NIOSH HEALTH HAZARD EVALUATION REPORT 

HETA #2001-0474-2943 

American Pop Corn Company 

Sioux City, Iowa 

July 2004 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports
ii

PREFACE

The Respiratory Disease Hazard Evaluations and Technical Assistance Program (RDHETAP) of the 

National Institute for Occupational Safety and Health (NIOSH) conducts field investigations of possible 

health hazards in the workplace. These investigations are conducted under the authority of Section 

20(a)(6) of the Occupational Safety and Health (OSHA) Act of 1970, 29 U.S.C. 669(a)(6), or Section 

501(a)(11) of the Federal Mine Safety and Health Act of 1977, 30 U.S.C. 951(a)(11), which authorize the 

Secretary of Health and Human Services, following a written request from any employers or authorized 

representative of employees, to determine whether any substance normally found in the place of 

employment has potentially toxic effects in such concentrations as used or found. 

RDHETAP also provides, upon request, technical and consultative assistance to federal, state, and local 

agencies; labor; industry; and other groups or individuals to control occupational health hazards and to 

prevent related trauma and disease. Mention of company names or products does not constitute 

endorsement by NIOSH. 

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Dr. Richard Kanwal, Randy Boylstein, and Chris Piacitelli of the Field 

Studies Branch (FSB), Division of Respiratory Disease Studies (DRDS). Field assistance was provided 

by Daniel Yereb, Stephen Martin, and Thomas Jefferson. In addition, the following DRDS staff assisted 

in the medical Survey: Diana Freeland, Terry Rooney, Christie Kerrigan, Jennifer Keller, Susan 

Englehart, Jim Taylor, and David Spainhour. Analytical support was provided by DataChem 

Laboratories. Desktop publishing was performed by Terry Rooney. Review and preparation for printing 

were performed by Penny Arthur. 

Copies of this report have been sent to employee and management representatives at American Pop Corn 

Company and to the OSHA Regional Office. This report is not copyrighted and may be freely 

reproduced. The report may be viewed and printed from the following internet address: 

http://www.cdc.gov/niosh/hhe. Single copies of this report will be available for a period of three years 

from the date of this report. To expedite your request, include a self-addressed mailing label along with 

your written request to: 

NIOSH Publications Office 

4676 Columbia Parkway 

Cincinnati, Ohio 45226 

800-356-4674 

After this time, copies may be purchased from the National Technical Information Service (NTIS) at 5825 

Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may be 

obtained from the NIOSH Publications Office at the Cincinnati address. 

For the purpose of informing affected employees, copies of this report 

shall be posted by the employer in a prominent place accessible to the 

employees for a period of 30 calendar days.
 

iii 

Highlights of the NIOSH Health Hazard Evaluation 

At American Pop Corn Company, Sioux City, Iowa

After NIOSH identified a risk for lung disease in workers exposed to airborne butter flavoring 

chemicals at a microwave popcorn plant in Missouri, the Iowa Department of Public Health 

asked NIOSH to see if workers at American Pop Corn Company were also at similar risk. 

What NIOSH Did

• We measured the air concentrations of butter 

flavoring chemicals at several locations within 

the microwave popcorn plant. 

• We conducted a questionnaire survey focusing 

on symptoms, medical history, and work history. 

• We tested workers’ lung function with 

spirometry. 

What NIOSH Found

• Air concentrations of diacetyl, a butter flavoring 

chemical known to cause injury to airways in 

animal studies, were highest in the mixing room 

(other areas in the plant had very low levels). 

• Diacetyl air concentrations in the mixing room 

were highest when liquid and paste-type 

flavorings were used. 

• Mixers’ exposure to diacetyl increased greatly 

when pouring flavorings into tanks. 

• Some of the dust in the air from powdered 

flavorings was small enough that it could be 

inhaled into the lung. 

• Six of 13 workers with experience as mixers had 

abnormal lung function. 

• Aside from mixers, workers in other areas of the 

plant did not appear to be at risk. 

What Managers Can Do

• Identify engineering solutions to decrease the 

potential for exposures to flavoring chemicals in 

the mixing room. 

• Train workers on the potential health risks 

from exposures to flavorings and on the best 

ways to minimize exposures. 

• Assure that all workers who enter the mixing 

room wear NIOSH-approved respirators that 

protect against dust and organic vapors (Provide 

respirators as part of a formal respiratory 

protection program that adheres to the 

requirements of the OSHA Respiratory 

Protection Standard.) 

• Perform regularly scheduled spirometry tests for 

all workers that enter the mixing room or work 

in the QC lab. 

• Periodically measure the amount of flavoring 

chemicals in the air, especially when processes 

or flavorings are changed. 

What Employees Can Do 

For all workers that enter the mixing room: 

• Know how to properly wear and maintain your 

respirator. 

• Wear your respirator 100 percent of the time 

when in the mixing room. 

• Keep all containers of flavorings tightly closed 

when not in use. 

• Understand and use all the exposure control 

devices and work practices that decrease the 

amount of flavorings in the air. 

For QC lab workers and all workers that enter the 

mixing room: 

• Participate in spirometry tests offered by your 

employer. 

• Promptly report any persistent shortness of 

breath or cough, or any problems with your 

eyes, nose, throat, or skin to your supervisor 

and your doctor and show them a copy of this 

page.

What To Do For More Information:

We encourage you to read the full report. If you 

would like a copy, either ask your health and 

safety representative to make you a copy or call 

1-513-841-4252 and ask for 

HETA Report #2001-0474-2943
iv

Health Hazard Evaluation Report 2001-0474-2943 

American Pop Corn Company 

Sioux City, Iowa 

July 2004 

Richard Kanwal, M.D. 

Randy J. Boylstein, M.S. 

Chris Piacitelli, C.I.H. 

SUMMARY

In July 2001, NIOSH received a request for technical assistance from the Iowa Department of Public 

Health to evaluate the risk for lung disease in American Pop Corn Company workers exposed to butter 

flavorings. This request was made after NIOSH investigated severe fixed obstructive lung disease 

consistent with bronchiolitis obliterans in former workers of a microwave popcorn plant in Missouri and 

identified an association between occupational lung disease and exposure to butter flavoring vapors. 

NIOSH conducted a walk-through survey at the American Pop Corn Company plant in Sioux City, Iowa 

on September 26, 2001. Limited industrial hygiene air sampling on that day showed that air 

concentrations of diacetyl, a predominant butter flavoring chemical measured as a marker of butter 

flavoring exposure, were very low compared to levels that were associated with abnormal lung function at 

the Missouri (index) plant. The company reported that workers who handled flavorings had used fullfacepiece respirators with particulate filters and organic vapor cartridges since shortly after the 

microwave popcorn plant began operating in December 1988. In June 2002, the company informed 

NIOSH that one of its mixing room workers had been diagnosed with fixed obstructive lung disease 

consistent with bronchiolitis obliterans. NIOSH conducted a medical survey from July 22 through July 

26, 2002, and an industrial hygiene survey from July 29 through August 1, 2002. The main findings from 

these surveys included: 

 

• The mixing room was isolated and ventilated separately from the packaging area; 

• All tanks of heated soybean oil and flavorings were located in the mixing room and had local 

exhaust ventilation; 

• Workers (mixers) measured flavorings in open containers in a separate area in the warehouse and 

then carried the flavorings into the mixing room and poured the flavorings into open tanks of 

heated soybean oil; 

• Area diacetyl air concentrations in the mixing room were 0.57 parts per million (ppm) parts air by 

volume when liquid and paste flavorings were in use on July 29 and were below the limit of 

detection of the sampling method when powder flavorings were in use on July 31 and August 1; 

• Personal diacetyl exposures for the mixers for the three days of sampling were 0.04, 0.004, and 

0.005 ppm respectively; 

• Mixers’ exposure to diacetyl increased to 80 to 120 ppm for several minutes while pouring liquid 

butter flavoring into a tank; 
 

v 

• Six of 13 workers with experience as mixers had abnormal lung function (three with fixed 

obstruction and three with restriction); 

• The average percentage of time that workers reported using respirators when in the mixing room 

prior to June 2002 was 20 percent (workers usually did not wear respirators when handling 

flavorings in the warehouse); 

• The highest measured diacetyl air concentration in the packaging area was 0.03 ppm; 

• Apart from workers with mixing experience, the prevalence of abnormal lung function in 

microwave popcorn plant workers did not differ significantly from the prevalence in nonmicrowave popcorn plant workers, and was similar to the expected prevalence based on national 

general population surveys; 

• Unlike the index plant, risk for lung disease in workers who popped many dozens of bags of 

product in microwave ovens per shift was not identified in this plant (these workers popped fewer 

bags per shift than at the index plant). 

NIOSH conducted an industrial hygiene survey on September 17 and 18, 2003 to measure air 

concentrations of respirable and total dust during the handling of powdered flavorings. This survey 

showed that: 

• Air concentrations varied depending on the particular powdered flavoring being handled and the 

manner in which it was handled 

• Some of the airborne dust was of respirable size 

The findings from the NIOSH medical and industrial hygiene surveys at this plant show 

an apparent risk for lung disease in mixing room workers at much lower air 

concentrations of butter flavoring chemicals than those initially measured at the Missouri 

index plant. Lung disease risk was not identified in other areas of the plant apart from 

mixing. Recommendations for engineering controls, use of personal protective 

equipment, and medical surveillance for exposed workers are provided in this report. 

Keywords: SIC 2099 (food preparations, not elsewhere classified); bronchiolitis obliterans, diacetyl, 

fixed obstructive airways disease, chronic obstructive pulmonary disease, butter flavoring, microwave 

popcorn, popcorn, flavorings.
 

Table of Contents 

Preface..........................................................................................................................................................ii

Acknowledgments and Availability of Report..........................................................................................ii

Highlights of the NIOSH Health Hazard Evaluation .............................................................................iii

Summary.....................................................................................................................................................iv

Introduction.................................................................................................................................................1

Background .................................................................................................................................................1

Methods........................................................................................................................................................2

Medical Evaluation .................................................................................................................................2

Industrial Hygiene Evaluation...............................................................................................................2

Results ..........................................................................................................................................................3

Industrial Hygiene Results .....................................................................................................................3

Microwave Popcorn Production Process ..........................................................................................3

Environmental Measurements...........................................................................................................4

Medical Results .......................................................................................................................................6

Discussion ....................................................................................................................................................8

Conclusions................................................................................................................................................10

Recommendations.....................................................................................................................................10

References..................................................................................................................................................12

Appendix A................................................................................................................................................27

Appendix B ................................................................................................................................................29

Appendix C................................................................................................................................................41

Appendix D................................................................................................................................................43

Evaluation Criteria ...................................................................................................................................45
Health Hazard Evaluation Report No.2001-0474-2943 Page 1 

INTRODUCTION

In July 2001, NIOSH received a request for 

technical assistance from the Iowa Department 

of Public Health to evaluate the risk for lung 

disease in American Pop Corn Company 

workers exposed to butter flavorings. This 

request was made after NIOSH investigated a 

cluster of severe fixed obstructive lung disease 

consistent with bronchiolitis obliterans in former 

workers of a microwave popcorn plant in 

Missouri and identified an association between 

occupational lung disease and exposure to butter 

flavoring vapors. 

