Skin and Respiratory 

Symptoms in Peanut 

Inspectors with 

Peanut Dust and 

Endotoxin Exposure

Loren C. Tapp, MD, MS

David Sylvain, MS, CIH

Health Hazard Evaluation Report

HETA 2008-0052-3115

Shann Peanut Company

Ambrose, Georgia

September 2010

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

Workplace

Safety and Health

 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/
The employer shall post a copy of this report 

for a period of 30 calendar days at or near 

the workplace(s) of affected employees. The 

employer shall take steps to insure that the 

posted determinations are not altered, defaced, 

or covered by other material during such 

period. [37 FR 23640, November 7, 1972, as 

amended at 45 FR 2653, January 14, 1980].
Health Hazard Evaluation Report 2008-0052-3115 Page i

Appendix A

Report Abbreviations.......................................................................ii

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

Summary .............................................................................v

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

Assessment.........................................................................4

Results.................................................................................6

Discussion .........................................................................11

Conclusions.......................................................................13

Recommendations.............................................................14

References ........................................................................18

Tables ................................................................................19

Contents

Acknowledgments and Availability of Report.....................30

Methods.............................................................................21

Occupational Exposure Limits and Health Effects.............23

Acknowledgments

Appendix B
Page ii Health Hazard Evaluation Report 2008-0052-3115

Abbreviations

μm micrometer

ACGIH® American Conference of Governmental Industrial Hygienists

CFR Code of Federal Regulations

COPD Chronic obstructive pulmonary disease

EU Endotoxin units

EU/m3 Endotoxin units per cubic meter

FDA Food and Drug Administration

FSIS Federal State Inspection Service

GDPH Georgia Division of Public Health

HP Hypersensitivity pneumonitis

IgE Immunoglobulin E

LAL Limulus amoebocyte lysate

mm Millimeter

NAICS North American Industry Classification System

NIOSH National Institute for Occupational Safety and Health

ODTS Organic dust toxic syndrome

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PBZ Personal breathing zone

PEL Permissible exposure limit

PFT Pulmonary function test

PPE Personal protective equipment

PVC Polyvinyl chloride

REL Recommended exposure limit

STEL Short-term exposure limit

TLV Threshold limit value

TWA Time-weighted average

USDA United States Department of Agriculture

VOC Volatile organic compound

WEEL Workplace environmental exposure limit
Health Hazard Evaluation Report 2008-0052-3115 Page iii

The National Institute for 

Occupational Safety and 

Health (NIOSH) received a 

request from the Georgia 

Division of Public Health 

(GDPH) to evaluate 

Federal State Inspection 

Service (FSIS) employees’ 

exposures and workrelated symptoms at 

Shann Peanut Company 

in Ambrose, Georgia. 

FSIS employees reported 

respiratory, skin, 

gastrointestinal, and 

flu-like symptoms while 

grading peanuts in middle 

to late October 2007.

Highlights of the

NIOSH Health

Hazard Evaluation

What NIOSH Did

● We visited the facility in December 2007 and October 

2008.

● We met with FSIS employees, GDPH and U.S. Department 

of Agriculture officials, and the facility’s owner.

● We checked the respirators and gloves that FSIS employees 

were given to use to see if they were protective.

● We spoke with FSIS employees confidentially about health 

concerns and reviewed their medical records.

● We looked for endotoxin in a dust sample taken from the 

air conditioner filter in the peanut grading room in 2007.

● We analyzed two different samples of peanuts for endotoxin 

and volatile organic compounds.

● We took air samples for endotoxin in the peanut grading 

room in 2008.

What NIOSH Found

● The peanut grading machines released dust indoors.

● FSIS employees were given dust masks that were not 

approved by NIOSH.

● Many FSIS employees reported skin, intestinal, lung, and 

flu-like symptoms.

● Endotoxin were found in the air conditioner filter dust, the 

peanut grading room air, and outdoor air.

● Respiratory abnormalities were found in medical records 

for some FSIS employees.

What FSIS Managers Can Do

● Vent peanut grading room dust outdoors.

● Change air conditioner filters routinely.

● Train employees before peanut season begins on 

agricultural dust hazards and how to prevent exposure.

● Provide NIOSH-approved N95 particulate respirators, and 

start a respiratory protection program for peanut inspectors.

● Encourage employees to report potential work-related 

health problems to their supervisor.
Page iv Health Hazard Evaluation Report 2008-0052-3115

Highlights of the

NIOSH Health

Hazard Evalution

(continued)

● Offer medical follow-up for employees experiencing workrelated symptoms.

● Provide nonlatex, powder-free disposable gloves for employees 

to prevent contact dermatitis.

● Start a management-employee health and safety committee.

● Review injury and illness logs monthly during peanut grading 

season to monitor work-related symptoms among peanut 

inspectors.

● Take air samples for endotoxin in FSIS peanut grading rooms 

throughout the state to further evaluate exposure.

What FSIS Employees Can Do

● Do not eat or drink in the peanut grading room.

● Wear nonlatex, powder-free disposable gloves when needed.

● Wear NIOSH-approved N95 particulate respirators when 

needed.

● Report any symptoms that you think may be related to work 

to your supervisor.

● Tell your doctor about your work exposures when seeking 

treatment for respiratory illness.
Health Hazard Evaluation Report 2008-0052-3115 Page v

We found that FSIS 

employees were exposed 

to airborne endotoxin 

during peanut grading. 

Occupational history, 

reported symptoms, 

and medical findings 

of FSIS employees are 

consistent with endotoxin 

exposure and possible 

chemical exposures 

such as mycotoxins. We 

recommend reducing 

dust exposure, training 

employees on the hazards 

of organic dust exposure, 

and providing FSIS 

peanut inspectors with 

appropriate respiratory 

and skin protection. 

Additional endotoxin 

sampling and review of 

injury and illness logs in 

peanut grading rooms 

throughout the state are 

advised.

Summary

On November 30, 2007, the GDPH submitted a request for 

technical assistance to NIOSH to address concerns about health 

symptoms in FSIS peanut inspectors who worked in the peanut 

grading room at Shann Peanut Company (Shann) in Ambrose, 

Georgia. FSIS employees began reporting irritation of the eyes, 

nose, respiratory tract, and skin; nausea; diarrhea; vomiting; 

headache; fever; and flu-like symptoms in middle to late October 

2007. Prior to our evaluation, FDA and USDA analyzed peanut 

samples for fungi, mycotoxins, and pesticides. GDPH officials 

conducted an epidemiologic assessment.

On December 5, 2007, we met with FSIS inspectors, GDPH 

officials, a USDA official, and the facility owner and walked 

around the peanut grading facility. We assessed ventilation in 

the grading room, examined the PPE provided to employees, and 

collected a sample of dust from the air conditioner filter in the 

grading room. We spoke with FSIS employees about their health 

concerns and reviewed their medical records. We later analyzed 

peanuts sent to us for endotoxin and VOCs. On October 22, 

2008, we returned to Shann and conducted PBZ air sampling for 

endotoxin in the grading room.

In 2007, we found that the grading room machinery did not vent 

peanut dust outdoors. FSIS inspectors reported wearing dust 

masks that were not NIOSH approved; they also reported skin, 

gastrointestinal, respiratory, and flu-like symptoms. Employee 

medical records reported respiratory abnormalities in seven 

employees. Endotoxin were found on the air conditioner filter 

and in peanut samples. During the 2008 site visit, endotoxin were 

found in the grading room air and outdoor air.

