or media,with significant organic content, may interfere with acid digestion and analysis ofsamples for metals; under these circumstances the sample may require that theorganic interferant be extracted out of the sample prior to digestion

2 Measurement

Once environmental chemicals are removed from an environmental sample, theycan be identified and quantified by laboratory methods, including elaborate andexpensive instruments

Laboratory instruments routinely used for measuring organic and inorganic stituents in environmental samples are discussed below

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a Gas Chromatography

In gas chromatography organic compounds are separated into individual componentsbased on their boiling point and relative affinity between the gas carrier phase andthe solid sorbant phase of the chromatographic column Compounds are separated

by increasing the temperature of the column during sample analysis; compounds oflarger molecular weight are eluted from the column last at these high temperatures.After separation, the individual components generate a quantifiable response regis-tered by a detector selected for the specific organic compounds of interest

b High Pressure Liquid Chromatography (HPLC)

Organic compounds which are not appropriate for gas chromatography (heat tive, high molecular weight) may be analyzed using a liquid carrier and increasingpressure during analysis

sensi-c Atomic Absorption Spectrophotometry

Both graphite furnace atomic absorption (GFAA) and flame atomic absorption(FLAA) detect metals by the absorption of a light (at a wavelength specific to themetal of interest) passing through an atomized aliquot of the sample injected intothe instrument FLAA is generally less costly and faster than GFAA, but detectionlimits are lower for GFAA

d Inductively Coupled Argon Plasma Spectrophotometry (ICP)

In ICP, atomized samples are heated in a high temperature plasma where metalsemit light at one or more wavelengths characteristic of that metal

3 Data Analysis

a Data Reduction

Environmental investigations can produce massive amounts of raw data that must

be evaluated and reduced into summary tables if it is to be successfully used in arisk assessment report Data reduction is accomplished by hand entry of analyticaldata into computer spreadsheets, word processing tables or databases; however,direct electronic data transfer (using computer diskettes, tape, or via modem) isautomating the process of the production of tabulated data There are an everincreasing number of information management systems software that can extractinformation from electronic databases or spreadsheets and produce graphic displays

of chemical concentrations superimposed over site plans Data reduction proceduresproduce chemical concentrations at given locations that are used as initial inputsinto the risk assessment and are ultimately reflected as calculated risks Howeverdata reduction is accomplished, mathematical methods and logic behind them must

be transparent and verifiable by reviewers

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b Data Validation

Data validation is the process of verification and evaluation which (1) confirms thatinvestigative and QC samples have been properly handled, under appropriate cus-tody, and submitted to the analytical laboratory for the correct analysis, (2) verifiesthat the laboratory analytical system was in control and capable of generatinganalytical results of expected quality, (3) verifies that the analytical results reportedwere accurate as reported, and (4) allows the data validator to qualify or rejectreported data based on sample contamination, method deficiencies, or analyticalanalysis which is out of control Data validation is accomplished by reviewing fieldlogs and notes, chain of custody forms, laboratory internal QC and external field

QC results, instrument raw data and chromatograms, laboratory reports, laboratorystandard operating procedures, and the site QA project plan or SAP

Persons performing data validation work must possess sufficient experience tointerpret the analytical data in terms of the project data quality objectives, PARCC,quantitation limits, method performance and risk assessment needs Validation per-sonnel should have standard protocols (based on U.S EPA’s Contract LaboratoryProgram [CLP] guidance documents or other method-specific criteria) or contractorspecific standard operating procedures to validate project data Remember that this

is the major yardstick by which acceptability of the data will be measured

c Data Reporting

Data reporting presents the analytical data to the project manager and risk assessor,along with a description of the limits of usefulness or data qualifiers, for results oranalyses that may not have met the designed needs of the investigation Datareporting is accomplished by providing data summary tables annotated with anyappropriate data qualifiers, and a data validation narrative that describes any sam-pling or analytical difficulties, reporting or detection limit deficiencies, laboratoryand validator qualified data, and the data validator’s overall assessment of the data

It is important to know who will prepare the project data report, in what time frame,and in what format