BACKGROUND

In August 2000, NIOSH learned that eight 

former workers of a microwave popcorn 

production plant in Missouri had moderate to 

severe fixed obstructive lung disease consistent 

with the rare illness, bronchiolitis obliterans. A 

NIOSH investigation at this plant revealed an 

excess of current workers with obstruction on 

spirometry testing. Increasing cumulative 

exposure to diacetyl, the predominant butter 

flavoring chemical present in the air of the plant, 

was associated with an increased prevalence of 

abnormal lung function.1

 In animal exposure 

experiments conducted by NIOSH, rats exposed 

to vapors from a butter flavoring used at this 

plant developed severe injury to their airway 

epithelium.2

 

In bronchiolitis obliterans, inflammation and 

scarring occurs in the small airways of the lung 

and can lead to severe, permanent shortness of 

breath.3

 The main respiratory symptoms are 

cough and shortness of breath on exertion that 

typically do not improve much when the worker 

goes home at the end of the workday or on 

weekends or vacations. Usually symptoms are 

gradual in onset and progressive, but severe 

symptoms can occur suddenly. Most cases do 

not respond to medical treatment. Lung function 

testing with spirometry generally reveals fixed 

airways obstruction, and some workers develop 

obstruction before they become symptomatic. 

Because medical treatment does not reverse the 

condition, some workers with severe disease 

have been placed on lung transplant waiting 

lists.4

In addition to lung disease, workers exposed to 

butter flavoring vapors may develop problems 

with their eyes and skin. Eye irritation is 

common, and occasionally workers report 

chemical burns of the eyes requiring medical 

treatment. Similarly, exposed workers may 

report skin irritation, and one worker at another 

plant developed a disabling skin allergy to butter 

flavorings.4

 

NIOSH’s first visit to American Pop Corn 

occurred on September 26, 2001, during which a 

walkthrough of the plant and limited industrial 

hygiene air sampling was performed. The air 

concentrations of diacetyl were very low 

compared to levels that were associated with 

abnormal lung function at the Missouri (index) 

plant (See Appendix A). Company management 

reported that general dilution ventilation and 

local exhaust ventilation of tanks in the mixing 

room, and mandatory use of full facepiece 

respirators with organic vapor cartridges and 

particulate filters by mixing room workers, had 

been implemented soon after the start of 

microwave popcorn production in December 

1988. 

In June 2002, the company informed NIOSH 

that a 37 year-old mixer (for six years) of 

soybean oil and butter flavorings for microwave 

popcorn production had just been diagnosed by a 

pulmonologist as having medical findings 

consistent with bronchiolitis obliterans. A 

NIOSH physician interviewed this worker and 

reviewed his medical records. His medical 

history and test results, including moderate to 

severe fixed obstruction on spirometry and a 

chest computerized tomography (CT) scan 

showing a mosaic pattern of lung attenuation 

bilaterally, were consistent with this diagnosis. 

The company also reported that a former mixer 

now working in another job at the plant had 

experienced declines in lung function over the 

past several years. NIOSH performed a detailed 

medical and environmental survey to further 

characterize the risk for lung disease in mixers 

and other microwave popcorn production 

workers. 
Page 2 Health Hazard Evaluation Report No. 2001-0474-2943 

METHODS

Medical Evaluation 

NIOSH performed a medical survey from July 

22 through July 26, 2002. All current 

employees in all areas of the plant (microwave 

popcorn plant workers, other production 

workers, and office workers), and former 

employees who had worked as oil and flavoring 

mixers or in the quality control lab in microwave 

popcorn production, were invited to participate. 

After obtaining signed informed consent from 

participants, NIOSH interviewers administered a 

standardized questionnaire (see Appendix B) to 

collect information on symptoms, medical 

diagnoses, smoking history, work history, and

work-related exposures. NIOSH technicians 

performed spirometry tests using a dry rolling 

seal spirometer interfaced to a personal 

computer and following American Thoracic 

Society guidelines,5

 with results compared to 

spirometry reference values generated from the 

Third National Health and Nutrition 

Examination Survey (NHANES III).6 The 

largest forced vital capacity (FVC) and forced 

expiratory volume in the first second of 

exhalation (FEV1) were selected for analysis. 

Obstruction was defined as an FEV1/FVC ratio 

and FEV1 below the lower limits of normal. 

Borderline obstruction was defined as an 

FEV1/FVC ratio below the lower limit of 

normal with a normal FEV1. Restriction was 

defined as an FVC below the lower limit of 

normal with a normal FEV1/FVC ratio. A 

mixed pattern (obstruction and restriction) was 

defined as an FEV1/FVC ratio, FEV1, and FVC 

below the lower limits of normal. Reversible 

obstruction was defined as an improvement in 

the FEV1 of at least 12% and at least 200 

milliliters after administration of albuterol. The 

prevalences of respiratory and other symptoms, 

self-reported medical diagnoses, and spirometry 

abnormalities among microwave popcorn 

production workers were compared to those of 

other workers in the plant. These prevalences 

were also compared to national data derived 

from NHANES III.7 

SAS software8 was used to perform Chi-square, 

Fisher’s exact test, and logistic regression 

analyses. A probability (p) value of 0.05 or less 

was used as the criterion for statistical 

significance (i.e., a 5 percent or less probability 

that the difference observed was due to chance). 

Unless specifically noted, the results and 

analyses presented below are based on current 

worker questionnaire responses and spirometry 

test results. 

Survey participants’ test results were mailed to 

their home addresses on August 27, 2002. A 

letter from NIOSH to company management on 

November 18, 2002 summarized analyses of the 

data from the medical survey and provided 

relevant recommendations. 

Industrial Hygiene Evaluation 

From July 29 through August 1, 2002, NIOSH 

performed an industrial hygiene survey that 

consisted of an inspection of the entire 

microwave popcorn production process, air 

sampling for butter flavoring chemicals as well 

as total and respirable dust, and collection of 

bulk flavoring samples. A letter from NIOSH to 

company management on February 28, 2003 

provided air sampling results and relevant 

recommendations. 

Quantitative area air sampling was performed 

for diacetyl, acetoin, 2-nonanone, total 

hydrocarbons, butyric acid, acetic acid, 

acetaldehyde, and total and respirable dust. In 

addition, diacetyl, acetoin, and 2-nonanone were 

collected on personal samplers. Diacetyl, 

acetoin, and 2-nonanone were collected on 

carbon molecular sieve (CMS) tubes at a flow 

rate of 50 cubic centimeters per minute (cc/min) 

and were analyzed quantitatively by gas 

chromatography (GC) according to NIOSH 

Method 2557.9

 Total hydrocarbons were 

collected on coconut shell charcoal (CSC) tubes 

at a flow rate of 100 cc/min and analyzed by GC 

according to NIOSH Method 1550.9

 Butyric 

and acetic acid were collected on silica gel 

sorbent tubes at a flow rate of 500 cc/min and 

analyzed by high pressure liquid 

chromatography (HPLC) according to NIOSH 

Method 7903.9

 Acetaldehyde was collected on 
Health Hazard Evaluation Report No.2001-0474-2943 Page 3 

solid sorbent tubes (XAD-2) at a flow rate of 50 

cc/min and analyzed by GC according to NIOSH 

Method 2538.9

 Total dust samples were 

collected at a flowrate of 2.0 liters per minute 

(lpm) and respirable dust samples at 4.2 lpm on 

polyvinyl chloride (PVC) filters behind BGI 

Respirable/Thoracic CyclonesTM and analyzed 

gravimetrically according to NIOSH Methods 

0500 and 0600, respectively.9

 

Area air samples were collected using semiquantitative sampling methods to assess the 

types of volatile organic compounds (VOCs) 

present in air during the production of 

microwave popcorn. The samples were 

collected on thermal desorption tubes at a flow 

rate of 20 cc/min and were analyzed by gas 

chromatography with a mass selective detector 

according to NIOSH Method 2549.9

 

A Gasmet DX-4010TM Fourier Transform 

Infrared (FTIR) Gas Analyzer (Temet 

Instruments Oy, Helsinki, Finland) was used to 

detect peak levels of selected volatile organic 

chemicals (VOCs) present in the breathing zones 

of workers during normal activities. The 

sampling was simultaneously videotaped in 

order to determine the process or task associated 

with a particular peak air concentration. During 

personal sampling the FTIR detection tube was 

attached to the worker in the breathing zone. 

One pair of North 7581TM organic vapor/P100 

respirator cartridges, previously worn by a mixer 

under normal working conditions for 

approximately 33 hours during mixing tasks, 

was collected to determine the remaining 

capacity of the carbon media in the cartridges 

under laboratory conditions. Carbon 

tetrachloride (CCl4) was used to determine the 

remaining capacity of the carbon media in the 

cartridges. This test is similar to that described 

in 42 CFR 84, Subpart L, Chemical Cartridge 

Respirators (Section 84.204). Each respirator 

cartridge was enclosed inside an exposure 

chamber having a constant concentration of 

1000 ppm CCl4. A vacuum pump was used to 

pull air from the exposure chamber through the 

respirator cartridge at 32 lpm. The temperature 

and relative humidity were maintained 

throughout the test at 25 °C and 50%, 

respectively. A Foxboro MIRAN 1A Infrared 

Analyzer was used to monitor the concentration 

of CCl4 downstream of the respirator cartridge. 

Breakthrough was considered to have occurred 

when the downstream CCl4 vapor concentration 

reached 5 ppm. The percentage of carbon 

capacity remaining in the used respirator 

cartridges was determined by the equation: 

remaining carbon capacity (%) = (tused / tc) x 100 

where tused is the time it took for breakthrough to 

occur with the used cartridges, and tc is the time 

it took for breakthrough to occur through new 

control cartridges of the same model and lot. 

 

On September 17 and 18, 2003, NIOSH returned 

to the American Pop Corn Company plant and 

used GrimmTM real-time optical particle 

counters (OPC) (Grimm Technologies, Inc., 

Douglasville, GA), with simultaneous 

videotaping, to determine airborne particulate 

levels and particle sizes of dust generated during 

the handling of four different powdered butter 

flavors. These measurements were obtained 

while a NIOSH investigator scooped the 

powders from their containers into a weighing 

tub in 3 different handling manners: easy – 

simulating an operator gently scooping powder; 

hurried – mimicking a worker who might be 

rushed while performing the task; and dropped – 

where the powder was dropped from a height of 

1 foot into the tub to simulate an extremely 

hastened transfer of powder. 

