Evaluation of Occupational 

Exposures to Illicit Drugs in 

Forensic Laboratories

HHE Report No. 2021-0115-3388

August 2023 
Authors: Jessica F. Li, MSPH, CIH

Dallas S. Shi, MD, PhD

Dylan T. Neu, BS

Sophia Chiu, MD, MPH

Melissa Charles, MS, CSP

Analytical Support: Bureau Veritas North America, Jennifer Roberts

Desktop Publisher: Shawna Watts

Editor: Cheryl Hamilton

Industrial Hygiene Field Assistance: Hannah Echt, M. Colleen O’Connor

Logistics: Donnie Booher, Kevin Moore

Keywords: North American Industry Classification System (NAICS) 922120 (Police Protection), 

Washington, Forensic Laboratory, Forensic Scientist, Law Enforcement, Illicit Drug, 

Methamphetamine, Cocaine, Heroin, Fentanyl, Opioid

Disclaimer

The Health Hazard Evaluation Program investigates possible health hazards in the workplace under 

the authority of the Occupational Safety and Health Act of 1970 [29 USC 669a(6)]. The Health 

Hazard Evaluation Program also provides, upon request, technical assistance to federal, state, and 

local agencies to investigate occupational health hazards and to prevent occupational disease or 

injury. Regulations guiding the Program can be found in Title 42, Code of Federal Regulations, 

Part 85; Requests for Health Hazard Evaluations [42 CFR Part 85]. 

Availability of Report

Copies of this report have been sent to the employer, employees, and union at the workplace. The 

state and local health departments and the Occupational Safety and Health Administration Regional

Office have also received a copy. This report is not copyrighted and may be freely reproduced.

Recommended Citation

NIOSH [2023]. Evaluation of occupational exposures to illicit drugs in forensic laboratories.

By Li JF, Shi D, Neu DT, Chiu S, Charles M. Cincinnati, OH: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, Health Hazard Evaluation Report 2021-0115-3388, 

https://www.cdc.gov/niosh/hhe/reports/pdfs/2021-0115-3388.pdf.
Table of Contents

Main Report

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

Our Approach ................................................................................................................................................... 1

Our Key Findings.............................................................................................................................................. 2

Our Recommendations.................................................................................................................................... 4

Supporting Technical Information 

Section A: Workplace Information............................................................................................................ A-1

Building...................................................................................................................................................... A-1

Employee Information ............................................................................................................................ A-1

History of Issue at Workplace................................................................................................................ A-1

Process Description ................................................................................................................................. A-2

Section B: Methods, Results, and Discussion .......................................................................................... B-1

Methods: Health and Safety Program and Document Review.......................................................... B-1

Results: Health and Safety Program and Document Review............................................................. B-2

Methods: Employee Health Assessment .............................................................................................. B-4

Results: Employee Health Assessment ................................................................................................. B-4

Methods: Work Processes, Practices, and Conditions........................................................................ B-5

Results: Work Processes, Practices, and Conditions........................................................................... B-5

Methods: Exposure Assessment .......................................................................................................... B-12

Results: Exposure Assessment ............................................................................................................. B-13

Methods: Ventilation Evaluations........................................................................................................ B-16

Results: Ventilation Evaluations........................................................................................................... B-16

Discussion ............................................................................................................................................... B-17

Limitations............................................................................................................................................... B-22

Conclusions............................................................................................................................................. B-22

Section C: Tables.......................................................................................................................................... C-1

Section D: References.................................................................................................................................. D-1
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1

Introduction

Request

Management at a state police agency was concerned about potential occupational exposure to illicit 

drugs, including methamphetamine, among employees working in the toxicology lab.

Workplace

The state toxicology laboratory (also toxicology lab) served the entire state, performing toxicology 

testing for law enforcement agencies and other submitting agencies and parties throughout the state. 

Toxicology laboratory division employees performed forensic analyses on a variety of biological 

materials, such as urine and blood, for the presence and amount of illicit and licit drugs. The request 

focused on occupational exposures to illicit drugs, specifically methamphetamine and cocaine. No 

work-related health effects related to potential exposure to drugs were noted in the request. The 

toxicology laboratory division, including the toxicology laboratory evidence vault, occupied one side of 

the third floor. At the time of our visit, 23 forensic scientists and one laboratory manager worked in the 

state toxicology laboratory.

Regional crime laboratory management agreed to include the regional crime laboratory in this health 

hazard evaluation because it was located near the state toxicology laboratory, separated by a shared 

hallway. The regional crime laboratory (also crime lab) analyzes suspected drug evidence for controlled 

substances and drugs of forensic interest, genetic material, firearms, and other items related to criminal 

offenses. It was one of five regional crime laboratories in the state, serving the needs of that geographic 

region. The regional crime laboratory was located on the second and third floors of the same building. 

The crime laboratory evidence storage vault was located on the second floor. Employees of the crime 

laboratory material analysis section, located on the third floor, performed forensic analyses on a variety 

of seized drug evidence. Two forensic scientists and one supervisor worked in the materials analysis 

section of the regional crime laboratory at the time of our visit.

Prior to the health hazard evaluation request, the toxicology laboratory division occupied and then 

vacated laboratory and office space that previously belonged to the regional crime laboratory, called the 

annex space. Shared common areas, including restrooms and a break room, were also located on the 

third floor along the shared hallway.

To learn more about the workplace, go to Section A in the Supporting Technical Information

Our Approach

We conducted a virtual site visit of the facility in March and April 2022 to gather preliminary 

information. During this virtual site visit, we completed the following activities:

• Conducted a virtual walkthrough of the facility, focusing on the second and third floors. 
2

• Evaluated building ventilation virtually with assistance from the law enforcement agency 

industrial hygienist.

• Held confidential medical interviews with 34 employees by video conferencing. 

We visited the facility in June 2022. During the site visit, we completed the following activities:

• Observed work process, work practices, and workplace conditions.

• Tested 13 toxicology laboratory forensic scientists’ hands for exposures to methamphetamine, 

cocaine, fentanyl, and heroin.

• Collected surface samples for methamphetamine, cocaine, fentanyl, and heroin on surfaces in 

the state toxicology laboratory, the materials analysis areas of the regional crime laboratory, 

annex laboratory areas, and common areas.

• Administered a written questionnaire to 23 toxicology laboratory employees.

• Reviewed relevant records and documents on the safety and health program, past cleaning 

activities in the former and current toxicology laboratory areas, and laboratory surface sampling 

results completed prior to the visit. 

• Spoke with facilities maintenance staff and continued the ventilation evaluation, focusing on 

areas that were not evaluated during the virtual evaluation.

• Visually inspected building ventilation systems.

To learn more about our methods, go to Section B in the Supporting Technical Information

Our Key Findings

Detectable levels of methamphetamine, cocaine, fentanyl, and heroin were found 

on surfaces

• In the toxicology laboratory, detectable levels of methamphetamine were found on a supply vent 

cover (1/1), return vent cover (1/1), centrifuges (2/4), and laboratory bench surfaces (3/11). 

Detectable levels of cocaine were found on the supply vent cover (1/1), return vent cover (1/1), 

and door handle (1/4).

• In the crime laboratory, detectable levels of methamphetamine were found on hood sashes 

(2/2), laboratory bench surfaces (2/2), keyboards (2/2), door handles (2/3), and at the bottom 

of a vestibule door leading to the shared hallway. Laboratory bench surfaces (2/2) and 

keyboards (2/2) had detectable amounts of methamphetamine, cocaine, fentanyl, and heroin.

• In the annex laboratory, we found detectable levels of methamphetamine and cocaine on a fume 

hood surface (1/1), a supply vent cover (1/1), a centrifuge (1/1), and on fume hood sashes 
3

(2/2). Methamphetamine was detected on a door handle in the annex laboratory (1/1). Cocaine 

was detected on a door handle in the annex office (1/1). 

• None of the surface samples collected in the toxicology lab exceeded the state remediation level 

for methamphetamine contamination of 1.5 micrograms per 100 square centimeters. This level 

is the same as a health-based remediation level for methamphetamine contamination calculated 

by the state of California. One sample collected from the fume hood sash of the crime 

laboratory exceeded this state limit for methamphetamine contamination in remediated spaces.

There are no relevant remediation levels for surfaces for cocaine, fentanyl, and heroin.

• On the hands of the 13 toxicology lab forensic scientists tested, we did not find detectable levels 

of methamphetamine, cocaine, fentanyl, or heroin. Scientists’ hands were tested before entering 

the laboratory at the beginning of the day and when leaving the laboratory at the end of the day.

Employees did not report any symptoms related to handling methamphetamine, 

cocaine, fentanyl, or heroin at work 

• Most employees reported no work-related health symptoms.

• Of those who did report a work-related health concern, none were from potential exposure to 

handling licit or illicit drugs.

Observed air flow between laboratories and surrounding areas may have affected 

the movement of drugs

• Pressurization between the state toxicology laboratory and the shared hallway indicated that air 

mostly flowed from the toxicology laboratory into the shared hallway. One doorway between

the toxicology laboratory and the hallway was observed to be neutrally pressured, meaning that 

air was likely to flow both into and out of the toxicology laboratory.

• One of the crime laboratory vestibule doorways was positively pressured compared with the 

shared hallway, meaning that air mostly flowed from the crime laboratory into the shared 

hallway at that door. The remainder of the doorways between the crime laboratory and the 

shared hallway were negatively pressured, meaning that air mostly flowed from the shared 

hallway into the crime laboratory from those doorways.

• Laboratory ventilation guidelines state that, in general, air should flow from low hazard areas to 

higher hazard areas. Keeping the desired airflow direction can slow the movement of air 

contaminants but does not completely stop it.

• Laboratory management provided records of fume hood velocity certified by a contractor for 

the years 2020 and 2021. Most fume hoods had a display that showed the hood’s face velocity.

For a few fume hoods, we verified that the display value aligned with our measurements.
4

Personal protective equipment (PPE) access, use, and training can be improved

• Lab coats were stored in the vestibule connecting offices to the toxicology laboratory. 

Employees may enter and exit the lab from vestibules that did not provide access to lab coats.

• New PPE was stored in the toxicology laboratory. Employees and visitors had to enter the lab 

to don new or change out PPE. 

• Lab coats and eye protection were observed being inconsistently worn by toxicology laboratory 

employees when in the laboratory for short periods of time or while not processing biological 

samples. This was consistent with medical interview and questionnaire findings.

• More training was both needed and desired: 

o Most toxicology laboratory employees did not know if trainings or written policies on 

PPE use existed. 

o More than half of the toxicology laboratory employees surveyed felt that trainings need 

to be improved. 

To learn more about our results, go to Section B in the Supporting Technical Information

Our Recommendations

The Occupational Safety and Health Act requires employers to provide a safe workplace.

Potential Benefits of Improving Workplace Health and Safety:

 Improved worker health and well-being  Enhanced image and reputation 

 Better workplace morale  Superior products, processes, and services

 Easier employee recruiting and retention  May increase overall cost savings

The recommendations below are based on the findings of our evaluation. For each recommendation, 

we list a series of actions you can take to address the issue at your workplace. The actions at the 

beginning of each list are preferable to the ones listed later. The list order is based on a well-accepted 

approach called the “hierarchy of controls.” The hierarchy of controls groups actions by their likely 

effectiveness in reducing or removing hazards. In most cases, the preferred approach is to eliminate 

hazardous materials or processes followed by using engineering controls to reduce exposure or shield 

employees. Until such controls are in place, or if they are not effective or practical, administrative 

measures and PPE might be needed. Read more about the hierarchy of controls at

https://www.cdc.gov/niosh/topics/hierarchy/. 
5

We encourage the laboratory to use a health and safety committee to discuss our 

recommendations and develop an action plan. Both employee representatives and 

management representatives should be included on the committee. Helpful guidance can be 

found in Recommended Practices for Safety and Health Programs at

https://www.osha.gov/shpguidelines/index.html. 