The acute respiratory and flu-like symptoms reported by FSIS 

employees were consistent with endotoxin exposure. The acute 

gastrointestinal and skin symptoms reported were consistent with 

exposure to chemical toxins, possibly mycotoxins. The persistence 

of symptoms in some workers after being removed from exposure 

was unusual. Persistent respiratory symptoms could be a result of 

additional lung insult from cigarette smoking or co-existing disease, 

such as COPD or asthma. In addition, persistence of symptoms 

might be explained by employees inadvertently taking home 

organic dust on their clothing and shoes and in their cars, thus 

continuing their exposure.
Page vi Health Hazard Evaluation Report 2008-0052-3115

Summary (continued)

Keywords: NAICS 424590 (Other Farm Product Material Merchant 

Wholesalers), peanuts, organic dust, endotoxin, skin, respiratory, and 

gastrointestinal symptoms

We recommend reducing dust in the peanut grading room by 

installing ductwork on machines to discharge dust outdoors. 

We recommend providing employee training on the hazards of 

organic dust and ways to prevent exposure, providing appropriate 

respiratory and skin protection to reduce exposure to irritants and 

allergens, and encouraging employees to report potential workrelated symptoms. FSIS management also should review injury and 

illness logs and conduct additional endotoxin sampling in FSIS 

peanut grading rooms throughout the state to monitor trends in 

work-related illness and exposures.
Health Hazard Evaluation Report 2008-0052-3115 Page 1

Introduction

On November 30, 2007, the GDPH submitted a request for 

technical assistance in evaluating respiratory and skin symptoms 

among state peanut inspectors who worked in the peanut grading 

room at Shann Peanut Company (Shann) in Ambrose, Georgia. 

Information provided to NIOSH indicated that FSIS employees 

began reporting symptoms in middle to late October 2007. 

Reported symptoms included skin rash; burning, itching, and 

peeling skin; irritation of the eyes, nose, and respiratory tract; 

nosebleeds; cough; shortness of breath; nausea; diarrhea; fever; and 

flu-like symptoms. We evaluated the workplace during site visits in 

December 2007 and October 2008. Interim letters were sent to the 

GDPH in January 2008 and October 2008.

Background 

Peanut growers bring harvested peanuts to Shann, where they are 

cleaned, dried, graded, and sold. Peanut grading is performed by 

seasonal FSIS employees. FSIS is the state agency that inspects 

and grades agricultural products. Peanut grading typically begins 

in late September or early October and continues into December. 

Throughout this period, eight to ten FSIS inspectors and aides are 

assigned to the Shann grading room where they handle peanut 

samples and operate the grading machines. During the grading 

season, FSIS inspectors and aides work 8 hours per day plus 

overtime as needed. FSIS inspector aides have the same work 

exposures as FSIS inspectors so, to simplify, we will refer to both 

job titles as FSIS inspectors in this report.

The Shann grading room is at the back of a small, single-story 

light-frame construction building that houses the Shann offices 

in the front of the building. The grading room is approximately 

30 feet long by 20 feet wide with an 8-foot ceiling and is separated 

from the office area by a floor-to-ceiling wall. The grading room is 

accessible from the office area through an interior doorway, which 

is kept closed when not in use, and through an exterior doorway 

at the back of the building. The room, equipped with an airconditioning unit that obtains room air through a supply grill near 

the floor at one end of the room, recirculates the air back to the 

room through seven ceiling-mounted diffusers.

Nine peanut grading machines are located along two walls in the 

grading room. Shann owns the machines, but they are operated 

and maintained by FSIS employees. Some grading machines 

are fitted with cyclones (inertial dust collectors for collecting 
Page 2 Health Hazard Evaluation Report 2008-0052-3115

Introduction 

(continued) large particulates). At the time of the first NIOSH site visit, the 

cyclones discharged dust into the grading room; at the time of the 

second site visit, the cyclones on the foreign material and presizer 

machines were fitted with PVC piping connected to exhaust vents 

outside the building (Figure 1). A freestanding ventilation unit 

beneath the work counter recirculated room air through a filter of 

undetermined efficiency.

Peanuts arrive at Shann in 10-ton open-top wagons. Shann 

employees tag each wagon, and dry and clean the peanuts in 

large machines as needed before grading. The grading process 

begins with an FSIS inspector using a mechanized probe to 

collect a sample of peanuts from eight locations within a wagon. 

The inspector carries the sample to the grading room where it 

is weighed, and the data are logged into the computer. Samples, 

which weigh 1500 to 1800 grams each, are brought into the 

grading room and put into the foreign material machine to 

separate the peanuts from miscellaneous debris. After debris 

removal, FSIS inspectors take 500 grams of peanuts from the 

sample for processing in the presizing, shelling, shaking, and 

splitting machines. Inspectors handle the samples when placing 

peanuts into the machines and when performing manual grading 

tasks at the large work counter in the center of the grading room. 

This process is repeated throughout the workday for samples that 

are obtained from wagons containing peanuts from growers.

Figure 1. Peanut grading machine with retrofitted exhaust 

ventilation duct in 2008
Health Hazard Evaluation Report 2008-0052-3115 Page 3

Introduction (continued) Prior Government Agency Response: 

October–December 2007

The following government agencies initiated an investigation in 

response to reports of health problems among FSIS employees 

who worked in the Shann grading room during the 2007 season: 

the GDPH, the Georgia Department of Agriculture, and offices 

and centers within the FDA and USDA. The epidemiologic 

investigation by the GDPH found that FSIS peanut inspectors at 

Shann began experiencing skin irritation and respiratory symptoms 

on October 16, 2007. FSIS employees related their symptoms to 

handling peanuts from one particular grower, reporting that these 

peanuts had an unusual odor. Nine inspectors with symptoms 

were seen by an infectious disease physician contracted by FSIS 

who suggested that the symptoms were consistent with exposure 

to a chemical irritant such as a mycotoxin. None of the peanut 

inspectors was hospitalized, but symptoms continued after initially 

handling that particular shipment of peanuts. As a result, the 

agencies’ investigations focused on the peanuts from that specific 

grower, even though no health problems were reported by that 

grower’s employees or by other employees of the processing 

company that handled peanuts from that grower. Because of 

employee health concerns, the Shann grading room was shut down 

from November 16, 2007, until the last week of December 2007.

The multi-agency investigation, which began prior to NIOSH 

involvement, included laboratory analyses of suspect peanut 

samples for mold, mycotoxins (including trichothecene 

mycotoxins, aflatoxin, Stachybotrys toxins, T-2 toxin, zearalenone, 

deoxynivalenol, ochratoxin, and cyclopiazonic acid), pesticides, and 

other chemicals. Although several genera of mold were identified 

in samples of the suspect peanuts, the types and amounts of mold 

contamination were not unusual. Trichothecene mycotoxins were 

detected in an initial screening sample; however, the results of 

this initial testing were only preliminary as the screening tests 

had not been validated for in-shell peanuts. Confirmatory tests 

for tricothecene mycotoxins were negative. Additional analyses 

of multiple samples did not identify mycotoxins. Analyses did 

not indicate the presence of pesticides or other chemicals in the 

peanuts.
Page 4 Health Hazard Evaluation Report 2008-0052-3115

Initial Site Visit: December 5, 2007 

We made an initial site visit on December 5, 2007. The site 

visit included an opening conference with District and County 

Department of Health officials, an official from the Georgia 

Department of Agriculture, several FSIS employees, and the 

owner of Shann. We toured the Shann facilities, including the 

grading room, and interviewed FSIS employees confidentially. 

During the tour, we observed transport and storage areas, the 

moisture shed where peanuts are dried, and a peanut cleaning 

operation performed by Shann employees. In the grading room, 

FSIS employees explained the steps involved in the peanut grading 

process and demonstrated the operation of peanut grading 

machines. Subsequent to the site visit, we reviewed medical records 

of 13 FSIS employees and reports of laboratory analyses from the 

FDA.

Confidential employee interviews were held with seven FSIS 

employees at the Shann facility during our first site visit. One 

additional FSIS and one Shann employee were later interviewed by 

phone.

