Evaluation of Exposures to 

Styrene during Cured-in-place 

Pipe Liner Preparation and 

during Pipe Repairs using Hot 

Water and Steam

HHE Report No. 2019-0080-3379

July 2021
Authors: Ryan F. LeBouf, PhD, CIH

Dru A. Burns, MS

Anand Ranpara, MS, MPH

Lisa Kobos, PhD

Analytical Support: Brian Tift

Desktop Publisher: Barbara Elbon

Industrial Hygiene Field Assistance: Stephen B. Martin, Marcia Stanton, Alyson Fortner

Logistics: Mike Beaty

Data Support: Brian Tift

Keywords: 237110 (Water and Sewer Line and Related Structures), Mississippi, cured-in-place pipe

installations (CIPP), CIPP liner wet-out facility, styrene, volatile organic compounds (VOCs)

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 U.S.C. § 669(a)(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 and employees at the plant. The state health

department and the Occupational Safety and Health Administration (OSHA) Regional

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

Recommended Citation

NIOSH [2021]. Evaluation of exposures and emissions during cured-in-place pipe liner preparation

and during pipe repairs using hot water and steam. By LeBouf RF, Burns DA, Ranpara A, Kobos L. 

Morgantown, WV: 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 2019-0080-3379, https://www.cdc.gov/niosh/hhe/reports/pdfs/2019-0080-3379.pdf.
Table of Contents

Main Report

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

Our Approach ...................................................................................................................................................2

Our Key Findings..............................................................................................................................................3

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

Supporting Technical Information 

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

Wet-out Building ......................................................................................................................................A-1

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

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

Process Description .................................................................................................................................A-1

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

Methods: .................................................................................................................................................... B-1

Results:....................................................................................................................................................... B-1

Methods: Exposure Assessment ............................................................................................................ B-5

Results: Exposure Assessment ............................................................................................................... B-7

Methods: Review of safety data sheets................................................................................................B-15

Results: Review of safety data sheets...................................................................................................B-15

Discussion ...............................................................................................................................................B-15

Smoking ...................................................................................................................................................B-21

Limitations...............................................................................................................................................B-21

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

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

Section D: Occupational Exposure Limits...............................................................................................D-1

Occupational Exposure Limits for Styrene and Acetone.................................................................. D-2

Section E: References.................................................................................................................................. E-1
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Introduction

Request

We received a management request for a health hazard evaluation at cured-in-place pipe (CIPP)

installations using hot water and steam curing techniques and also at a facility where liners are prepared 

(wet-out facilities) before being shipped to installation sites. The company was interested in 

characterizing and controlling styrene exposures to employees during preparation and installation of the 

liners. Styrene is classified as a probable carcinogen and has been associated with adverse health 

outcomes in exposed workers, including but not limited to hearing loss, balance and concentration 

problems, tiredness, and altered vision. Inhalation of styrene has also been associated with the 

development and worsening of respiratory illnesses. 

Workplace

We assessed multiple workplaces during this evaluation. For the wet-out facility, four employees were 

working inside one facility where the resins were mixed and combined with the liners prior to shipment 

to the installation sites. An administrative building was within walking distance of the wet-out facility 

but was not assessed during our site visit. For installations, the workplaces were outside at seven 

installation sites where employees repaired underground sewer and storm drain lines (pipes) using liners 

containing resin cured with steam or hot water. Six to eight employees were present at each installation 

site. 

The following lists are brief process descriptions for the preparation of liners and installation of liners

using hot water or steam curing.

CIPP liner preparation at the wet-out facility

• Liner laid out on pinch roller assembly.

• Catalyst mixed with styrene and then combined with resin.

• Resin mixture injected at front end of the liner and squeezed through the liner using the pinch 

roller. 

• Vacuum used to help distribute the resin throughout the liner.

• Liner sometimes manually manipulated to distribute the resin evenly throughout the liner.

• Finished liner containing resin folded and placed onto a refrigerated truck.

CIPP liner installation

• Liner transported to the job site on refrigerated truck to reduce unwanted curing.

• Damaged pipe scoped using closed-circuit television (CCTV), and pipe cleaned with highpressure water (jet-cleaning).

• Employees positioned liner above upstream manhole and prepared for inversion.
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• Liner inverted through damaged section of pipe using compressed air or water pressure, which 

also kept the liner pressed against the inner walls of the pipe.

• Liner cured in place using heat from steam or near-boiling water. The temperature required to 

cure the liner depended on the catalyst used.

• Employees entered upstream and downstream manholes to manually cut away excess sections of 

cured liner. During steam-cured installations, employees sometimes cut away excess sections of 

the cured liner outside the manhole. 

• Cured liner scoped by CCTV truck operator to ensure successful installation.

• Laterals remotely cut into cured liner using a robotic cutting tool, if necessary.

The water-cured CIPP process installations were sub-contracted to the company for the Mississippi 

Department of Transportation (MDOT) to rehabilitate storm drains on a highway. The steam-cured 

CIPP process installations were used to repair smaller, 8-inch diameter residential waste water pipes,

and the water-cured CIPP process was used to repair 24-inch diameter non-residential waste water 

pipes. The company reported the health and safety of employees was their number one priority and 

wanted to proactively protect their employees by requesting that NIOSH assess workers’ exposure to 

styrene. 

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

Our Approach

We visited the wet-out facility and water- and steam-cured CIPP installation sites on one occasion for 

each process to learn more about how the work was conducted and assess employee exposures to 

styrene and other volatile organic compounds (VOCs). We conducted opening and closing meetings 

with employees and management to discuss NIOSH, why we were there, and what to expect. 

Employees at the company were not represented by unions. At the opening meetings, we also collected 

employees’ contact information if they wanted to receive their personal sampling results. At the closing 

meetings, we provided immediate feedback to employees and management on observations during the 

visit and opportunities for improvement. We shared preliminary results with the company by phone as 

soon as they were available after each site visit. 

The following is a list of what we did during our site visits:

• We observed the work process, including tasks and activities conducted by the employees, to 

better understand the process and the risk factors for exposure and emissions. We also observed 

the use of personal protective equipment (PPE).

• We assessed exposures and emissions of styrene and other VOCs during preparation and 

installation of CIPP liners to understand how much and where these were occurring to 

determine if control measures were needed. 
3

o We collected air samples from some employees’ breathing zones during specific tasks at 

the CIPP installation sites and the wet-out facility and during the workday (full-shift) at 

the wet-out facility to measure personal exposures to styrene.

o We measured process emissions at various area locations.

o We measured personal exposures to and area process emissions of total volatile organic 

compounds (TVOCs). 

o We collected bulk and cured process materials during surveys to measure styrene 

emission rates.

• We collected safety data sheets for process ingredients during the site visits to identify hazardous 

ingredients and confirm that adequate control measures, including PPE, were used.

