occupational chemical exposure surveillance: design and validation of a survey rukmani ramaprasad,...
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Occupational Chemical Exposure Surveillance: Design and Validation
of a Survey
Rukmani Ramaprasad, MSc, MS
Lisa Huguenin, PhD
Paula Knudson, MS, CIH
Eileen Senn, MS, CIH
David Valiante, MS, CIH
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Research Funding
This study on exposure surveillance methodology was funded by the National Cancer Institute through NIOSH’s National Occupational Research Agenda (NORA)
Three-year study began October 1999
Research staff include in-house research scientists and consultants on survey design, statistics, and scanning software
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Occupational Chemical Exposure: Why Survey?
Timely & cost effective - Occupational exposure assessment through personal and/or area monitoring is costly and time consuming. Methods to estimate exposure for worker population in timely & cost effective manner are needed to prevent occupational chemical exposure.
Estimate exposure hazard - This research focuses on developing a survey to mail to employers to estimate exposure hazard or the potential for worker exposure.
Initiate primary prevention - The estimates derived from the survey could be used to engage in primary prevention activities at selected workplaces by mitigating or eliminating exposure.
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Research Aims:Design and Validation of a Survey
Design survey to learn how targeted chemicals are handled at specific workplaces and characterize exposure hazard
Validate and audit survey responses
Develop scoring method to rank workplaces based on exposure hazard
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Selection of chemicals
six known or probable human carcinogens
Selection of industries
Standard Industrial Classification (SIC) codes based on where the selected chemicals are likely to be handled
Survey Design: Key Elements
o cadmium
o ethylene oxide
o formaldehyde
o lead
o methylene chloride
o crystalline free silica
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Survey Design: Types of Industries/ Chemicals Targeted
Industry Chemical(s) Targeted
Primary metal, pigments, non-ferrous foundries
Lead, cadmium
Solvents, paint remover, rubber
Methylene chloride
Pottery, brick, tile, refractory, concrete, abrasives
crystalline free silica
Health care and surgical supplies
Formaldehyde, ethylene oxide
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Survey Design: Sample Selection
New Jersey workplaces that may use one of the targeted chemicals is identified from MarketPlace, a national database of businesses. Workplaces with one employee are excluded.
A stratified random sample of workplaces is selected using size of workforce as strata. Each workplace is selected for only one chemical. Final survey will be sent to 700 workplaces.
A random sample of respondents will be selected to audit and validate responses on-site
Survey Design:Key Survey Questions
Is the chemical handled?
What is the quantity of the chemical handled?
How is the chemical handled?
What are the patterns of handling?
How many workers handle the chemical?
What are their job titles and duties?
Are controls to reduce exposures in place?
The survey questions address the three routes of exposure – inhalation, ingestion and dermal contact and exposure control mechanisms in place.
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Chemical Exposure Surveillance:Research Methods
Develop & pre-test Chemical Survey design
Develop & pre-test on-site validation methods
Develop & pre-test scoring system
Mail final version of survey to 700 workplaces Conduct on-site validation and audit of a sample
of survey respondents
Score final version survey responses
Survey: Pre-tests
Evaluate survey design Do employers understand the study’s objectives? Are instructions and questions clear and easy to read? Is the order of the questions logical?
Evaluate protocol Are procedures practical and useful? Can deadlines be met?
Evaluate employer cooperation Do employers complete and return survey?
Three rounds of pre-tests have been conducted to evaluate and improve the survey based on telephone follow up of respondents and non-respondents.
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Pre-tests: Response Rates
Pre-test
Number of Workplaces
Surveyed Response Rate1st 38 77%
2nd 50 44%
3rd 116 17%
4th 80 Pending
Survey: Key Revisions
Narrowed selection of chemicals From original 34 carcinogens To six – many OSHA 6B chemicals not in use
Changed source for identification of workplaces From workplaces reporting chemical use in the New
Jersey Right to Know database To those in selected SIC codes from MarketPlace
database Changed “chemical use” questions
From: “Is chemical produced or used?”Answer - Yes or No
To: “How is lead typically handled at this worksite?”Answer - Yes or No to 17 statements
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Survey: Key Revisions (cont’d) Survey Packet - 1st Pretest
2 cover letters, suggested steps, FAQs, 3 survey forms (37 questions total)
Survey Packet - 4th Pretest Brochure with Confidentiality Statement Instruction sheet Chemical Survey (39 questions) Participant Form (12 questions)
Survey formatted for use with scanning software (Cardiff Teleform™)
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What’s Next?
Pre-test on-site validation and audit methods Select sample of 700 employers and conduct
final survey Select random sample of respondents and
conduct on-site validation
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Challenges Ahead
Survey Survey is not mandatory Must rely on employer cooperation Can’t offer financial incentives Balance number of questions vs.employers’ time
On-site validation Gain employers’ cooperation for on-site visit Finalize method to determine validity of responses