We collected a dust sample from the air conditioner filter in 

the FSIS grading room and several peanut shells that contained 

crystalline-like structures. Approximately 2 weeks after the site visit, 

the Georgia Department of Agriculture provided us with a plastic 

bag containing peanuts from storage bins that were graded when 

employee symptoms began (“suspect peanuts”) and a separate bag 

containing other peanuts (“comparison peanuts”). Air conditioner 

filter dust and peanut samples were analyzed for endotoxin 

(Appendix A).

Because peanut grading had been suspended prior to our 2007 site 

visit, we were unable to observe actual grading room operations 

or conduct exposure monitoring. The grading room was reopened 

the last week of December 2007 to finish grading the remaining 

peanuts. FSIS management reported that six different FSIS 

inspectors worked that week, wearing Tyvek® suits, respiratory 

protection, goggles, gloves, and foot covers, and that none of these 

employees reported symptoms.

Assessment
Health Hazard Evaluation Report 2008-0052-3115 Page 5

Assessment (continued) Second Site Visit: October 22, 2008 

During a second site visit in the 2008 grading season we observed the 

grading process and conducted air sampling for endotoxin. PBZ air 

samples were collected on eight FSIS employees inside the grading 

room. For comparison, an area air sample was collected outdoors, 

approximately 3 feet above the ground and 30 feet from the entrance 

to the grading room. A second area air sample was collected in the 

Shann office employees’ lunchroom for comparison. The lunchroom 

was selected for background sampling because it was in the same 

building as the grading room and had not been associated with health 

problems in 2007. Sampling and analytical methods are given in 

Appendix A.
Page 6 Health Hazard Evaluation Report 2008-0052-3115

Initial Site Visit: December 5, 2007 

In December 2007, when an FSIS employee demonstrated how the 

grading machines operated, we noted that the machines generated 

and released dust into the grading room air. We were shown 

single-strap dust masks that were provided to FSIS employees for 

voluntary use. These masks are not NIOSH-approved and do not 

provide adequate protection against airborne particulate exposure. 

No respiratory protection program was in place. In addition, we 

observed that when the grading machines were in operation, they 

produced a considerable amount of noise.

At the time of the 2007 site visit, the air-conditioner filter in the 

grading room had a thick layer of dust. FSIS employees stated 

that the filter had not been changed during the 2007 grading 

season. Analysis of the dust sample collected from the filter found 

1,500,000 EU/gram of dust, which suggests that endotoxincontaining dust had been released in or near the grading room. 

Because no one knew how long the filter had been in use, we could 

not determine when the contaminated dust had been deposited on 

the filter. Dust from the filter may have been released back into the 

room.

Analysis for endotoxin in the samples of suspect and comparison 

peanuts showed that the suspect peanuts contained less endotoxin 

than the “nonsuspect” peanuts. The endotoxin concentration in 

the suspect peanut sample was 260 EU/gram; the concentration 

in the comparison sample was 1400 EU/gram. We do not know, 

however, if the suspect peanuts that were submitted for analysis 

were truly representative of the peanuts that were thought to be 

associated with employees’ symptoms in 2007. Qualitative VOC 

analysis detected no obvious differences between the two samples 

of peanuts.

Qualitative microscopic analysis of peanut shells containing small, 

glassy crystals found that the crystals displayed many, but not all, 

of the optical properties of quartz. In the absence of elemental 

or x-ray diffraction analysis to supplement optical microscopy, 

the crystals were reported as “possible quartz.” Dust, which 

accompanied the peanut shell sample, contained insect parts, 

synthetic fibers, trichomes (hair-like structures found on plant 

surfaces), cellulose, hair, wood dust, starch, skin cells, pollen, 

opaque material, and a brownish/orange dust that appeared to be 

peanut dust.

Results
Health Hazard Evaluation Report 2008-0052-3115 Page 7

Results (continued) Second Site Visit: October 22, 2008

None of the FSIS employees who worked in the Shann grading 

room in 2007 was employed in the grading room in 2008. While 

the 2007 staff reported a distinctive, unusual odor that they 

associated with peanuts from a particular grower, the 2008 staff 

stated that they had not noticed any unusual odors, nor had they 

experienced health problems during the 2008 season. The lead 

FSIS inspector in 2008 stated that approximately one third of the 

peanuts that had been graded during the preceding few days were 

from the grower of the suspect peanuts in 2007. She also noted 

that the air-conditioner filter had been changed several times since 

our initial site visit. Respiratory protection was voluntary, and 

none of the employees wore respiratory protection in the grading 

room. FSIS employees did not wear hearing protection or gloves. 

Employees did not eat or drink in the grading room.

The results of PBZ air sampling for endotoxin are presented in 

Table 1. TWA concentrations are reported for the actual sampling 

periods. The geometric mean PBZ concentration was 320 EU/m3. 

The range was 170 to 680 EU/m3. Area samples indicated TWA 

concentrations of 9.8 EU/m3 in the lunchroom and 380 EU/m3

outdoors.

The highest TWA exposure to endotoxin occurred near the 

B-side foreign materials machine, where miscellaneous debris was 

separated from the peanut samples. This was one of two foreign 

material machines that had been retrofitted with PVC pipe to 

discharge dust outdoors. The PVC pipe connection, however, still 

allowed the cyclone to discharge partly into the room, rather than 

discharging entirely outdoors.

Airborne dust was not observed at the foreign material machines 

or elsewhere in the grading room on the sampling date. As shown 

in Table 2, particle-count data suggest that fewer airborne particles 

were present in the grading room than in the lunchroom and 

outdoors. During the site visit, tractors and wagons generated 

visible airborne dust that appeared to result in the relatively high 

outdoor particle counts.
Page 8 Health Hazard Evaluation Report 2008-0052-3115

Results (continued)

Employee Interviews

We attempted to contact all full-time FSIS peanut inspectors 

and all part-time FSIS inspectors who had reported symptoms 

to the Georgia District Epidemiologist. The list provided by the 

Epidemiologist indicated that nine full-time and five part-time 

employees had reported symptoms. Eight FSIS employees (six of 

nine full-time and two of 16 part-time employees) who worked at 

the Shann facility in the 2007 peanut season were interviewed 

either in person (seven) or by phone (one). For this evaluation, 

full-time employees were defined as working more than 15 days at 

the Shann grading facility. We could not reach three full-time and 

three part-time FSIS employees. We interviewed one additional 

Shann employee by phone who had reported symptoms to family 

members.

Of the eight interviewed FSIS employees, the average age was 41 

years (range: 20 to 66 years), and the average number of years 

worked as an FSIS inspector was 9 (range: 1 to 25 years). Of the six 

full-time employees, the average number of days worked at Shann 

was 35 (range: 29 to 39 days). The two part-time employees worked 

3 and 4 days at Shann. No employees worked at other peanut 

grading sites after the Shann peanut grading room was shut down 

in November 2007. Seven employees were female, and seven were 

current smokers.

Employees reported grading peanuts with an odd odor beginning 

on October 12, 2007. Between October 16, 2007, and November 

1, 2007, six of the eight employees reported skin irritation (i.e., 

described as having one or more of the following: burning; itching; 

mild edema; erythema; or papular rash) and eye, nose, and throat 

irritation. One reported eye, nose, and throat irritation without 

rash, and one reported rash, but no eye, nose, and throat irritation. 

Seven employees reported headaches and six reported diarrhea; 

four of the six also had nausea, vomiting, or loss of appetite. Five 

reported flu-like symptoms including fatigue, body aches, chills, 

cough, and shortness of breath. Seven employees reported smoking 

cigarettes; only one reported respiratory symptoms that existed 

prior to this peanut season. No employees wore protective gloves. 

Reportedly, dust masks provided for workers were rarely worn.

Our evaluation focused on FSIS employees and did not include an 

evaluation of the 10 to 12 Shann employees; however, one Shann 
Health Hazard Evaluation Report 2008-0052-3115 Page 9

Results (continued)

employee who worked outside reported persistent symptoms of 

cough, shortness of breath, and wheezing that began in early to 

mid-October 2007.