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

Our Key Findings

Company took a proactive approach to employee safety and health

• The company submitted a health hazard evaluation request to assess whether styrene exposures 

to employees were concerning.

• The company was receptive to initial recommendations aimed at reducing styrene exposure to 

employees.

• The company was vigilant about traffic safety on a busy highway during CIPP installations.

Employees did not always follow permit-required confined space entry protocols

• We did not observe continuous monitoring of toxic gases before and during entry into a

confined space.

• We observed employees who did not tie off before entering storm drains. We observed 

employees wearing a harness attached to a rope. The rope was not always attached to a winch on 

the tripod. In the event of an emergency, the top man would have to pull the worker out of the 

hole.

• We observed attendant employees break contact with the employee in the hole to get tools or 

help somewhere else on the site for brief periods of time.

• Not all confined spaces were permit-required confined spaces. Some manholes/access grates 

were not deep enough to require the employee to be tied off.

Employees were exposed to styrene emissions from cured liner and other process 

materials

• One employee’s exposure to styrene during steam “pre-cure” was 105.5 parts per million (ppm) 

and exceeded the NIOSH short-term exposure limit (STEL) for styrene of 100 ppm and the

American Conference of Governmental Industrial Hygienists (ACGIH) STEL of 20 ppm.
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• One employee’s exposure to styrene during “inversion” tasks was 33.6 ppm, which exceeded the 

ACGIH STEL of 20 ppm.

• One employee’s exposure while checking thermocouples during steam-cured cooldown reached 

an elevated concentration of 1,125 ppm TVOCs (this value was adjusted for styrene based on a 

response factor provided by the instrument manufacturer).

• The highest styrene exposures occurred when employees were near cured liner or wet (uncured) 

liner. For steam, these high exposure tasks were during “pre-cure”, “inversion”, and “cutting the 

cured liner”. For water, the only high exposures were during “cutting the cured liner.”

• Styrene air concentrations downwind of the process were higher than upwind. 

Worksite conditions and unexpected process difficulties increased employee

exposure to the wet liner.

• Employees entered the refrigerated truck to place or remove liners containing resin and styrene, 

or to cool down during hot temperatures.

• One employee placed their torso into a cured liner section to remove the tie back.

• When the liner did not make the turn into a degraded pipe, employees manually maneuvered

and used lift equipment to assist the transition of the liner into the host pipe. We note the wet 

liner still emits styrene even though it has a polyethylene outer lining.

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.

Benefits of Improving Workplace Health and Safety:

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

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

 Better employee recruiting and retention  Could increase overall cost savings

The recommendations below are based on the findings of our evaluation. The company was receptive 

to these recommendations. The company reported a “safety first” mentality to protecting worker health,

and this culture was observed during our investigation. 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 and install engineering controls to reduce exposure or shield employees. Until such 
5

controls are in place, or if they are not effective or feasible, administrative measures and personal 

protective equipment might be needed. Read more about the hierarchy of controls: 

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

We encourage the company 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”: 

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

Recommendation 1: Reduce employee exposure to styrene and other process 

emissions

Why? Styrene is emitted into the air during preparation of the liner at the wet-out facility and during 

curing of the liner with steam and hot water. Controlling styrene emissions at the source is one of the 

most effective control strategies. You can remove or reduce styrene emissions by using local exhaust 

ventilation or dilution ventilation. 

We measured high employee exposures to styrene during cutting the cured liner. Depending on work 

site conditions, styrene emitted into the air while cutting the cured liner could create a safety hazard 

and unnecessarily expose employees to high styrene concentrations for a short period of time. In 

2017, an employee died at a CIPP installation site in Illinois because the employee entered a liner 

section they thought was cured. That employee got stuck and became incapacitated. These types of 

work-related deaths are preventable. Styrene and styrene-adjusted TVOCs (as measured by real-time 

photoionization detectors) air concentrations should not exceed the OSHA ceiling limit of 200 ppm 

and should be below the NIOSH immediately dangerous to life or health limit of 700 ppm. 

We measured an employee’s exposure to styrene in excess of the NIOSH short-term exposure limit 

for styrene of 100 ppm and a peak exposure to TVOCs of 1,125 ppm. Exposures to styrene and 

other process emissions could be reduced by implementing recommendations outlined here to reduce 

employee exposure to styrene and other process emissions.

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

Substitute process ingredients for ones that do not contain styrene or have 

less styrene

• Investigate the use of process ingredients that do not have styrene or have less styrene.

Continuously operate ventilation blower fans before and during entry to

access holes after curing 
6

• Ventilate access holes after curing and before the employee enters the hole to cut the 

cured liner to reduce the styrene air concentration in the hole. Also, check real-time 

stryene air concentrations before the employee enters the hole to make sure it is safe to 

enter (less than 200 ppm/if feasible, less than 100 ppm/if 15 minutes or more, less than 

50 ppm). 

• After curing, continuously ventilate access holes and monitor confined space 

atmosphere including TVOC air concentratons while the employee is in the hole.

• If feasible, flush the cured liner with forced air to decrease the styrene concentration 

before entering the confined space.

Continuously operate ventilation wall fans at wet-out facility during 

working hours to reduce styrene air concentrations

• Ventilate wet-out facility during the work day while employees are present in the 

production space and the liner wet-out process is occurring to reduce the styrene air 

concentrations from process emissions.

Ventilate the reefer truck at wet-out facility and at liner installation sites

• Use ventilation to dilute air in refrigerated truck:

o While loading the truck with liner at the wet-out facility, and

o Before entering the truck to remove the liner at CIPP installation site, and

o Any time an employee needs to enter the refrigerated truck when uncured or 

cured liner is being stored in the truck.

• Ensure VOC air concentrations are safe in the truck before entry (less than 200 ppm/if 

feasible, less than 100 ppm/if 15 minutes or more, less than 50 ppm).

Educate employees on the dangers of placing head or torso into pipe with 

freshly cured liner

• Warn employees about safety and health concerns related to placing their head or torso 

into pipe with freshly cured liner. Employees might get stuck in uncured liner if curing is 

not complete. Employees might be exposed to high concentrations of styrene 

immediately after curing. 

Close or cover containers of process ingredients to reduce emissions at 

wet-out facility

• Close container lids or cover open containers of process ingredients when not in use to 

reduce emissions at wet-out facility.
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Minimize the amount of time the employee interacts with cured liner, liner 

that is curing, or process materials

• Employees’ exposure to hazardous process emissions can be reduced by limiting the 

amount of time spent around material that emits styrene or other VOCs. 

Recommendation 2: Monitor employee exposure to styrene during short-term tasks 

Why? We measured one employee exposure to styrene that exceeded the NIOSH recommended 

short-term exposure limit of 100 ppm during steam “pre-cure”, where the process temperature 

needed to activate curing had not been reached. We encourage you to continue to periodically 

monitor employee exposures for short durations when they work near or handle process materials. 