Recommendation 1: Reduce methamphetamine, cocaine, fentanyl, and heroin on 

surfaces

Why? We have no indication that the surface levels of methamphetamine, cocaine, fentanyl, and 

heroin we detected have impacted employees’ health. However, following sound occupational health 

practice, we recommend minimizing the levels of these drugs and potential workplace exposures to 

controlled substances.

How? At your workplace, we recommend these specific actions:

Establish and encourage employees to follow a consistent policy for using 

fume hoods when handling evidence biological and bulk drug samples. 

Review and update cleaning protocols to keep laboratory and other 

surfaces as free as practicable of contaminants. 

• Continue or increase the frequency of routine deep cleaning of laboratory surfaces.

• Use wet cleaning methods or a vacuum equipped with a high efficiency particulate air 

filter for cleaning laboratory surfaces.

• Remove cleaning equipment that could aerosolize particles, such as vacuum cleaners 

without high efficiency particulate air filters and compressed air canisters. This will help 

to prevent employees dry sweeping and using other dry-cleaning methods when cleaning 

laboratory surfaces.

• Provide, at a minimum, annual training to ensure compliance with approved cleaning 

practices.

• Consider using a detergent and water solution, as recommended by the Environmental 

Protection Agency, when deep cleaning or cleaning large areas. The Environmental 

Protection Agency discourages the use of methanol for remediation activities due to 

flammability and other hazards.

• Change cleaning protocols as needed to reflect the most up-to-date research on surface 

cleaning and contaminant removal for drugs commonly found in submitted evidence.
6

Update laboratory protocols to reduce employees’ exposure to controlled

substances. 

• Eliminate measuring net weights of evidence whenever it is not needed for law 

enforcement purposes or legal proceedings. Changing this practice will reduce the risk 

of drugs becoming airborne during transfer from packaging to scales.

• Educate all employees, including contracted janitorial staff, on work practices to 

minimize possible aerosolization of and surface contamination with evidence materials. 

For example, instruct employees to refrain from transporting loose evidence materials 

without an enclosed container.

Improve health and safety training in the toxicology laboratory. 

• Many toxicology laboratory employees stated they wanted more or better training. 

Current training can be improved by using formalized and varied methods including 

visual or interactive training.

• Consider testing employees’ knowledge before and after training to evaluate their

understanding of the training objective. 

Remind employees handling biological samples to practice principles of 

bloodborne pathogen exposure prevention. 

• Educate employees about the importance of practicing universal precautions for 

bloodborne pathogens when handling samples and other solutions, such as capping 

tubes before vortex-mixing. These principles will help employees prevent exposure to 

illicit drugs from biological evidence and drug standards. 

Provide space and encourage employees to store personal items outside 

of laboratory areas and vestibules. 

Encourage employees with any work-related health concerns to talk to 

their healthcare providers about their potential workplace exposures to 

illicit drugs. 

Review and update PPE practices and storage policies. 

• Increase the availability and locations for laboratory coat storage in vestibules in the 

toxicology laboratory.

• Store new PPE in vestibules or in office areas outside of the toxicology laboratory. This 

prevents potential contamination of unused PPE, provides better access, and makes it 

easier to change into new PPE.
7

• Consider establishing a set of required PPE when employees enter the toxicology 

laboratory or when they perform specific tasks or work with specific evidence in the 

crime laboratory. Display PPE requirements clearly at all entrances to the toxicology 

laboratory.

• Create schedules for replacing PPE items. Train employees on any changes to this 

policy.

• Tell employees not to hang used laboratory coats inside the toxicology laboratory, on 

the backs of their laboratory bench chairs, or on other laboratory equipment. 

• Encourage toxicology laboratory employees to only enter and exit the laboratory 

through vestibules where required PPE is stored and available for use.

• Establish glove-use policy for workstation and analytical instrument keyboards in the 

toxicology and crime laboratories to determine if gloves should or should not be used 

on keyboards.

• Provide training on the correct use of PPE, including when to use, store, and replace it.

Determine if forensic scientists who handle drug evidence should be 

enrolled in the respiratory protection program

• Past health hazard evaluations done in forensic labs found respiratory protection to be 

another effective control for preventing unnecessary exposure to illicit drugs in the air. 

• Where voluntary use of N95 respirators is allowed for protection against illicit drug 

particles, provide employees with Appendix D of the Occupational Safety and Health 

Administration’s Respiratory Protection Standard or the state’s equivalent standard.

Recommendation 2: Consult the building facilities manager or a ventilation 

engineer to modify ventilation systems to maintain differential pressures to prevent 

the spread of hazardous substances in the building

Why? Maintaining building ventilation and differential pressure are important strategies to reduce the 

potential spread of infectious diseases and the movement of hazardous materials in laboratories.

How? At your workplace, we recommend these specific actions:

Determine desired directional airflow between rooms in the building. 

• Laboratory ventilation guidelines specify that “airflow shall be from areas of low hazard 

to higher hazard.” Maintaining directional airflow opposes the migration of air 

contaminants.
8

• Redesign or adjust existing controls on ventilation systems for desired directional 

airflow between laboratories and other spaces, such as offices and shared common 

areas.

Provide dedicated ventilation to the evidence storage vault. 

• Past HHEs evaluating occupational exposures in evidence rooms and storage areas may 

provide additional information:

o HHE Report No. HETA-2018-0150-3340, Evaluation of Potential Occupational 

Exposures to Narcotics in a County Evidence Room (cdc.gov)

o HHE Report No. HETA-2010-0017-3133, Evaluation of Police Officers’ 

Exposures to Chemicals While Working Inside a Drug Vault – Kentucky 

(cdc.gov)

Continue maintaining fume hoods with quarterly inspections conducted by 

laboratory staff and annual inspections conducted by a contractor.

• Continue ensuring that fume hood face velocities are within ANSI/ASSP 

recommendations of 80–120 feet per minute. 

• Consider asking the fume hood contractor to conduct tracer gas containment tests 

according to ANSI/ASSP guidance if concerns exist about the effectiveness of fume 

hood containment. 

Recommendation 3: Address other potential health and safety issues at your 

workplace

Why? A workplace can have multiple health hazards that cause worker illness or injury. Similar to the 

ones identified above, these hazards can potentially cause serious health symptoms, lower morale and 

quality of life for your employees, and possibly increased costs to your agency. We saw the following 

potential issues at your workplace:

• Hazard communication

• Training effectiveness

Although they were not the focus of our evaluation, these issues could impact your workers’ health 

and safety and should be addressed. 
9

How? At your workplace, we recommend these specific actions:

Increase hazard communication and conduct job hazard analyses to 

identify potential hazards and ways to control for them. 

• Find more information on job hazard analysis here: 

https://www.osha.gov/sites/default/files/publications/osha3071.pdf. 

• Place signs at each laboratory entrance displaying required PPE and other important 

health and safety messages.

• Create health and safety policies and procedures that are efficient and specific to a 

forensic scientist’s tasks.

Evaluate the effectiveness of existing training programs and make 

improvements based on employee feedback and training posttests. 

Recommend forensic scientists leave laboratory areas when they are not 

doing lab work. 

Encourage employee involvement in the health and safety committee to 

address other workplace concerns and solicit feedback on existing 

practices. 

• Openly discuss plans to make changes that affect employees’ work and allow for time 

for feedback.

• Committee actions could include working to address concerns brought up during 

medical interviews and questionnaires such as: 

o Exposure to solvents

o Musculoskeletal disease and ergonomic concerns: encourage employees to 

request an ergonomic assessment through the law enforcement ergonomics 

program or report any concerns to their supervisors

o Mental health and workplace stress

o Safety issues outside of the building

Provide opportunities for employees to submit anonymous feedback or 

concerns regarding laboratory health and safety. 
Supporting Technical Information

Evaluation of Occupational Exposures to Illicit Drugs 

in Forensic Laboratories

HHE Report No. 2021-0115-3388

August 2023
A-1

Section A: Workplace Information

Building

The state toxicology laboratory (toxicology lab) is the only laboratory in the state analyzing biological 

evidence for drug content. The regional crime laboratory (crime lab) is one of the regional laboratories 

within the crime lab division. Laboratories within the crime lab division evaluate any items associated 

with a criminal trial. The state toxicology lab and the part of the regional crime lab evaluating drug 

evidence are located on the third floor of a four-story building, separated by a shared hallway. The 

evidence storage vault for the toxicology lab was located within the toxicology lab, and the crime lab 

evidence storage vault storing drug evidence was located on the second floor.

Built in the early 1900s, and renovated in the 1980s, the 100,000-square foot building was owned by the 

city and leased to the state police agency at the time of our in-person visit. The building was renovated 

as dedicated laboratory space with office space before the state toxicology lab and the regional crime lab 

moved in, which was in the early 2000s. 

Employee Information

Number of employees at the time of our in-person evaluation: 28 toxicology lab employees and 

30 crime lab employees (2 crime lab employees analyzed seized drug evidence). 

Length of shift: 8 hours, Monday through Friday.

Union: Yes. 

History of Issue at Workplace

Previous Issues

Because of space constraints and increased demand, the toxicology lab had recently expanded into a 

laboratory and office space formerly used by the crime lab (annex space). This annex space was across 

the hallway from the toxicology labs and offices. Following this expansion, the toxicology lab division 

discovered that biological evidence extracts analyzed in the toxicology lab by employees occupying the 

annex offices contained methamphetamine. However, repeat confirmation testing done on these 

samples was negative for methamphetamine. An investigation to find the cause of these discrepant test 

results found that all samples were handled by forensic scientists occupying the office areas of the 

annex space. Toxicology lab management then removed all toxicology lab personnel from the annex 

space.

During further investigation to find the origin of the discrepant result, management learned that 

methamphetamine synthesis was used as a training tool in the annex space in the early 2000s. The 

agency hired a remediation contractor to clean the annex office areas, vestibules, and hallway. Although 

toxicology lab personnel no longer occupied the annex offices or labs, discrepant results for

methamphetamine were still identified, with confirmation testing confirming no methamphetamine in 

samples that had initially tested positive for methamphetamine. 
A-2

Request Basis

Past surface sampling found detectable levels of methamphetamine, cocaine, and other drugs on 

surfaces in the toxicology lab and the annex space. The annex office, vestibules, and hallway were

cleaned by a remediation contractor; the annex office was subsequently renovated. The toxicology lab 

was cleaned by a remediation contractor and by lab management. Toxicology lab management was 

concerned about the potential for adverse health effects from unintentional employee exposure to illicit 

drugs that could result from these detectable levels on surfaces.

Process Description

Toxicology Lab 

• State and local law enforcement agencies, medical examiners, coroners, and other governmental 

entities submitted biological evidence to the state toxicology lab to analyze for the presence of drugs 

or alcohol. These results could help determine if drugs or alcohol contributed to a crime or a death. 

• Submitted biological evidence was most commonly blood or urine. Blood samples went into blood 

collection tubes and urine samples into cups, and then they were properly packaged and labeled. 