Medical Record Review 

Medical records of 13 FSIS employees were reviewed, including 

records of the eight interviewed employees and five employees 

who were not interviewed. The additional five FSIS employees 

included one part-time and two full-time FSIS peanut inspectors 

who worked at Shann, one FSIS office employee who worked 

at a different location and handled paperwork from Shann, 

and one FSIS employee reporting symptoms and on the GDPH 

Epidemiologist’s list, but whose work history could not be 

found. Ten of these employees were seen by an infectious disease 

physician, ten by a pulmonary medicine physician, five by an 

occupational medicine clinic, five by an employer-contracted 

physician knowledgeable in occupational medicine, two by a 

dermatologist, one by a nephrologist, and one by a medical 

toxicologist. All 13 employees were diagnosed with “toxic exposure” 

or “occupational exposure consistent with an irritant chemical” by 

at least one physician.

Medical record reviews showed that 12 employees reported skin 

burning, itching, or rash, and most reported this was the first 

symptom to occur. Ten of these 12 employees had skin findings 

on medical examination; seven had findings of papules, plaques, 

or skin lesions described as exzematous, erythematous, scaly, or 

excoriated; one had redness of the face and upper arms; one had 

redness and mild swelling of both hands and forearms; and one 

who reported an intermittent rash had no skin findings on initial 

exam, but on a later exam had two skin lesions with no description 

on the lower extremities. Two of the 12 employees reported that 

their skin symptoms had resolved before their first examination 

on November 20, 2007. Two employees were referred for 

dermatological consultation, and two employees did not keep their 

follow-up appointments. Diagnoses in those with persistent rash 

included contact dermatitis (one employee) and fungal infection of 

the scalp (one employee); two were referred for further evaluation 

by an allergist.

Twelve employees reported respiratory symptoms; one employee 

reported symptoms resolving after November 15, 2007, when 
Page 10 Health Hazard Evaluation Report 2008-0052-3115

Results (continued)

the grading room was shut down, one reported a dry cough, but 

no other symptoms, and ten were seen by a pulmonologist. Of 

these ten, all underwent chest x-rays (all with normal results) 

and pulmonary function testing; seven displayed obstructive 

or restrictive lung changes on pulmonary function testing, two 

had normal pulmonary function testing, and one had very mild 

changes interpreted as within normal limits by the pulmonologist. 

The seven employees with lung changes were diagnosed with 

one or more of the following: reactive airways disease, COPD, 

emphysema, chronic tobacco abuse, or asthma. Because of the 

smoking history of these employees, we were unable to assess if 

the abnormal lung findings were due to the effects of smoking, 

workplace exposures, or a combination of both.

Six FSIS employees had blood analyses for total IgE and blood 

immunoassay testing (ImmunoCAP®) for HP (referred to as 

the Farmer’s Lung Panel). The Farmer’s Lung Panel included 16 

allergens: 12 fungi and mold allergens; one feather mix; and one 

pigeon, one pork, and one beef allergen. Two of six employees had 

elevated total IgE, indicating a history of a Type I hypersensitivity 

disorder such as allergic rhinitis, allergic asthma, atopic dermatitis, 

food allergy, allergic urticaria (hives), and anaphylaxis. No 

employees had detectable reactions to the Farmer’s Lung Panel.

Additional diagnoses not suspected to have a relationship with 

work exposures among the 13 employees included recurrent 

urinary tract infection, anemia, gastroesophageal reflux disease, 

possible peptic ulcer disease, and possible irritable bowel syndrome. 

Chronic diagnoses included diabetes mellitus, hypertension, and 

chronic hepatitis C infection.
Health Hazard Evaluation Report 2008-0052-3115 Page 11

Even though a definitive causal relationship cannot be established, 

analysis of air and dust samples suggests that exposure to endotoxin 

during the 2007 grading season may have been sufficient to 

explain the acute respiratory and flu-like symptoms experienced 

by the employees. The acute skin symptoms experienced by FSIS 

employees were most consistent with a chemical exposure such as 

a mycotoxin. However, Manfreda et al. found skin itch and rash to 

be associated with endotoxin exposure [Manfreda et al. 1986].

The persistent nature of symptoms in some employees was 

puzzling because, generally, in an acute exposure, once a person 

is removed from the exposure to either endotoxin or mycotoxin, 

the symptoms slowly get better and resolve within a few days to 

a few weeks [Kirkhorn and Garry 2000; Spurzem 2002; Eduard 

2009]. One possibility is that employees carried dust on their 

clothing and shoes into their cars and homes, and so continued 

having some exposure and symptoms. Another possibility is that 

co-existing health conditions may have increased susceptibility, 

worsened symptoms, and caused longer recuperation times. Some 

employees who are “allergic” individuals, or have a propensity to 

develop allergies, may have developed an allergy to an unidentified 

ingredient in the peanut dust.

Symptoms were reported among all full-time FSIS inspectors, but 

not other employees, with one exception. The high prevalence 

of respiratory symptoms reported among full-time FSIS 

employees at Shann suggests that the exposure was an irritant 

compound because all persons would be equally susceptible, 

unlike an allergenic compound, which would affect only allergic 

individuals. The wide range of biological activity associated with 

endotoxin exposure including inflammatory, hemodynamic, and 

immunological responses could explain the respiratory and flulike symptoms among the FSIS employees. The high prevalence 

of acute skin symptoms could be explained by skin exposure to an 

irritant compound, which could include chemicals sprayed on the 

plants and soil as pesticides, plant residues on the peanut samples 

that could cause acute urticarial skin symptoms, or mycotoxins. 

Although intense efforts by USDA and FDA were taken to find 

mycotoxins or unusual fungal species in the peanut samples, none 

were found, and the peanuts were released for further processing. 

It is possible that the sample of suspect peanuts subjected to this 

testing did not contain the same contaminant as the peanuts that 

made the employees sick.

Discussion
Page 12 Health Hazard Evaluation Report 2008-0052-3115

Discussion (continued)

Exposure to organic dust occurs in many agricultural industries. 

Organic dust typically contains a variety of substances including 

vegetable products, insect fragments, pollens, pesticides, bird 

and rodent urine and feces, and bacteria and fungi. Some fungi 

produce mycotoxins. Mycotoxin production seems to be affected 

by environmental conditions. Mycotoxins, depending on their 

potency and concentration, have been associated with health 

symptoms in agricultural environments.

Microorganisms in organic agricultural dust include Gramnegative bacteria, which are characterized by the presence of 

endotoxin in the outer bacterial cell wall membrane. Endotoxin, 

a lipopolysaccharide complex, is released when the bacteria die 

and disintegrate. Exposure to endotoxin can lead to symptoms 

of cough, wheeze, shortness of breath, chest tightness, and 

conjunctivitis. Continued or repeated exposure can result in 

chronic health effects including chronic bronchitis, reactive airway 

dysfunction syndrome, asthma, chronic airways obstruction, HP, 

and emphysema [Castellan 1995]. A NIOSH publication providing 

information on agricultural dust exposures and ODTS can be 

found at http://www.cdc.gov/niosh/docs/94-102/pdfs/94-102.

pdf. Additional information on agricultural dust, endotoxin, and 

mycotoxin is given in Appendix B.

The presence of endotoxin in air samples collected in 2008 

suggests that airborne endotoxin exposure is likely during peanut 

grading and other activities where peanut crops are handled 

or processed. Endotoxin concentrations in all but one PBZ air 

sample appear to equal or exceed the 8-hour TWA exposure limit 

of 200 EU/m3 established by the Dutch Expert Committee on 

Occupational Standards [DECOS 1998]. In 1998, the Dutch 

Expert Committee on Occupational Standards recommended a 

health-based exposure limit of 50 EU/m3, which was later raised 

to 200 EU/m3 to accommodate economic feasibility for the 

agricultural industry [DECOS 1998].
Health Hazard Evaluation Report 2008-0052-3115 Page 13

Conclusions

Analysis of peanut bulk samples and air conditioner dust in 2007 

and area and PBZ air samples in 2008 provides evidence that FSIS 

peanut inspectors are at risk of exposure to airborne endotoxin 

during routine operations in FSIS peanut grading rooms. Although 

airborne endotoxin concentrations in grading rooms can vary 

between seasons, crops, and locations, air samples collected 

in the Shann grading room in 2008 indicate that exposure to 

airborne endotoxin may exceed levels that have been associated 

with symptoms of cough, wheeze, shortness of breath, chest 

tightness, mucous membrane irritation, and signs of acute airflow 

obstruction [Castellan et al. 1987; Smid et al. 1994; Milton et al. 