Additionally, changes in process emissions and potential employee exposures can be caused by 

different environmental and work conditions on site, changes to the process or process materials, 

different employee behaviors, and use of source control measures like ventilation. Additional 

consideration should be given to monitoring employee exposures especially after process changes, 

material changes, or changes to environmental and work conditions.

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

Conduct personal sampling in employee’s breathing zone for short 

duration tasks that require close interaction with cured or uncured liner 

process materials

• Use sorbent tube air sampling (OSHA method Org-89) to monitor employee exposures

to styrene for short duration task lasting for more than one minute. 

• Use evacuated canister air sampling (NMAM 3900) or length of stain indicator tubes to 

monitor employee exposures to styrene for short duration tasks lasting for less than one 

minute.

• Additional information for air sampling methods (OSHA method Org-89 and NMAM 

3900) can be found in the Supporting Technical Information on page B-5 of this report.

• If styrene exposures exceed occupational exposure limits after ventilation, employees 

will need respiratory protection equipped with organic vapor cartridges as part of a 

comprehensive respiratory protection program that meets the requirements of OSHA’s 

Respiratory Protection standard (29 CFR 1910.134) and includes medical evaluations, fit 

testing, maintenance, and training. Some states have applicable Federal OSHA-approved 

State plans. 
8

Recommendation 3: Continue to educate employees on safe work practices for 

confined space entry according to established company protocols 

Why? A confined space is defined as a space large enough to enter, difficult to exit, and not designed 

for continuous occupancy. A permit-required confined space is defined as a confined space that has 

or can develop a hazardous atmosphere, has material that can engulf a person, has a configuration 

that can trap or cause asphyxiation of a person, or contains any other serious safety and health 

hazards. Work-related injuries and deaths during confined space entry are preventable. Unsafe air 

concentrations of styrene might develop in the manhole or storm drain access hole because of the 

amount of styrene emitted into this small space during the process. 

We observed that employees did not always follow confined space entry protocols. Although 

confined space entry was not the focus of this evaluation, this health and safety issue should be 

addressed. 

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

Encourage employees to follow established company safety procedures to 

protect employees during confined space entry.

• Monitor the confined space atmosphere in the manhole/access point hole for styrene in 

addition to using a 4-gas meter to monitor oxygen, carbon monoxide, hydrogen sulfide, 

and the lower explosive limit before and during entry to ensure the atmosphere is safe 

for occupancy throughout the installation process. 

• For styrene, real-time or instantaneous styrene air concentrations may be estimated 

using colorimetric gas detector tubes or a photoionization detector that measures total 

VOCs which can be adjusted based on response factors for styrene provided by the 

manufacturer. Do not enter the space until the concentration is below the OSHA ceiling 

limit of 200 ppm for styrene. If feasible, wait until the concentration is below 100 ppm. 

If the employee is expected to spend more than 15 minutes in the space, wait until the 

concentration is below 50 ppm, which is one-half the NIOSH short-term exposure 

limit. 

• Begin continuous forced air ventilation to the access point holes using ambient air 

dilution to reduce styrene air concentration before entering to cut cured liner. Do not 

stop the forced air ventilation until the employee exits the confined space.

• Before entering the confined space, employees should tie off to a tripod with a winch 

that can assist and quickly pull up the employee should an unsafe condition arise.

• Always have a top man monitoring the employee in the hole. If the top man must break 

contact with the employee in the hole, make sure there is another person present to 

monitor the employee in the hole before leaving.
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• Educate employees on the company’s permit-required confined space program and 

ensure the program aligns with OSHA permit-required confined space entry regulations. 

For further guidance, see 29 CFR 1926.1200-1213 and this OSHA publication 

https://www.osha.gov/Publications/OSHA3825.pdf.

Recommendation 4: Continue to educate employees on the safety and health 

hazards associated with process ingredients 

Why? We reviewed safety data sheets of process ingredients provided by the company. We found 

process ingredients that could be hazardous if employees are exposed to them in sufficient quantities 

including styrene, tetrohydrofuran, resins, and initiators. Initiators are chemicals or chemical mixtures 

that help the resin mixture begin to harden or cure. OSHA’s Hazard Communication Standard, also 

known as the “Right to Know Law” [29 CFR 1910.1200] requires that employees are informed and 

trained on potential work hazards and associated safe practices, procedures, and protective measures.

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

Ensure workers understand potential hazards in the workplace and how to 

protect themselves

• Conduct initial and periodic training with employees to share information on potential 

hazards from process ingredients, the actions the company is taking to protect 

employees from exposures, and how employees can protect themselves from exposure. 

• Use process ingredients that are inhalational hazards such as styrene and other VOCs in 

well-ventilated areas. 

• Supply employees with non-latex gloves (nitrile or VitonTM gloves) and remind them to 

wear them when working with the liner, resin, or other cured and uncured process 

materials that contain styrene and other chemicals.

• Storage areas and confined spaces should be adequately ventilated before entering.

• Employees should not eat, drink, or smoke in areas where process materials are used. 

• Employees should wash their hands and face before eating. 

• Wear hearing protection when indicated; we did not formally assess noise during our 

visits. A noise survey would be necessary to determine the need or level of hearing 

protection and inclusion in a hearing conservation program. 
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Recommendation 5: Implement a Smoking Cessation Program for Employees 

Why? In workplaces with risk of occupational lung disease, prevention of smoking-related lung 

disease is important and makes the detection of work-related adverse effects easier.

The Centers for Disease Control and Prevention offers tools and resources for setting up 

smoking cessation programs at 

https://www.cdc.gov/tobacco/stateandcommunity/index.htm.
Supporting Technical Information

Evaluation of Exposures to Styrene during Cured-inplace Pipe Liner Preparation and during Pipe Repairs 

using Hot Water and Steam

HHE Report No. 2019-0080-3379

July 2021
A-1

Section A: Workplace Information

Wet-out Building

Size: 11,100 square feet (approximate)

Floors: One-story

Employee Information

# of employees at time of evaluation: 4-8 employees depending on process

Length of shift: 8-10 hours depending on process

Union: No

Mean age: Not determined

Mean tenure at job: Not determined

History of Issue at Workplace

Request basis: Company expressed the desire to proactively protect employees by characterizing 

employees’ exposure to styrene and implement recommendations to control process emissions, when

appropriate. 