Tissues and other body fluids might also be submitted for analysis. Rarely, nonbiological evidence 

might also be submitted for testing.

• Biological evidence samples were shipped or hand-delivered to the property and evidence custodian 

at the facility. The custodian recorded received evidence into the laboratory database, secured the 

evidence in the toxicology lab evidence vault, and managed evidence release into and out of the 

evidence vault.

• Forensic scientists analyzed received evidence for the presence of drugs or alcohol. Forensic 

scientists analyzed a set (approximately 30) of evidence samples in vials at one time for analytes 

based on written lab protocols. Depending on the analyte(s) of interest, the forensic scientist 

prepared samples in laboratory fume hoods and ran extracts of the sample on analytical instruments 

in the instrument room. Generally, scientists used analytical techniques including immunoassays, gas 

chromatography-mass spectrometry, and liquid chromatography with tandem mass spectrometry or 

time of flight mass spectrometry to identify drugs in evidence samples. Evidence analyzed for 

alcohol and volatiles used headspace gas chromatography.

• Samples that were being processed were stored in a secure, locked refrigerator in the toxicology lab

when not in use. 

• When completed, forensic scientists returned evidence to the evidence room. In most cases, 

evidence was returned to the submitting entity after the required retention period. If permission was 

given by the submitting entity, the evidence was disposed of. 

• Scientists concluded a case by writing results into a report, which was then issued to the submitting 

entity.
A-3

• Depending on analysis progress, forensic scientists might only work in the lab for part of their shift 

or not at all. Scientists wrote reports on personally assigned computers located in designated cubicle 

spaces in the toxicology division offices.

In 2020 and 2021, the state toxicology lab received approximately 16,000 cases per year. About two

thirds of cases pertained to impaired driving, and one third were coroner and medical examiner cases.

Crime Lab

Analyzing suspected seized drugs in the crime lab typically involved the qualitative examination of 

suspected drug evidence to see if the material contained a controlled substance, designer drug, or other 

drugs of known forensic interest. The analysis combined techniques such as recording weights, 

performing chemical extractions, and using instruments. At least two uncorrelated analytical techniques 

were used to conclusively identify a seized drug. Other forensic scientists in the crime lab system 

analyzed genetic material, firearms, and other evidence items related to criminal offenses.
B-1

Section B: Methods, Results, and Discussion

Our objectives were as follows:

• Evaluate the extent of work-related exposure to methamphetamine, cocaine, fentanyl, and 

heroin among forensic scientists.

• Evaluate the prevalence of work-related symptoms among employees in the toxicology lab and 

the crime lab.

• Identify and evaluate controls to protect forensic scientists and laboratory managers from 

exposure to controlled substances.

Methods: Health and Safety Program and Document Review

We reviewed the following documents from the toxicology lab division:

• Safety and Wellness Manual (dated Jan 2018)

• Safety Plan (dated Oct 2021) 

• Operations Manual (dated Oct 2020)

• Amines Test Method Standard Operating Procedure (SOP) (dated Apr 2020)

• Basic Drugs Testing Method SOP (dated Aug 2018)

• Cocaine Test Method SOP (dated Sep 2018)

• Fentanyl Test Method SOP (dated Apr 2021) 

• Fentanyl Screening SOP (dated Apr 2021)

• Testing Quality Assurance Manual (dated Oct 2021)

We reviewed the following documents from the crime lab division:

• Safety and Wellness Manual (dated Jan 2018)

• Safety Orientation Checklist (dated Apr 2020)

• Quality Operations Manual (dated Aug 2020)

• Safety Manual (dated Apr 2017)

• Laboratory Response Technical Procedures (dated Nov 2017)

• Covid Cleaning Protocols (no date)
B-2

Results: Health and Safety Program and Document Review

Both Labs

The safety and wellness manual applied to both the toxicology lab and the crime lab. This manual discussed

broad safety and health topics such as respiratory protection program elements and general PPE usage. 

The manual also outlined the roles and responsibilities of health and safety personnel. It dictated that 

supervisors should ensure employees have proper training, receive appropriate PPE, and use and 

maintain PPE as required. The manual also specified disinfecting work surfaces after completing

procedures. In addition, the manual stated that reusable items should undergo scheduled 

decontamination as well as immediate cleaning when visibly contaminated.

Toxicology Lab

The toxicology lab division’s operations manual detailed the operational responsibilities of the testing 

laboratory. It listed personnel responsibilities and mentioned that “supervisors will ensure that 

employee training meets or maintains competency requirements,” however, it did not list specific 

training requirements. The testing quality manual detailed equipment maintenance requirements but did

not mention cleaning or decontaminating equipment.

We reviewed the SOPs for the testing of amines, basic drugs, cocaine metabolites, and fentanyl. While 

the cocaine metabolites testing procedures mentioned that using a fume hood was required, no other 

controls or PPE were listed as requirements in the other SOPs.

The safety plan outlined the safety and health program for the toxicology lab division. This document 

listed which personnel and processes had the potential to be exposed to infectious, toxic, or hazardous 

materials. The document further detailed the potential routes of exposures and the events (such as 

broken glassware) that could lead to such exposures; these were separated into biological and chemical 

hazards.

In the biological laboratory safety section, protective measures included “general attention to laboratory 

cleanliness and hygiene” but did not list strategies on how to achieve this goal. Scientists were instructed 

to handle tubes with biological specimens under vacuum. They were also told to conduct procedures 

with high potential for generating droplets (blending, sonicating, vigorous mixing, vortex-mixing) and

procedures involving hazardous substances (including biological specimens, derivatizing agents, acids, 

bases, and solvents) in fume hoods with the sash down. The required PPE listed included lab coats, 

impermeable gloves, and “some type of eye/face protection.” Employees were instructed to change 

gloves “as needed, to prevent cross contamination,” but the plan offered no specific guidance on how 

to prevent cross contamination.

This section also discussed universal precautions such as not eating, drinking, or handling cosmetics or 

contact lenses in the lab area. It also required employees to wash hands after working with biological 

specimens and before leaving the lab. In the plan, scientists were prohibited from wearing soiled lab 

coats in public areas. The plan did not include guidance on when to discard and replace disposable lab 

coats.

Work surfaces and utensils used for biological materials were required to be decontaminated with 

bleach solution daily or after completion of a procedure. All spills were to be cleaned promptly and with 
B-3

impermeable gloves and other appropriate protective clothing, although the exact PPE is not 

mentioned. Later in the section, it mentioned that gloves should be changed and hands washed after 

completing each specimen.

Medical waste, defined as “blood, human tissue, or any gloves, wipes, absorbent pads, disposable tubes 

or pipettes, rags or disposable glassware, or other items contaminated with blood” was to be disposed 

in appropriate medical waste containers.

The chemical laboratory safety section offered information on elements of safety operation, along with 

storage and spill instructions. This section built upon the biological hazard section and provided broad 

information on wearing PPE but did not elaborate on PPE for specific chemical hazards. For example, 

this section specified that “protective glasses should be worn to guard against ultraviolet and infrared 

exposure” but did not specify which protective glasses and where this exposure may occur.

Crime Lab

The safety manual was designed to protect employees from potential health hazards in the laboratory. 

This document designated safety personnel, discussed control measures and detailed the chemical 

hygiene program. To avoid potential contamination from chemicals or evidence, the personal hygiene 

section of this document restricted eating, drinking, smoking, or applying cosmetics in any lab area 

unless designated by the lab manager. Hand washing was recommended after contact with evidence, 

chemicals, or any other hazardous materials, as well as after working at any hood. Hand washing was

also recommended before exiting the lab to common areas.

The safety manual specified that fume hoods were the primary engineering control in the lab and should 

be used for operations that might result in the release of toxic or hazardous chemical vapors or dust. 

Examples of chemicals of moderate and high chronic or high acute toxicity listed included 

diisopropylfluorophosphate, hydrofluoric acid, and hydrogen cyanide. The manual emphasized the use 

of fume hoods when handling chemicals but did not specify if or what types of drug evidence should be 

handled in fume hoods. The manual instructed scientists to clean hoods after each use. In addition, the 

manual stated that fume hoods should be evaluated quarterly to ensure a face velocity of 60 to 100 feet 

per minute (fpm), and that a contractor should inspect fume hoods annually to ensure performance.

The PPE section of the safety manual required removing rings and dangling jewelry and tucking away 

loose hair during laboratory operations. In general, scientists should “wear eye and hand protection and 

a laboratory coat.” This section also dictated that lab coats and shoes be worn while using hazardous 

chemicals and that lab coats be removed before entering common areas. This section recommended

appropriate eyewear when handling potentially hazardous materials. The eye protection required for 

these operations was to be determined by the lab manager. Gloves were similarly recommended as 

necessary. The guidelines for gloves included properly selecting and inspecting gloves based on the 

permeability of common chemicals. Gloves were to be replaced periodically depending on the 

frequency of use and permeability of the substance being used. Scientists were instructed to “avoid 

touching doorknobs, draw handles, or other common-use items that may later be touched by ungloved 

individuals” and to remove gloves before eating or leaving the laboratory. Respirator use was voluntary 

only, but information about the types of respirators available was detailed in the manual.
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The lab housekeeping section of the safety manual recommended cleaning and disinfecting countertops 

as appropriate. It further stated that cleaning “should be done at the end of an operation or the end of 

each day,” and equipment should be returned clean and ready for use. However, the manual did not

mention cleaning in between testing or when there is visible contamination.

Methods: Employee Health Assessment

Confidential Medical Interviews

During our virtual visit, we invited 17 toxicology and 17 crime lab employees to participate in 

confidential semi-structured medical interviews by randomly selecting a representative sample based on 

job titles. Interviews covered basic demographics, work history and practices, health and safety 

concerns, PPE use, training, and possible work-related health effects or direct exposure to controlled 

substances during the 3 months preceding our virtual visit.

Written Questionnaires

We used the results of the virtual interviews to design a written questionnaire that we administered 

during our in-person visit. We invited all forensic scientists, laboratory technicians, laboratory aides, and 

property and evidence custodians from the toxicology lab to participate. We also invited crime division 

employees who handle bulk drugs (two employees total) working on the third floor to complete a 

written questionnaire. Questionnaires covered basic demographics, work history and practices, training 

history, PPE use, cleaning practices, possible work-related health effects, controlled substance direct 

exposure incidents, and health and safety concerns. In total, 23 employees participated in the written 

questionnaire; all were from the toxicology lab division.

Findings from interviews and written questionnaires on training, PPE use, and cleaning are reported 

separately as contributions to the assessment of work processes, practice, and conditions.

Results: Employee Health Assessment

Confidential Medical Interviews

As part of our virtual site visit, 34 employees working across the toxicology and crime lab divisions 

participated in confidential medical interviews. This included 20 scientists, 5 supervisors, 6 laboratory 

technicians or property and evidence custodians, and 3 administrative assistants. Of the 34 employees, 

26 (76%) were female and 8 (24%) were male, and the median age was 41 years (range: 32–45 years). 

Demographic information and data on job characteristics for both toxicology and crime lab employees 

interviewed are in Table C1.

Of 17 toxicology division employees interviewed, median job tenure was 5 years (range: 6 months–21 

years), and the median number of work hours per week was 40 (range: 40–62 hours per week). Of 

17 crime division employees interviewed, median job tenure was 17 years (range: 1–26 years), and the 

median number of work hours per week was 40 (range: 30–50 hours per week).

