TM

NIOSH HEALTH HAZARD EVALUATION REPORT 

HETA #2004-0012-2948 

U.S. Customs and Border Protection 

Canine Enforcement Training Center 

Front Royal, Virginia 

December 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 Hazard Evaluation 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 (OSHA) 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 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. 

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. Mention of company names or products does not constitute 

endorsement by NIOSH. 

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Chad Dowell of HETAB, Division of Surveillance, Hazard Evaluations and 

Field Studies (DSHEFS). Analytical support was provided by Ardith Grote, Division of Applied Research 

and Technology (DART) and DataChem Laboratories, Salt Lake City, Utah. Desktop publishing was 

performed by Shawna Watts. Editorial assistance was provided by Ellen Galloway. 

Copies of this report have been sent to employee and management representatives at Canine Enforcement 

Training Center and 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: 

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 Health Hazard Evaluation 

Highlights of the NIOSH Health Hazard Evaluation

Evaluation of Pseudo Drug Preparation

NIOSH received a management request from the U.S. Customs and Border Protection to conduct a health 

hazard evaluation survey at the Canine Enforcement Training Center. The evaluation looked at potential 

exposures and health effects from pseudo drugs prepared at the Center. 

What NIOSH Did

# We collected air samples in the pseudo drug 

building for acetic acid, benzaldehyde, 

methyl benzoate, piperonal, and total 

particulates. 

# We collected a bulk sample of the pseudo 

drug for silica content analysis. 

# We talked to workers and management 

about the chopping of marijuana bales. 

What NIOSH Found

# Total particulate and acetic acid air 

concentrations were above the OSHA 

exposure limit. 

# Cellulose air concentrations were above the 

ACGIH exposure limit. 

# Two employees reported being sick 

following the chopping of marijuana bales 

inside a building. 

# Install ventilation in the mix room. 

# Purchase bulk powdered chemicals in 

smaller drums. 

# Evaluate current respiratory protection 

program and training. 

# Allow gasoline-powered engines to be used 

outdoors only. 

# Monitor for carbon monoxide when 

gasoline-powered engines are used. 

What the Customs Employees Can 

Do 

# Use slow, smooth movements when 

handling powders. 

# Keep the distance powder is dropped to a 

minimum. 

# Substitute moldy bales of marijuana with 

less moldy. 

# Operate gasoline-powered engines only 

outside. 

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 #2004-0012-2948

What Customs Managers Can 

Do
iv 

Health Hazard Evaluation Report 2004-0012-2948 

U.S. Customs and Border Protection 

Canine Enforcement Training Center 

Front Royal, Virginia 

December 2004 

Chad H. Dowell, M.S. 

SUMMARY

The National Institute for Occupational Safety and Health (NIOSH) received a request for a Health 

Hazard Evaluation (HHE) at the U.S. Customs and Border Protection’s Canine Enforcement Training 

Center (CETC) in Front Royal, Virginia. The request concerned potential exposures from the preparation 

of pseudo narcotics. NIOSH conducted an initial site visit on November 12 – 14, 2003, and follow up 

visits on March 1 and 4, 2004. 

Preparation of pseudo narcotics includes the mixing of acetic acid, benzaldehyde, methyl benzoate, 

piperonal, cab-o-sil,® and microcrystalline cellulose. Seven personal breathing zone (PBZ) air samples 

were collected for total particulates on workers in the mix room. Nine general area (GA) air samples were 

collected for total particulates in the mix and package rooms. Two PBZ air samples were collected for 

acetic acid on workers in the mix room and four GA air samples were collected in the mix and package 

room. Three GA air samples were collected for benzaldehyde and piperonal and four GA air samples for 

methyl benzoate in the mix room. 

The particulates contained cab-o-sil® and microcrystalline cellulose. All of the PBZ air samples collected 

for total particulates on workers in the mix room exceeded the OSHA PEL for particulates not otherwise 

classified (PNOC) and the ACGIH TLV for cellulose. Concentrations ranged from 21 to 110 milligrams 

per cubic meter (mg/m3

) with an average of 43 mg/m3. Workers lean forward and place their heads inside 

drums, scooping out powder near the bottom. This accounts for the high exposure to airborne dust. One of 

two PBZ air samples collected for acetic acid on workers in the mix room exceeded the NIOSH REL, 

OSHA PEL, and ACGIH TLV. This sample was collected on the worker who measures acetic acid. All 

other air samples collected were below relevant evaluation criteria. 