Previous issues: None

Process Description

Cured-in-place Pipe Liner Preparation

The purpose of liner preparation is to impregnate a length of cured-in-place pipe (CIPP) liner with a 

liquid resin-catalyst mixture. Liner preparation took place inside a large rectangular warehouse fitted 

with four general exhaust fans and two large garage doors. During our sampling campaign, two of the 

four exhaust fans were broken. The two operational fans were run at the suggestion of the NIOSH staff 

members during second and third days of the visit. The resin-catalyst mixture was prepared by mixing 

styrene, resin, and catalyst using a resin-pump static mixer machine (Figure A1).

Figure A1. Employee sitting at controls of resin-pump static mixer station at wet-out facility. The red buckets contained styrene 

and catalyst. The white bucket with a filter on top was used to transfer styrene-catalyst mixture to the hopper of the resin-pump 

static mixer, located to the immediate right of the controls, December 2019. Photo by NIOSH.
A-2

Proportions of resin, catalyst, and styrene used in the mixture were dependent upon the length of liner 

to be “wetted.” Employees laid out a dry length of liner along a roller assembly and pulled it through a 

pinch roller. The resin mixture was injected into the liner using the resin-pump static mixer and an 

injection port attached to the pulled-out front end of the liner. Employees attached vacuum lines to 

multiple points along the length of the liner on the roller assembly to remove excess air from the liner, 

facilitating the spread of the resin mixture throughout the inner section of the liner. Employees 

manually cut holes into sections of the liner to attach the vacuum lines. Before these sections of the 

liner could be impregnated with the resin-catalyst mixture, the holes were patched using a 

tetrahydrofuran-based adhesive. Employees maintained uniform spread of the resin mixture across the 

length of the liner. This was primarily accomplished by the pinch roller, but employees occasionally had 

to use hand tools or physically mount the liner on the roller assembly to spread the mixture using their 

body weight (Figure A2).

Figure A2. Employee at wet-out facility using body weight to spread resin mixture in liner and holding vacuum tube with right 

hand, December 2019. Photo by NIOSH.

For very long liners, the resin mixture was sometimes injected into multiple sections of the liner 

simultaneously. Once the liner was fully impregnated with the resin mixture, employees folded and 

situated these “wetted” sections into a refrigerated semi-trailer (reefer truck). The final section of the 

liner was not impregnated with the mixture and marked as “dry” to allow the field installation teams to 
A-3

attach the liner to equipment used to invert the liner into a damaged underground pipe. The resin-pump 

static mixture was cleaned by flushing thoroughly with acetone. Any excess resin, catalyst, or acetone 

was placed into a waste bin located outside the rear door of the facility. Employees typically but not 

always wore nitrile or latex gloves and safety goggles during the wet-out process (Figure A3).

Figure A3. Employee repairing hole in completed liner at wet-out facility, December 2019. Photo by NIOSH.

CIPP Installation: General Process Overview

Refrigerated trucks transported resin-impregnated felt liners to job sites to reduce unwanted curing. 

Equipment on the job site included a closed-circuit television (CCTV) camera truck, jetter truck, a 

refrigerated truck, a combination inversion/boiler truck, and a one-ton general purpose truck with an 

air compressor for hand-held power tools. Installation crews consisted of five to six general laborers, a 

CCTV truck operator, jetter truck operator, combination inversion and boiler truck operator, foreman, 

and superintendent. On-site work was directed by the foreman and supervised by the superintendent. 

Upon arriving on site, employees scoped the damaged pipe with a CCTV robot. The pipe was cleaned 

with pressurized water using a device called a jetter. Employees positioned the liner above the upstream 

manhole in preparation for inverting the liner through the damaged pipe. The liner was inverted 
A-4

through the pipe using pressure from compressed air or water, which also held the liner tight against the 

walls of the damaged pipe. Once inverted through the pipe, the liner was cured in-place using heat from 

steam or hot water. The liner was cured at a proprietary temperature for a predetermined duration 

depending upon the length, thickness, and diameter of the liner. One general laborer was tasked with 

installing thermocouples, wherever it was possible to access the liner and monitor the temperature of 

the liner during curing. After curing, the liner was cooled using air or water. Once the liner was cool 

enough to handle, employees entered the upstream and downstream manholes and manually cut away 

excess sections of cured liner with power tools. Sometimes, a blower ventilator fan was used to provide 

dilution ventilation to the manholes while employees were inside. Finally, the newly cured liner was 

scoped via CCTV to ensure successful installation, and a remotely controlled robot cut out lateral 

connections, if necessary. Employees wore hard hats, safety goggles, disposable gloves, long pants, high 

visibility gear, and hearing protection. When cutting the cured liner, employees also wore disposable 

coveralls. On-site specifics for liner installation and for the water and steam curing process are 

described in the respective sections below.

Water Cured-in-place Pipe

The water-cured liner installation process is typically used to repair host pipes 24 inches in diameter or 

larger. The installations took place between the hours of 6:00 p.m. and 6:00 a.m. with around an hour at 

the beginning and end of the repairs to close or open one lane of traffic in each direction. Most 

installations were conducted in 10-hour shifts. Once on site, the jetter truck operator cleaned the host 

pipes with high pressure water prior to liner installation. The CCTV truck operator collected and 

monitored video of the host pipes during the initial cleaning. General laborers then unloaded the 

upstream, felt end of the cold liner from the refrigerated truck and secured it to a large hydraulic lift on 

the inversion/boiler truck (Figure A4).

Figure A4. Employees removing liner from refrigerated truck during water-cured CIPP installation, March 2019. Photo by 

NIOSH.
A-5

Concurrently, other general laborers attached a long, thin line called a “lay flat” to the downstream end 

of the liner. The lay flat line was used to recirculate water from the liner back to the boiler truck during 

liner inversion and curing. Once the lay flat was in place with the liner attached to the lift, the 

inversion/boiler truck operator inverted the liner through itself and into the host pipe using water 

pressure. The liner inversion process typically required general laborers to manually manipulate the liner 

as it was inverted into the host pipe (Figure A5).

Figure A5. Employees pulling dry liner through itself under lift on boiler truck during water-cured CIPP installation, March 2019. 

Photo by NIOSH.

Once liner inversion was complete, the inversion/boiler truck operator introduced hot water to the 

recirculating liner and lay flat system to begin the curing process. The duration of curing was based on 

the length, thickness, and diameter of the liner but varied depending on site conditions such as 

temperature and the presence of standing water in the pipes. During the curing process, one employee 

monitored the temperature at positions along the length of the liner using thermocouples, while the 

inversion/boiler truck operator monitored water temperature. Once the liner reached a predetermined 

temperature along its entire length, curing was deemed complete. The liner was then cooled down by 

recirculating cold water. Once the liner was cool enough to handle, employees on the upstream side 

began cutting and tearing the felt section of liner away from inversion/boiler truck lift. At the same 

time, an employee on the downstream side descended into the manhole and manually cut out excess 

cured liner with hand-held power tools (Figure A6).
A-6

Figure A6. Employee cutting water-cured liner inside of access hole at CIPP installation, March 2019. Photo by NIOSH.