4 QA/QC Measures

Since scientists cannot hold or see individual atoms of single elements or the severalatoms comprising compounds, they must rely on the information provided by theirlaboratory methods and instruments QC samples are taken to ensure that the ana-lytical methods are performing properly Any QC method should clearly describestep by step procedures for preparation of standards and reagents, sample prepara-tion, sample analysis, and data reporting, as well as the concentration range of themethod, the reporting limits and method detection limits of the method (if different),and potential interferences and limitations of the method (which can be matrixdependent or affected by other substances in the sample medium) Method accep-tance criteria for standards, surrogate compounds, spikes, duplicates, and other

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internal method performance and quality control checks, should be clearly stated inthe method

There are numerous ways to assure that laboratory methods, instrumentation,and findings are accurate and precise DQOs are qualitative and quantitative state-ments that specify the quality of the data required to support decisions DQOs aredetermined based on the end use of the data to be collected PARCC data qualityindicators evaluate analytical data precision (measurement of agreement of a set ofreplicate results, among themselves, without assumption of any prior information

as to the true result, and assessed by means of duplicate/replicate sample analysis);

Table 3 PARCC Data Quality Indicators

Data Quality

Precision Reduce uncertainty of data

through assessment of the variability in sample measurements; determine confidence in distinguishing site concentrations of compounds of concern from background or upgradient concentrations

Collect and analyze sufficient numbers of field replicate samples; increase frequency of field duplicate samples for heterogeneous matrices (soils and waste)

Accuracy Increase confidence in

distinguishing site concentrations of compounds

of concern from background or upgradient concentrations;

inaccurate data can result in false positives or errors in the quantitation of compounds of concern

Follow well written, proven sample collection and analytical SOPs that meet accuracy needs for data at key quantitation limits

Representativeness Avoidance of false negatives

and false positives due to field sampling contamination

Use an unbiased sample collection design and mixing of samples to adequately represent the sample conditions; include blanks and

QC sample collection/analysis

to monitor false positives (blank contamination), false negatives, and biased results (spike sample recoveries) Completeness May decrease sample

representativeness for identification of false negatives and estimation of average concentrations

Stipulate completeness goals for sampling and sample analysis; require SOPs for sample collection, handling, and analysis to provide for complete and valid sample collection and analysis

Comparability Ability to combine analytical

results across sampling episodes and time periods

Use the same sampling techniques, sampling design, and analytical methods across episodes and time periods

Note: SOPs = standard operating procedures.

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accuracy (nearness of a result, or the mean [X] of a set of results, to the true valueand assessed by means of reference samples and percent recoveries); representative-ness (extent to which data measure the objectives of the data collection); complete-ness (measure of the amount of useable data resulting from a data collection activity,given the sample design and analysis); and comparability (measure of the equiva-lence of the data to other data sets or historical data) (see Table 3)

Achievement of DQOs is measured through attainment of project data qualityindicator goals for PARCC Development of DQOs is detailed in the September

1994 Guidance for the Data Quality Objective Process, and the Data Quality Objectives Decision Error Feasibility Trials Guide and Software.

Analysis of calibration standards are used to determine that the analytical ment is correctly identifying and quantifying the chemicals in the environmentalsamples This is done by injecting known concentrations of a chemical into a piece

instru-of equipment and evaluating the instrument’s response Analysis instru-of calibration dards verify the linearity of the response of the instrument to the concentration(s)

stan-of the analyte(s) stan-of interest in the calibration standard

C Blanks

Blanks are used to determine if analytical methods, materials, or instruments arereporting chemicals in an environmental sample that are really not there Blanks areartificial samples designed to monitor the introduction of artifacts into the process.For aqueous samples, reagent water is used as a blank matrix; however, a universalblank matrix does not exist for solid samples, and, therefore, no matrix is used Theblank is taken through the appropriate steps of the process Several types of labo-ratory blanks are described below (see Table 4)

1 Trip Blank

A Trip Blank (also known as a Travel Blank) accompanies VOC containers fromshipment from the laboratory, to sampling in the field, and receipt by the laboratory.Analysis of the trip blank measures potential contamination of VOC containers andsamples by volatile vapors

2 Field Blank

A Field Blank (also known as a Rinsate Blank) is used to monitor cleanliness ofequipment after field cleaning/decontamination of equipment Laboratory-gradewater is dispensed into a clean container for use in the field

a Method Blank

Method Blank (also known as a Laboratory Blank) measures contamination duced by sample preparation solutions; absorption of contaminant vapors or partic-ulates; contaminated sample standards or surrogates; and glassware; and contami-nation attributable to laboratory instrumentation, equipment, or glassware

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