1996].

The acute respiratory and flu-like symptoms reported in 2007 by 

FSIS employees and the associated medical findings are consistent 

with endotoxin exposure. However, the persistence of symptoms 

reported by some employees after being removed from exposure 

does not fit with recognized endotoxin- or mycotoxin-related 

illness. We suspect that this may have resulted from “take-home” 

contamination (i.e., endotoxin in peanut dust that was carried 

home on employees’ clothing) and which may have resulted 

in continued exposure to endotoxin while away from work. In 

addition, some employees may have been more susceptible to lung 

and skin disorders or had co-existing pulmonary or skin disease.
Page 14 Health Hazard Evaluation Report 2008-0052-3115

Recommendations

NIOSH strongly encourages employers to use a “hierarchy of 

controls” approach for protecting workers from occupational safety 

and health hazards. This hierarchy can be summarized as follows:

● Elimination

● Substitution

● Engineering controls

● Administrative controls

● Personal protective equipment

Control methods at the top of the list are potentially more effective 

and protective than those at the bottom. Following the hierarchy 

normally leads to the implementation of inherently safer systems, 

ones where the risk of illness or injury has been substantially 

reduced.

Elimination and substitution, while most effective at reducing 

hazards, also tend to be the most difficult to implement in 

an existing process, and do not apply to FSIS grading rooms.

Engineering controls, the next tier in the hierarchy, are used to 

remove a hazard or place a barrier between the worker and the 

hazard. Well-designed engineering controls, such as local exhaust 

ventilation, which can be highly effective in protecting workers and 

is typically independent of worker interactions, can provide a high 

level of protection.

Administrative controls are management-dictated work practices 

and policies to reduce or prevent exposures to workplace hazards. 

The effectiveness of administrative changes in work practices 

for controlling workplace hazards is dependent on management 

commitment and employee acceptance. Regular monitoring and 

reinforcement are necessary to ensure that control policies and 

procedures are not circumvented in the name of convenience or 

production.

Because PPE is the least effective means for controlling employee 

exposures, proper use of PPE requires a comprehensive 

program and calls for a high level of employee involvement and 

commitment to be effective. The use of PPE requires the choice 

of the appropriate equipment to reduce the hazard and the 

development of supporting programs such as training, change-out 

schedules, and medical assessment if needed. PPE should not be 
Health Hazard Evaluation Report 2008-0052-3115 Page 15

Recommendations

(continued) relied upon as the sole method for limiting employee exposures. 

Rather, PPE should be used until engineering and administrative 

controls can be demonstrated to be effective in limiting exposures.

Engineering Controls 

1. Install or modify ductwork on all cyclone-equipped 

machines to discharge dust outdoors. If working properly, 

the cyclone dust collectors installed on some of the grading 

machines should capture coarse dust; however, cyclones will 

not capture fine particles. Unless ducted outdoors, these 

fine dust particles will be released into the peanut grading 

room, where the dust may be inhaled by grading room 

employees. A simple way to reduce exposure to agricultural 

dust and endotoxin would be to install ductwork on the 

cyclones to discharge fine particles outdoors.

2. Inspect and change the air conditioner filter routinely and 

document in a maintenance log.

Administrative Controls

1. Conduct employee training at the beginning of each peanut 

grading season to educate employees on best work practices 

to limit dust exposure, proper hygiene (e.g., employees 

should not bring food or drink into the peanut grading 

room), PPE use, and potential hazards of organic dust 

exposure.

2. Encourage employees to report all potential work-related 

skin and respiratory symptoms to their supervisors. Because 

the work-relatedness of skin and respiratory diseases may be 

difficult to establish, employees with possible work-related 

health problems should be fully evaluated by a physician, 

preferably one familiar with occupational conditions. A 

complete evaluation would include a full medical and 

occupational history, a medical exam, a review of exposures, 

possibly diagnostic tests (such as pulmonary function 

testing or skin patch testing), and complete follow-up to 

note the progress of the affected employee. Individuals 

with definite or possible occupational diseases or illnesses 

should be protected from exposures to substances that 

cause or exacerbate the disease or illness. In some cases of 
Page 16 Health Hazard Evaluation Report 2008-0052-3115

Recommendations

(continued) allergic respiratory or skin disease, employees may have to be 

reassigned with retention of pay and employment status to 

areas where exposure is minimal or nonexistent.

3. Establish an employee-management health and 

safety committee or working group to discuss the 

recommendations in this report and develop an action 

plan. Those involved in the work can best set priorities and 

assess the feasibility of our recommendations for the specific 

situations in the peanut grading room.

4. Conduct a noise survey in the peanut grading room to 

determine if a hearing conservation program is needed to 

protect peanut inspectors from gradual loss of hearing from 

excessive noise. Noise-induced hearing loss is an irreversible 

condition that progresses with exposure to excessive noise. 

Elements of an effective hearing conservation program 

include exposure monitoring, audiometric testing, hearing 

protectors, training, and recordkeeping. For additional 

information, see the OSHA website at http://www.osha.

gov/dts/osta/otm/noise/hcp/index.html and booklet at 

http://www.osha.gov/Publications/osha3074.pdf.

5. Although we are not aware of health problems among 

FSIS peanut graders during previous seasons or at other 

locations, it is possible that symptoms have occurred but 

were not recognized. FSIS management should review 

and monitor injury/illness logs of all grading locations 

periodically (e.g., monthly) during peanut grading season 

to identify work-related respiratory illness. If respiratory 

illness is reported, the work location should undergo 

an environmental evaluation to characterize endotoxin 

exposure. FSIS managers should report clusters of illness to 

GDPH to identify public health risks that may be associated 

with the handling and grading of peanuts. (See the GDPH 

website at http://health.state.ga.us/epi/disease/report.asp

for more information on reporting illness clusters.) This 

information would enable public health agencies to develop 

interventions to ensure the safe handling and processing of 

peanuts.

6. Conduct PBZ sampling for endotoxin in FSIS peanut 

grading rooms throughout the state to characterize 

exposures. PBZ sampling results will help determine if 

additional engineering controls may be needed in addition 

to the cyclone dust collector exhaust systems that are on 

some machines.
Health Hazard Evaluation Report 2008-0052-3115 Page 17

Recommendations

(continued) Personal Protective Equipment 

1. Provide FSIS peanut inspectors with NIOSH-approved N95 

particulate filtering facepiece respirators in the context of 

a respiratory protection program when exposure to organic 

dust cannot be avoided. Respiratory protection should be 

provided in the context of a written respiratory protection 

program that includes the following elements:

•	 Respiratory program administration

•	 Respirator selection

•	 Respirator inspection

•	 Permissible practices for respirator use

•	 Respirator storage

•	 Respirator limitations

•	 Respiratory protection training

•	 Fit testing

•	 Program evaluation

•	 Medical surveillance

More information on the OSHA respirator standard is 

 available at http://www.osha.gov/SLTC/

 respiratoryprotection/index.html.

2. Provide disposable nonlatex, powder-free gloves for FSIS 

peanut inspectors to reduce skin exposure to skin irritants 

and allergens.