There is a potential for excessive particulate and acetic acid exposure in the mix room of 

the pseudo drug building. Based on a description of other work activities not directly 

observed, there is a potential for respiratory hazards during the chopping of marijuana 

bales. Recommendations such as ventilation improvements, modified work practices, and 

use of respiratory protection are included in this report. 

Keywords: SIC 9229 (Public Order and Safety, Not Elsewhere Classified), pseudo drugs, acetic acid, 

benzaldehyde, methyl benzoate, piperonal, cab-o-sil,® microcrystalline cellulose, carbon monoxide, 

marijuana, mold, canine training 
Table of Contents 

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

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

Highlights of Health Hazard Evaluation .................................................................................................iii

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

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

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

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

Acetic Acid...............................................................................................................................................2

Benzaldehyde and Piperonal..................................................................................................................2

Methyl Benzoate......................................................................................................................................2

Total Particulate......................................................................................................................................3

Silica .........................................................................................................................................................3

Evaluation Criteria .....................................................................................................................................3

Acetic Acid...............................................................................................................................................4

Benzaldehyde...........................................................................................................................................4

Methyl Benzoate and Piperonal.............................................................................................................4

Total Particulates....................................................................................................................................4

Results ..........................................................................................................................................................4

Acetic Acid...............................................................................................................................................4

Benzaldehyde...........................................................................................................................................5

Methyl Benzoate......................................................................................................................................5

Total Particulates....................................................................................................................................5

Discussion ....................................................................................................................................................5

Conclusions and Recommendations..........................................................................................................6

References....................................................................................................................................................7

Health Hazard Evaluation Report No. 2004-0012-2948 Page 1 

INTRODUCTION

On October 10, 2003, the National Institute for 

Occupational Safety and Health (NIOSH) 

received a request for a Health Hazard 

Evaluation (HHE) at the U.S. Customs and 

Border Protection’s Canine Enforcement 

Training Center (CETC) in Front Royal, 

Virginia. The request concerned potential 

exposures from the preparation of pseudo 

narcotics. NIOSH conducted an initial site visit 

on November 12 – 14, 2003, and follow up 

visits on March 1 and 4, 2004. 

The initial site visit began with an opening 

conference and facility tour of the “pseudo 

building.” The evaluation consisted of general 

area (GA) and personal breathing zone (PBZ) air 

sampling for acetic acid, benzaldehyde, methyl 

benzoate, piperonal, and total particulates. In 

addition, one bulk sample of the pseudo drug 

was analyzed for silica content. This report 

presents the results of our evaluations, including 

conclusions and recommendations. 

BACKGROUND

CETC develops course content and provides 

training for all U.S. Customs Service Canine 

Enforcement Officers and other federal, state, 

local, and foreign law enforcement agencies. 

Currently there are over 500 canine teams 

throughout the United States. The CETC has a 

staff of approximately 40, which consists of 

instructors, animal caretakers, storage 

specialists, and administrative personnel. The 

CETC’s average canine population is 100 to 150 

dogs, with yearly training output of greater than 

100 canine enforcement teams. 

Storage specialists are responsible for the 

training aids used at the CETC and throughout 

the United States. Training aids can consist of 

the odors of marijuana, hashish, heroin, cocaine, 

methamphetamine, ecstasy, currency, and other 

non-narcotic hazardous substances. At the 

CETC, pseudo ecstacy, heroin, 

methamphetamine, and cocaine are prepared 

four times a year by storage specialists. 

The pseudo narcotics are produced in the 

“pseudo building,” which is a separate building 

approximately 17 feet wide by 38 feet long. The 

building is equally divided into two rooms, the 

mixing room and the storage room. The 

preparation of pseudo narcotics includes the use 

of acetic acid, benzaldehyde, methyl benzoate, 

piperonal, cab-o-sil,® and microcrystalline 

cellulose. The liquid ingredients are measured 

using a graduated cylinder; dry ingredients are 

measured using a scale on an open table in the 

mixing room. 