After completing the tear down of the felt section of liner from the inversion/boiler truck lift, an 

employee descended into the upstream manhole to also cut out excess cured liner with hand-held power 

tools. Employees wore hard hats, safety goggles, disposable gloves, long pants, high visibility gear, and 

hearing protection. When cutting the cured liner, employees also wore disposable coveralls. 

Steam Cured-in-place Pipe

The steam-cured liner installation process is typically used to repair host pipes 24 inches in diameter or 

smaller. The installations took place between the hours of 7:00 a.m and 7:00 p.m. with most conducted 

in 10-hour shifts. Once onsite, the jetter truck operator cleaned the host pipes with high pressure water 

prior to liner installation. The CCTV truck operator collected and monitored video of the host pipes 

during the initial cleaning. After the host pipe had been cleaned and scoped, the refrigerated truck 

containing the cold liner, the boiler truck, large air compressor, and inversion machine called a 

“shooter” were positioned near the upstream manhole. The shooter was positioned directly above the 

upstream manhole with the refrigerated truck as close as possible. Then general laborers entered the 

refrigerated truck bed to manually remove the cold liner and attach it to the shooter using a manifold 

called a “can.” Occasionally, the upstream manhole was not close to an access road, requiring the 

employees to manually drag the entire length of the liner from the refrigerated truck to the manhole. 

With the liner in place, employees attached an air hose from the large air compressor to the shooter. 

The combination inversion-machine and boiler truck operator then used levers on the shooter to 

introduce compressed air in bursts into the liner to invert it through itself and into the host pipe. 

During this process, general laborers were tasked with manually feeding the liner into the shooter. 

Occasionally, the inversion-machine operator would lubricate the liner by adding mineral oil or water to

ease the liner movement through the host pipe. Once the liner reached the downstream manhole, 
A-7

inversion was complete. Compressed air was continually supplied to the liner to keep it inflated against 

the inner walls of the host pipe. On the downstream side, employees trimmed excess uncured liner and 

attached an exhaust line to the end of the liner using metal clamps. The exhaust line terminated in an 

automotive muffler to reduce the level of sound generated during the curing process. With the exhaust 

line attached, employees on the upstream side removed the shooter, leaving the liner attached to the can 

and compressed air line with the assembly hanging from a tripod directly above the upstream manhole. 

The boiler truck operator then introduced steam into the liner to begin curing. Once curing was 

completed, the steam line at the upstream manhole was replaced with a compressed air line to cool the 

liner. When the liner was cool enough to handle, one employee at each manhole used powered hand 

tools to cut away excess sections of cured liner. Employees either entered or reached into the manhole 

to cut the cured liner depending on the size of the manhole (Figures A7–A9). Employees wore hard 

hats, safety goggles, disposable gloves, long pants, high visibility gear, and hearing protection. When 

cutting the cured liner, employees also wore disposable coveralls.

Figure A7. Employee cutting steam-cured liner partially inside of manhole at CIPP installation, June 2019. Photo by NIOSH.
A-8

Figure A8. Employee cutting excess section of steam-cured liner outside of manhole at CIPP installation, June 2019. Photo by 

NIOSH. 

Figure A9. Employee cutting steam-cured liner fully inside of manhole at CIPP installation, June 2019. Photo by NIOSH.
B-1

Section B: Methods, Results, and Discussion

Methods: Observations of Work Processes, Practices, Conditions, and Personal 

Protective Equipment

We observed the work process, including tasks and activities conducted by employees and their use of

personal protective equipment (PPE). We visited the wet-out facility over three days in December 2019, 

water-cured CIPP installation sites over four days in March 2019, and steam-cured CIPP sites over

three days in June 2019. 

Results: Observations of Work Processes, Practices, Conditions, and Personal 

Protective Equipment

Facility Layout, Site Information, and Work Practices

Wet-out Facility

o General information

o Administrative offices were situated in another building at the same complex as the wetout facility building.

o The designated eating and drinking area was in the same wet-out facility building without 

any separation from the process area. 

o The foreman had an enclosed office that lacked ventilation. The office was located on 

the opposite end of the facility from the process (Figure B1).

o The duration of the process and amount of the materials used to wet the liner depended

on the dimension of the liner. Specific proportions of styrene, catalysts, and resin were 

mixed to produce a desired amount of resin mixture to infuse in the liner. 

o Excess resin-catalyst mixture was drained from the liner by cutting holes in the liner 

along its length. Once drained, holes were manually sewn shut and covered with a patch 

using an adhesive containing tetrahydrofuran. 

o Excess resin, catalyst, and acetone was placed in the waste disposal area outside close to 

the rear door of the facility, which was also the smoking area.

o Employees did not always wear gloves to protect against dermal exposure to chemical 

process ingredients.

o During liner rolling, two employees were present inside the refrigerated truck to fold and 

place the finished liner containing resin. 

o All the containers used to prepare resin-catalyst mixture were cleaned using acetone.

o Four employees, including a foreman and three general laborers, were present for 

sampling on both days. The four employees and vice president of the company attended 

the opening meeting on the second day. 

o On the first day at the facility, we conducted a walkthrough survey of the facility, set up 

equipment for sampling on the next day, met with employees, and learned about the wet-out 

process.
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o See Figure B1 for a diagram of the liner “wet-out” facility showing building dimensions, 

work areas, ventilation fans, and air concentrations of styrene at area sampling locations.

o No samples were collected on the first day.

o On the second day, the facility did not have wall ventilation fans operating or the large overhead 

door open. 

o Two pounds of styrene were used to prepare the resin-catalyst mixture for the liner.

o Employees produced a liner that was 43-linear feet long with an 18-inch diameter and 

9-millimeter (mm) thickness.

o On the third day, ventilation fans were turned on and outside doors were opened based on our 

recommendation.

o 106 pounds of styrene were used to prepare the resin-catalyst mixture for the liner.

o Employees produced a liner that was 538-linear feet long with a 23.25-inch diameter and 

11-mm thickness.

o

Shipping Basket Location Day Sampling Basket Styrene Air Concentration Sampling Duration

Number (ppm) (min)

Food/Drink 2 1 0.2 280

Inside Reefer Truck 2 2 2.4 282

Mixing Area 1 3 7.2 380

Mixing Area 2 3 2.2 280

Mixing/Injecting Machine 1 4 4.6 383

Mixing/Injecting Machine 2 4 6.4 280

Office 1 5 1.0 365

Reefer Truck Door 1 6 4.4 383

Reefer Truck Door 2 6 0.6 181

Refrigerated Storage Area 1 7 1.2 381

Refrigerated Storage Area 2 7 0.2 280

Waste/Smoking Area 1 8 1.9 446

Figure B1. Diagram of liner wet-out facility showing building dimensions, work areas, ventilation fans, and air concentrations of styrene at 

area sampling locations, December 2019.