Of 17 crime division employees, 2 (12%) reported a direct skin, respiratory, or mucous membrane 

exposure to suspected illicit drugs at work. One of the two could not recall the specifics of the exposure 

incident. The other employee reported exposure to methamphetamine from synthesizing 
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methamphetamine for training purposes in the early 2000s. Neither employee reported any health 

symptoms or concerns from these exposures.

Although health symptoms from direct exposure to suspected illicit drugs were absent, across the 

toxicology and crime lab divisions, 11 of 34 (32%) employees reported one or more work-related health 

symptoms (4 toxicology division employees and 7 crime division employees). Health concerns from 

work included headache (1), eczema (1), allergies (1), musculoskeletal issues (5), and mental health 

issues (3). Most musculoskeletal issues were reported to be from poor ergonomics.

Written Questionnaire

During our in-person visit, 23 forensic scientists, laboratory technicians, laboratory aides, and property 

and evidence custodians working in the toxicology lab division completed a questionnaire (Table C2). 

Of the respondents, 19 (83%) were female and 4 (17%) were male. The median age of the respondents 

was 42 years (range: 25–58 years), and median job tenure was 4 years (range: 3 months–21 years). For 

the 2 weeks prior to our visit, the respondents worked a median of 40 hours per week (range: 16–45 

hours per week).

None of the 23 employees who participated in the written questionnaire reported any health symptoms 

from direct exposure to suspected illicit drugs.

Methods: Work Processes, Practices, and Conditions

We observed the following in the toxicology lab and regional crime lab:

• Work processes, work practices, and workplace conditions

• Employee use of PPE

Self-reported use of PPE, cleaning, and hygiene practices were collected from interviews with 

toxicology and crime lab employees and from written questionnaires with toxicology lab employees as 

described in the previous section.

Results: Work Processes, Practices, and Conditions

Work Processes and Practices

Both Labs

Reported cleaning practices were gathered from both interviews and the written questionnaire. Most 

interviewed employees reported cleaning at work (n = 29 of 34, 85%). Areas cleaned included 

laboratory benchtops, fume hoods, tools, equipment, and other work areas in the laboratory. All 

employees who reported cleaning reported wearing some form of PPE such as gloves, lab coats, and/or 

gowns. Solutions used for cleaning varied and included water, diluted bleach, detergent, diluted ethanol, 

and methanol.

Toxicology Lab

Work descriptions included laboratory and office work with employees spending 5% to 100% of their 

time in the laboratory areas. Laboratory employees’ reported work activities included extraction of 

drugs and alcohol from biological specimens (blood, urine, serum), accepting and inventorying samples, 
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making reagents, and performing proficiency testing on samples from external agencies. Office work 

included data review, data analysis, report write-up, and training. Of the 17 toxicology division 

employees who participated in interviews, 4 (24%) reported a direct skin, respiratory, or mucous 

membrane exposure to suspected illicit drugs at work. In two of those four exposures, a sample spilled 

or splashed onto the employee. The remaining two reported exposures were from general handling of 

samples in the toxicology lab vault and in the annex area. None of the employees reported health 

symptoms from the exposures.

In the toxicology lab, employees shared 11 laboratory workstations, each containing a laboratory 

benchtop, a fume hood, and equipment for sample and reagent preparation. Although each scientist did 

not have a dedicated workstation, they did have preferred areas and generally used the same one or two 

workstations. Shared lab equipment included evaporators, centrifuges, vacuum manifolds, incubators, 

and analytical instrument workstations. Analytical instrument workstations were in the instrument room 

in the toxicology lab and consisted of an analytical instrument (e.g., gas chromatograph-mass 

spectrometer) connected to a computer with a monitor, keyboard, and mouse. Two laboratory 

workstations were dedicated to analyzing alcohols and other volatile substances. These were separated

from the other 11 laboratory workstations and were shared among toxicology lab forensic scientists.

Scientists might spend only part of the working day in the lab or might conduct lab work on one day 

and write reports another day at their desk in the toxicology division offices. Of the 23 respondents 

who completed a written questionnaire, all worked with biological samples either in the laboratory or 

the toxicology lab storage vault room. Median hours worked in the lab or vault were 10 hours per week 

(range: 10 minutes–35 hours). The flow of work was determined by the individual scientist. Scientists 

prepared reagents, control solutions, and biological sample extractions in batches in the fume hood of 

laboratory workstations. Biological evidence requiring the same analyses were batched together.

Scientists prepared reagents by dissolving compounds into a solution. They used these reagents to 

prepare samples for analysis on various analytical instruments. We observed instances of dry reagent 

spilling out of its large container while a scientist prepared reagent solution. Reagents, controls, and 

biological samples in tubes were often vortex-mixed to ensure samples and solutions were fully mixed. 

We observed instances of scientists vortex-mixing solutions using gloved thumbs instead of caps to 

cover the tops of tubes. After samples were extracted, this extract was placed into autosampler vials for 

analysis using analytical instrument workstations.

The median number of samples handled over the 2 weeks preceding our visit was 90 (range: 0–10,000). 

Employees reported samples contained methamphetamine, cocaine, tetrahydrocannabinol (THC), 

heroin, and other drugs (e.g., fentanyl, benzodiazepine, morphine, oxycodone, opioids, amphetamine, 

and other amines) (Table C3). The median number of samples processed under a fume hood was 

74 (range: 0–300) with most employees (n = 18 of 23, 78%) reporting using the hood to process all 

their samples. Use of a fume hood to process samples was reported to be the default procedure, 

especially for samples containing possible bloodborne pathogens or biohazards.

We observed waste that potentially contained bloodborne pathogens being placed in biohazard waste 

bins located at each workstation and throughout the laboratory. Waste not containing bloodborne 

pathogens was discarded in the regular trash stream. Most toxicology lab employees reported receiving 
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training on proper handling and disposal of biological samples on the written questionnaires (n = 20 of 

23, 87%). Fewer employees reported receiving training on cleaning and decontamination procedure for 

handling samples with suspected illicit drugs (n = 15 of 23, 65%). More than half of toxicology lab 

employees felt that training needs to be improved (n = 13 of 23, 57%).

In the toxicology laboratory, methanol was reported as the cleaning solution chosen most often for 

cleaning surfaces before and after lab work and after fume hood use. We observed scientists frequently 

wiping down surfaces with 50% methanol and deionized water. Because of the batched nature of lab 

work, it was unclear when scientists wiped down bench and hood surfaces during analysis. We observed 

scientists cleaning surfaces at the beginning and end of the day. We also observed a variety of cleaning 

solutions available in the lab, some specifically for removing infectious agents. According to 

management in April 2021, the staff deep cleaned the fume hoods but the method and cleaning agent 

used for this deep cleaning were unclear. After this deep cleaning, the lab implemented cleaning logs to 

document daily hood cleaning. We observed that these logs were not filled out every day and did not 

indicate when or if a fume hood was used on a particular day.

From the written questionnaires, 14 of 23 (61%) toxicology lab employees reported cleaning in the 

2 weeks prior to our visit (Table C4). The areas cleaned included lab benches (n = 13), hoods (n = 11), 

common lab areas (n = 7), and shared equipment (n = 4). Most respondents who cleaned reported 

cleaning more than one area (n = 11 of 23, 48%) and reported cleaning several times a day (n = 9 of 23, 

39%). Types of cleaning included using a wet cloth or paper to wipe surfaces (n = 13), removing 

biohazards or other waste (n = 8), using a dry cloth to wipe surfaces (n = 2), and other types of cleaning 

(n = 2). Cleaning solutions used were methanol (n = 12), disinfectant wipes (n = 11), bleach (n = 10), 

and water (n = 4). Almost all employees who reported cleaning (n=14) also reported receiving guidance 

on using methanol or bleach for cleaning fume hood surfaces (n = 13 of 14, 93%).

Employee hygiene practices were analyzed based on written questionnaire responses. Of 23 toxicology 

lab employees, 14 (61%) reported that they always washed their hands upon entering or leaving the 

laboratory, 8 (35%) reported sometimes washing their hands upon entering or leaving the laboratory, 

and 1 (4%) did not answer this question (Table C4). Hand washing after glove removal was reported by 

21 of the 23 (91%) employees: 11 of 23 (48%) reported always washing their hands after glove removal,

and 10 of 23 (43%) reported sometimes washing their hands after glove removal. Most toxicology lab 

employees (n = 16 of 23, 70%) reported always washing their hands before eating or drinking and 7 of 

23 (30%) reported sometimes washing their hands before eating or drinking. None of the respondents 

reported ever eating in the laboratory area.

Scientists shared concerns about dirt and unknown debris falling out of the vent covers in the 

toxicology lab and potential exposures to solvents in the instrument room.

Crime Lab

Work descriptions included laboratory, office, and field work. Laboratory employees’ reported work 

activities included creating and making reagents, cannabis quantification testing, examining and testing 

evidence (bullets, firearms, cartridges, etc.), and DNA extraction and testing.

In the crime lab material analysis section, forensic scientists analyzing seized drug evidence each had 

their own laboratory workstation. A laboratory workstation consisted of a laboratory benchtop, fume 
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hood, computer with monitor, keyboard, and mouse. Scientists shared analytical instrument 

workstations consisting of an analytical instrument connected to a computer with a monitor, keyboard, 

and mouse. For some analytical instrument workstations, each of the two scientists had their own 

workstations due to the low number of scientists analyzing seized drug evidence.

Forensic scientists collected submitted drug evidence from evidence storage on the second floor of the 

building and transported it into the lab on the third floor. Unlike in the toxicology lab division, crime 

lab forensic scientists work on one case at a time. We observed scientists placing barrier paper on the 

laboratory bench and opening packaged evidence on this paper to prevent substances from 

contaminating the bench. Scientists emptied containers of powdered and crystalline drug evidence onto 

weighing paper and weighed the contents to record a net weight. According to laboratory protocols, 

scientists were able to forego collecting net weights. Instead, they could record the weight with the

packaging if the scientist suspected that contents could be a safety risk and note how the amount of 

drug evidence was assessed. We only observed scientists weighing evidence after removal from 

packaging.

For pills and tablets, scientists counted the number of pills or tablets. Scientists took a sample from the 

evidence for analysis and repackaged the remainder of the evidence. The sample taken depended on the 

form of the evidence, a small amount of powder or crystal from powdered or crystalline drugs, or a 

single pill or tablet from a number of pills or tablets. We observed scientists working in fume hoods 

when adding reagents to drug evidence or handling solvents. We observed scientists changing nitrile 

gloves frequently throughout casework.

For certain types of analyses involving compounds in solid form (e.g., infrared spectroscopy), scientists 

transported the sample to the analytical instrument workstation on pieces of weighing paper. After 

analyses, the barrier paper and the remaining sample was disposed of in the trash. Gloves were also 

disposed of in the trash. Scientists cleaned surfaces and equipment with a methanol solution after each 

discrete case. Contracted janitorial staff emptied the trash and removed it from the crime lab. We 

observed naloxone kits available for use in the event of an opioid-related emergency.

In the crime lab, we noted the presence of vacuums without high efficiency particulate air (HEPA) 

filtration. We also noted the presence of a can of compressed air near a scientist’s workstation.

Employee Use of Personal Protective Equipment

Self-reported use of PPE reported in confidential interviews included responses from both toxicology

and crime lab employees. Responses from written questionnaires only included toxicology laboratory 

employees.

Both labs

From interview responses, PPE used most frequently in the toxicology and crime labs were gloves, 

gowns or laboratory coats, safety goggles, and respirators (including masks or filtering facepiece 

respirators). Other types of PPE were worn with less frequency. Only crime lab employees reported 

wearing Tyvek suits, hair nets, disposable sleeves, face shields, and full facepiece respirators.