RESULTS

Industrial Hygiene Results 

Microwave Popcorn Production Process 

The American Pop Corn Company plant consists 

of several buildings. One of these is used solely 

for activities related to the production of 

microwave popcorn. Other activities, such as 

cleaning and storing of kernel popcorn, 

packaging of popcorn for non-microwave use, 

and office work, occur in other buildings on the 

plant property. 
Page 4 Health Hazard Evaluation Report No. 2001-0474-2943 

In microwave popcorn production, kernel 

popcorn is combined with a mixture of soybean 

oil, salt, flavorings, and colorings in microwave 

bags. The oil and flavorings mixture is 

produced in a mixing room (approximately 20 

by 25 feet) which opens to a common hallway 

through a double door. In this room, one or two 

workers (i.e., mixers) per shift fill 400-gallon 

and 500-gallon mixing tanks with heated 

soybean oil and add salt to the oil through a high 

shear mixer. (During the survey, tank 

temperatures ranged from 131o to 134o 

Fahrenheit.) Coloring and flavorings are 

measured by hand in a storage area (located in 

the warehouse) and manually added to the 

mixing tanks in the mixing room. The mixture 

is piped to other tanks in the mixing room and 

then to the packaging lines. The tanks have 

loose-fitting lids and local exhaust ventilation. 

The local exhaust air moves through a scrubber 

before being vented outdoors. The mixing room 

is on a general dilution ventilation system that is 

separate from other plant areas; this system is 

designed to move air into the mixing room from 

the plant’s ventilation system and then out of the 

building through an exhaust vent. NIOSH 

testing with smoke indicator tubes showed the 

mixing room to be under negative pressure with 

respect to the hallway. During the NIOSH 

survey, mixing room workers wore fullfacepiece, air-purifying respirators with organic 

vapor cartridges and particulate filters while 

they were in the mixing room. 

The flavoring storage area in the warehouse 

(approximately 10 by 20 feet) has solid walls on 

three sides and thick plastic sheeting on its 

fourth side separating it from the rest of the 

warehouse. A refrigeration unit cools and 

recirculates air in this room. There was no 

additional ventilation in this area at the time of 

the survey. During the NIOSH survey, mixing 

room workers wore full-facepiece respirators 

while handling open containers of flavorings. 

Some flavorings are stored in a refrigerator 

located adjacent to this storage area in the 

warehouse. Containers of flavorings were kept 

sealed when not being used. Some empty, open 

flavoring containers (five-gallon buckets) 

containing residual flavorings were located 

outside the storage area on a nearby pallet in the 

warehouse. Company management informed 

NIOSH that this practice was discontinued 

within one week of the survey. 

Packaging of microwave popcorn occurs in a 

large room across the hallway from the mixing 

room. The hallway entrance to this room was 

kept closed and this room had a general dilution 

ventilation system separate from the mixing 

room and flavoring storage areas. Some of the 

entrances to this room from the warehouses were 

kept open. This room had eight packaging lines 

where packaging machines combine kernel 

popcorn (from holding bins located in a room 

above the machines) with the oil and flavorings 

mixture (piped from the mixing room) in 

microwave bags that are then sealed. Additional 

machines are used to place the bags into cartons 

and boxes. There were approximately 15-30 

workers in this room per shift. 

In the quality control (QC) lab (approximately 

10 by 15 feet in size) one worker per shift uses 

several commercial microwave ovens to test 

recently produced microwave popcorn products. 

This worker microwaves approximately 75 bags 

of microwave popcorn per nine-hour work shift. 

The room had a strong odor of butter flavor. 

Testing with smoke indicator tubes showed the 

lab to be under negative pressure with respect to 

the hallway. The lab had only general dilution 

ventilation in July 2002. During the survey in 

September 2003, NIOSH observed that a local 

exhaust hood system had been installed to 

exhaust air from the microwave ovens and the 

weigh station area in the lab. QC workers 

reported that the air quality had improved in the 

lab due to these changes. (The butter odor was 

much less intense than in July 2002.) Visual 

testing with smoke indicator tubes showed that 

the hood appeared to be able to exhaust the 

intended work zone adequately. 

Environmental Measurements 

Table 1 lists the means and ranges for diacetyl, 

total dust, and respirable dust time-weighted 

average (TWA) air concentrations for twelve 

different job categories. Diacetyl concentrations 

(area and personal combined) are reported in 

parts per million parts air by volume (ppm). 
Health Hazard Evaluation Report No.2001-0474-2943 Page 5 

Total and respirable dust concentrations are 

reported in milligrams per cubic meter of air 

(mg/m3

). The mean diacetyl air concentration in 

the mixing room was 0.08 ppm and the highest 

measured concentration was 0.57 ppm. The 

highest measured diacetyl air concentration in 

the packaging area (bartelt operator) was 0.03 

ppm. Total dust concentrations in the mixing 

room ranged from 1.4 mg/m3

 to 3.8 mg/m3. 

Respirable dust in the mixing room ranged from 

0.09 to 0.31 mg/m3

. Ambient total dust levels 

ranged from 0.02 mg/m3

 to 0.40 mg/m3 and all 

other total dust levels in the plant were below 

0.40 mg/m3

. These levels are below the 

Occupational Safety and Health Administration 

(OSHA) permissible exposure limit (PEL) for 

particulates not otherwise regulated (PNOR) of 

15 mg/m3

 as an eight-hour TWA (5 mg/m3 for 

respirable dust) and the American Conference of 

Governmental Industrial Hygienists (ACGIH®) 

threshold limit value (TLV®) for particulates not 

otherwise specified (PNOS) of 10 mg/m3

 for 

inhalable particulates as an eight-hour TWA (3 

mg/m3

 for respirable particulate). 

Table 2 shows the mixing room air 

concentrations of diacetyl on three different days 

for both area and personal samples. When only 

powdered flavorings were used, area air 

concentrations were below the limit of detection 

of 0.001 ppm diacetyl compared to 0.57 ppm 

when a liquid and a paste flavoring were used. 

The highest concentration measured in the 

mixers’ breathing zones (0.05 ppm) when a 

liquid and a paste flavoring were in use was 10 

times higher than the highest concentration 

measured on the other days when only powder 

flavorings were used. 

Other analytes sampled throughout the plant 

were generally below the limit of detection of 

the sampling method used (or were present at 

low levels) and are not presented in tabular 

format. Acetoin levels ranged from less than the 

minimum detectable concentration of 0.002 ppm 

to a maximum of 0.03 ppm (personal sample 

from a mixer). Levels of 2-nonanone ranged 

from less than the minimum detectable 

concentration of 0.001 ppm to a maximum of 

0.02 ppm (area sample at a packaging machine 

operators station). Acetic acid was detected in 

only three out of thirty samples at just above the 

minimum detectable concentration of 0.02 ppm. 

Butyric acid was not detected in any of the thirty 

samples collected above the minimum detectable 

concentration of 0.03 ppm. Acetaldehyde was 

detected in sixteen out of twenty-nine samples 

but all measured concentrations were between 

the minimum detectable concentration of 0.007 

ppm and the minimum quantifiable 

concentration of 0.024 ppm. 

Figures 1A-C show results of the semiquantitative area air samples collected to assess 

the types of volatile organic compounds (VOCs) 

present in the air of the mixing room during the 

production of microwave popcorn. Figure 1A is 

the chromatogram from a day when the 

company used only paste and liquid flavorings 

and Figures 1B and 1C are from two days when 

only powdered flavorings were used. The 

diacetyl peak (peak #20) goes off scale on the 

day that pastes and liquids were used and is 

almost non-detectable on the two consecutive 

days when only powder flavors were used. (See 

Figure 1D for identification of the chemicals 

represented by the various peaks in Figures 1AC.) 

Table 3 shows the levels of total hydrocarbons 

found at various locations throughout the plant 

during three days of sampling. The analysis 

excluded the contribution of both diacetyl and 

acetoin but represents all other hydrocarbons 

present in the air, which could include cleaners 

and solvents used in the plant. 

Figure 2 shows an example of the results of 

FTIR real-time monitoring for diacetyl and 

simultaneous videotaping in the mixing room 

while liquid and paste flavors were being used 

on July 30, 2002. Diacetyl levels peaked at 83 

ppm near the breathing zone of a mixer for 

approximately five minutes during mixing 

activities, which included pouring several fivegallon containers of liquid butter flavoring into 

mixing tanks. 

The respirator cartridge capacity evaluation of a 

pair of North 7581TM OV/P100 cartridges used 

by mixers at American Pop Corn Company 

revealed that an average of 97.8% of the carbon 

media’s capacity to filter out organic vapors 
Page 6 Health Hazard Evaluation Report No. 2001-0474-2943 

within the cartridges remained after 33 reported 

hours of normal use by a mixer. 

During the September 2003 survey, three 

different techniques for hand-scooping four 

different powder flavorings were used to 

simulate possible worker situations. Figure 3 

shows the dust air concentrations generated 

during these simulations. The handling of all 

four powders generated airborne dust that 

contained particles of respirable size. The 

highest levels of dust occurred when the 

powders were dropped into a weighing tub. One 

of the flavors, Powder 2 (oiled), had been misted 

with soybean oil by the flavoring manufacturer 

at the request of American Pop Corn due to the 

original product’s dustiness. The oil-misted 

powder generated much less dust, even when the 

product was dropped from a height of one foot. 

Medical Results 

Participation 

One hundred fifty-seven of 193 (81%) current 

plant employees participated in the survey. This 

included 87 of 103 (84%) from microwave 

popcorn production and 70 of 90 (78%) from all 

other areas of the plant. An additional 8 former 

workers also participated.

Symptoms 

Table 4 contains questionnaire data on the 

prevalences of several symptoms including 

reported trouble breathing in the last 12 months, 

shortness of breath on exertion, cough, 

wheezing, fever and chills, and unusual fatigue, 

according to work area and smoking status for 

current workers. Fourteen percent of microwave 

popcorn production workers and nineteen 

percent of other plant workers reported having 

had any trouble breathing during the last 12 

months. Current and former smokers in both 

groups of workers reported this finding more 

often than nonsmokers. Shortness of breath 

when “hurrying on level ground or walking up a 

slight hill” was more common among current 

and former smokers in microwave popcorn 

production (44%) than it was among current and 

former smokers in other areas of the plant 

(25%). Shortness of breath when “walking with 

people your own age on level ground” was 

reported by eight percent of microwave popcorn 

production workers and by three percent of 

workers in other areas of the plant. A large 

proportion of workers reporting shortness of 

breath on exertion said that it started after they 

began working at the plant. Usual cough was 

reported by similar percentages of workers from 

microwave popcorn production (19%) and other 

areas of the plant (20%). Chronic cough (cough 

on most days for three consecutive months or 

more during the year) with onset after hire was 

more common among current and former 

smokers in microwave popcorn production 

(12%) than among current and former smokers 

in other areas of the plant (5%), but the numbers 

in these categories were small. Similar 

percentages of workers in both microwave 

popcorn production (7%) and other areas of the 

plant (9%) reported wheezing apart from colds 

with onset after hire. Frequent fever, chills, and 

night sweats were also reported by six percent of 

workers in microwave popcorn production and 

ten percent of workers in other areas of the 

plant. Unusual fatigue lasting more than a few 

days or occurring frequently was reported by 

seventeen percent of workers in microwave 

production and by eleven percent of workers in 

other areas of the plant. Overall, none of the 

observed differences regarding any symptoms 

between ever-smokers in microwave production 

and ever-smokers in other areas of the plant 

were statistically significant. The same was true 

for never-smokers. When compared to national 

data from NHANES III after adjusting for age, 

sex, race, and smoking history, the prevalences 

among microwave popcorn production workers 

of shortness of breath when “hurrying on level 

ground or walking up a slight hill”, chronic 

cough, and wheezing apart from colds were 

similar to expected prevalences (Tables 5 and 6). 