Steam-cured CIPP Installation Sites

• General Information

o One steam-cured liner was installed each day. The duration of a steam-cured installation 

depended on the length of the liner and ease of access to the damaged pipe at each 

location.

o Seven workers, including a foreman, were present at steam-cured installation sites each 

day.

Styrene Concentrations at Specific Locations in Wet-Out 
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o There were five work trucks on the installation site, including a reefer truck, a water 

(jetter) truck, a boiler truck, a CCTV truck, and a heavy pickup with an air compressor 

for cutting tools. An inversion machine called the “shooter” was positioned directly 

above the inlet manhole to facilitate inverting the liner through the damaged pipe using 

air pressure. 

o Inversion of the liner through the damaged pipe was a loud process and not all 

employees were wearing hearing protection.

o After inversion, the precure process began, during which the liner was inflated and 

preliminarily heated using the air compressor. When a certain temperature threshold was 

reached, the boiler was turned on to add more heat to approximately 140 degrees 

Fahrenheit, at which point the catalyst helps initiate polymerization and hardening of the 

resin.

o Many processes during steam-cured installation were conducted manually without gloves

and contributed to employees’ dermal exposure to styrene. 

o We observed employees entering the manhole/access grates to cut excess liner. 

Employees did not test the atmosphere prior to entering the confined space of the 

manhole. Entry into the manhole to cut the cured liner was sometimes necessary 

depending on the depth of the manhole. We observed some employees coughing after 

exposure to process emissions when they entered the manhole to place thermocouples 

before curing began.

o All steam-cured liners had diameters of 8 inches. Additional liner and site information 

and environmental conditions are presented in Table 1.

• Day 1 installation occurred between a residential backyard and golf course. The inlet manhole 

was approximately 5 feet deep. Employees cut cured liner in two minutes on inlet side. 

• Day 2 installation occurred between backyards in a residential area while it was raining. The inlet

manhole was approximately 10 feet deep, which allowed an employee to enter the manhole to 

cut the cured liner. Mineral oil was used as a lubricant to facilitate liner entry into the degraded 

pipe because it was raining during inversion. Employees lifted liner above their heads to feed 

into the inversion machine (shooter).

• Day 3 installation occurred in a commercial area with direct on-street access. The outlet 

manhole was approximately 3 feet deep. A second site installation was attempted but stopped 

because of incorrect liner dimensions. No air samples were collected from the second site.

Water-cured CIPP Installation Sites

• The company was subcontracted by a general contractor to perform storm drain repairs for 

Mississippi Department of Transportation (MDOT).

• MDOT inspectors were present each day to monitor and facilitate work.

• General observations for all sites and days included:

o One water-cured liner was installed each day. The duration of a water-cured installation 

depended on the length of the liner, ease of access to the damaged pipe at each location, 

and the ease with which the liner made the turn into the damaged pipe in the manhole. 
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o Installations occurred on a busy four-lane coastal highway with a median with two lanes 

in each direction. The coastal highway had an occasional turning lane, and some areas 

with a pull off for parking on the coast side.

o A public restroom was available at one installation site near pull off area and at local 

businesses.

o Process water was obtained from a company water truck or fire hydrants depending on 

accessibility.

o There were five work trucks at the installation sites including a reefer, water (jetter), 

boiler/lift, TV truck, and heavy pickup truck with an air compressor for cutting tools.

o Seven workers were present on the first day including a foreman, a superintendent, and 

five general laborers. Eight workers, including a foreman, a superintendent, and six

general laborers were present on Days 2–4. 

o The liner was 24 inches in diameter and 9 mm thick but variable in length depending on 

the day. The liner entered the storm drain through manholes with a diameter of 2.0 feet 

or access grates with dimensions of 3.5 feet by 4.5 feet, with a variable depth that was

approximately 6 feet to 7 feet. 

o Water pressure from raising the liner 20 feet while adding water to the liner was used to 

force the liner into the manhole and through sections of degraded pipe.

o Curing was conducted for 1 hour to 1.5 hours. The curing was checked with 

thermocouples added at each manhole/access grate along the liner. Small rocks were also 

thrown at the cured liner to check for a hard sound indicating that the liner was starting 

to cure. At the end of curing, an employee would throw a heavy metal bar with a pointed 

end that was attached to a rope at the cured liner while listening for a “crack” to indicate 

the cure was complete. The metal bar was also used to release water from the liner at the 

end of curing.

o We observed employees entering the manhole/access grates to cut the excess liner. 

Employees did not always adhere to company safety protocols for confined space entry. 

Some employees wore a harness with a rope attached that was not properly secured to a 

tripod winch, while other employees entered the manhole/access grates with no harness 

or rope. Sometimes, the tripod winch was used to hoist large pieces of liner out of the 

manhole, while the employee was still in the hole.

o Employees cut the excess cured liner using pneumatic- or electrical-powered chainsaws 

and angle grinders with a cutting blade. The bottom of cured liner in access grates 

between inlet and outlet was occasionally left uncut, but inlet and outlet ends were 

completely cut and trimmed. Dust generated during cutting was noticeably less when 

water was present on the bottom cuts than when cutting the top or sides of the liners.

o Blower ventilation fans (8-inch diameter, 615 cubic feet per minute of free air) were used 

frequently, but not always, to reduce styrene vapors using ambient dilution air during 

cutting and grinding. 

o Additional site information and environmental conditions are presented in Table C1.

• Day 1 installation occurred between the inlet located at the outside of the pull-off area toward 

the coast and the outlet located at the inside of the turning lane at the median between the two 
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inside lanes of opposing traffic. Two access grates were located between the inlet and the outlet.

During pre-cure, rainwater that accumulated in the storm drain had to be pumped out while the 

water temperature was approaching its set point. This environmental issue slowed down the 

process and increased the time required to reach an adequate cure temperature.

• Day 2 installation occurred between the inlet access grate located inland and the outlet manhole 

located on the boardwalk off the access road by the coast.

• Day 3 installation occurred between the inlet access grate located inland and the outlet access 

grate located on the outside of the highway by the coast. A problem was encountered with 

getting the liner to make the turn during inversion. Employees had to lower and raise the lift and 

remove/add water to get the liner to make the turn. 

• Day 4 installation occurred between the inlet located on the outside of the turning lane to enter 

the access road toward the coast and the outlet located at the inside of the median inland.

Wooden boards were placed at the outlet to stop the liner from continuing through the 

downstream storm drain.

