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 JMorawetz@ICWUC.org

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