Spirometry Abnormalities and Worker 

Reports of Respiratory Illnesses 

Table 7 contains the prevalences of 

abnormalities on NIOSH spirometry testing and 

self-reported history of bronchitis, chronic 

bronchitis, pneumonia, and asthma in current 

workers. Bronchitis was reported by ten percent 

of workers in microwave popcorn production 
Health Hazard Evaluation Report No.2001-0474-2943 Page 7 

and by thirteen percent of workers in other areas 

of the plant. Chronic bronchitis with onset after 

hire was reported infrequently in microwave 

popcorn production and other areas of the plant. 

Pneumonia was reported by five percent of 

workers in microwave popcorn production and 

by nine percent of workers in other areas of the 

plant. Asthma was reported most frequently 

among current and former smokers in other 

areas of the plant (18%). Few microwave 

popcorn production workers reported asthma 

and none reported onset after hire. The 

difference in onset of asthma after hire in 

microwave popcorn production workers (0%) 

compared to workers in other areas (9%) was 

statistically significant. Otherwise, there were 

no statistically significant differences between 

ever-smokers in microwave popcorn production 

and ever-smokers in other areas of the plant with 

regard to reported respiratory illnesses. The 

same was true for never-smokers. 

The prevalences of obstruction (including 

borderline obstruction and mixed pattern), 

restriction without obstruction, and any 

abnormality on spirometry tests in current 

workers are presented in Table 7. The 

percentage of workers with any abnormality on 

spirometry was somewhat higher among 

microwave popcorn production workers (17%) 

than among workers in other areas of the plant 

(13%) and both current/former smokers and 

never-smokers in microwave popcorn 

production had somewhat higher percentages of 

abnormalities than the corresponding groups in 

other areas of the plant. The percentage of 

workers with obstruction or a mixed pattern was 

similar in microwave popcorn production (9%) 

and in other areas of the plant (11%). 

Restriction was more common in microwave 

popcorn production (8%) than in other areas of 

the plant (1%). None of the differences were 

statistically significant. 

When compared to national general population 

data from NHANES III after adjusting for age, 

sex, race, and smoking history, the prevalences 

among microwave popcorn production workers 

of self-report of physician diagnosed chronic 

bronchitis and asthma, and of spirometry 

abnormalities on NIOSH tests, were similar to 

expected prevalences (Tables 5 and 6). The 

prevalence ratios for obstruction and restriction 

in Tables 5 and 6 are slightly different than first 

reported by NIOSH to the company in the 

November 2002 letter (see Appendix C) because 

the earlier ratios were only adjusted for age and 

smoking history. Also, the number of workers 

reported earlier to have restriction was higher 

because workers with a mixed pattern were 

included in both the “obstruction and mixed 

pattern” and “restriction” categories. In Tables 

5 and 6, workers with a mixed pattern are only 

included in the “obstruction and mixed pattern” 

category. 

Spirometry Abnormalities in Workers Who 

Reported Working in Quality Control 

Ten current workers reported performing 

repeated popping of microwave popcorn in 

microwave ovens for quality control, presently 

or at some time in the past. Of the five who 

reported also having worked as mixers, three 

had abnormal spirometry results. The other five 

had normal results. 

Spirometry Abnormalities in Workers Who 

Reported Working in the Mixing Room 

Thirteen current workers reported ever having 

worked as a mixer, for at least one day. Six of 

these workers (including the two workers 

discussed in the Background section) had 

abnormal spirometry results (one had borderline 

obstruction, two had a mixed pattern, and three 

had restriction). Four of five who had worked

eight months or more as mixers had abnormal 

spirometry compared to two of eight who had 

worked less than eight months (six of these eight 

reported ten days or less of work as a mixer). 

Among current workers, there was a statistically 

significant association between ever having 

worked as a mixer and having an abnormal 

spirometry test compared to never having 

worked as a mixer, after adjusting for the effects 

of smoking (odds ratio 6.5, 95% confidence 

interval 1.9 – 22.4). 

Among former workers, two of five that 

reported having worked as a mixer had abnormal 

spirometry results (one with obstruction, and one 

with a mixed pattern). 
Page 8 Health Hazard Evaluation Report No. 2001-0474-2943 

Respirator Use among Ever-Mixers 

The 13 current workers who reported ever 

having worked as a mixer were asked what 

percentage of the time they used a respirator 

prior to June 2002 (a) for weighing or handling 

open containers of flavorings, (b) while pouring 

flavorings into tanks in the mixing room, (c) 

while pouring other ingredients into tanks in the 

mixing room, (d) while checking the levels in 

the tanks, and (e) for other duties in the mixing 

room. The reported percentages of time 

respirators were used during these activities 

ranged from 0 to 100%. The median reported 

percentage was 20% for all activities, except for 

(c) where the median was 50%. The reported 

percentages of time respirators were used were 

similar among workers with spirometry 

abnormalities and workers with normal 

spirometry. 

Workers Entering the Mixing Room for 

Reasons Other Than Mixing 

Forty-five current workers reported having spent 

time in the mixing room while doing other jobs 

at the plant (e.g., supervisor, maintenance, 

electrician, quality control, machine operator, 

etc.). Only eight of them reported using a 

respirator when they entered the mixing room. 

Nine of the 45 had abnormal spirometry tests. 

Six of these nine had also worked as mixers. 

DISCUSSION

Nature of the Disease

Bronchiolitis obliterans is a rare lung disease 

characterized by inflammation and scarring of 

the small airways of the lung, which can lead to 

severe, permanent shortness of breath. The 

constrictive form of bronchiolitis obliterans can 

occur after inhalation of nitrogen dioxide, silo 

gases, ammonia, chlorine, hydrogen fluoride, 

ozone, phosgene, fly ash, and sulfur dioxide.3 In 

occupational settings, an incident of 

overexposure often results in severe initial 

symptoms of pulmonary edema, followed by 

apparent recovery. Persistent shortness of breath 

occurs weeks later due to bronchiolitis 

obliterans. Apart from work-related exposures, 

most bronchiolitis obliterans cases are due to 

bone marrow or lung transplants. When 

bronchiolitis obliterans develops insidiously, as 

in the case of post-transplant patients, there are 

often no respiratory symptoms during the early 

stages of disease, even though lung function 

tests may be abnormal.14 As lung function 

continues to decline, respiratory symptoms 

eventually develop. Several workers that have 

developed bronchiolitis obliterans in the setting 

of butter flavoring exposure during microwave 

popcorn production,4 and during the manufacture 

of flavorings,10,11 have experienced a slow onset 

of symptoms similar to post-transplant patients. 

In affected individuals, lung function testing 

with spirometry typically shows obstruction 

(low FEV1/FVC ratio and FEV1) that does not 

improve with use of an inhaled bronchodilator. 

In moderate to severe disease, increased residual 

volume may occur. The chest x-ray is usually 

normal, but high resolution lung computerized 

tomography with inspiratory and expiratory 

views may show heterogeneous aeration on the 

expiratory view. The diagnosis of bronchiolitis 

obliterans is likely when the clinical history 

includes one of the known causes, the more 

common lung diseases are ruled out, and the 

above spirometry and radiology findings are 

present. The diagnosis can be confirmed by 

identifying bronchiolitis in an open (or 

thoracoscopic) lung biopsy specimen. However, 

the pathologic process in the lung is patchy in 

distribution, and it is only with great care, 

special stains, and the examination of many 

biopsy sections that the typical lesion can be 

identified. Because the process of obtaining the 

tissue is invasive and the yield is not certain, 

affected individuals and their physicians should 

discuss in detail whether or not a lung biopsy for 

a tissue diagnosis is necessary. 

Exposures to Flavoring-Related Chemicals 

 

Flavorings are often complex mixtures of 

ingredients, many of which can be irritating to 

the skin, eyes, and respiratory system.12 The 

effects of these ingredients may be additive, 

such that exposures to concentrations of 

compounds that would not cause harm as a sole 

exposure may be harmful if combined with 

exposures to other compounds. NIOSH 
Health Hazard Evaluation Report No.2001-0474-2943 Page 9 

measured the air levels of diacetyl and acetoin, 

two common ingredients in butter flavoring, as 

indicators of exposure to butter flavoring vapors. 

Animal experiments at NIOSH indicate that 

diacetyl is one of the chemicals in butter 

flavoring that can lead to airway injury.13 The 

other chemical components that may contribute 

to toxicity, and the levels of exposure that are 

considered safe, are still not known. 

Recommended air exposure limits have not been 

established for most chemicals used in 

flavorings.12 Also not known is the relative 

safety of powdered flavorings compared to 

liquids or pastes. Powders that are formulated 

(i.e., encapsulated) to have lower emissions of 

volatile flavoring chemicals may pose lower 

risk. However, inhalation of airborne powder 

when handling these flavorings may increase 

worker risk for lung problems. 

Exposures and Worker Health at American 

Pop Corn Company 

At 0.08 ppm (area and personal measurements 

combined), the average diacetyl air 

concentration measured in the mixing room at 

American Pop Corn was among the lowest that 

NIOSH has measured in the mixing areas of 

several microwave popcorn plants.1,15,16,17,18

Average diacetyl air concentrations in the 

packaging area were even lower. (Many were 

below the limit of detection of the sampling 

method.) While the NIOSH medical survey did 

not identify significant evidence that packaging 

workers were at increased risk for lung problems 

related to work exposures, NIOSH tests did find 

that six of 13 workers with past mixing 

experience had abnormal spirometry tests. 

Three of these six workers had obstruction or a 

mixed pattern, and three had restriction. 

Although fixed obstruction on spirometry is the 

most common finding in workers with flavoringrelated lung disease, it is possible that restriction 

may also occur with this type of exposure. One 

of the eight index cases from the plant where the 

association of bronchiolitis obliterans with 

microwave popcorn production was first 

observed has restriction on spirometry, but has 

chest CT scan findings that are similar to those 

of the other seven cases.4

 Some workers with 

mixing experience at the American Pop Corn 

Company plant may have developed abnormal 

lung function due to brief, intense exposures 

during mixing activities, such as those that occur 

when workers weigh and measure flavorings, 

pour them manually into open tanks of heated 

soybean oil, and look into tanks, especially if 

respiratory protection is not consistently and 

appropriately utilized. This risk can be present 

even when ventilation maintains low average air 

concentrations of flavoring chemicals. 