The preparation process begins with the mixing 

of the liquid chemical odorants and a limited 

amount of cab-o-sil® or microcrystalline 

cellulose in a large glass jar or a glass dish. The 

contents of the initial mixing and the remainder 

of the cab-o-sil® and microcrystalline cellulose 

are then added to a small Paterson Kelly blender 

where they are blended for 15 to 20 minutes 

depending on what odor is being produced. 

After the mix is blended in the small blender, it 

is transferred to the larger Paterson Kelly 

blender, using a 5-gallon bucket. Additional cabo-sil® and microcrystalline cellulose are added 

to bring the mix to the final weight. The mix is 

again blended for 15 to 20 minutes and then 

transferred to a 55-gallon trash can. The trash 

can is lined with a bag that is used to seal the 

trash can to the bottom of the blender during the 

transfer. After the preparation is completed, the 

pseudo drug is transferred and weighed into 

smaller bags for shipment throughout the 

country. 

In addition to the preparation of pseudo drugs at 

the CETC, bales of marijuana are chopped for 

use in training aids. The marijuana is chopped 

using a gasoline-powered yard chipper/shredder. 

The chopped marijuana is transferred and 

weighed into smaller bags for shipment to the 

different ports throughout the country. The 

process is normally conducted outside; however 

when it is cool outside the process is conducted 

inside an enclosed building. The chopping of 

marijuana bales was not observed by NIOSH; 

discussion and recommendations are based on 

descriptions from management and employees. 
Page 2 Health Hazard Evaluation Report No. 2004-0012-2948 

METHODS

This evaluation assessed exposure to acetic acid, 

benzaldehyde, methyl benzoate, piperonal, 

silica, and total particulates in the pseudo 

building during the preparation of pseudo 

ecstacy, heroin, methamphetamine, and cocaine. 

Air samples were only collected on the specific 

days the chemicals were used; however, this 

report does not distinguish between the days 

chemicals were used to protect the proprietary 

mixture of the individual pseudo drugs. 

Acetic Acid 

Two PBZ air and four GA air samples were 

collected for acetic acid analysis. Acetic acid air 

samples were collected on silica gel sorbent 

tubes at a calibrated flow rate of 100 cubic 

centimeters per minute (cc/min). The sorbent 

tubes were analyzed using a NIOSH draft 

method for acetic acid. Silica gel tubes were 

desorbed with water and then analyzed by high 

performance liquid chromatography (HPLC) 

with a Supelco Discovery HS C-18 column and 

a gradient mobile phase of acetonitrile and 

water. The limit of detection (LOD) and limit of 

quantification (LOQ) for acetic acid air samples 

is 0.002 and 0.008 microgram per sample 

(μg/sample), respectively. The corresponding 

minimum detectible concentration (MDC) and 

minimum quantifiable concentration (MQC) for 

this method are 0.0001 and 0.0004 parts per 

million (ppm), respectively, based on a sample 

volume of 6.1 liters. 

Benzaldehyde and 

Piperonal 

Three GA air samples for benzaldehyde analysis 

and three GA air samples for piperonal analysis 

were collected during the preparation of pseudo 

drugs. Side-by-side sample collection was 

performed with XAD-7 sorbent tubes and 

stainless steel thermal desorption tubes in two 

configurations, 3-bed and Tenax. No validated 

method exists for these two compounds; 

therefore, results should be considered estimates. 

XAD-7 sorbent tubes were desorbed with 

methylene chloride and then analyzed by a 

thermal desorber interfaced directly to a gas 

chromotograph and mass-selective detector (TDGC-MSD) with a 15-meter RTX-5Amine fused 

silica capillary column. 

The 3-bed thermal desporption tubes contained 

the following sorbent materials: the first section 

contains Carbopack YTM, the second section 

contains Carbopack BTM, and the last section 

contains Carboxen 1003TM. The Tenax thermal 

desportion tubes contained only one bed of 

sorbent, Tenax TA. Prior to sampling, the 

thermal desporption tubes were conditioned by 

heating at 320°C-375°C for 1.5 hours. Samples 

were collected at a calibrated flow rate of 50 

cc/min. The 3-bed thermal desorption tubes were 

then dry purged with helium for 30 minutes at 

100 cc/min prior to analysis. Tenax-TA tubes 

were analyzed without any prior drying. The 

samples were desorbed in a Perkin-Elmer ATD 

400 automatic thermal desorption system at 

300°C for 10 minutes. A 30 meter DB-1 fused 

silica capillary column was used for analyses. 