3. Educate employees on the hazards of agricultural dust 

exposure and the possible hazard of taking contamination 

home on work clothes. Employees should not wear 

contaminated clothing from work to home.
Page 18 Health Hazard Evaluation Report 2008-0052-3115

References

Castellan R, Olenchock S, Kinsley K, Hankinson J [1987]. Inhaled 

endotoxin and decreased spirometric values: an exposure response 

relation for cotton dust. N Engl J Med 317(10):605–610.

Castellan RM [1995]. Respiratory health effects of inhaled 

endotoxins: byssinosis and beyond. In: McDuffie H, Dosman J, 

Semchuk K, Olenchock S, eds. Agricultural Health and Safety - 

Workplace, Environment, Sustainability. Boca Raton, FL: CRC 

Press, pp. 97–100.

DECOS [1998]. Endotoxins: health-based recommended 

occupational exposure limit. The Hague, Netherlands: Health 

Council of The Netherlands, Dutch Expert Committee on 

Occupational Standards.

Eduard W [2009]. Fungal spores: A critical review of the 

toxicological and epidemiological evidence as a basis for 

occupational exposure limit setting. Crit Rev Toxicol 39(10):799–

864.

Kirkhorn SR, Garry VF [2000]. Agricultural lung diseases. Environ 

Health Perspect 108(suppl 4):705–712.

Manfreda J, Holford-Strevens V, Cheang M, Warren CPW [1986]. 

Acute symptoms following exposure to grain dust in farming. 

Environ Health Perspect 66:73–80.

Milton DK, Wypij D, Kriebel D, Walters MD, Hammond SK, 

Evans JS [1996]. Endotoxin exposure-response in a fiberglass 

manufacturing plant. Am J Ind Med 29(1):3–13.

Smid T, Heederick D, Houba R, Quanger PH [1994]. Dust- and 

endotoxin-related acute lung function changes and work-related 

symptoms in workers in the animal feed industry. Am J Ind Med 

25(6):877–888.

Spurzem JR, Romberger DJ, Von Essen SG [2002]. Agricultural 

lung disease. Clin Chest Med 23:795–810.
Health Hazard Evaluation Report 2008-0052-3115 Page 19

Tables

Table 1. Air sampling results for endotoxin (October 2008)

Job Title Location Time

(minutes)

Concentration

(EU/m3)*

TWA Concentration

(EU/m3)†

Inspector Weigh-in

0830–1141

(191) 360

260

1330–1657

(207) 160

Aide Grain analysis 

computer

0823–1141

(198) 220

200

1335–1658

(203) 190

Inspector A-side

0825–1142

(197) 380

340

1331–1658

(207) 300

Inspector A-side

sheller

1023–1143

(80) 860

550

1336–1517

(101) 310

Aide A-side 0852–1141

(169) 470 470

Aide

B-side

foreign 

materials

0829–1141

(192) 780

680

1322–1656

(214) 590

Inspector B-side

splitter

0827–1141

(194) 200

170

1313–1658

(225) 140

Lead Inspector B-side 

presizer

0820–1143

(203) 290

210

1314–1654

(220) 140

—

Area sample

Shann lunch 

room

0930–1651

(441) 9.8 9.8

— Outdoor area 

sample

0838–1650

(492) 380 380

Dutch Expert Committee on Occupational Standards 8-hour TWA exposure 

limit‡ 200

* EU/m3 – Endotoxin units per cubic meter of air. 15 EUs = 1 nanogram endotoxin

† TWA concentration for the morning and afternoon sampling periods

‡ Prior to adopting the 200 EU/m3 limit as an economically feasible limit for the agricultural industry, the 

Dutch Committee proposed a health-based 8-hour TWA limit of 50 EU/m3.
Page 20 Health Hazard Evaluation Report 2008-0052-3115

Tables (continued)

Table 2. Average number of particles per liter of air by particle size

 Particle Size

 (μm)

Location 

Grading Room

 (n=7)

 Lunch Room

 (n=5)

Outdoor

 (n=5) (n=1)*

0.3 10,000 37,000 63,000 72,000

0.5 3100 4300 4000 9400

1.0 4300 2900 1100 10,000

3.0 2300 840 490 4900

5.0 310 43 35 840

10.0 310 22 30 1600

Each value is the arithmetic mean of n counts, where n = number of measurements.

* This measurement is reported separately because of the apparent difference between the size distribution 

of particles in this outdoor measurement versus that of the other five outdoor measurements.
Health Hazard Evaluation Report 2008-0052-3115 Page 21

Initial Site Visit: December 5, 2007 

Air-conditioner dust and peanuts from each bulk sample were sent to EMLab P&K (Cherry Hill, New 

Jersey; Phoenix, Arizona) to be analyzed for endotoxin (a component of the cell membrane of Gramnegative bacteria). Samples were analyzed using the LAL assay, kinetic chromogenic method [Cambrex 

2005]. For these analyses, 9 EU were equivalent to one nanogram of endotoxin.

The peanut shells that contained crystalline-like structures were prepared and analyzed by polarized light 

microscopy according to NIOSH Method 9002 [NIOSH 2010]. Microscopy was performed by the NIOSH 

Division of Applied Research and Technology, Chemical Exposure and Monitoring Branch.

Suspect and nonsuspect peanuts were submitted to the NIOSH Division of Applied Research and 

Technology, Chemical Exposure and Monitoring Branch, for qualitative headspace analysis of VOCs. Each 

set of peanuts was provided to the laboratory in a separate plastic bag, with both sets inside a larger plastic 

bag. Because plastic is known to give off VOCs, headspace samples were collected inside each individual 

bag containing peanuts, and inside the empty outer bag as a control or blank sample. Headspace samples 

were collected on stainless steel thermal desorption tubes that contained three beds of sorbent material: 

Carbopack YTM (90 mg), Carbopack BTM (115 mg), and Carboxen 1003TM (150 mg). Prior to sampling, the 

tubes were conditioned by heating at 375°C for 1.5 hours. The thermal desorption tubes were analyzed 

by an automatic thermal desorption system with an internal focusing trap packed with graphitized carbon 

sorbents. The thermal unit was interfaced directly to a chromatograph with a mass selective detector. A 

30-meter Rtx-1MS fused silica capillary column was used for the analyses. In addition, several peanuts 

from each set were extracted with methanol. Three peanuts were placed in a 30-milliliter glass vial, about 

10 milliliters of methanol was added, and the vials were tumbled gently overnight to aid extraction. The 

methanol extracts were analyzed by gas chromatography-mass spectrometry.

Second Site Visit: October 22, 2008 

Air samples were collected with endotoxin-free 3-piece 37-mm closed-face cassettes, preloaded with 0.45-

μm pore-size polycarbonate membrane filters. Samples were collected with AirCheck2000 personal air 

sampling pumps (SKC, Eighty Four, Pennsylvania) calibrated at 2 liters per minute preshift and postshift 

with a DryCal DC Lite primary airflow meter (Bios International Corp., Butler, New Jersey). Endotoxin 

analysis was performed by EMLab P&K (Cherry Hill, New Jersey; Phoenix, Arizona) using the LAL 

assay, kinetic chromogenic method. For air sample analysis, 15 EU were equivalent to one nanogram of 

endotoxin.

An ART Instruments model HHPC-6 handheld airborne particle counter (ART Instruments, Grants 

Pass, Oregon) was used in the grading room, Shann lunch room, and outdoors. Particle count data were 

reported during three 21-second periods in the morning, and three periods during the afternoon; 1 liter 

of air was sampled during each period. The particle counter provided a real-time estimate of the number 

of airborne particles having an aerodynamic diameter no greater than 10 μm, the upper size limit of the 

Appendix A: Methods
Page 22 Health Hazard Evaluation Report 2008-0052-3115

Appendix A: Methods (continued)

respirable particulate fraction. This information was displayed simultaneously in six size ranges for each 

sample.

References 

Cambrex [2005]. Limulus Amebocyte Lysate (LAL), Kinetic-QCL. Catalog Number: 50-650U. Walkersville, 

MD.