 

Air concentrations of total and respirable dust in 

the mixing room were below the OSHA PEL for 

particulates not otherwise regulated (PNOR) and 

the ACGIH TLV for particulates not otherwise 

specified (PNOS). However, the PNOR PEL 

and PNOS TLV may not be fully protective with 

regard to levels of dust in the mixing room, as 

some of the dust is due to flavoring powders, the 

inhalation of which may pose a risk for lung 

disease. 

Average diacetyl air concentrations in the 

quality control (QC) lab were below the 

sampling method’s limit of detection, and work 

in quality control was not identified as an 

independent risk factor for lung disease. 

However, the microwave popping of many 

dozens of bags of product per shift was 

associated with abnormal lung function in 

quality control workers in another plant.1

 It is 

possible that QC workers at American Pop Corn 

have lower risk due to lower exposures because 

fewer bags are popped, or because there is 

greater ventilation of the quality control room 

compared to the other plant. NIOSH surveys at 

other microwave popcorn plants have found that 

average air concentrations of diacetyl in QC labs 

are generally lower than in the mixing rooms 

and packaging areas. QC workers may be at risk 

from brief, intense exposures during microwave 

popping and opening bags of product even when 

general dilution ventilation maintains low 

average exposures. Also, QC workers’ 

exposures may be substantially different from 

those of mixers because of the much higher 

temperatures that occur in microwave popping 

of product compared to the temperatures of oil 

and flavorings in heated tanks. Shortly after the 

NIOSH surveys, American Pop Corn Company 

management installed a local exhaust ventilation 

system for the microwave ovens in the QC lab in 
Page 10 Health Hazard Evaluation Report No. 2001-0474-2943 

an attempt to reduce any potential risk to quality 

control workers from QC-related exposures. 

Diacetyl air concentrations in the mixing room 

were substantially higher on the day when liquid 

and paste flavorings were used in production 

compared to the days when only powdered 

flavorings were used (Table 2). When NIOSH 

heated samples of these butter flavorings to 

approximately 120 degrees Fahrenheit in the 

laboratory and measured the relative amounts of 

volatile organic compounds (VOCs) emitted, the 

liquid and paste butter flavorings emitted 

amounts of diacetyl that were approximately ten 

(or more) times higher than the amounts emitted 

by the powdered butter flavorings. Many of the 

other compounds emitted also followed this 

pattern. In general, the powders emitted 

substantially lower amounts of VOCs than did 

liquids or pastes. Lower emission from the 

powders could be due to lower amounts of the 

specific chemical ingredients in the powders 

compared to the liquids and pastes (NIOSH does 

not know the percent by weight compositions of 

these flavorings). However, some powdered 

flavorings are encapsulated in such a way that 

there is much less release of these chemicals 

during microwave popcorn production, which 

may explain the lower VOC emissions from the 

powders used at American Pop Corn. 

The survey results of respirator use by mixers 

and others with access to the mixing room 

indicated that past respirator use was sporadic or 

non-existent by many of these workers prior to 

June 2002. American Pop Corn Company 

management indicated that it had placed greater 

emphasis on compliance with respirator use by 

workers entering the mixing room after the 

diagnosis of work-related lung disease in a 

mixer in June 2002. 

 

The results of the respirator cartridge capacity 

evaluation indicate that, at the levels of organic 

vapors present during the 33 hours of use, these 

cartridges were adequately working to remove 

contaminants from the breathing air of the mixer 

wearing them and had not reached their 

maximum life span. Given similar conditions in 

the mixing room, the same model of cartridge 

could be safely used for a period of one week 

(40 hours) before needing to be changed. Other 

brands of cartridges or changes in the conditions 

of the mixing room would require independent 

evaluation. 

CONCLUSIONS

Despite good ventilation and low average air 

concentrations of diacetyl in the mixing room at 

American Pop Corn Company, some workers 

with a history of mixing experience probably 

were affected by brief, intense exposures during 

processes that involve the open handling of 

flavorings. Evidence of significant risk for lung 

disease in packaging workers and QC lab 

workers was not identified. There was less 

exposure to flavoring-related chemicals when 

powdered flavorings were in use, but some of 

the airborne dust generated when these 

powdered flavorings were handled was 

respirable, suggesting potential risk to workers if 

inhaled. 

RECOMMENDATIONS

The following recommendations were provided 

by NIOSH to American Pop Corn Company 

from November 2002 through July 2003: 

1. Engineering Controls 

• Implement general dilution ventilation 

for the pre-mixing area in the warehouse 

where flavorings are stored and 

weighed. Maintain negative pressure in 

this area relative to the warehouse. 

Provide local exhaust ventilation to the 

part of this area where open measuring 

and weighing of flavorings occurs. 

• Regularly check and maintain all 

ventilation systems to minimize the 

possibility of a malfunction. 

• Perform periodic air sampling for 

diacetyl to verify that the ventilation 

systems in use are functioning 

optimally. 
Health Hazard Evaluation Report No.2001-0474-2943 Page 11 

• Obtain engineering consultation to 

identify process changes that would 

allow the handling of flavorings in 

closed or sealed systems for addition to 

heated soybean oil. 

2. Flavoring Substitution 

Although much remains to be learned regarding 

the compounds in butter flavorings that may 

have toxicity and what are safe levels of 

exposure, the possibility of replacing liquid or 

paste flavorings formulations with low 

emissions powders should be explored. A 

powdered flavoring that generates little dust 

when handled, and has low emissions of VOCs 

before and after it is added to heated soybean 

oil, may be safer than a dustier powder that can 

be inhaled by workers. 

3. Work Practices 

• Always keep containers of flavorings 

tightly sealed when not in use. Empty 

flavoring containers that still have 

residual flavorings in them also need to 

be tightly sealed. If they are to be 

washed, the worker doing this should 

wear a respirator. 

• Limit access to the mixing room and to 

areas where flavorings are handled to 

only those workers whose job duties 

require them to be in those areas. 

4. Respiratory Protection Program 

• Maintain a written respiratory 

protection program that meets the 

requirements of the OSHA 

Respiratory Protection Standard (29 

CFR 1910.134). 

• Require mandatory respirator use for 

mixers, and any other workers that 

enter the mixing room and flavoring 

pre-mixing area in the warehouse. 

• Assure that workers understand how 

and when to wear a respirator, the 

nature of the respiratory hazard, and 

that a respirator must be used 100% 

of the time when handling open 

containers of flavorings and for any 

duties in the mixing room. 

• Continue to use NIOSH-certified 

full-facepiece respirators with 

organic vapor cartridges and 

particulate filters, or use more 

protective respirators. 

5. Medical surveillance with spirometry 

• Perform spirometry tests 

 Every three to four months 

for all mixers of oil and 

flavorings and all microwave 

QC lab workers. 

 Every six months for all nonmixers who enter the mixing 

room frequently. 

 Obtain baseline spirometry 

on workers before they are 

assigned to these areas. 

 Assure that the technician 

performing spirometry 

follows the guidelines of the 

American Thoracic Society5

(ATS) to ensure high quality 

tests. 

 Assure that the physician 

reviewing the spirometry 

tests is familiar with this 

report. 

• Compare spirometry results over 

time to identify any declines in lung 

function. (See Appendix D, July 

2003 NIOSH letter to American Pop 

Corn Company containing 

recommendations for a spirometry 

testing program.) 

• Encourage mixing room and QC lab 

workers to report any persistent 

shortness of breath or cough to their 

supervisor (or the company health 

and safety department) and to their 

physician. 
Page 12 Health Hazard Evaluation Report No. 2001-0474-2943 

• Refer any symptomatic workers and 

those with abnormal or declining 

spirometry results for further medical 

evaluation to establish a diagnosis. 

• Prevent further flavoring exposure 

for any worker with lung disease or 

impairment that is considered to be 

either likely due to, or worsened by, 

flavorings exposure. (Obtain 

physician guidance on the affected 

worker’s work restrictions in this 

circumstance.) 

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(NIOSH) Publication No. 85-171-1710. 

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M, Friend S, Schwegler-Berry D, Goldsmith WT 

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Page 14 Health Hazard Evaluation Report No. 2001-0474-2943 

Table 1. Time-weighted average diacetyl (area and personal) and total and respirable dust air 

concentrations by job 

Diacetyl (ppm) Total Dust (mg/m3

) Respirable Dust (mg/m3) Job / Area N Mean Min Max N Mean Min Max N Mean Min Max 

Mixing room 8 0.08 ND 0.57 3 2.40 1.40 3.80 3 0.23 0.09 0.31 

Bartelt Operator* 8 0.006 ND 0.03 3 0.08 0.04 0.12 4 0.03 0.01 0.04 

Langen Operator* 1 ND ND ND - - - - - - - - 

Quality Control 6 ND ND ND 3 0.08 0.06 0.10 3 0.03 0.01 0.05 

Production 

Worker* 6 0.002 ND 0.004 3 0.04 0.02 0.06 3 0.03 0.02 0.03 

Stacker* 6 ND ND ND 3 0.17 0.05 0.30 3 0.04 0.01 0.06 

Maintenance 1 ND ND ND 2 0.13 0.05 0.21 2 0.08 0.01 0.15 

Supervisor 4 ND ND ND 2 0.03 0.02 0.04 2 0.01 0.01 0.01 

Fork Lift Operator 1 ND ND ND - - - - - - - - 

Sanitation 1 ND ND ND - - - - - - - - 

Poly Packaging** 2 ND ND ND 1 0.30 0.30 0.30 1 0.01 0.01 0.01 

Office 2 ND ND ND - - - - - - - - 

Ambient 2 ND ND ND 2 0.21 0.02 0.40 2 0.03 0.01 0.05 

*Microwave popcorn packaging area **Plain kernel (non-microwave) popcorn packaging 

N – Number of samples collected ppm – parts per million parts air 

mg/m3

 – milligrams per cubic meter of air - Indicates no samples taken in this area 

ND – not detectable; measurements were below the limit of detection (0.001 ppm) 
Health Hazard Evaluation Report No.2001-0474-2943 Page 15 

Table 2. Air concentrations of diacetyl in the mixing room 

Date Shift Type 

Concentration 

(ppm) 

Type of butter flavored 

popcorn being made1

Type of butter flavor 

being used 

7/29/2002 1st area 0.57 

7/29/2002 1st personal 0.05 

7/29/2002 1st personal 0.03 

low fat butter #1 

low fat butter #2 

paste 

liquid 

7/31/2002 2nd area ND 

7/31/2002 2nd personal 0.004 

butter 

heavy butter 

powder 

powder 

8/01/2002 2nd area ND 

8/01/2002 2nd personal ND 

8/01/2002 2nd personal 0.005 

heavy butter powder 

1

Not the actual product name ppm – parts per million parts air 

ND – not detectable; measurements were below the limit of detection (0.001 ppm). 