Personal Protective Equipment

At CIPP installations, we observed employees and MDOT personnel onsite wearing long pants, 

hardhats, steel-toed shoes, reflective vests, hearing protection, and safety glasses. Hearing protection 

was not always used. When cutting, most employees wore chemically resistant coveralls (Lakeland 

Polyethylene-coated ChemMax®1 suits with hoods) and latex gloves. At the wet-out facility, we 

observed employees wearing safety glasses and occasionally wearing latex gloves. Respiratory protection 

was not required or worn at any process location.

Smoking

We noticed that some employees smoked cigarettes, which can contribute to lung disease.

Methods: Exposure Assessment

We assessed exposures and emissions of styrene and other volatile organic compounds (VOCs) during 

preparation and installation of CIPP liners. We collected air samples from some employees’ breathing 

zones during specific tasks at the CIPP installation sites and the wet-out facility and during the full

workday at the wet-out facility. Breathing zone air samples were collected to measure task-based and 

full-shift personal exposures to styrene using sorbent tubes and OSHA method ORG-89 [OSHA 1991]. 

For sorbent tubes, coconut shell charcoal tubes impregnated with t-butylcatechol (Part No. 226-73, 

SKC, Inc.) were attached to a personal air sampling pump (SKC Pocket Pump) flowing at 50 milliliters 

per minute. No adjustments were made to the full-shift exposures to account for time not sampled. The 

sampling strategy for task-based samples was not designed specifically for comparison to exposure 

limits, but when the samples were collected for 15 minutes, we directly compared them to applicable 

short-term exposure limits to determine whether occupational exposure limits had been exceeded. 

Sorbent tube samples were analyzed for styrene in accordance with OSHA method ORG-89 [OSHA 

1991]. A limit of detection is the lowest mass that can be measured by an analytical method. The limit 

of detection was 0.9 microgram (μg) per sample for styrene, corresponding to 0.3 parts per million

(ppm) for a sample duration of 15 minutes. Limit of quantitation was 3.0 μg per sample for styrene, 
B-6

corresponding to 0.9 ppm for a sample duration of 15 minutes. Limits of detection expressed as air 

concentration (in ppm) will vary depending on the sampling volume. Data were log-transformed before 

further analyses because environmental data are often log-normally distributed. We summarized styrene 

air concentration estimates using geometric means and geometric standard deviation by process and 

either task or location. We conducted a statistical comparison among processes using an ANOVA with 

Tukey’s post-hoc analysis on log-transformed personal task exposures to styrene with a significance 

level of 0.05. 

We measured process emissions at various area locations using the same sorbent tube method described 

above and instantaneous evacuated canisters (NMAM 3900) [NIOSH 2018]. The evacuated canister 

sampling setup consisted of a 450-mL evacuated canister equipped with an instantaneous flow 

controller designed for a short sampling duration of less than 30 seconds. The limits of detection were 

0.0003 ppm for acetone and 0.0005 ppm for styrene based on a 1.5 times dilution but will vary 

depending on sample pressure and injection volume. The limits of quantitation were 0.0010 ppm for 

acetone and 0.0018 ppm for styrene. We measured real-time personal exposures to and area process 

emissions of total volatile organic compounds using photoionization detectors with a 10.6 eV lamp 

(Tiger Cub for personal samples and Tiger for area samples; resolution 0.001 ppm). We collected near 

real-time air concentrations of styrene using a fourier-transform infrared spectrometer (Model DX4040, 

Gasmet Technologies) at the water-cured installation but the instrument failed. We did not use the 

spectrometer during the two additional surveys, and no spectrometer results are presented here. We 

collected bulk and cured process materials during surveys to measure styrene emission rates using a 

micro-chamber thermal extractor (Markes International, Inc., Sacramento, CA) and thermal desorption 

tubes (Universal tubes with inert coating, Markes International, Inc.). 

Personal full-shift air sampling for styrene using sorbent tubes at the wet-out facility

We collected four personal full-shift samples using sorbent tubes and OSHA method ORG-89 for 

styrene on the second day of our survey at the wet-out facility.

Area full-shift air sampling for styrene using sorbent tubes at the wet-out facility

We collected 12 area full-shift air samples using sorbent tubes and OSHA method ORG-89 for styrene 

on the second and third day of our survey at the wet-out facility.

Personal task air sampling for styrene using sorbent tubes during all processes

We collected a 109 personal task samples using sorbent tubes and OSHA method ORG-89 for styrene

during all process assessments. Nine samples were collected at the wet-out facility on the third day. 

Over three days, 46 samples were collected from steam-cured installations sites. Over four days, 54 

samples were collected from the water-cured installation sites.

• To summarize data, we grouped tasks by primary task or combined tasks with similar exposure 

potential or proximity to the source. Some task groups included multiple types of tasks. 

“Assisting cutting cured liner” task included one sample where the employee also cut the cured 

liner; six samples (one water and five steam) where the employee assisted with tearing down the 

work site after liner installation had been completed, and two samples for water-curing where 

the employee was also supervising the installation. “Cutting cured liner” task included nine 
B-7

samples for steam-curing where the employee assisted with tearing down the worksite after liner 

installation. “Inversion” task samples were only collected during inversion of the liner. “Other

tasks” included assisting or directly tearing down the lift. For water-curing, “pre-cure/cure/

cooldown” task included three samples with only pre-cure occurring and six samples including 

all three tasks. For steam-curing, “pre-cure/cure/cooldown” task included one sample when

only pre-cure and cure were occuring at the time and two samples when all three tasks were 

occurring.

Area air sampling for styrene using sorbent tubes upwind and downwind of source 

We collected 127 area air samples for styrene using sorbent tubes and OSHA method ORG-89 upwind 

and downwind of emission source at the steam- and water-cured installation sites.

Area air sampling for styrene and acetone using instantaneous canisters at or around source 

We collected 27 area task air samples for styrene and acetone upwind and downwind of source at wetout facility and steam- and water-cured installation sites using instantaneous canisters and NMAM 3900

[NIOSH 2018].

Real-time personal and area monitoring for total volatile organic compounds using 

photoionization detectors

We measured 124 real-time personal and area monitoring of total volatile organic compounds (TVOCs)

at wet-out facility and steam- and water-cured installation sites using photoionization detectors.

Styrene emission from cured liner and other process materials 

We measured styrene emission rates from seven samples of bulk process material or cured liner

including one sample of steam-cured liner, one sample of water-cured liner, and five samples of process 

materials from the wet-out facility. In the emission chamber, the temperature ranged from 22.9 degree 

Celsius (°C) to 25.6°C, and the humidity ranged from 36% to 47% relative humidity (RH).

Results: Exposure Assessment

Personal full-shift air sampling for styrene using sorbent tubes at the wet-out facility

All four personal full-shift air samples were well below the NIOSH REL of 50 ppm styrene. Personal 

full-shift samples had a geometric mean of 4.7 ppm styrene and geometric standard deviation of 1.3. 