NIOSH [2010]. NIOSH manual of analytical methods (NMAM®). 4th ed. Schlecht PC, O’Connor PF, 

eds. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease Control 

and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 

94–113 (August, 1994); 1st Supplement Publication 96–135, 2nd Supplement Publication 98–119; 3rd 

Supplement 2003–15. [http://www.cdc.gov/niosh/nmam/]. Date accessed: July 2010.
Health Hazard Evaluation Report 2008-0052-3115 Page 23

In evaluating the hazards posed by workplace exposures, NIOSH investigators use both mandatory (legally 

enforceable) and recommended OELs for chemical, physical, and biological agents as a guide for making 

recommendations. OELs have been developed by Federal agencies and safety and health organizations to 

prevent the occurrence of adverse health effects from workplace exposures. Generally, OELs suggest levels 

of exposure that most employees may be exposed up to 10 hours per day, 40 hours per week for a working 

lifetime without experiencing adverse health effects. However, not all employees will be protected from 

adverse health effects even if their exposures are maintained below these levels. A small percentage may 

experience adverse health effects because of individual susceptibility, a preexisting medical condition, and/

or a hypersensitivity (allergy). In addition, some hazardous substances may act in combination with other 

workplace exposures, the general environment, or with medications or personal habits of the employee 

to produce health effects even if the occupational exposures are controlled at the level set by the exposure 

limit. Also, some substances can be absorbed by direct contact with the skin and mucous membranes in 

addition to being inhaled, which contributes to the individual’s overall exposure.

Most OELs are expressed as a TWA exposure. A TWA refers to the average exposure during a normal 8- 

to 10-hour workday. Some chemical substances and physical agents have recommended STEL or ceiling 

values where health effects are caused by exposures over a short period. Unless otherwise noted, the STEL 

is a 15-minute TWA exposure that should not be exceeded at any time during a workday, and the ceiling 

limit is an exposure that should not be exceeded at any time.

In the United States, OELs have been established by Federal agencies, professional organizations, state 

and local governments, and other entities. Some OELs are legally enforceable limits, while others are 

recommendations. The U.S. Department of Labor OSHA PELs (29 CFR 1910 [general industry]; 29 

CFR 1926 [construction industry]; and 29 CFR 1917 [maritime industry]) are legal limits enforceable in 

workplaces covered under the Occupational Safety and Health Act. NIOSH RELs are recommendations 

based on a critical review of the scientific and technical information available on a given hazard and the 

adequacy of methods to identify and control the hazard. NIOSH RELs can be found in the NIOSH Pocket 

Guide to Chemical Hazards [NIOSH 2005]. NIOSH also recommends different types of risk management 

practices (e.g., engineering controls, safe work practices, employee education/training, personal protective 

equipment, and exposure and medical monitoring) to minimize the risk of exposure and adverse health 

effects from these hazards. Other OELs that are commonly used and cited in the United States include 

the TLVs recommended by ACGIH, a professional organization, and the WEELs recommended by the 

American Industrial Hygiene Association, another professional organization. The TLVs and WEELs are 

developed by committee members of these associations from a review of the published, peer-reviewed 

literature. They are not consensus standards. ACGIH TLVs are considered voluntary exposure guidelines 

for use by industrial hygienists and others trained in this discipline “to assist in the control of health 

hazards” [ACGIH 2009]. WEELs have been established for some chemicals “when no other legal or 

authoritative limits exist” [AIHA 2009].

Outside the United States, OELs have been established by various agencies and organizations and include 

both legal and recommended limits. Since 2006, the Berufsgenossenschaftliches Institut für Arbeitsschutz 

Appendix B: Occupational Exposure Limits and Health Effects
Page 24 Health Hazard Evaluation Report 2008-0052-3115

Appendix B: Occupational Exposure Limits and Health Effects (continued)

(German Institute for Occupational Safety and Health) has maintained a database of international 

OELs from European Union member states, Canada (Québec), Japan, Switzerland, and the United 

States available at http://www.dguv.de/bgia/en/gestis/limit_values/index.jsp. The database contains 

international limits for over 1250 hazardous substances and is updated annually.

Employers should understand that not all hazardous chemicals have specific OSHA PELs, and for some 

agents the legally enforceable and recommended limits may not reflect current health-based information. 

However, an employer is still required by OSHA to protect its employees from hazards even in the absence 

of a specific OSHA PEL. OSHA requires an employer to furnish employees a place of employment free 

from recognized hazards that cause or are likely to cause death or serious physical harm [Occupational 

Safety and Health Act of 1970 (Public Law 91–596, sec. 5(a)(1))]. Thus, NIOSH investigators encourage 

employers to make use of other OELs when making risk assessment and risk management decisions to 

best protect the health of their employees. NIOSH investigators also encourage the use of the traditional 

hierarchy of controls approach to eliminate or minimize identified workplace hazards. This includes, in 

order of preference, the use of: (1) substitution or elimination of the hazardous agent, (2) engineering 

controls (e.g., local exhaust ventilation, process enclosure, dilution ventilation), (3) administrative controls 

(e.g., limiting time of exposure, employee training, work practice changes, medical surveillance), and (4) 

personal protective equipment (e.g., respiratory protection, gloves, eye protection, hearing protection). 

Control banding, a qualitative risk assessment and risk management tool, is a complementary approach 

to protecting employee health that focuses resources on exposure controls by describing how a risk 

needs to be managed. Information on control banding is available at http://www.cdc.gov/niosh/topics/

ctrlbanding/. This approach can be applied in situations where OELs have not been established or can be 

used to supplement the OELs, when available.

Agricultural Dust 

Organic dust exposure is known to occur in many agricultural industries. Organic dust is made up of 

a variety of substances including vegetable products, insect fragments, microbes, endotoxin, pollens, 

pesticides, and bird and rodent urine and feces, among others. Microbes and their toxins are known 

biohazards in organic dust, having broad chemical and specific allergenic properties. Acceptable levels 

of airborne microbes have not been established, primarily because relatively low air concentrations of 

allergens may cause allergic reactions in susceptible individuals. Approximately one of every six individuals 

in the United States is reported to have allergies [Blumenthal 1998], with about 30% of the population 

having the predisposition to becoming allergic [Simon 2000]. It is well known that predisposed individuals 

exposed to airborne organic dust containing fungal, bacterial, plant, or animal antigens can develop 

hypersensitivity illnesses, including allergic rhinitis, allergic asthma, and HP to airborne organic materials 

[Castellan 1995; Balmes 1996a; Melo and Cartier 1996; Rose 1996].

 

The current strategy for evaluating microbial contamination involves identifying sources of microbial 

growth and components, and potential routes of spread. Air samples for microbes, endotoxin, or other 

microbial components can be collected to document the presence of suspected microbial contaminants.
Health Hazard Evaluation Report 2008-0052-3115 Page 25

Appendix B: Occupational Exposure Limits and Health Effects (continued)

Endotoxin 

Endotoxin is a lipopolysaccharide complex found in the outer cell wall of Gram-negative bacteria that 

is released when the bacteria die [Hagmar et al. 1990; Olenchock 1997]. Gram-negative bacteria are 

ubiquitous in the environment. Endotoxin produces a wide range of biological responses including blood 

vessel changes, inflammation, and allergic reactions. Airborne endotoxin exposures between 45 and 

400 EU/m3 have been associated with symptoms of cough, wheeze, shortness of breath, chest tightness 

and mucous membrane irritation, and signs of acute airflow obstruction [Castellan et al. 1987; Smid et 

al. 1994; Milton et al. 1996]. Chronic health effects that have been associated with airborne endotoxin 

exposures include chronic bronchitis, bronchial hyperreactivity, chronic airways obstruction, HP, and 

emphysema [Castellan 1995]. A permanent decrease in pulmonary function, along with respiratory 

symptoms, has been reported in epidemiologic studies [Milton 1999]. Endotoxin exposure has also been 

associated with skin itch and rash [Manfreda et al. 1986], but has not been well documented.