Table 3. Total Hydrocarbons excluding diacetyl and acetoin 

Date 

Concentration 

(mg/m3

) 

Job / Area Description 

7/29/2002 0.71 Ambient 

7/31/2002 0.21 Ambient 

7/29/2002 0.72 Machine Operator* 

7/31/2002 1.02 Machine Operator* 

1/8/2002 1.44 Machine Operator* 

1/8/2002 1.21 Machine Operator* 

7/29/2002 0.82 Maintenance 

1/8/2002 1.10 Maintenance 

7/29/2002 0.43 Manager 

1/8/2002 0.17 Manager 

7/29/2002 0.65 Mixer 

7/31/2002 0.51 Mixer 

1/8/2002 0.41 Mixer 

7/29/2002 0.85 MW** Quality Control 

7/31/2002 0.42 MW** Quality Control 

1/8/2002 0.21 MW** Quality Control 

7/29/2002 1.00 Production worker 

7/31/2002 0.93 Production 

1/8/2002 1.31 Production 

7/29/2002 0.58 Stacker 

7/31/2002 0.85 Stacker 

1/8/2002 0.78 Stacker 

7/31/2002 0.73 Poly packaging*** 

1/8/2002 0.49 Poly Quality Control 

7/31/2002 0.19 Office 

7/29/2002 0.56 Other 

7/29/2002 0.93 Other 

7/31/2002 0.45 Other 

7/31/2002 1.16 Other 

1/8/2002 1.51 Other 

 *Bartelt or Langen operator (microwave popcorn packaging) 

**Microwave production ***Plain kernel (non-microwave) popcorn packaging 
Page 16 Health Hazard Evaluation Report No. 2001-0474-2943 

Table 4. Worker symptoms by current work area and smoking status 

Microwave popcorn plant workers Workers in other plant areas (including office) 

Current/former smoker (N=41) 

Never smoker (N=46) 

Total (N=87) 

Current/former smoker (N=44) 

Never smoker (N=26) 

Total (N=70) 

Any trouble breathing in last 12 months 7 (17%) 5 (11%) 12 (14%) 11 (25%) 2 (8%) 13 (19%) 25 (1Shortness of breath on exertion: B Hurrying on level ground or walking up slight hill  - Onset after hire B Walking with people your own age on level ground  - Onset after hire 

18 (44%) 12 (29%) 4 (10%) 4 (10%) 

10 (22%) 8 (17%) 3 (7%) 3 (7%) 

28 (32%) 20 (23%) 7 (8%) 7 (8%) 

11 (25%) 8 (18%) 1 (2%) 1 (2%) 

5 (19%) 5 (19%) 1 (4%) 1 (4%) 

16 (23%) 13 (19%) 2 (3%) 2 (3%) 

44 (233 (29 (6%9 (6%

Usually cough 11 (27%) 5(11%)** 16 (19%) 10 (23%) 4 (15%) 14 (20%) 30 (1Chronic cough* B Onset after hire 

6 (15%) 5 (12%) 

4 (9%)** 4 (9%) 

10 (11%) 9 (10%) 

5 (11%) 2 (5%) 

3 (12%) 3 (12%) 

8 (11%) 5 (7%) 

18 (114 (9

Wheezing B Aside from cold B Onset after hire 

11 (27%) 9 (22%) 3 (7%) 

8 (17%) 4 (9%) 3 (7%) 

19 (22%) 13 (15%) 6 (7%) 

14 (32%) 7 (16%) 4 (9%) 

8 (31%) 4 (15%) 2 (8%) 

22 (31%) 11 (16%) 6 (9%) 

41 (224 (112 (8

Fever/chills/sweats 1 (2%) 4 (9%) 5 (6%) 4 (9%) 3 (12%) 7 (10%) 12 (8Unusual fatigue 5 (12%) 10 (22%) 15 (17%) 4 (9%) 4 (15%) 8 (11%) 23 (1

N= total individuals in category *Usually cough on most days for 3 consecutive months or more during the year. **One individual did not answer cough questions. 
Health Hazard Evaluation Report No.2001-0474-2943 Page 17 

Table 5. Prevalence ratios for respiratory symptoms, self-report of physician diagnosed respiratory 

disease, and spirometry abnormalities in microwave popcorn plant workers, with expected 

numbers from NHANES III 

Condition No.b # Obsc # Expd O/E (95% CI) 

Shortness of breath when hurrying on the 

level or walking up a slight hill 

 < 40 years 

 ≥ 40 years 

 Total 

36 

47 

83 

8 

18 

26 

5.4 

12.5 

17.9 

1.5 (0.8-2.9) 

1.4 (0.9-2.3) 

1.5 (1.0-2.1) 

Chronic cougha 

 < 40 years 

 ≥ 40 years 

 Total 

35 

47 

82 

2 

8 

10 

2.3 

4.5 

6.8 

0.9 (0.2-3.2) 

1.8 (0.9-3.5) 

1.5 (0.8-2.7) 

Wheezing aside from a cold 

 < 40 years 

 ≥ 40 years 

 Total 

36 

47 

83 

4 

8 

12 

3.4 

5.4 

8.9 

1.2 (0.4-3.0) 

1.5 (0.8-2.9) 

1.4 (0.8-2.4) 

Asthma confirmed by MD 

 < 40 years 

 ≥ 40 years 

 Total 

36 

47 

83 

2 

3 

5 

2.4 

3.7 

6.1 

0.8 (0.2-3.0) 

0.8 (0.3-2.4) 

0.8 (0.4-1.9) 

Chronic bronchitis confirmed by MD 

 < 40 years 

 ≥ 40 years 

 Total 

36 

47 

83 

0 

4 

4 

1.0 

3.3 

4.3 

0.0 (0.0-3.9) 

1.2 (0.5-3.1) 

0.9 (0.4-2.4) 

Obstruction or Mixed Pattern 

 < 40 years 

 ≥ 40 years 

 Total 

36 

45 

81 

2 

4 

6 

1.0 

3.4 

4.4 

1.9 (0.5-7.0) 

1.2 (0.5-3.1) 

1.4 (0.6-3.0) 

Obstruction (including borderline) 

or Mixed Pattern 

 < 40 years 

 ≥ 40 years 

 Total 

36 

45 

81 

2 

6 

8 

2.5 

6.0 

8.5 

0.8 (0.2-2.9) 

1.0 (0.5-2.2) 

0.9 (0.5-1.8) 

Restriction (without obstruction) 

 < 40 years 

 ≥ 40 years 

 Total 

36 

45 

81 

0 

6 

6

1.8 

3.8 

5.6 

0.0 (0.0-2.1) 

1.6 (0.7-3.5) 

1.1 (0.5-2.3) a

Usually cough on most days for 3 consecutive months or more during the year 

b

6 participants (including one with restriction) excluded from analysis due to missing information on age, 

race, or spirometry result 

c

Number observed 

d

Number expected 
Page 18 Health Hazard Evaluation Report No. 2001-0474-2943 

Table 6. Prevalence ratios for respiratory symptoms, self-report of physician diagnosed respiratory 

disease, and spirometry abnormalities in microwave popcorn plant workers (excluding evermixers), with expected numbers from NHANES III 

Condition No.b # Obsc # Expd O/E (95% CI) 

Shortness of breath when hurrying on the 

level or walking up a slight hill 

 < 40 years 

 ≥ 40 years 

 Total 

32 

40 

72 

5 

16 

21 

4.7 

11.3 

16.0 

1.1 (0.4-2.5) 

1.4 (0.9-2.3) 

1.3 (0.9-2.0) 

Chronic cougha 

 < 40 years 

 ≥ 40 years 

 Total 

31 

40 

71 

1 

7 

8 

1.9 

4.0 

5.9 

0.5 (0.1-3.0) 

1.7 (0.8-3.6) 

1.4 (0.7-2.7) 

Wheezing aside from a cold 

 < 40 years 

 ≥ 40 years 

 Total 

32 

40 

72 

3 

6 

9 

2.9 

4.8 

7.6 

1.0 (0.4-3.1) 

1.3 (0.6-2.7) 

1.2 (0.6-2.2) 

Asthma confirmed by MD 

 < 40 years 

 ≥ 40 years 

 Total 

32 

40 

72 

2 

3 

5 

2.1 

3.2 

5.2 

1.0 (0.3-3.5) 

0.9 (0.3-2.8) 

1.0 (0.4-2.2) 

Chronic bronchitis confirmed by MD 

 < 40 years 

 ≥ 40 years 

 Total 

32 

40 

72 

0 

4 

4 

0.9 

3.0 

3.9 

0.0 (0.0-4.4) 

1.3 (0.5-3.4) 

1.0 (0.4-2.6) 

Obstruction or Mixed Pattern 

 < 40 years 

 ≥ 40 years 

 Total 

32 

38 

70 

1 

3 

4 

0.9 

3.0 

3.9 

1.1 (0.2-6.4) 

1.0 (0.3-3.0) 

1.0 (0.4-2.7) 

Obstruction (including borderline) 

or Mixed Pattern 

 < 40 years 

 ≥ 40 years 

 Total 

32 

38 

70 

1 

4 

5 

2.2 

5.2 

7.4 

0.5 (0.1-2.6) 

0.8 (0.3-2.0) 

0.7 (0.3-1.6) 

Restriction (without obstruction) 

 < 40 years 

 ≥ 40 years 

 Total 

32 

38 

70 

0 

4 

4 

1.6 

3.2 

4.8 

0.0 (0.0-2.5) 

1.2 (0.5-3.2) 

0.8 (0.3-2.2) a

Usually cough on most days for 3 consecutive months or more during the year 

b

6 participants (including one with restriction) excluded from analysis due to missing information on age, 

race, or spirometry result 

c

Number observed 

d

Number expected 
Health Hazard Evaluation Report No.2001-0474-2943 Page 19 

Table 7. Self-reported diagnoses and spirometry abnormalities by current work area and smoking status 

Microwave popcorn plant workers Workers in other plant areas (including 

office) 

Current/former smoker (N=41) 

Never smoker (N=46) 

Total (N=87) 

Current/former smoker (N=44) 

Never smoker (N=26) 

Total (N=70) 

Bronchitis confirmed by MD while working in plant 

4 (10%) 5 (11%) 9 (10%) 8 (18%) 1 (4%) 9 (13%) 

Chronic bronchitis confirmed by MD B Onset after hire 

2 (5%) 1 (2 %) 

2 (4%) 1 (2 %) 

4 (5%) 2 (2%) 

4 (9%) 2 (5%) 

0 0 

4 (6%) 2 (3%) 

Pneumonia while working in plant 2 (5%) 2 (4%) 4 (5%) 4 (9%) 2 (8%) 6 (9%) Asthma confirmed by MD B Onset after hire 

4 (10%) 0 

1 (2%) 0 

5 (6%) 0 

8 (18%) 5 (11%) 

2 (8%) 1 (4%) 

10 (14%) 6 (9%) 

Abnormal Spirometry B obstruction (incl. Borderline) + mixed B restriction (without obstruction) 

9 (22%) 5 (12%) 4 (10%) 

6 (14%) * 3 (7%) 3 (7%) 

15 (17%) 8 (9%) 7 (8%) 

7 (16%) ** 7 (16%) 0 

2 (8%) 1 (4%) 1 (4%) 

9 (13%) 8 (11%) 1 (1%) 

N= Total individuals in category. * There were 2 individuals that were not included in the percent calculation. One did not undergo spirometry testing and the othcould not be interpreted. ** There was 1 individual that did not undergo spirometry testing. 
Page 20 Health Hazard Evaluation Report No. 2001-0474-2943 

Figure 1A. GC-MS chromatogram of mixing room air sample, July 29, 2002. Only paste 

and liquid butter flavorings were in use. Peak number 20 represents diacetyl. 
Health Hazard Evaluation Report No.2001-0474-2943 Page 21 

Figure 1B. GC-MS chromatogram of mixing room air sample, July 31, 2002. Only 

powdered butter flavorings were in use. Peak number 20 represents diacetyl. 
Page 22 Health Hazard Evaluation Report No. 2001-0474-2943 

Figure 1C. GC-MS chromatogram of mixing room air sample, August 1, 2002. Only 

powdered butter flavorings were in use. Peak number 20 represents diacetyl. 
Health Hazard Evaluation Report No.2001-0474-2943 Page 23 

Figure 1D. Key of peaks for Figures 1A-C 
Page 24 Health Hazard Evaluation Report No. 2001-0474-2943 
Health Hazard Evaluation Report No.2001-0474-2943 Page 25 

Figure 2. Results of FTIR real-time diacetyl air concentrations in the mixing room on July 

30, 2003. The diacetyl peak occurred immediately after the mixer poured several fivegallon containers of liquid butter flavoring into a mixing tank (over two minutes) and then 

closed the lid to the tank. 