Stock solutions in methanol, containing known 

amounts of benzaldehyde and piperonal, were 

used to prepare standards to estimate 

concentrations. All standard spikes were 

prepared on Tenax-TA tubes. The LOD and 

LOQ for benzaldehyde air samples are 0.021 

and 0.070 μg/sample. The LOD and LOQ for 

piperonal air samples are 0.029 and 

0.097 μg/sample. The LOD for benzaldehyde 

and piperonal was based on the lowest prepared 

spiked standard. The corresponding MDC and 

MQC for benzaldehyde for this method are 

0.00078 and 0.0025 ppm, respectively, based on 

a sample volume of 6.1 liters. The corresponding 

MDC and MQC for the piperonal method are 

0.00078 and 0.0026 ppm, respectively, based on 

a 6.1 liter sample. 

Methyl Benzoate 

Four GA air samples were collected for methyl 

benzoate analysis during the preparation of 

pseudo drugs. Sampling was conducted with 

stainless steel thermal desoprtion tubes 

containing the following sorbent materials: 

Carbopack YTM, Carbopack BTM, and Carboxen 
Health Hazard Evaluation Report No. 2004-0012-2948 Page 3 

1003TM. Prior to sampling, the thermal 

desoprtion tubes were conditioned by heating at 

375°C for 2 hours. Samples were collected at a 

calibrated flow rate of 50 cc/min. The thermal 

desorption tubes were dry purged with helium 

for 30 minutes at 100 cc/min prior to analysis. 

The samples were then desorbed in a PerkinElmer ATD 400 automatic thermal desorption 

system at 300°C for 10 minutes. A 30-meter DB1 fused silica capillary column was used for 

analyses. Stock solutions in methanol, 

containing known amounts of various solvents 

identified on the thermal desorption tubes, were 

used to prepare standards to estimate 

concentrations. The LOD and LOQ for methyl 

benzoate are 0.02 and 0.06 μg/sample. The 

corresponding MDC and MQC for this method 

are 0.0005 and 0.002 ppm, respectively, based 

on a sample volume of 6.1 liters. Results should 

be considered estimates since a validated 

method was not used. 

Total Particulate 

Seven PBZ and nine GA air samples were 

collected for total particulate analysis during the 

preparation of pseudo drugs. Air samples were 

collected on tared 37-millimeter (mm) diameter, 

(5-micrometer [μm] pore-size) polyvinyl 

chloride (PVC) filters at a calibrated flow rate of 

2 liters per minute (Lpm). The filters were 

gravimetrically analyzed (filter weight) 

according to NIOSH Method 0500.1

 The LOD 

for total particulate air samples was 

0.02 milligram per sample (mg/sample). The 

MDC for this method is 0.03 milligram per 

cubic meter (mg/m3

), based on a sample volume 

of 692 liters. 

Silica 

A bulk sample of the pseudo drugs, containing 

the cab-o-sil,® was analyzed for quartz and 

cristobalite content. The sample was analyzed 

for silica according to NIOSH Method 75001

, 

modified for the analysis of bulk material. The 

sample was quantitated against a 30 μm silica 

standard. The LOD and LOQ for quartz bulk 

samples are 0.8% and 2%, respectively. The 

LOD and LOQ for cristobalite bulk samples are 

1% and 2%, respectively. 

EVALUATION CRITERIA

As a guide to the evaluation of the hazards posed 

by workplace exposures, NIOSH field staff 

employ environmental evaluation criteria for the 

assessment of a number of chemical and 

physical agents. These criteria are intended to 

suggest levels of exposure to which most 

workers may be exposed up to 10 hours per day, 

40 hours per week for a working lifetime 

without experiencing adverse health effects. It 

is, however, important to note that not all 

workers will be protected from adverse health 

effects even though their exposures are 

maintained below these levels. A small 

percentage may experience adverse health 

effects because of individual susceptibility, a 

pre-existing 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 worker to produce health effects 

even if the occupational exposures are controlled 

at the level set by the criterion. These combined 

effects are often not considered in the evaluation 

criteria. Also, some substances are absorbed by 

direct contact with the skin and mucous 

membranes, and thus potentially increases the 

overall exposure. Finally, evaluation criteria 

may change over the years as new information 

on the toxic effects of an agent become 

available. 