Interactions between endotoxin exposure and smoking may increase the risk of respiratory symptoms 

[Manfreda et al. 1986]. Experimentally, an interaction between bacterial and fungal spores and endotoxin 

was shown to enhance the development of ODTS [Kirkhorn and Garry 2000].

Endotoxin has become accepted as a cause for human health effects in recent years; however, no 

universally accepted OELs have been developed because of the variability of sampling and analytical 

methods, and because of a lack of data showing a consistent dose-response relationship. The LAL assay is 

the most commonly used method of analyzing endotoxin [Milton 1999].

In the Netherlands, the Dutch Expert Committee on Occupational Standards has recommended a healthbased exposure limit of 50 EU/m3

 for exposure to airborne endotoxin in the working environment, 

averaged over an 8-hour working day [Spaan et al. 2006]. This was based on epidemiologic studies showing 

evidence of respiratory health effects at concentrations near this level [Castellan et al. 1987; DECOS 1998; 

Zock et al. 1998]. This exposure limit was later raised to 200 EU/m3 to accommodate economic feasibility 

for the agricultural industry [DECOS 1998].

Organic Dust Toxic Syndrome and Hypersensitivity Pneumonitis 

HP, which is called “farmer’s lung” in agricultural workers, and ODTS have both been related to airborne 

exposure to high levels of organic dust and endotoxin and have many similarities. Symptoms of both 

diseases occur 4–8 hours after exposure and result in self-limited flu-like illness with chest tightness, 

shortness of breath, dry cough, fever, chills, muscle aches, and fatigue. Symptoms of ODTS usually resolve 

within 2–12 days after removal from exposure and no allergic sensitization occurs. In HP, sensitization 

develops, and symptoms may progress in one third of patients. ODTS cannot be distinguished from HP 

by clinical symptoms; further pulmonary evaluation such as PFTs, oxygen saturation, and chest x-ray, is 

needed. In ODTS, these will be normal [Kirkhorn and Garry 2000]. In HP, oxygen saturation will be low, 

and PFTs will usually show restrictive lung abnormalities, but may show either restrictive or obstructive 
Page 26 Health Hazard Evaluation Report 2008-0052-3115

Appendix B: Occupational Exposure Limits and Health Effects (continued)

abnormalities in chronic disease. Chest x-ray findings may show small, scattered nodules; diffuse, patchy 

infiltrates (ground glass appearance); linear interstitial markings; or they may be normal. Abnormal 

findings on bronchoalveolar lavage or high-resolution computerized tomography are often needed to 

confirm a diagnosis of HP, and lung biopsy is needed in some cases [Balmes 1999b; Lacasse et al. 2003].

A continuum of respiratory illnesses may exist depending on the level of exposure. For example, highlevel exposures may cause ODTS-like symptoms but with x-ray findings and decreased oxygen saturation 

(normally not found with ODTS). Repeated subacute exposures may lead to unrecognized loss of lung 

function. Persons who develop antibodies (i.e., the body recognizes the foreign substance as an allergen) to 

molds and thermophilic bacteria, which are commonly found in organic dust, may or may not have allergic 

symptoms. Up to 90% of those with acute symptoms will have antibodies, but persons without symptoms 

can also have antibodies, so their presence does not indicate disease. Once a person is sensitized, 

continued low exposure to organic dust can lead to progressive irreversible lung disease, including 

emphysema [Kirkhorn and Garry 2000].

Fungi and Mycotoxin 

Like bacteria, fungi are ubiquitous in the environment, and many types of fungi produce mycotoxins. 

Fungi can produce health effects by four mechanisms: infections (e.g., pulmonary aspergillosis); irritant 

reactions (e.g., burning, blistering skin); allergic reactions (e.g., allergic rhinitis); and toxic reactions (e.g., 

gastrointestinal symptoms from ingesting mycotoxins) [Trout et al. 2004]. Mycotoxins are nonvolatile 

fungal metabolites that do not nourish the fungi or have any apparent physiologic function, but may help 

reduce competition from other organisms. Many fungi capable of producing mycotoxins do not produce 

mycotoxins at all times, but appear to be affected by the type of fungi; genetic susceptibility of the host 

plant; and environmental characteristics such as moisture content, temperature, aeration, microbial 

population, and stress factors. They are also hard to classify because of their diverse chemical structures 

and biological effects [Bennett and Klich 2003]. Antibiotics (penicillin), immunosuppressants (cyclosporin 

A), and cholesterol-lowering medications (lovastatin) are examples of mycotoxins that benefit human 

health [Sudakin 2003].

Exposure to fungi and their mycotoxins can occur by ingestion, inhalation, or skin contact. Depending 

on the route of exposure, concentration, and type of mycotoxin, exposure to mycotoxins may lead to a 

variety of health effects, including toxic effects of the kidney, liver, nervous system, and gastrointestinal 

tract; birth defects; hormonal imbalance; immunosuppression; cancer; and skin irritation [Bennett 

and Klich 2003]. The most commonly recognized health effects are from acute or chronic ingestion of 

mycotoxin-contaminated foods, particularly nuts and grains. This type of exposure has been associated 

with gastrointestinal illness (nausea, vomiting, diarrhea, abdominal cramping). For example, cases of 

trichothecene mycotoxicosis from eating bread made from wheat contaminated with Aspergillus and 

Fusarium were identified in India [Bhat et al. 1989].
Health Hazard Evaluation Report 2008-0052-3115 Page 27

Appendix B: Occupational Exposure Limits and Health Effects (continued)

Human illness from mycotoxins has also been associated with bioaerosol exposures in agricultural 

or industrial environments. Most recent reviews of stachybotryotoxicosis have been in regard to 

indoor environments; recent reviews regarding occupationally-related agricultural exposure were 

not found [Sudakin 2003]. Russian investigators reported stachybotryotoxicosis in humans who had 

contact with straw or hay in areas where horses had the disease [Drobotko 1942]. These individuals 

reportedly developed severe dermatitis, chest pain, sore throat, bloody rhinitis, cough, and (in some) 

leucopenia [Drobotko 1942; Newberne 1974; Hintikka 1977]. In experimental human studies, mold 

placed on the skin reproduced this clinical syndrome [Drobotko 1942; Forgacs 1972]. An outbreak of 

stachybotryotoxicosis was reported in Eastern Europe in 1977. Twenty-three agricultural workers loading 

moldy hay developed shortness of breath, sore throat, bloody nasal discharge, and burning and watering 

eyes. The affected workers also had reddened, swollen, crusted skin on the face, and dermatitis in the groin 

and buttocks. Employee symptoms occurred within 24 hours of exposure and resolved within 1 week of 

cessation of exposure [Andrassy 1979; Page and Trout 2001].

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Acknowledgments and

Availability of Report

The Hazard Evaluations and Technical Assistance Branch 

(HETAB) 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 Act of 1970, 29 U.S.C. 669(a)(6) which authorizes 

the Secretary of Health and Human Services, following a written 

request from any employer 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. HETAB 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.

The findings and conclusions in this report are those of the 

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Mention of any company or product does not constitute 

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Furthermore, NIOSH is not responsible for the content of these 

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This report was prepared by Loren C. Tapp and David Sylvain of 

HETAB, Division of Surveillance, Hazard Evaluations and Field 

Studies. Analytical support was provided by Joe Fernback and 

Ardith Grote of the Division of Applied Research and Technology, 

Bureau Veritas North America (Novi, Michigan), and EmLabs 

P&K (Cherry Hill, New Jersey). Health communication assistance 

was provided by Stefanie Evans. Editorial assistance was provided 

by Ellen Galloway. Desktop publishing was performed by Robin 

Smith.

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NIOSH [2010]. Health hazard evaluation report: skin and respiratory symptoms 

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Disease Control and Prevention, National Institute for Occupational Safety and 

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