0

10

20

30

40

50

60

70

80

90

1:26 AM

1:33 AM

1:40 AM1:48 AM

1:55 AM

Time

PPM
Page 26 Health Hazard Evaluation Report No. 2001-0474-2943 

0.00E+00

5.00E+07

1.00E+08

1.50E+08

2.00E+08

2.50E+08

3.00E+08

3.50E+08

4.00E+08

4.50E+08

12:00 PM 12:30 PM 1:00 PM

Time

Concentration (particles / cubic meter of air)

0.3-10.0 μm

0.3->20.0 μm

Powder 1 Powder 2

Powder 2

(Oiled) Powder 3

easy

easy

easy

easy

hurried hurried hurried

hurried

drop

drop

drop

drop

Particle size ranges 

represented by lines

Figure 3. Real-time air sampling data during simulated hand scooping of four different 

powder butter flavorings. 
Health Hazard Evaluation Report No.2001-0474-2943 Page 27 

APPENDIX A 

May 30, 2002 

HETA 2001-0474 

Mr. Greg Hoffman 

American Popcorn Company 

4332 Grant Street 

Sioux City, Iowa 51108 

Dear Mr. Hoffman: 

This letter is in followup to a site visit conducted on September 26, 2001, by the National 

Institute for Occupational Safety and Health (NIOSH) at your American Popcorn Company 

microwave popcorn plant in Sioux City, Iowa. NIOSH conducted this visit in response to a 

request for technical assistance made by the Iowa Department of Health (DOH). The Iowa DOH 

requested that NIOSH evaluate adverse health effects associated with employment in the 

microwave popcorn industry. Results from this site visit were communicated to you previously 

by telephone. 

NIOSH collected area air samples using semi-quantitative sampling methods to assess the types 

of volatile organic compounds present in air during the production of microwave popcorn. The 

samples were collected from three locations: the mixing room, the machine operators area, and 

the stacking area. The samples were collected on thermal desorption tubes and were analyzed by 

gas chromatography with a mass selective detector according to NIOSH Method 2549. 

The major organic compounds identified in plant air included propane, butanes, ethanol 

isopropanol, fluorodichloroethane, toluene, limonene, a-pipene, 1-phenoxy-2-propanol, and 

methyl ethyl ketone. Other compounds detected included diacetyl, diacetone alcohol, various 

C6 - C14 aliphatic hydrocarbons, dipropylene glycol methyl ether, di-tert-butylbenzene, and 

trichloroethylene. These results provide a perspective on the types of compounds present in air 

during the production of microwave popcorn. 

NIOSH also obtained quantitative sampling results for diacetyl and acetoin at the three sampling 

locations. These ketones are major constituents of the butter flavorings used in the production 

process. The diacetyl and acetoin samples were collected on charcoal sorbent tubes at a flow 

rate of 50 cubic centimeters per minute (cc/min). The samples were analyzed quantitatively by 

gas chromatography according to NIOSH Method 2557. Two of the diacetyl samples had 

concentrations below the minimum detectable concentration of 0.008 parts per million air by 

volume (ppm). Only one of the three diacetyl samples had a detectable concentration, and that 

concentration was equal to the minimum detectable concentration of 0.008 ppm. That sample 

was collected in the 
Page 28 Health Hazard Evaluation Report No. 2001-0474-2943 

Mr. Greg Hoffman - Page 2 

mixing room. All three acetoin samples were below the minimum detectable concentration for 

that compound in air (approximately 0.008 ppm). 

At present, the specific chemical component(s) and concentration(s) in the flavorings that cause 

obstructive respiratory problems in the microwave popcorn industry are unknown. Additionally, 

there are no applicable exposure standards or guidelines for diacetyl or acetoin. However, the 

diacetyl and acetoin concentrations measured at American Popcorn Company are hundreds of 

times lower than those measured at another microwave popcorn plant where obstructive 

respiratory health problems have been found among workers. These sampling results indicate 

that the engineering controls in place at American Popcorn Company are effective in maintaining 

ketone concentrations below or at the detectable limit. When combined with the use of 

respiratory protection in the mixing room, worker exposures to volatile organic compounds from 

microwave popcorn production should be minimal to non-detectable. 

If you have any questions about these sampling results, please contact me by phone (304-285-

5959) or E-mail (gkullman@cdc.gov). My colleagues and I thank you and your staff at 

American Popcorn for your cooperation and commitment to occupational safety and health. 

 Sincerely, 

Greg J. Kullman, Ph.D., CIH 

 Hazard Evaluations and Technical 

 Assistance Team 

 Field Studies Branch 

 Division of Respiratory Disease Studies 

cc: 

John Johnson, Iowa Department of Health 
Health Hazard Evaluation Report No.2001-0474-2943 Page 29 

APPENDIX B 

Medical Questionnaire 
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Health Hazard Evaluation Report No.2001-0474-2943 Page 41 

APPENDIX C 

Table 3 and Table 4 from NIOSH letter to American Pop Corn Company, November 18, 2002 

Table 3. Airway obstruction and mixed pattern on spirometry testing by current work area, comparison with expected from 

 Current and former smokers Never smokers All participan

 No. # 

Exp 

# Obs Ratio 

Obs/Exp (95% CI) 

No. # Exp # Obs Ratio 

Obs/Exp (95% CI) 

No. # Exp # Ob

Microwave plant – < 40 yrs old – > 40 yrs old 

– Total 

18 23 41 

1.7 4.7 6.2 

1 4 5 

0.6 (0.1 , 3.3) 0.9 (0.3 , 2.2) 0.8 (0.3 , 1.9) 

19 24** 43** 

1.1 1.6 2.7 

1 2 3 

0.9 (0.2 , 5.2) 1.2 (0.3 , 4.6) 1.1 (0.4 , 3.3) 

37 47 84 

2.8 7.1 9.2 

2 6 8 

Office & Other – < 40 yrs old – > 40 yrs old 

– Total 

10 33* 43 

0.9 6.7 6.4 

0 7 7 

0 (0.0 , 4.3) 1.0 (0.5 , 2.2) 1.1 (0.5 , 2.3) 

12 14 26 

0.7 0.9 1.6 

0 1 1 

0 (0.0 , 5.5) 1.1 (0.2 , 6.3) 0.6 (0.1 , 3.5) 

22 47 70 

1.7 7.1 7.7 

0 8 8 

CI= confidence interval. * 1 individual did not undergo spirometry testing. ** Age data were missing for 2 individuals, and 1 individual did not undergo spirometry testing. 
Page 42 Health Hazard Evaluation Report No. 2001-0474-2943 

Table 4. Restriction on spirometry testing by current work area, comparison with expected from NHANES III 

 Current and former smokers Never smokers All particip

 No. # Exp # Obs Ratio 

Obs/Exp (95% CI) 

No. # 

Exp 

# Obs Ratio 

Obs/Exp (95% CI) 

No. # Exp # Ob

Microwave plant – < 40 yrs old – > 40 yrs old 

– Total 

18 23 41 

1.2 3.4 4.4 

1 5 6 

0.8 (0.2 , 4.7) 1.5 (0.6 , 3.4) 1.4 (0.6 , 3.0) 

19 24** 43** 

0.9 2.0 2.7 

0 4 4 

0 (0.0 , 4.3) 2.0 (0.8 , 5.1) 1.5 (0.6 , 3.8) 

37 47 84 

2.1 5.8 7.3 

1 9 10 

Office & Other – < 40 yrs old – > 40 yrs old 

– Total 

10 33* 43 

0.7 4.9 4.6 

0 2 2 

0 (0.0 , 5.5) 0.4 (0.1 , 1.5) 0.4 (0.1 , 1.6) 

12 14 26 

0.6 1.2 1.6 

0 1 1 

0 (0.0 , 6.4) 0.9 (0.2 , 4.7) 0.6 (0.1 , 3.5) 

22 47 70 

1.3 5.8 6.1 

0 3 3 

CI= confidence interval. * 1 individual did not undergo spirometry testing. **Age data were missing for 2 individuals, and 1 individual did not undergo spirometry testing. 
Health Hazard Evaluation Report No.2001-0474-2943 Page 43 

APPENDIX D 

July 16, 2003 

HETA 2001-0474 

Greg Hoffman 

Vice President of Production 

American Pop Corn Company 

One Fun Place, Box 178 

Sioux City, Iowa 51102 

Dear Mr. Hoffman: 

This letter contains our recommendations for spirometry testing of your workers that are potentially 

exposed to flavoring-related chemicals in the course of their work. Please note that we are recommending 

more frequent testing than we did in our November 2002 letter. We are also recommending a more 

conservative approach to follow-up of workers with abnormalities on testing than we have in recent 

phone conversations (i.e., if a test is of good quality, immediately send for medical evaluation any 

workers with abnormalities or excessive declines as indicated below, rather than waiting and re-testing). 

NIOSH Recommendations for a Spirometry Testing Program at 

American Pop Corn Company 

Purpose: To detect obstructive lung disease in workers that may be related to inhalation of flavoring 

chemicals. 

General Considerations 

Spirometry is the most sensitive and reliable test to detect airways obstruction. Performance of 

spirometry must carefully follow the guidelines of the American Thoracic Society (see attached) to ensure 

high quality tests. Worker spirometry test results should be reviewed by a physician who is aware of the 

potential for workplace exposure to flavoring chemicals to adversely affect lung function, has reviewed 

these recommendations, and the American Thoracic Society guidelines. 