Most interviewed employees reported wearing lab coats or gowns at work (n = 30 of 34, 88%). A 

majority wore disposable gowns (n = 20 of 30, 67%) but some wore lab coats (n = 8 of 30, 27%) and 
B-9

some wore both (n = 2 of 30, 7%). Of the 30 employees who wore lab coats or gowns, 12 (40%) 

reported always wearing them for specific tasks such as performing DNA extractions, handling messy 

crime evidence, cleaning, or opening samples. The rest wore them occasionally and not with every task.

Safety glasses were worn with varying degrees of frequency. From confidential interviews, 25 employees 

(13 toxicology lab and 12 crime lab) reported wearing safety glasses at work; 10 of the 25 reported 

wearing glasses for specific tasks, such as waste disposal, opening biological samples, testing firearms, 

performing DNA extractions, and filling liquid nitrogen.

In response to questions on mask use, 22 employees (7 of 17 toxicology lab and 15 of 17 crime lab) 

reported wearing masks at work. Toxicology lab employees reported wearing either surgical/disposable 

masks (n = 1) or cloth masks (n = 2) while crime lab employees reported wearing surgical/disposable 

masks (n = 5), KN95 or unfitted N95 respirators (n = 4), and full-face respirators with dual filters 

(n = 1). Of 22 toxicology and crime lab employees who reported wearing masks at work, 9 (41%) did 

not specify what type of masks they wore. Most toxicology employees reported wearing masks as a 

COVID-19 precaution (6 of 7, 86%) while most crime lab employees reported wearing masks for 

specific tasks (12 of 15, 80%).

Toxicology Lab

Among 23 questionnaire respondents in the toxicology lab, 10 (43%) reported being without any PPE 

while in the lab 3–5 times a day during the 2 weeks prior, 6 (26%) reported being without PPE more 

than 5 times a day during the 2 weeks prior, 4 (17%) reported never being without PPE during the 

2 weeks prior, and 3 (13%) reported being without PPE 1–2 times a day during the 2 weeks prior

(Figure B1). The most frequent reason for why an employee chose not to wear any PPE was because 

they were not handling any samples, but five employees said they did not wear PPE because they were 

doing something quickly in the lab.

Figure B1: Frequency of employees being in the toxicology lab without wearing any PPE in the 2 weeks 

preceding our evaluation (n = 23). 

6

10

3

4

>5 times

3-5 times

1-2 times

Never

In the 2 weeks prior, most toxicology lab 

employees have been in the lab without 

wearing any PPE
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Toxicology lab forensic scientists wore disposable lab coats. We observed inconsistent lab coat use. We 

observed scientists not wearing lab coats when entering the lab for tasks that did not involve working 

with samples or at the hood. These tasks included obtaining samples and preparing for analysis. From 

written questionnaires, 14 of 23 (61%) toxicology lab employees reported wearing a lab coat or gowns 

with all tasks in the 2 weeks prior and 8 of 23 (35%) reported sometimes wearing lab coats or gowns in 

the 2 weeks prior.

There was a sign posted on the door between the toxicology offices and the vestibule with biosafety 

information. This sign stated that PPE was available for use but did not specify which PPE was 

required to enter the toxicology lab. Clean lab coats and eye protection were stored inside the lab near 

the vestibule door. Most lab coats were stored hanging in this vestibule connecting the toxicology 

offices with the toxicology lab. When hanging in the vestibule, lab coats were often touching one 

another. We observed some lab coats hung up at workstations near fume hoods and on the backs of 

chairs.

From 23 written questionnaires, 22 toxicology lab employees reported wearing lab coats or gowns at 

work. Of the 22 toxicology lab employees who reported wearing lab coats or gowns at work, 9 (41%) 

changed their lab coat/gown less than once a day or once a day, 5 (23%) changed their coat only when 

it got dirty, and 8 (36%) did not change their lab coat or gown at all in the 2 weeks prior to our visit or 

reported changing their lab coat once a week. Management and scientists noted the inability to source 

lab coats and nitriles gloves in correct sizes due to supply chain issues, which may have impacted the 

frequency of replacing or changing these PPE. About half (n = 12 of 22, 54%) of the toxicology lab 

employees who reported wearing lab coats or gowns at work reported receiving training or written 

guidance on when to wear lab coats or gowns or how frequently to change them; 3 of 22 (14%) 

reported no training or communication on lab coat or gown use, and 7 of 22 (32%) said they did not 

know of any training or written policies and procedures on use of lab coats or gowns (Figure B2).

We observed eye protection (safety glasses) being worn inconsistently while employees conducted lab 

work. While in the lab but not conducting lab work, few scientists wore eye protection. We also 

observed scientists handling eye protection with gloved hands. Of 23 employees who completed written 

questionnaires, 12 (52%) toxicology lab employees reported always wearing eye protection in the lab, 

7 (30%) reported sometimes wearing eye protection in the lab, and 4 (17%) reported never wearing eye 

protection in the lab. Of 19 employees who reported always or sometimes wearing eye protection in the 

lab, 2 (11%) reported wearing it because of personal preference, 12 (63%) reported wearing for specific 

job duties, and 5 (26%) reported wearing for both specific job duties and because of personal 

preference. Figure B2 summarizes written questionnaire information. Most employees who reported 

wearing eye protection said they received training or written policies and procedures on when to wear 

eye protection (n = 14 of 19, 74%); 1 of 19 (5%) reported no training or communication on use of eye 

protection, and 4 of 19 (21%) reported that they did not know of any training or written policies and 

procedures on use of eye protection.
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74%

54%

57%

5%

14%

13%

21%

32%

30%

Safety glasses or

goggles

(N=19)

Gowns or lab coat

(N = 22)

Gloves

(N = 23)

Up to a third of toxicology lab employees did not know if 

there is any training or written policies on the PPE they use

Yes No Don't Know

Figure B2: Knowledge of training or written policies on the use of gloves, gowns, or safety glasses as 

reported by toxicology lab employees. 

All toxicology lab employees reported glove use. Written questionnaire responses were similar to 

findings from the confidential interviews with 21 of 23 (91%) toxicology lab employees reporting that 

they always wore gloves and 2 of 23 (9%) employees reporting that they sometimes wore gloves in the 

laboratory. Most employees (n = 19 of 23, 83%) changed gloves several times a day. Three employees 

reported changing gloves depending on the level of self-assessed contamination on their gloves. We 

observed most scientists changing nitrile gloves frequently, but this varied by scientist. We observed

scientists using gloved hands to type on transaction and analytical instrument keyboards.

Of 23 toxicology lab employees, 13 (57%) received training or written policies and procedures on when 

to wear gloves and how often to change their gloves; 3 (13%) reported no training or communication 

on glove use, and 7 (30%) stated that they did not know of any training or written policies and 

procedures (Figure B2). 

We did not observe any scientists using respirators during our visit and did not observe respirators 

being available in the lab. Scientists in the toxicology lab were not enrolled in a respiratory protection 

program. Written questionnaire responses from toxicology lab employees were similar to findings from 

confidential interviews with 9 out of 23 toxicology lab employees (39%) stating they wore masks at 

work, and 4 out of 9 employees (44%) reporting that they wore surgical or disposable masks. Eight of 

the nine employees (89%) who wore masks at work reported not having received any training or written 

guidance on when and where to wear a mask.

Work Conditions

At the end of our virtual interviews, we asked employees to share additional work-related health and 

safety concerns they had. Most (29 of 34) interviewed employees reported no additional concerns. 
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Among the remaining five employees, concerns included exposure to noise and carcinogenic chemicals, 

lack of airflow in the vault room, and general workflow disruption because of drug contamination 

concerns and legal proceedings.

Methods: Exposure Assessment

We assessed exposure based on past sampling reports, surface sampling, and handwipe sampling.

Past Sampling Reports

We reviewed past surface sampling results completed by a contractor before and after remediation 

events in the annex office area, vestibules, and hallway, and one of the fume hoods in the toxicology 

lab. We also reviewed past surface sampling results collected by toxicology management staff and

analyzed by a federal agency.

Surface Sampling

We sampled 60 surfaces throughout the third floor for methamphetamine, cocaine, fentanyl, and heroin 

using a swab wetted with methanol. We focused surface sampling on commonly touched surfaces and 

surfaces that may indicate if substance migration could have occurred. The sample area was 100 square 

centimeters (cm2) using a template on all surfaces except keyboards and door handles (including 

refrigerator and freezer door handles). On keyboard surfaces, we took a sample of approximately 

100 cm2. On door handles, we took a sample of the whole handle. Most surface samples were taken by 

the same NIOSH investigator, with a few exceptions including the vent covers in the toxicology lab.

Neither the federal government nor consensus organizations have set occupational standards limits on 

surfaces for methamphetamine, cocaine, fentanyl, or heroin. The U.S. Environmental Protection 

Agency (EPA) has developed voluntary laboratory cleanup protocols for methamphetamine and 

fentanyl [EPA 2021]. Some states have developed guidelines for remediation of spaces contaminated 

with methamphetamine. According to the EPA as of August 2021, 21 states require or recommend that 

methamphetamine labs be cleaned to meet a quantitative remediation standard. These state remediation 

standards range from 0.05 micrograms (μg) to 1.5 μg per 100 cm2 for methamphetamine, with the most 

common standard set at 0.1 μg per 100 cm2 [EPA 2021].

A company that manufactures fentanyl has developed a tentative workplace surface contamination limit 

of 1 μg fentanyl per 100 cm2 [Van Nimmen and Veulemans 2004]. The province of Alberta, Canada,

established a remediation benchmark on surfaces for fentanyl of less than 1.0 nanogram (ng) per 

100 cm2 for wipe samples, a value based on the lowest feasible limit of detection for fentanyl of 1 ng, 

not health considerations [EPA 2021]. Alberta has also established a remediation benchmark in air. 

According to the EPA as of August 2021, there are no state or federal standards in the United States for 

determining the successful remediation of fentanyl.

Handwipe Sampling

We took handwipe samples of 13 toxicology lab forensic chemists’ hands for methamphetamine, 

cocaine, fentanyl, and heroin before (prelab) and after (postlab) working in the lab. Participants were 

asked to wash hands thoroughly before the prelab handwipe sampling to remove potential drug 

contamination from nonlaboratory sources. Employees were allowed to wash their hands as they 

normally would during their work in the lab. Postlab handwipe samples were taken when the employee 
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ended work in the lab and before they washed their hands for the last time. For each employee, we 

sampled the palm side of both hands using a swab wetted with methanol. The same NIOSH 

investigator took all handwipe samples.

Results: Exposure Assessment

Past Sampling Reports

Remediation Contractor

After discovering biological sample extracts that were incorrectly identified as containing 

methamphetamine, toxicology lab management hired a contractor, certified by the state health 

department for drug lab decontamination, to provide remediation and decontamination services to 

some areas suspected of having elevated levels of methamphetamine on surfaces. The contractor 

collected surface samples before and after remediation activities. Surface samples were collected using 

disposable templates of 100 cm2 for discrete samples and 25 cm2 for composite samples on cotton 

gauze pads wetted with methanol. Most of the collected surface samples were discrete samples. The 

detection limit for surface samples was 0.030 μg per sample.

Pre-remediation surface sampling occurred on two separate occasions: June 2019 and November 2019. 