The primary sources of environmental 

evaluation criteria for the workplace are: (1) 

NIOSH Recommended Exposure Limits 

(RELs),2

 (2) the American Conference of 

Governmental Industrial Hygienists’ (ACGIH®) 

Threshold Limit Values (TLVs®),3

 and (3) the 

U.S. Department of Labor, Occupational Safety 

and Health Administration (OSHA) Permissible 

Exposure Limits (PELs).4

 Employers are 

encouraged to follow the OSHA limits, the 

NIOSH RELs, the ACGIH TLVs, or whichever 

are the more protective criteria. 

OSHA requires an employer to furnish 

employees a place of employment that is free 

from recognized hazards that are causing or are 
Page 4 Health Hazard Evaluation Report No. 2004-0012-2948 

likely to cause death or serious physical harm 

[Occupational Safety and Health Act of 1970, 

Public Law 91–596, sec. 5(a)(1)]. Thus, 

employers should understand that not all 

hazardous chemicals have specific OSHA 

exposure limits such as PELs and short-term 

exposure limits (STELs). An employer is still 

required by OSHA to protect their employees 

from hazards, even in the absence of a specific 

OSHA PEL. 

A time-weighted average (TWA) exposure 

refers to the average airborne concentration of a 

substance during a normal 8- to 10-hour 

workday. Some substances have recommended 

STEL or ceiling values which are intended to 

supplement the TWA where there are 

recognized toxic effects from higher exposures 

over the short term. 

Acetic Acid 

Inhalation of acetic acid can cause irritation of 

the nose and throat. Higher concentrations can 

cause inflammation of the airways and 

accumulation of fluid in the lungs. Acetic acid 

vapors and liquid can cause eye irritation. 

Concentrated solutions can cause severe burns 

and permanent eye damage. Acetic acid is also a 

strong irritant to the skin. Acetic acid is a normal 

body component and does not accumulate in the 

body. It is rapidly transformed and excreted, or 

used in the production of chemicals required for 

bodily functions.5

The NIOSH REL, OSHA PEL, and ACGIH 

TLV for acetic acid are 10 ppm. NIOSH and 

ACGIH have also established a short-term 

exposure limit (STEL) of 15 ppm.2,3 

Benzaldehyde 

Occupational exposure to benzaldehyde can 

occur through dermal contact and inhalation. 

Inhalation of benzaldehyde can cause irritation 

of the eyes, nose, and throat. A concentration of 

20 mg/m3

 was found irritating to the eyes and 

respiratory tract in a study of human volunteers.6

Acute toxicity of benzaldehyde administered 

orally varied by animal species; oral lethal dose 

of 50% (LD50) for rats and mice was 

1300 milligrams per kilogram (mg/kg) and 

27.8 mg/kg respectively.6,7 Toxicological data 

indicate that adverse acute and chronic effects 

occur only at fairly high dosages and overall 

toxicity is moderate. The American Industrial 

Hygiene Association (AIHA) Workplace 

Environmental Exposure Level (WEEL) for 

benzaldehyde is 2 ppm. 6 In addition to the 

WEEL, AIHA has established a STEL of 4 ppm. 

Methyl Benzoate and 

Piperonal 

Methyl benzoate and piperonal are widely used 

as flavoring and odorant agents. No information 

is available on occupational exposure. 

Total Particulates 

Microcrystalline cellulose and cab-o-sil® are 

considered “nuisance” dust by OSHA and are 

classified as particulates not otherwise regulated 

(PNOR). OSHA has established a PEL for 

PNOR (total dust) of 15 mg/m3

. ACGIH has 

established a TLV of 10 mg/m3

 for cellulose. 

Both criteria were established to minimize 

mechanical irritation of the eyes and nasal 

passages and to prevent visual interference. 

NIOSH has not established an REL for PNOR or 

cellulose. 

