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September 10, 1992 Mary Paxton Benzene Task Force Meeting with Bill Farland
At 11:30 on Tuesday, September 1, representatives of API's BTF met at ~EPA with Bill Farland and other individuals involved in EPA's reevaluation of its risk assessment for benzene (attendance list follows).
Bill Farland introduced his group to us and explained what they would be doing about benzene in response to the request from MobiLe Sources under the Clean ALr AcL_ Nothing specific was said- about reviews for butadiene or formaldehyde.
Bob Sonawane will be overseeing the updating of the 1985 interim risk assessment for benzene. They will determine whether health endpoints in addition to cancer should be considered when esti~ating health risks; a contractor is now preparing chapters summarizing the available information on an endpoint-by-endpoint basis. They are hoping to receive a complete first draft by November or December and to have a document ready fo~ review by the :>AE- by ~the end of March 1993. Hugh McKinnon noted that when the scienti-fic data generated since 1985 has been gathered, they will recommend what changes in the risk assessment should be cons ide red and poin~t out what research is in progress that might infl~ence the result. They intend to meet their deadline by havi:1g a revision ready in the early summer of 1993.
Pat 3eatty reviewed the progress that has been made- in the API/WSPA(/CMA) research project on benzene since our las~t meeting with Farland in March 1991 (handout attached). There was some discussion of how Pausentbach's new exposul:'-e estimates for the Pl~ofilm cohort were derived, reasons for using the proportional hazard's model, and the variables being considered in Crump's sensLtivity analysis.
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BP-00007919
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Attendees
American Petroleum InstitutP
Benzene Task Force
Pat l!eat ty
Chevron
CosmCJ CiPerna
Mobil
Bob Lrew
API
Mary Paxton
API
Environmental Protection Agency
Office of Research & Development
Office of Health & Environmental Assessment
Bill Farland
Director
Human Health Ass-essment Group
Hugh McKinnon
Director
Char}es Ris
Deputy Director
Jim Cogli-ano
Cancer S~atistics & Epidemiology, Branch
Chief
Bob ~;onawane
Reproductive & Developmental Toxicity, Branch
Chief
David Bayliss
Epidemiologist
Chao Chen
Statistician
Arthur Chiu
Pathologist
Eric Clegg
Reproductive toxicologist
Larry Valcovic
Geneticist
BP-00007920
Meeting Objectives
I II 1-
Understand EPA's current activities and schedule related to reassessment of benzene
<'
and butadiene risks
Describe API's current. benzene~related 'I activities and summarize new information I developed by API relevant to benzene risk assessment
Determine how API can contribute to EPA's
reassessment of llenzene risk
SLIDE 1
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API Basic Biology Research - In Progress
Travis - pharmacokinetics of benzene
CIIT - metabolism and kinetics of metabolites
Irons . and Ross - mechanistic studies of
metabolite effects on bone marrow stem cells
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I
Cbx - modeling of pharmacokinetic,, meta-
bolism, and pharrnacodynamics leading to
leukemogenesis
SLIDE 2
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APl Basic Biology Research - Future Direction
Travis's pharmacokinetic work has resulted in
a PK model for benzene that should be
valuable
The other research projects are long-range and unlikely to influence the benzene risk assessment in 1992
Benzene Research Workshop on September 21-23, 1992, will develop ideas for future research efforts by API
SLIDE 3
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API/WSPA Epidemiology on Pliofilm Cohort
Paustenbach re-evaluation of worker e~pO~l,lre
levels
~
ENVIRON re-analysis of the mortality data and estimation of risks of occupath~nal exposure
Crump sensitivity analysis of models and assumptions (ongoing)
....
SLIDE 4
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Pliofilm Cohort Exposure Reevaluation
Paustenbach was unable to get more data from Goodyear, but interviewed ~ credible Ohio Pliofilm worker~ who provided import~nt historical information
Exposure data re-analyzed, considering many forms of indirect evidence
Concluded that exposure levels were g~neraUy similar to those estimatetJ by Crump and Allen (OSHA, 1984) and considerably higher than those estimated by Rinsky
Published 1992, Journal of Toxicology and Environmental Health 36:177-231
SLIDE 5
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Update of Pliofilm Cohort Mortality
ENVIRON incorpc;rated mortality information for 1981 through 1987
No evidence of ..solid tumor.. response
No additional multiple myelomas
Seven new cases of hematopoietic tumors;, including 5 leukemias in males and 1 in a female
Applied proportional hazards model to estimate risk
Proportional hazards model indicates that, in the occupational exposure range, cancer potency is approximately one tenth of EPA's 1985 estimate
Accepted for publication in Risk Analysis, 1992
SLIDE 6
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Crump Analysis of Pliofilm Data
Use of all the cohort's cancer mortality and exposure information shows response to benzene exposure is clearly non-linear
Fitting absolute (additive) and relative (multiplicative) risk models
Using weighted; lagged, and ca.,mulative
exposure measures
Estimating slopes for a variety of cancer endpoints in an effort to define tumor type(s) responding to benzene exposure {best basis for risk assessment)
SLIDE 7
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