Pre-remediation surface sampling found multiple samples with detectable amounts of 

methamphetamine on surfaces in the annex space labs and office area, including in the vestibules and 

hallway. One pre-remediation sample with detectable amounts of methamphetamine was collected on 

the bypass grille of a fume hood in the toxicology lab. This same hood had been used to process some 

of the sample extracts that had been incorrectly identified as containing methamphetamine. Surface 

samples with levels that exceeded the state remediation standard for surfaces were collected from the 

floor of the annex lab, a vent cover (return grille) in the annex lab, and floors in the vestibules (2) and 

hallway (1) surrounding the annex labs and office area. Three surface samples collected in the annex 

office area also had detectable levels of cocaine. Carpet vacuum samples collected in February 2020 also 

found detectable levels of methamphetamine in the carpet near a vestibule door and in the annex office 

area.

In April 2020, the contractor performed decontamination and cleanup activities in the toxicology lab 

and annex office area, vestibules, and hallway. Details of how this cleaning was performed were not 

included in the documentation. The first set of post-remediation surface samples collected by the 

contractor found detectable amounts of methamphetamine on surfaces in the annex office area,

vestibules, and hallways. One sample, from the floor of the hallway, exceeded the state remediation 

standard for methamphetamine on surfaces of 1.5 μg per 100 cm2. The areas that were decontaminated 

before this first set of post-remediation surface samples was unclear from the contractor documentation 

provided by the toxicology lab management.

In May 2020, the contractor performed decontamination and cleanup activities in the annex office area, 

the vestibules, and hallways, and the hood in the toxicology lab. Decontamination activities for most 

surfaces were washing and rinsing of surfaces three times. The hood was also vacuumed with a HEPA 

vacuum before washing and again 48 hours after washing. For the annex office area, all remaining 

personal items and a metal bookshelf that had methamphetamine on a collected surface sample was 
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disposed of. All drop ceiling tiles, vent covers, and light bulbs were removed and disposed of. The 

ceiling tracks were washed and rinsed three times. The ductwork serving the area was cleaned with 

compressed air or powered soft bristled brushes.

The second set of post-remediation surface samples collected by the contractor found detectable 

amounts of methamphetamine on surfaces in the annex office area, vestibules, and hallway. All these 

results were under the state remediation standard for methamphetamine.

The final set of surface samples by the remediation contractor were taken March 2021 in the toxicology 

lab and labeled as “pre-remediation surface sampling” and identified one surface sample with detectable 

levels of methamphetamine. This sample was taken on the back wall of a fume hood, on a baffle near a 

slot where air would exhaust out of the hood. No other decontamination or remediation services were 

provided by the contractor.

Federal Agency

Toxicology lab management contacted the National Institute of Standards and Technology (NIST) to 

measure background levels of drugs on surfaces throughout the lab. In May 2021, toxicology lab 

management staff collected surface samples from 100 surfaces throughout the toxicology labs and 

offices. The materials and methods for this surface sampling differed from those used by the contractor 

and for this evaluation. The samples were collected on dry meta-aramid wipes from a surface area of 

approximately 5 inches by 5 inches using a template. Management staff were instructed to collect 

samples using one directional sweeping motion. The limit of detection for each surface wipe sample was 

10 ng per wipe.

Although not directly comparable to other results or to state remediation standards, these results 

provided information on surfaces that have had drugs particles on them. During this sampling event, 

surfaces sampled included door bench surfaces, hood surfaces, door handles, floors, and vent covers. 

There were detectable levels of methamphetamine on 3 of 4 instrument room supply vent covers and a 

main lab return vent cover. Cocaine was also identified on each of these surfaces; additionally, one other 

sample taken from a return vent cover in the toxicology lab detected cocaine but not methamphetamine 

in the sample.

Each quarter (3 months) since this initial sample collection, toxicology lab management staff or the 

agency industrial hygienist collected 25 surface samples throughout the toxicology lab for analysis by 

NIST. Subsequent quarterly surface sampling events did not find detectable levels of drugs. The 

locations of these samples were not listed in provided documents.

NIOSH Surface Sampling

Table C5 shows surface wipe sampling results collected in the toxicology lab, crime lab, annex lab and 

office area, and common areas on the third floor of the building for this evaluation. The reportable limit 

for each surface wipe sample is 1 ng or 0.001 μg per wipe.

Toxicology Lab

In the toxicology lab, the highest drug concentrations were found on surface wipe samples collected on 

vent covers (one supply and one return) containing methamphetamine (0.021 μg/100 cm2 and 0.044 

μg/100 cm2, respectively) and cocaine (0.0042 μg/100 cm2 and 0.0059 μg/100 cm2, respectively).
B-15

Of the four surface wipe samples collected on lab centrifuges, two had reportable concentrations of 

methamphetamine. Of 11 surface wipe samples collected on laboratory benches, 3 had reportable 

concentrations of methamphetamine. Of four surface wipe samples collected on door handles, one had 

a reportable concentration of cocaine.

The remaining surface wipe samples collected in the toxicology lab did not have reportable amounts of 

any of the four drugs. None of the surface wipe samples collected in the toxicology lab exceeded the 

state remediation guideline of 1.5 μg per 100 cm2 or the lower, more commonly used state or local 

remediation guideline for methamphetamine of 0.1 μg per 100 cm2 [EPA 2021]. No toxicology lab 

surfaces had reportable concentrations of fentanyl or heroin.

Crime Lab

In the crime lab, we collected surface samples to determine drug levels on surfaces used by forensic 

scientists analyzing bulk drug evidence. The highest levels of drugs were collected on surface wipe 

samples from hood sashes. Of the two samples collected on hood sashes, two had reportable 

concentrations of methamphetamine, cocaine, and heroin, and one contained fentanyl. Both laboratory 

bench surface samples had reportable concentrations of methamphetamine, cocaine, fentanyl, and 

heroin. Both surface samples collected from computer workstation keyboards had reportable 

concentrations of methamphetamine, cocaine, fentanyl, and heroin.

We collected surface samples to determine drug levels on commonly touched surfaces. Of three surface 

samples collected on door handles in the crime lab, two had reportable concentrations of 

methamphetamine, cocaine, and heroin.

We collected a surface sample at the bottom of the door between a crime lab vestibule and the shared 

hallway to determine if drugs were present. This surface sample had reportable concentrations of 

methamphetamine and cocaine.

Annex Lab and Office

In the annex lab, we collected surface samples to determine drug levels on surfaces that are commonly

touched by laboratorians or could indicate a history of drug particle movement. A sample collected on a 

hood surface had reportable concentrations of methamphetamine and cocaine. Of two samples 

collected on hood sashes, both had reportable concentrations of methamphetamine and cocaine, and 

one had reportable concentrations of heroin. A sample collected on a centrifuge also had reportable 

concentrations of methamphetamine and cocaine. A sample collected on a supply vent cover had 

reportable concentrations of methamphetamine and cocaine. A door handle had reportable 

concentrations of methamphetamine.

In the annex office area, a door handle between the office and the shared hallway had reportable 

concentrations of cocaine.

Common Areas

Two surface wipe samples were taken from the shared break room. A surface sample collected using a 

template placed on exhaust vents on the side of a free-standing microwave had a reportable 

concentration of methamphetamine.
B-16

Handwipe Sampling

Of 13 toxicology lab forensic scientists who participated in prelab and postlab handwipe sampling, none 

had reportable amounts of methamphetamine, cocaine, fentanyl, or heroin on their hands before 

entering the lab to conduct work or after leaving the lab for the day. The reporting limit was 1 ng or 

0.001 μg per sample for each of the four drugs.

Methods: Ventilation Evaluations

Virtual Ventilation Evaluation

Prior to the virtual ventilation evaluation, the following NIOSH equipment was shipped to laboratory 

management: TSI® Alnor Balometer Capture Hood EBT73, a fog generator to visualize the airflow at 

doorways, and a laser tape measure. With video conferencing, a NIOSH ventilation engineer guided the 

law enforcement agency industrial hygienist to measure airflow at all accessible ventilation duct grilles 

and covers in the toxicology and crime labs. Toxicology lab management had requested the evaluation 

of the annex lab only occur during the on-site evaluation to reduce the potential for migration of drugs 

from the annex lab into other areas. At doorways, the law enforcement agency industrial hygienist was 

instructed to determine the movement of air (into or out of the room) with the door open and closed. 

The volume of each room or area was also recorded.

On-site Ventilation Evaluation

We met with city facilities staff to review building ventilation specifications. A NIOSH ventilation 

engineer visually inspected and measured separation distances for rooftop air handlers and visually 

inspected above the drop ceiling in toxicology and crime labs for leaky or misconnected ducting and 

signs of concern.

We verified pressurization measurements collected during the virtual evaluation using a fog generator 

for toxicology and crime labs on the third floor. We selected fume hoods at random to confirm that 

instantaneous face velocity measurements displayed by the fume hood were correct by confirming face 

velocities with a TSI® VelociCalc Multi-Function Ventilation Meter 9565. We collected airflow 

measurements using a TSI® Alnor Balometer Capture Hood and visualized pressurization and airflow at 

doorways using a fog generator in the annex lab and office areas.

We reviewed photographs taken by the law enforcement agency’s industrial hygienist of a drug evidence 

storage vault on the second floor. This evidence storage vault was not served by building ventilation.

Results: Ventilation Evaluations

Some ventilation components and equipment were managed by the city, the owner of the building, and 

some components and equipment were managed by the law enforcement agency. The air handling units 

serving office and administration areas were on the east side of the building while the air handling units 

serving the laboratory areas were on the southwest side of the building. The laboratories were ventilated 

with a single pass system without recirculation. The exhaust systems were located on the northwest 

portion of the building. The separation distance between the laboratory exhaust and laboratory intake 

was 30.5 feet; the lab exhaust systems were directed upwards.
B-17

Facilities staff reported that regular maintenance was performed quarterly or semiannually depending on 

the unit, prefilter, or filter. Filtration had been increased as much as feasible, up to minimum efficiency 

reporting value (MERV) 13, for occupied areas of the building, to better protect against infectious 

disease spread. The visual inspection of ventilation systems and connections above the drop ceiling in 

the toxicology and crime labs found no obvious irregularities. All the observed exhaust ducting from 

the fume hoods were weld sealed and caulked where necessary. The fume hood exhausts were 

controlled by Phoenix Control valves that appeared to be functioning. There were no misconnected or 

leaking ducts or signs of animals.

On the toxicology side of the floor, air flowed into the toxicology lab at two doorways: the vestibule 

between the northern toxicology lab offices and the toxicology lab and the northern vestibule between 

the hallway and the toxicology lab. The northern door between the toxicology lab and the instrument 

room remained open during our visit. At this door and another door between the toxicology lab and the 

instrument room, air flowed from the instrument room into the toxicology lab. The instrument room 

also had a door leading directly into the shared hallway without a vestibule. At this door, we observed 

that pressurization was neutral, and air flowed both into and out of the instrument room from the 

shared hallway. These observations align with the volumetric airflow measurements in these rooms.

At the southern vestibule of the crime lab, air flowed from the lab into the hallway. The door between 

the crime lab and the vestibule remained open during our site visit. At this door, the airflow direction 

was inconsistent, flowing into the crime lab closer to the floor and neutral to flowing out of the crime 

lab at chest height. At the middle vestibule of the crime lab, air flowed from the crime lab into the 

vestibule and air flowed from the hallway into the vestibule. These observations aligned with the 

volumetric airflow measurements we collected.