Who should be tested and how often? * 

• Mixers every three to four months 

• Non-mixers who enter the mixing room frequently need testing every six months 

• Every three to four months for Quality Control (QC) workers (i.e., those who microwave many 

bags of product per work shift) 

• Workers newly assigned to work in QC, mixing, or in a job requiring frequent entry into mixing 

room need a baseline test prior to starting work in these areas. 

*These revised recommended testing intervals replace our previous recommendations for American Pop Corn 

Company 

Criteria

• Obstruction: FEV1/FVC ratio below the lower limit of normal as indicated by the Hankinson 

1999 spirometry interpretation algorithm. 
Page 44 Health Hazard Evaluation Report No. 2001-0474-2943 

Mr. Greg Hoffman – Page 2 

• Excessive decline in FEV1: A decrease greater than 300 milliliters from the baseline value. This 

threshold assumes that both the baseline and current test sessions are of excellent quality. 

Abnormal Spirometry or Excessive Decline in FEV1: How to Proceed? 

• Abnormal spirometry in new worker: 

o Refer the worker to their personal physician for evaluation (unless he/she has already had 

an evaluation and/or diagnosis). Provide the physician with information on flavoringrelated lung disease (e.g. August 2002 New England Journal of Medicine article, or 

NIOSH Alert when published). 

o Avoid placement of the worker in QC or mixing job, or job requiring frequent entry into 

mixing room. 

• Obstruction, or decline in FEV1 greater than 300 milliliters, in a current worker 

o Refer the worker to an occupational medicine physician or pulmonary specialist (provide 

the physician with information on flavoring-related lung disease) for further evaluation 

which may include the following medical tests: 

 Full pulmonary function testing with spirometry followed by bronchodilator, 

diffusing capacity (DLCO), and lung volumes 

 Chest x-ray 

 High resolution chest CT scan with inspiratory and expiratory views 

o Prevent any further exposure of the worker to flavoring chemicals if the physician 

diagnoses flavoring-related lung disease or other lung disease that may be exacerbated by 

exposure to flavoring chemicals. 

• Any suspicion of flavoring-related lung disease in a current worker should prompt an evaluation 

of the workplace to identify any contributing factors. These may include: 

o Ventilation or other equipment malfunction 

o Lack of worker compliance with, or understanding of, company policies regarding 

respiratory protection or work practices to prevent exposure to flavoring-related 

chemicals. 

We encourage you to continue to periodically send us copies of spirometry tests performed by your 

technician so that we can review them for quality. The quality of the tests you have sent so far has been 

excellent. As always, please do not hesitate to call with any questions or concerns that you have. 

Sincerely, 

Richard Kanwal, M.D. 

Medical Officer 

Respiratory Disease Hazard Evaluation and 

 Technical Assistance Program 

Field Studies Branch 

Division of Respiratory Disease Studies 

Enclosures 

Rick Hartle (HETAB) 
Health Hazard Evaluation Report No.2001-0474-2943 Page 45 

EVALUATION CRITERIA

To assess the hazards posed by workplace exposures, NIOSH investigators use a variety of environmental 

evaluation criteria. These criteria suggest exposure levels to which most workers may be exposed for a 

working lifetime without experiencing adverse health effects. However, because of wide variation in 

individual susceptibility, some workers may experience occupational illness even if exposures are 

maintained below these limits. The evaluation criteria do not take into account individual 

hypersensitivity, pre-existing medical conditions, possible interactions with other work place agents, 

medications being taken by the worker, or environmental conditions. 

The primary sources of evaluation criteria for the workplace are: NIOSH Criteria Documents and 

Recommended Exposure Limits (RELs)1

, the Occupational Safety and Health Administration (OSHA) 

Permissible Exposure Limits (PELs)2

, and the American Conference of Governmental Industrial 

Hygienists (ACGIH®) Threshold Limit Values (TLVs®).3

 The objective of these criteria for chemical 

agents is to establish levels of inhalation exposure to which the vast majority of workers may be exposed 

without experiencing adverse health effects. 

Occupational health criteria are established based on the available scientific information provided by 

industrial experience, animal or human experimental data, or epidemiologic studies. Differences between 

the NIOSH RELs, OSHA PELs, and ACGIH® TLVs® may exist because of different philosophies and 

interpretations of technical information. It should be noted that RELs and TLVs are guidelines, whereas 

PELs are standards which are legally enforceable. OSHA PELs are required to take into account the 

technical and economical feasibility of controlling exposures in various industries where the agents are 

present. The NIOSH RELs are primarily based upon the prevention of occupational disease without 

assessing the economic feasibility of the affected industries and as such tend to be conservative. A Court 

of Appeals decision vacated the OSHA 1989 Air Contaminants Standard in AFL-CIO v OSHA, 965F.2d 

962 (11th cir., 1992); and OSHA is now enforcing the previous 1971 standards (listed as Transitional 

Limits in 29 CFR 1910.1000, Table Z-1-A). However, some states which have OSHA-approved State 

Plans continue to enforce the more protective 1989 limits. NIOSH encourages employers to use the 1989 

limits or the RELs, whichever are lower. 

Evaluation criteria for chemical substances are usually based on the average personal breathing zone 

exposure to the airborne substance over an entire 8- to 10-hour workday, expressed as a time-weighted 

average (TWA). Personal exposures are usually expressed in parts per million (ppm), milligrams per 

cubic meter (mg/m3

), or micrograms per cubic meter (μg/m3). To supplement the 8-hour TWA where 

there are recognized adverse effects from short-term exposures, some substances have a short-term 

exposure limit (STEL) for 15-minute peak periods; or a ceiling limit, which is not to be exceeded at any 

time. Additionally, some chemicals have a "skin" notation to indicate that the substance may be absorbed 

through direct contact of the material with the skin and mucous membranes. 

It is important to note that not all workers will be protected from adverse health effects if their exposures 

are maintained below these occupational health exposure criteria. A small percentage may experience 

adverse health effects because of individual susceptibility, a pre-existing medical condition, previous 

exposures, and/or hypersensitivity (allergy). In addition, some hazardous substances may act in 

combination with other work place exposures, or with medications or personal habits of the worker (such 

as smoking, etc.) to produce health effects even if the occupational exposures are controlled to the limit 

set by the evaluation criterion. These combined effects are often not considered by the chemical specific 

evaluation criteria. Furthermore, many substances are appreciably absorbed by direct contact with the 

skin and thus potentially increase the overall exposure and biologic response beyond that expected from 
Page 46 Health Hazard Evaluation Report No. 2001-0474-2943 

inhalation alone. Finally, evaluation criteria may change over time as new information on the toxic 

effects of an agent become available. Because of these reasons, it is prudent for an employer to maintain 

worker exposures well below established occupational health criteria. 

Diacetyl, Acetoin, and 2-Nonanone

The ketones, diacetyl, acetoin, and 2-nonanone are predominant components of artificial butter flavorings 

and are extremely irritating to skin, eyes, mucous membranes and the respiratory tract. Currently, there 

are no NIOSH, OSHA, or ACGIH® occupational exposure standards or guidelines for them. 

Acetaldehyde 

Acetaldehyde is a colorless liquid used as a flavoring agent and adjuvant. When ingested or inhaled it can 

irritate the eye, nose, and throat. The Food and Drug Administration regulates it as a direct food additive 

and a synthetic flavoring substance. The OSHA PEL is 200 ppm (8-hour TWA). Acetaldehyde is 

considered a potential occupational carcinogen by the U.S. Environmental Protection Agency (EPA), the 

International Agency for Research on Cancer (IARC), and NIOSH. For this reason NIOSH recommends 

that occupational exposure levels of acetaldehyde be kept at the lowest feasible concentration (LFC). 

ACGIH® has a ceiling limit of 25 ppm. 

Acetic acid and Butyric acid

 

Acetic acid is a colorless liquid with a strong vinegar-like odor. It is used in making dyes, drugs, plastics, 

food additives, and insecticides. The OSHA PEL is 10 ppm (8-hour TWA). NIOSH has an REL of 10 

ppm (10-hour TWA) and a ceiling limit of 15 ppm. ACGIH® also has a TLV® of 10 ppm (8-hour TWA) 

and a ceiling limit of 15 ppm. 

Butyric acid is a colorless liquid with the smell of rancid butter. It is a low molecular weight fatty acid 

and can be found as a fermentation product in butter and beer. It is used in the manufacture of plastics. 

Currently, there are no NIOSH, OSHA, or ACGIH® occupational exposure standards or guidelines. 

Volatile Organic Compounds 

Volatile organic compounds (VOCs) describe a large class of chemicals which are organic 

(i.e., containing carbon) and have a sufficiently high vapor pressure to allow some of the compound to 

exist in the gaseous state at room temperature. These compounds are emitted in varying concentrations 

from numerous indoor sources and chemicals including, but not limited to, carpeting, fabrics, adhesives, 

solvents, paints, cleaners, waxes, cigarettes, combustion sources, and the flavorings used in the 

production of microwave popcorn. 

Studies have measured wide ranges of VOC concentrations in indoor air as well as differences in the 

mixtures of chemicals which are present. Research also suggests that the irritant potency of these VOC 

mixtures can vary. The use of total VOC concentration as an indicator, however, has never been 

standardized and neither NIOSH nor OSHA currently has specific exposure criteria for VOC mixtures. 

Particulates, Not Otherwise Classified 

Often the chemical composition of the airborne particulate does not have an established occupational 

health exposure criterion. It has been the convention to apply a generic exposure criterion in such cases. 

Formerly inappropriately referred to as “nuisance” dust, the preferred terminology for the non-specified 
Health Hazard Evaluation Report No.2001-0474-2943 Page 47 

particulate is now "particulates, not otherwise classified” (PNOC) (ACGIH® TLV®), or "particulates, not 

otherwise regulated" (PNOR) (OSHA PEL). 

The OSHA PELs for PNOR are 15.0 mg/m3

 (total dust) and 5.0 mg/m3 (respirable fraction), determined 

as 8-hour averages. The ACGIH® recommended TLV® for exposure to PNOC is 10.0 mg/m3

 (total dust, 

8-hour TWA) and 3 mg/m3 (respirable dust). [See page 5 of this report]. These are generic criteria for 

airborne dusts which do not produce significant organic disease or toxic effect when exposures are kept 

under reasonable control. These criteria are not appropriate for dusts that have a biologic effect and may 

not be appropriate for evaluating general particulate matter in microwave popcorn packaging facilities. 

References 

1. NIOSH [2003]. Pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health and 

Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute 

for Occupational Safety and Health, DHHS (NIOSH) publication No.97-140. 

2. CFR [1997]. 29 CFR 1910.1000 Code of Federal Regulations. Washington, DC: U.S. Government 

Printing Office, Office of the Federal Register. 

3. ACGIH [2003]. 2003 TLVs® and BEIs®; threshold limit values for chemical substances and physical 

agents. Cincinnati, OH: American Conference of Governmental Industrial Hygienists. 
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