RESULTS

PBZ and GA air sampling was conducted on 

November 12 – 14, 2003, and March 1 and 4, 

2004, for acetic acid, benzaldehyde, methyl 

benzoate, piperonal, and total particulates. In 

addition to the air samples, a bulk sample was 

collected on November 14, 2003 for silica 

analysis. Piperonal and silica were not detected 

(ND [less than the MDC]). 

Acetic Acid 

Two PBZ air samples for acetic acid were 

collected on workers in the mix room, where the 

acetic acid is used. The two PBZ air 

concentrations were 2.4 and 11 ppm. The higher 

sample was collected on the worker who 

measured the acetic acid. This worker’s 
Health Hazard Evaluation Report No. 2004-0012-2948 Page 5 

exposure to acetic acid is over the OSHA PEL of 

10 ppm. 

Four GA air samples for acetic acid were 

collected throughout the pseudo drug building. 

GA air concentrations for acetic acid ranged 

from ND (less then 0.0001 ppm) to 7.3 ppm. 

Three of the four GA air samples were collected 

in the mix room. These samples ranged from 1.1 

to 7.3 ppm with an average of 3.6 ppm. The 

remaining GA air sample, collected in the 

package room, was ND. 

Benzaldehyde 

Three GA air samples for benzaldehyde were 

collected in the mix room. GA air concentrations 

for benzaldehyde ranged from 0.067 to 

0.28 ppm, with an average of 0.16 ppm, well 

below the WEEL of 2 ppm. Samples were 

collected on XAD-7, 3-bed, and Tenax thermal 

desorption tubes, however only the 3-bed 

thermal desorption tube results are stated in the 

text. This is based on the lab recommendation 

because of better recovery on the 3-bed thermal 

desorption tubes. 

Methyl Benzoate 

Four GA air samples were collected throughout 

the pseudo drug building. GA air concentrations 

for methyl benzoate ranged from 0.0034 to 

0.43 ppm, with an average of 0.21 ppm. The 

highest three concentrations were collected in 

the mix room. 

Total Particulates 

Seven PBZ air samples were collected on the 

two workers in the mix room of the pseudo drug 

building. PBZ air concentrations ranged from 21 

to 110 mg/m3

 with an average of 43 mg/m3. All 

of the PBZ air samples exceed the ACGIH TLV 

of 10 mg/m3

 for cellulose and the OSHA PEL of 

15 mg/m3

 for PNOC. 

Nine GA air samples were collected throughout 

the pseudo drug building. GA air concentrations 

ranged from ND (less than 0.03 mg/m3

) to 

13 mg/m3

. Six of the nine GA air samples were 

collected from the mix room. These samples 

ranged from 2.9 to 13 mg/m3

 and had an average 

of 7.1 mg/m3

. The remaining three samples 

collected in the package room ranged from ND 

to 0.16 mg/m3

 with an average of 0.048 mg/m3. 

DISCUSSION

PBZ air concentrations for total particulates 

were much higher than the GA air 

concentrations. In previous air sampling 

conducted by Federal Occupational Health, GA 

air concentrations for total dust were below the 

PEL.8

 When workers have to lean over and 

reach into drums, GA air sampling is not 

representative of the employee’s exposures. 

Exposure sampling is best conducted using PBZ 

air samples for particulates when employees 

reach into drums. 

During the site visit, workers talked about the 

installation of a fan in a window and an opening 

in the bottom of the exit door to increase cross 

ventilation in the room. A vertical air shower 

should be used instead, because cross ventilation 

can pull the dust into the workers’ breathing 

zone. A vertical air shower would push airborne 

dust out of the worker’s breathing zone, until the 

dust is captured and exhausted from the work 

area (see Figure 1).9

 Without the air shower, 

eddy currents can form around the worker and 

stir up dust. 

The drums containing bulk microcrystalline 

cellulose and the drums used to transfer product 

in the mix room have a height of approximately 

34 inches. When manually transferring powder 

from these drums, workers must lean forward 

and place their heads inside the drum to scoop 

out the powder near the bottom. In this position, 

the worker is exposed to a high level of airborne 

dust, even under a ventilated booth. Maintaining 

a space between the worker’s face and the top of 

the drum enables the booth ventilation to capture 

the dust before it reaches the worker’s breathing 

zone. 