At the annex lab vestibule, air flowed from the shared hallway into the vestibule. Air flowed from the 

annex office area into the vestibule between the annex office area and annex hallway. Air also flowed 

from the annex hallway into the crime lab.

Employees had reported ventilation and indoor environmental quality concerns in the crime lab 

evidence storage vault. With assistance from the agency industrial hygienist, we observed that air flowed 

out of the two side rooms in the evidence storage vault into the main evidence storage area, and from 

the main evidence storage area into the evidence technician office area. Air flow between the crime lab 

main evidence storage area and other areas were not evaluated.

We did not measure fume hood face velocities as part of our ventilation evaluation because lab 

management provided documentation of fume hood certifications performed by a contractor in 2020 

and 2021. When the contractor identified fume hoods that had face velocities outside of the laboratory 

ventilation standard of an average face velocity of 80–120 fpm [ANSI/ASSP 2022], they conducted the 

required maintenance or repairs and retested the fume hood to ensure compliance with the standard.

Discussion 

Although employees at this state police agency’s toxicology and crime labs reported no symptoms 

associated with acute exposure to illicit drugs, we identified the potential for unintentional exposure on 

contaminated surfaces.
B-18

Work Processes, Practices, and Conditions 

Exposure to illicit drugs can cause health effects. Known health effects of methamphetamine toxicity 

include activation of the sympathetic nervous system (dilated pupils, sweating, agitation, anxiety, 

elevated heart rate and blood pressure, heart arrhythmias, stroke, seizures, and high body temperature). 

Severe heroin and tetrahydrocannabinol exposure leads to activation of the parasympathetic nervous 

system (lethargy, slow breathing, slow heart rate, low blood pressure, and low body temperature)

[Becker 2012; Enevoldson 2004].

While the health effects associated with high levels of exposure to drugs are known, less is known about 

effects at low levels of exposure.

Occupational health best practice calls for minimizing exposure to these and other substances because 

of the known hazards at higher levels of exposure and the unpredictable nature and origin of the 

evidence. During our site visit, work practices that were inconsistent with the health and safety manual 

or incongruent with workflow processes created opportunities for potential drug exposure. For 

example, in the toxicology lab, we observed instances of scientists vortex-mixing solutions (including 

biological samples) without capping tubes, creating a potential for dermal exposure to illicit substances 

and bloodborne pathogens in biological samples. This practice also does not align with the practice of 

universal precautions.

The handling of drug evidence can lead to transfer of trace particulate onto various laboratory surfaces 

[Sisco et al. 2020a]. In the crime lab, we observed scientists placing barrier paper on the laboratory 

bench. While using barrier papers to prevent surface contamination is often standard practice in 

forensic laboratories, this may pose a greater risk for aerosolization of evidence being handled since 

transfer and disposal of barrier paper over the trash containers can create airborne drug exposure. We 

also observed crime lab employees collecting net weights. Because of the unpredictable form, amount, 

and contents of incoming evidence, measuring net weights poses a potential risk of hazardous 

substances exposure to forensic scientists, and may contribute to drug background levels and be a 

potential source of inhalation exposure [Sisco et al. 2020b]. Measuring net weight requires extra 

handling of uncontained evidence without the use of controls: removing substances from packaging, 

transferring substances to disposable weighing paper or a weigh dish, and placing this into and 

removing it from a balance. These steps create opportunities for spills and aerosolization that could lead 

to potential drug exposure. Although protocols allowed a scientist to forego collecting net weights and 

record the weight with the packaging if the scientist suspected the contents to contain a safety risk, this 

places the burden on scientists to perform a risk assessment every time they handle evidence. 

Additionally, past HHEs have observed that the suspected identity of evidence contents by law 

enforcement or forensic scientists may not align with its actual identity [NIOSH 2020a]. These 

exposures can be minimized if standard policy is to measure gross weights or encourage law 

enforcement agencies to consider not requiring measuring net weight as part of evidence analysis if it 

may not change the outcome of a criminal trial.

Scientists in both labs used a methanol solution to clean laboratory surfaces and hoods. A study by 

Sisco et al. [2019] found that cleaning with methanol removed nearly all (over 97%) drug residue or 

particulate from a phenolic resin surface, however, it is unclear if diluting methanol with water decreases 
B-19

efficacy. More research is needed to evaluate this and other factors that impact cleaning efficiency, 

including the force, direction, and frequency of cleaning. Sisco et al. [2019] emphasizes the importance 

of establishing appropriate cleaning procedures and protocols, stating that remaining surface 

background is likely the result of gradual residue buildup or from infrequent cleaning. For cleaning of 

large surface areas or surfaces expected to contain higher amounts of methamphetamine and fentanyl 

and potentially heroin and other illicit opioids, the EPA recommends a detergent-water solution 

[EPA 2021].

Training is another key element to an effective health and safety program. We found that more than 

half of toxicology lab employees felt that training needed to be improved. Suggestions by employees 

included making training more visual and interactive rather than reading manuals. This is in line with a 

study that found behavioral modeling as being more effective than other types of training [Burke et al. 

2006]. Behavioral modeling is a hands-on training method where the trainee observes a role model 

performing a task in a safe manner, practices the task, and then receives and incorporates feedback 

designed to improve safety when performing the task. Having clear guidelines and integrating training 

methods like behavioral modeling can prevent work-related unintentional exposure to illicit drugs 

among laboratory workers.

Strengthening training on PPE use can also minimize risk to potential drug exposure. Employees from 

both labs reported wearing gloves, gowns, and/or safety glasses most of the time. However, we 

observed inconsistent PPE use, unclear policies on PPE use and replacement, and improper storage of 

PPE, such as hanging lab coats side by side where they are touching each other. We also observed that 

employees can enter and exit the lab from vestibules that did not provide access to lab coats and other 

PPE, suggesting employees can enter the laboratory without any PPE. This is consistent with selfreports from toxicology lab employees as most reported having been in the lab without wearing any 

form of PPE in the 2 weeks prior to our visit.

When updating PPE guidelines, employers can take two approaches: a geographical approach or a taskbased approach. In a geographical approach, PPE standards are recommended and enforced by area. 

This can work well for the toxicology lab division where overall tasks are similar regardless of the 

sample contents and where we would expect trace amounts of drugs in the samples. About half of 

toxicology lab employees described wearing PPE for certain tasks while the rest cited a physical location 

(i.e., lab) as the reason for wearing their PPE. A clear policy of where and what PPE is required can 

help with adherence to PPE standards and minimize confusion surrounding why PPE is required.

Because of the variability in incoming evidence, task-based protocols may be more effective for the 

crime lab division. Guidance on what PPE should be used for a specific type and amount of evidence 

and associated handling practices can reduce exposure. Policies on how scientists should process 

evidence and should notify scientists working nearby when they are processing evidence items that 

could result in unintended exposure can also help with risk assessment and risk management in the 

laboratory. PPE should always be used in the context of an overall health and safety program that 

provides adequate training, retraining, and periodic testing of the workers’ knowledge of the proper use 

of PPE.
B-20

Exposure Assessment

Few surfaces in the toxicology lab had reportable amounts of drugs. Methamphetamine was identified 

on laboratory surfaces, with the highest amount found on a supply vent cover in the instrument room 

and a return vent cover in the main lab. The presence of methamphetamine and cocaine found on the 

supply vent cover does not determine that drugs have been in or have been transported by the building 

HVAC systems but could also be from particles adhering to the surface of the vent cover. 

Methamphetamine and cocaine were found on the supply and return air vents indicating that these 

substances were in the lab air in the past. Although the amounts of methamphetamine were highest on 

the vent covers in the toxicology lab, the amount was low relative to other surfaces where drugs were 

detected. No surfaces in the toxicology lab had levels exceeding the state remediation guideline for 

methamphetamine.

A study evaluating background drug levels in forensics labs found that in toxicology labs, 

methamphetamine was present on less than 20% of surfaces sampled (average concentration of 

between 0.0 and 0.1 ng per cm2). Cocaine was found on just over 20% of surfaces sampled (average 

concentration under 0.1 ng per cm2) [Sisco and Najarro 2019]. In this evaluation, the highest amounts 

of drugs identified in the toxicology lab were found on surfaces related to drug standards preparation.

Lower levels were found on or near analytical instrumentation, another area where drug standards might 

be used.

In the crime lab, we found reportable levels of drugs on most surfaces where drugs are handled. This is 

expected due to the nature of the work [NIOSH 2020a,b; Sisco and Najarro 2019; Sisco et al. 2018]. 

Areas commonly used for analyzing drugs had the highest levels of drugs, including hood sashes, 

laboratory bench surfaces, and keyboards. A sample taken of the bottom of the door where we 

observed that air flowed from the crime lab into the shared hallway found detectable levels of 

methamphetamine and cocaine, supporting that pressurization is important to preventing the migration 

of substances out of the crime lab. One sample, collected on the surface of a hood sash, exceeded the 

state remediation level and the health-based remediation standard established by California for 

methamphetamine of 1.5 μg per 100 cm2. No other samples collected exceeded this state limit.

In a study sampling areas inside and outside of a crime lab, sampling from areas outside of the crime 

lab, where lower levels of drugs were found on surfaces, showed that 48% of all samples contained 

methamphetamine (range: 0.004–1387.45 ng per cm2), and 82% of samples contained cocaine (range: 

0.002–412.4 ng per cm2) [Sisco and Najarro 2019]. Two past health hazard evaluations (HHEs)

conducted in forensic labs evaluating drug evidence found methamphetamine in 89% (17/19, range: 

0.0017–1.6 μg per 100 cm2) and 100% (39/39, range: 0.0088–59 μg per 100 cm2) and cocaine in 100% 

(19/19, range: 0.026–5.8 μg per 100 cm2) and 100% (39/39, range: 0.004–6.6 μg per 100 cm2) of surface 

wipe samples collected in the crime lab [NIOSH 2020a,b]. The levels of methamphetamine and cocaine 

found in the crime lab were within the ranges found in the prior evaluations. In the toxicology lab in 

this HHE, methamphetamine was found in 18% (7/40) samples and cocaine was found in 8% (3/40) 

samples. The reportable limit (also the detection limit) for the sampling wipes used in this HHE was 

1 ng per wipe, lower than those used by Sisco and Najarro [2019].
B-21

The amount of fentanyl found in the crime lab on a hood sash, two laboratory bench surfaces, and two 

keyboards exceeded the benchmark for fentanyl remediation of under 1 ng per 100 cm2 (or 0.001 μg per 

100 cm2) established by Alberta, Canada [EPA 2021]. This established limit is not health-based. The 

EPA notes that health-based limits may be lower than this limit depending on the fentanyl analog. We 

found no detectable amounts of fentanyl on any other surface samples. Occupational limits currently do 

not exist for illicit drugs on surfaces. However, prudent occupational health practice would be to 

implement and improve strategies to minimize levels on surfaces to reduce potential exposures.

In the annex lab, levels of methamphetamine were below the state remediation guideline of 1.5 μg per 

100 cm2. A surface sample collected from the hood surface and hood sash exceeded the most 

commonly adopted state remediation guideline of 0.1 μg per 100 cm2 [EPA 2021]. These results align 

with the post-remediation surface samples collected by the remediation contractor. Cocaine was 

detected in most samples where methamphetamine was detected, and heroin was detected in a sample 

collected on the hood sash.

We collected two samples in the break room to see if drugs had migrated to common areas where they

were not handled. A sample collected at the microwave exhaust found levels just about the reportable 

limit, suggesting that low amounts of methamphetamine had been present in the air.

