Misuse of Exposure Reporting in Acute Risk Assessment
John S. Morawetz
International Chemical Workers Union Council/UFCW
Center for Worker Health & Safety Training
Cincinnati, Ohio
(513) 621-8882 [email protected]
Acute Exposure Guideline Levels
Since 1996 the EPA has convened meetings of a National Advisory Committee for Acute Exposure Guideline Levels (AEGLs)
Committee of Toxicology of the National Research Council and National Academy of Sciences
“Once in a lifetime short term exposures” for general public
Health Outcomes
• AEGL-1 Notable discomfort
• AEGL-2 Irreversible or serious, long lasting effects including impaired ability to escape
• AEGL-3 Death or life threatening
Time Periods
• Levels are set for 5 time periods: • 10 and 30 minutes, 1, 4 and 8
hours for each health outcome
• Total of 15 levels per chemical
Application
• General population including infants, children, asthmatics and other susceptible groups
• Unlike occupational recommendations, intended for once in a lifetime exposure
CaveatsPrimary - Control Exposures; hierarchy of controls
Substitution
Pollution Prevention
Need Multi disciplinary efforts
Toxicologists, Physicians, Epidemiologists, Industrial Hygienists, Statisticians, Engineers
Caveats
• “Intended to be used as planning tools”• “when an actual chemical emergency
occurs, there often is no time to measure airborne concentrations”
• “Not to be used as safe limits for routine operations or definitive delineators between safe and unsafe exposure conditions” (AIHA, ERPG handbook, 2000)
AEGL Committee’s misuse of human studies
• Inaccurate reporting in draft report
– Time period of sample
– Area vs. personal vs. bulk
– TWA vs. instantaneous
– Anecdotal vs. case or full study
• Rejection of reconstruction studies
• Inappropriate use of range of data
Inaccurate Reporting
• Inaccurate summary of level – “No exposure measurements” SOP– Incorrect range reported - phosphine
• Time period associated with measurement– “No exposure time noted” phosphine
(Wilson)– Range of levels with no time period
• trichloroethane – fatality reconstruction• methanol – NIOSH HHE
Inaccurate Reporting
• Area vs. personal samples
–Propylene Glycol Dinitrate
–Hydrogen Cyanide (Leeser)•Reported only "routine" instantaneous samples (1 to 3 ppm) rather than available personal samples
Inaccurate Reporting
• Area vs. personal samples
–Methanol –AEGL stated "measured in the vicinity of the duplicators".
–NIOSH HHE (1981) states "Breathing zone samples were collected for methyl alcohol vapors over a 25 minute sampling period".
Inaccurate Reporting
Bulk vs. Area vs. Personal samples– “raw acetylene contained less than 3 ppm
“Used as a personal exposure – phosphine
Case reports described as anecdotal- phosphorous trichloride- trichlorethylene
Rejection of fatality reconstruction studies
• Simulation of task with sampling
• Phosphine (Hager)
• Trichloroethane
Inappropriate use of range of data
• Attributed to which exposure level? AEGL - Single Upper limit of rangeExamples:
Propylene Glycol Dinitrate–Maximum value of 400 inst.
SamplesHydrogen Cyanide
–34 samples in 8 job titles
Hydrogen Cyanide Exposures by Job Title
Leeser, 1990
00.5
11.5
22.5
33.5
ppm
High Low Geo. Mean
Summary
• Multi disciplinary Risk Assessment committees– Draft reports– Committee discussion and recommendation– Final approval
• Accurate summary of original articles
• Uranium Hexafluoride
Composition of CommitteePreponderance of one expertise
Bias towards one expertise
Current Issues–Hydrogen Cyanide
– Leeser: used as primary study
– Grabois study, 1954
–Industrial Hygiene survey with NO health survey
–Occupational Application of AEGLs
–Emergency Response
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