During the preparation of all pseudo drugs, 

workers used disposable filtering face pieces. 

CETC’s respiratory protection program covers 

the pseudo drug process and requires either 
Page 6 Health Hazard Evaluation Report No. 2004-0012-2948 

disposable filtering face pieces or half-face 

respirators with acid gas/N95 combination 

cartridges. During the preparation process, 

workers were wearing the filtering face pieces 

upside down. This provided no respiratory 

protection against the high levels of airborne 

dust. 

While not observed by the NIOSH industrial 

hygienist, workers and management expressed 

concern about the chopping of marijuana bales. 

Concerns included potential carbon monoxide 

(CO) and dust exposures associated with the 

gasoline-powered chopper and moldy marijuana 

bales. Management reported that two workers 

became ill and were transported to the hospital 

for CO exposure the last time bales were 

chopped. The chopping was conducted with a 

gasoline-powered yard chipper/shredder inside a 

closed garage because of the cool temperature 

outside. All gasoline-powered engines produce 

CO. The use of gasoline engines inside buildings 

has caused many cases of CO poisonings and 

fatalities.10 Gasoline-powered choppers produce 

hazardous levels of CO when used in doors, 

even for short periods of time. 

In addition to the potential CO exposure, 

workers were concerned about potential 

exposure to dust from the chopping of marijuana 

bales. In agriculture, low quality hay or straw 

bales used for dairy cow bedding commonly 

contain high levels of microorganisms such as 

bacteria or fungi.11,12,13 Bales of marijuana have 

the potential to contain the same high levels of 

microorganisms if mold is present. Workers may 

be exposed to airborne microorganisms from the 

dust generated when the bales are chopped. One 

worker reported the presence of a moldy bale 

while chopping the last time. Mold indicates 

severe contamination by microorganisms. 

Visibly moldy bales of marijuana pose the 

greatest exposure risk. 

CONCLUSIONS AND 

RECOMMENDATIONS

Air monitoring performed during the preparation 

of pseudo drugs revealed worker exposure above 

the TLV for cellulose, PEL for total particulates, 

and the REL and PEL for acetic acid. While not 

observed by the NIOSH industrial hygienist, the 

chopping of marijuana bales has the potential for 

CO and dust exposures. The following 

recommendations should reduce employee 

exposure during the preparation of pseudo drugs 

and chopping of marijuana bales. 

1. Use a semi downdraft ventilation booth 

to control dust exposure. All tasks 

associated with the manual transfer of 

powdered ingredients (weighing, 

scooping, etc.) should be performed 

inside the booth under the air shower. 

Figure 1 shows how the semi downdraft 

booth should be configured. 

2. Limit bulk and transfer drum height to 

25 inches. Use shorter drums to 

eliminate the need for workers to place 

their heads inside the drum. Maintaining 

a space between the worker’s face and 

the top of the drum enables the booth 

ventilation to capture the dust before it 

reaches the worker’s breathing zone. 

3. Re-evaluate the written respiratory 

program based on OSHA’s Respiratory 

Protection Standard (29 CFR 1910.134). 

The program should outline the 

appropriate respirator based on the 

hazard, change-out schedules, and 

employee training on how to wear a 

respirator and store it safely. 

4. Use engineering controls, as mentioned 

in recommendation #1; such controls are 

the preferred method to protect workers 

from exposure. Until controls are 

implemented, workers in the pseudo mix 

room should wear a powered airpurifying respirator (PAPR) equipped 

with a hood or helmet (protection factor 

equal to or greater than 25) and N95 

cartridges during the preparation of all 

pseudo drugs. During the preparation of 

pseudo drugs that require acetic acid, 

PAPR equipped with a hood or helmet 

and acid gas/N95 combination 

cartridges should be used in the pseudo 
Health Hazard Evaluation Report No. 2004-0012-2948 Page 7 

mix room. Because of the infrequent 

use, cartridges should be replaced at the 

end of each shift. 

5. Instruct workers to use slow, smooth 

movements when handling powder to 

keep airborne dust concentrations low. 

Keep to a minimum both the powder 

transport distances between 

bulk/transfer drums and process 

containers and the height from which 

the powder is dropped into containers. 