None of the wipes collected from toxicology lab scientists’ hands before and after they conducted work 

in the lab had reportable amounts of methamphetamine, cocaine, fentanyl, or heroin. This suggests that 

despite reportable levels of these drugs found on surfaces throughout the floor, scientists have minimal 

to no exposure from touching surfaces and are not likely to have much or any take-home exposure.

Ventilation

Airflow can facilitate or reduce the movement of particles between spaces. We observed that at some 

toxicology lab doorways, air flowed into the lab from surrounding areas, and at one crime lab vestibule 

door, air flowed from the lab into the shared hallway. Maintaining pressurization can be an important 

part of any facility’s plan for controlling the movement of contaminants and infectious particles. The 

ANSI/ASSP Z9.5-2022 laboratory ventilation standard recommends that “airflow shall be from areas 

of low hazard to higher hazard.” This standard further explains that “ ‘Space pressurization’ or 

‘directional airflow’ between spaces is one of many tools available to limit exposure to laboratory 

hazards. Effectively applied, it opposes migration of air contaminants; it does not eliminate it” 

[ANSI/ASSP 2022]. Air movement can be impacted by many factors, which effective pressurization 

can overcome. Therefore, pressurization should be used with other engineering and administrative 

controls to help prevent worker exposure to laboratory hazards.

An effective engineering control is local exhaust ventilation (LEV), which is designed to capture 

harmful substances where they are generated. In both laboratories, the main type of LEV installed were

laboratory fume hoods. Ideally, all evidence should be handled and analyzed in a fume hood. We 

observed that in general, scientists in both labs used fume hoods when they were handling solvents and 

other reagents but might not use fume hoods when handling biological or bulk drug evidence. When 

employees can be exposed to high-hazard materials in air (like powdered opioids and other controlled 

substances), laboratory ventilation guidance and pharmaceutical industry resources prioritize product 

containment and isolation through exposure control devices, such as variable air volume fume hoods, 
B-22

laminar flow ventilated hoods or cabinets, and ventilated glove boxes [ASHRAE 2015, 2018; Wood 

2010]. All fume hoods in the toxicology and crime labs were certified annually by an outside contractor 

to ensure velocities within the ANSI/ASSP recommended face velocity of 80–120 fpm, with the crime 

lab manual specifying a range of 60–100 fpm [ANSI/ASSP 2022]. 

Limitations 

This evaluation was subject to several limitations. First, industrial hygiene sampling can only document 

exposures and levels at the time of sampling in the locations sampled. These results may not be 

representative of conditions during other days. Second, surface sampling was based on professional 

judgment and results may not be representative of all surfaces in the location. Third, because the 

interviews asked employees about past workplace processes, practices, and conditions; exposures; and 

health effects, these results are subject to recall bias. 

Conclusions

Employees reported no symptoms associated with acute exposure to methamphetamine, cocaine, 

fentanyl, or heroin. However, we identified the potential for unintentional exposures to these and other 

substances on contaminated surfaces. We provided recommendations to assist both laboratories in 

minimizing exposure to these substances. These recommendations included changing workplace 

practices to reduce exposure risk, modifying building ventilation, and training employees on protocols 

to improve employee safety.
C-1

Section C: Tables

Table C1. Participant demographic information and job characteristics from virtual interviews (n = 34)

Demographic characteristics Toxicology laboratory 

employees 

(n = 17)

Crime laboratory 

employees

(n = 17)

Male, No. (%) 2 (12) 6 (35)

Age in years, Median (Range) 39 (26–48) 42 (26–65)

Job characteristics

Years with this state agency, Median (Range) 5 (0.5–21) 17 (1–26)

Hours worked per week, Median (Range) 40 (40–62) 40 (30–50)

Job title, No. (%)

 Scientist or technician 9 (53) 15 (88)

 Lab manager, property & 

 evidence custodian, or other

8 (47) 2 (12)

Table C2. Participant demographic information and job 

characteristics from written questionnaires (n = 23)

Demographic characteristics Median (Range)

Male, No. (%) 4 (17)

Age in years 42 (25–58)

Job characteristics 

Years with toxicology laboratory 4 (0.25–21)

Hours worked in the past 2 weeks 80 (32–90) 

Hours worked in the laboratory or vault 

room in the past 2 weeks

20 (1–60)

Job titles, No. (%) 

 Scientist or technician 15 (65) 

 Property & evidence custodian or 

 other

8 (35) 
C-2

Table C3. Frequency, location, and potential exposure from work with biological samples from written 

questionnaires administered to toxicology laboratory employees (n = 23)

Number of samples handled in the past 2 weeks, Median (Range) 90 (0–1000)

Number of samples processed under a fume hood, Median (Range) 74 (0–300)

Number of employees processing samples under a fume hood, No. (%)

 Yes 18 (78)

 No 5 (22)

Number of employees reporting potential exposure to the following drugs, No. (%)

 Methamphetamine 10 (43)

 Cocaine 7 (30)

 Heroin 6 (26)

 Tetrahydrocannabinol 7 (30)

 Other drugs 8 (35)

 Unknown 11 (48)
C-3

Table C4. Description of self-reported cleaning and hygiene 

practices as abstracted from written questionnaires administered 

to toxicology laboratory employees (n = 23)

Cleaning Practices No. (%)

Participated in cleaning 

 Yes 14 (61)

 No 9 (39)

Areas of cleaning* 

 Lab bench 13 (57)

 Common areas in the lab 7 (30)

 Shared equipment 4 (17)

 Hood 11 (48)

 Vault room 0 (–) 

Types of cleaning* 

 Clean surfaces with dry cloth 2 (9)

 Clean surfaces with wet cloth/paper 13 (57)

 Remove biohazard or other waste 8 (35)

 Other types of cleaning 2 (9)

Types of cleaning solution used* 

 Water 4 (17)

 Disinfectant wipes 11 (48)

 Bleach 10 (43)

 Methanol 12 (52)

Hygiene Practices 

Washing hands upon entering/leaving the lab 

 Always 14 (61) 

 Sometimes 8 (35) 

 Never 0 (–) 

 Missing 1 (4)

Washing hands before eating/drinking 

 Always 16 (70)

 Sometimes 7 (30)

 Never 0 (–) 

Washing hands after glove removal 

 Every time 11 (48)

 Sometimes 10 (43)

 Never 0 (–) 

 Missing 2 (9)

*Participants could choose more than one option
C-4

Table C5. Surface sample results (μg/100 cm2) 

Area Location Methamphetamine Cocaine Fentanyl Heroin

Tox Lab Supply vent cover 0.044 0.0042 NR NR

Tox Lab Return vent cover 0.021 0.0059 NR NR

Tox Lab Centrifuge 0.0025 NR NR NR

Tox Lab Centrifuge 0.0011 NR NR NR

Tox Lab Centrifuge NR NR NR NR

Tox Lab Centrifuge NR NR NR NR

Tox Lab Laboratory bench surface 0.0019 NR NR NR

Tox Lab Laboratory bench surface 0.0014 NR NR NR

Tox Lab Laboratory bench surface 0.0013 NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Laboratory bench surface NR NR NR NR

Tox Lab Door handle NR 0.0021 NR NR

Tox Lab Door handle NR NR NR NR

Tox Lab Door handle NR NR NR NR

Tox Lab Door handle NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Hood surface NR NR NR NR

Tox Lab Instrument keyboard NR NR NR NR

Tox Lab Instrument keyboard NR NR NR NR

Tox Lab Instrument keyboard NR NR NR NR

Tox Lab Transaction keyboard NR NR NR NR
C-5

Table C5 continued. Surface sample results (μg/100 cm2) 

Area Location Methamphetamine Cocaine Fentanyl Heroin

Tox Lab Transaction scanner NR NR NR NR

Tox Lab Freezer door handle NR NR NR NR

Tox Lab Freezer lock surface NR NR NR NR

Tox Lab Refrigerator door handle NR NR NR NR

Crime Lab Hood sash 2.1 0.12 NR 0.0046

Crime Lab Hood sash 0.53 1.6 0.059 0.059

Crime Lab Laboratory bench surface 0.43 0.086 0.055 0.053

Crime Lab Laboratory bench surface 0.089 0.062 0.0027 0.0037

Crime Lab Bottom of door 0.080 0.017 NR NR

Crime Lab Keyboard 0.078 0.21 0.056 0.015

Crime Lab Keyboard 0.0068 0.019 0.0039 0.0029

Crime Lab Door handle 0.048 0.058 NR 0.0037

Crime Lab Door handle 0.0077 0.035 NR 0.0013

Crime Lab Door handle NR NR NR NR

Annex Lab Hood surface 0.29 0.052 NR NR

Annex Lab Hood sash 0.15 0.11 NR NR

Annex Lab Hood sash 0.038 0.043 NR 0.0016

Annex Lab Supply vent cover 0.066 0.016 NR NR

Annex Lab Centrifuge 0.030 0.0022 NR NR

Annex Lab Door handle 0.0038 NR NR NR

Annex Office Door handle NR 0.0023 NR NR

Break Room Microwave exhaust 0.0015 NR NR NR

Break Room Table NR NR NR NR

NR = not reportable, meaning the result was under the reporting limit of 1 ng (0.001 μg) per sample

Tox Lab = toxicology lab
D-1

Section D: References

Cleaning and Decontamination

EPA [2021]. Voluntary guidelines for methamphetamine and fentanyl laboratory cleanup. Washington, 

DC: U.S. Environmental Protection Agency,

https://www.epa.gov/sites/default/files/documents/meth_lab_guidelines.pdf. 

Sisco E, Najarro M, Burns A [2019]. Quantifying the effectiveness of cleaning agents at removing drugs 

from laboratory benches and floor tiles. Forensic Chem 12:1–7, 

http://doi.org/10.1016/j.forc.2018.11.002. 

Occupational Exposures in Drug Evidence Storage

NIOSH [2010]. Evaluation of police officers’ exposures to chemicals while working inside a drug vault - 

Kentucky. By Fent KW, Durgam S, West C, Gibbins J, Smith J. Cincinnati, OH: U.S. Department of 

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

Occupational Safety and Health, Health Hazard Evaluation Report 2010-0017-3133, 

https://www.cdc.gov/niosh/hhe/reports/pdfs/2010-0017-3133.pdf. 

NIOSH [2019]. Evaluation of potential occupational exposures to narcotics in a county evidence room. 

By Feldmann KD, Hatcher S. Cincinnati, OH: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 

Health Hazard Evaluation Report 2018-0150-3340, 

https://www.cdc.gov/niosh/hhe/reports/pdfs/2018-0150-3340.pdf. 

Health Effects and Toxicology of Illicit Drug Exposure 

Becker DE [2012]. Basic and clinical pharmacology of autonomic drugs. Anesth Prog 59(4):159–169, 

http://doi.org/10.2344/0003-3006-59.4.159. 

Enevoldson TP [2004]. Recreational drugs and their neurological consequences. J Neurol Neurosurg 

Psychiatry 75(Suppl 3):iii9–iii15, http://doi.org/10.1136/jnnp.2004.045732. 

Methamphetamine and Other Illicit Drugs on Surfaces

NIOSH [2020a]. Evaluation of occupational exposure to illicit drugs at controlled substances 

laboratories. By Broadwater KR, Jackson DA, Li JF. Cincinnati, OH: U.S. Department of Health and 

Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

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D-2

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Promoting productive workplaces through safety 

and health research

HHE Report No. 2021-0115-3388