6. Substitute visibly moldy bales of 

marijuana with less contaminated 

marijuana bales before chopping. In 

addition, workers should wear at a 

respirator with the minimum protection 

equal to that of a half-face respirator 

(protection factor equal to or greater 

than 10) with N95 cartridges during the 

chopping process. 

7. Use gasoline engines outside; NOT 

inside buildings or in partially enclosed 

areas. Use CO monitors to ensure that 

CO levels do not exceed an 8-hour 

TWA of 35 ppm or a 5-minute ceiling of 

200 ppm in the area where gasoline 

engines are used. In addition, train 

employees to recognize symptoms of 

CO poisoning. 

REFERENCES

 1. NIOSH [2003]. NIOSH manual of 

analytical methods. 4th ed. 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. 2003-154. 

 2. NIOSH [1992]. Recommendations for 

occupational safety and health: compendium of 

policy documents and statements. 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. 92-100. 

 3. ACGIH [2004]. 2004 TLVs® and BEIs®: 

threshold limit values for chemical substances 

and physical agents. Cincinnati, OH: American 

Conference of Governmental Industrial 

Hygienists. 

 4. CFR [2003]. 29 CFR 1910.1000. Code of 

Federal Regulations. Washington, DC: U.S. 

Government Printing Office, Office of the 

Federal Register. 

 5. NIOSH [1979]. A guide to workrelatedness of disease. Revised ed.. Cincinnati, 

OH: U.S. Department of Health and Human 

Services, Public Health Service, Centers for 

Disease Control, National Institute for 

Occupational Safety and Health, DHHS 

(NIOSH) Publication No. 79-116. 

 6. AIHA [1999]. Benzaldehyde. In: 

Workplace Environmental Exposure Level 

Guide, 1999 WEELs Complete Set. Fairfax, VA: 

American Industrial Hygiene Association. 

 7. Bishop J [1990]. NTP technical report on 

the toxicology and carcinogenesis studies of 

benzaldehyde in F344/N rats and B6C3F mice. 

Research Triangel Park, NC: U.S. Department of 

Health and Human Services, Public Health 

Service, National Institutes of Health, National 

Toxicology Program Toxicity Report Series No. 

378, DHHS (NIH) Publication No. 90-2833. 

 8. Thomas K [1995]. Industrial hygiene 

survey. Philadelphia, PA: Federal Occupational 

Health. Task order 95-301 for U.S. Customs 

Service Canine Enforcement Training Center. 

 9. NIOSH [1997]. Control of Dust From 

Powder Dye Handling Operations. Washington, 

DC: 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. 97-107. 
Page 8 Health Hazard Evaluation Report No. 2004-0012-2948 

 10. NIOSH [1996]. Preventing Carbon 

Monoxide Poisoning from Small GasolinePowered Engines and Tools. Washington, DC: 

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. 96-118a. 

 11. Merchant JA [1987]. Agricultural 

exposures to organic dusts. Occupational 

Medicine. 2(2): 409-425. 

 12. NIOSH [1997]. Control of Organic Dusts 

From Bedding Choppers in Dairy Barms. 

Washington, DC: 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-

103. 

 13. Kirkhorn SE, Gary VF [2000]. 

Agricultural lung diseases. Environmental 

Health Perspectives. 108 Supplement 4: 705-

712. 
Health Hazard Evaluation Report No. 2004-0012-2948 Page 9 

Figure 1 

U.S. Customs and Border Protection 

Canine Enforcement Training Center 

HETA 2004-0012-2948 

Semi Downdraft Ventilation Booth 

Filtered air enters from the ceiling of the booth, collects dust as it flows 

past the worker, and exhausts out the back of the booth through grates 

(side view).
DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention National Institute for Occupational Safety and Health 4676 Columbia Parkway Cincinnati, OH 45226-1998 OFFICIAL BUSINESS Penalty for private use $300 

Delivering on the Nation's promise: 

Safety and Health at work for all people 

through research and prevention

To receive NIOSH documents or information 

about occupational Safety and Health topics 

contact NIOSH at: 

1-800-35-NIOSH (356-4674) 

Fax: 1-513-533-8573 

E-mail: pubstaft@cdc.gov

or visit the NIOSH web site at: 

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