The range of exposures to styrene was 3.4 ppm to 6.0 ppm collected over 355 minutes (5.9 hours) to 

372 minutes (6.2 hours). 

Area full-shift air sampling for styrene using sorbent tubes at the wet-out facility

Styrene concentrations in area full-shift air samples at the wet-out facility ranged from 0.2 ppm to 7.2 

ppm (Figure B1). Sampling durations ranged from 280 minutes (4.7 hours) to 446 minutes (7.4 hours). 

The highest area air concentration of 7.2 ppm styrene was measured at the mixing area on the first day 

when wall ventilation fans were not operating. On the second day in the same location, we measured an 

area air concentration of 2.2 ppm styrene when wall ventilation fans were operating. In the refrigerated 
B-8

storage area, we also observed a reduction in air concentration from 1.2 ppm styrene on the first day to 

0.2 ppm styrene on the second day.

Personal task air sampling for styrene using sorbent tubes during all processes

We collected 46 personal task samples for styrene during steam-cured CIPP installations (Table C2).

Three of these samples were collected for 16 minutes, of which one employee exposure measured 105.5 

ppm during a “pre-cure” task. During this sample, the employee was banding together the end of a liner

and also entered the manhole to place a thermocouple. This sample was the highest measured exposure

to styrene of all three industrial hygiene surveys and exceeded the NIOSH 15-minute short-term 

exposure limit (STEL) of 100 ppm styrene and the ACGIH STEL of 20 ppm. The other two personal 

task exposures for styrene were 33.6 ppm and 8.5 ppm, both collected during “inversion” tasks, and 

one was above the ACGIH STEL of 20 ppm The remaining 43 personal task exposures during steamcured installations were sampled for durations shorter or longer than 15 minutes. All remaining 

exposures during steam-cured installations were below 43.4 ppm styrene, which was collected during an 

“inversion” task for a sample duration of 32 minutes.

The highest geometric mean for task samples collected during steam-cured installations occurred during 

“inversion” tasks (9.3 ppm styrene, maximum 43.4 ppm styrene) followed by “cutting cured liner” tasks

(2.2 ppm styrene, maximum 29.6 ppm styrene). Of the 54 personal samples collected during watercured CIPP installations, the highest geometric mean for task samples occurred during “cutting cured 

liner” tasks (19.2 ppm styrene; maximum 55.3 ppm styrene) followed by “assisting cutting cure liner” 

tasks (0.9 ppm styrene; maximum 7.2 ppm styrene). The geometric mean for task samples collected at 

the wet-out facility was 4.1 ppm styrene for “all tasks.” The maximum styrene concentration of 12.5 

ppm at the wet-out facility occurred when an employee was getting process ingredients from a 

refrigerated storage area for 18 minutes. The geometric mean for styrene concentrations measured 

during steam-cured processes was 23 times higher than for water-cured processes, indicating possible 

exposure differences in the process or increased dilution of ambient air during sampling of water-cured 

tasks. An ANOVA with Tukey’s post-hoc analysis on log-transformed personal task measurements for 

styrene revealed a significant difference in mean exposures across processes with wet-out facility and 

steam (p=0.69) having higher exposures than water processes (p<0.05).

Task sampling durations for steam processes were generally shorter than water processes. For example, 

“cutting cured liner” tasks had a median duration of 19 minutes for steam-cured versus 89 minutes for 

water-cured. This difference in task sample durations was likely because of the liner dimensions and 

complexity of the installation sites. Additionally, “inversion” task sample durations for steam-cured 

processes was generally shorter than for water-cured processes (median 50 minutes versus 108 minutes). 

Area air sampling for styrene using sorbent tubes upwind and downwind of source 

We observed higher air concentrations for styrene downwind of the manhole/grate in most area 

samples (Table C3). As an example, we measured less than 0.04 ppm styrene upwind of an access grate

and 1.5 ppm styrene downwind during cutting the cured liner at a water-cured liner installation site 

(Figure B2).
B-9

Figure B2. Representative diagram showing chemical plume (blue shading) of total volatile organic compounds (TVOC) 

downwind of access grate during water-cured CIPP installation, March 2019. TVOC air concentrations in parts-per-million (ppm) 

were adjusted for styrene using a response factor from the manufacturer. Low TVOC air concentrations measured upwind of 

access grate compared to high TVOC air concentrations measured downwind of access grate. Black line with arrow in compass 

depicts wind direction. Red center with blue outer regions and white cross hairs depicts chemical plume showing higher TVOC 

concentrations next to the access grate that get lower as the chemical emissions travel downwind or crosswind from the access

grate. 

For the steam-cured process, the geometric mean for styrene air concentration downwind of the outlet 

manhole/grate was 0.4 ppm (maximum 6.2 ppm), which was more than 0.2 ppm (maximum 3.3 ppm) 

upwind. For the water-cured process, the geometric mean for styrene air concentration downwind of 

the outlet manhole/grate was 0.7 ppm (maximum 13.6 ppm), which was higher than 0.2 ppm 

(maximum 0.3 ppm) upwind. The highest geometric mean for styrene air concentrations was 4.3 ppm 

(maximum 10.6 ppm) and occurred close to the face of the manhole/grate.

Area air sampling for styrene and acetone using instantaneous canisters at or around source 

For source sampling using instantaneous canisters, we observed the highest air concentrations of 

styrene at the door of the reefer truck when the employee opened it (253.3 ppm, 215.9 ppm, and 135.3 

ppm) during steam-cured process (Table C4). One sample collected at the door of the reefer truck 

during a steam-cured process measured 0.2 ppm styrene; this sample was likely an outlier and 

presumably sampled upwind of the truck door or before the air in the reefer truck had a chance to 

migrate out of the truck door. We did not collect source samples at the door of the reefer truck during 

water-cured processes. For area sampling, the highest air concentration was 35.9 ppm styrene on day 3 

of water-cured process, upwind of the inlet during cutting the cured liner. The next highest air 

concentrations of styrene were 24.7 ppm and 23.4 ppm at the door to the refrigerated storage area of 

the wet-out facility. The highest air concentration for acetone was 42.5 ppm at the pinch roller during 

injection of liquid in the liner at the wet-out facility, followed by 37.3 ppm at breathing height in the 

refrigerated storage area and 35.6 ppm at breathing height in the mixing area of the wet-out facility. 
B-10

Real-time personal and area monitoring for total volatile organic compounds using 

photoionization detectors

We performed real-time personal exposure and area monitoring of TVOCs using photoionization 

detectors (PID). The resultant concentrations were styrene-adjusted using the PID instrument 

manufacturer’s styrene correction factor of 0.45. We collected 136 total samples at the wet-out facility 

and steam- and water-cured CIPP installation sites. 

For real-time PID area monitoring during CIPP installations, styrene-adjusted TVOC concentrations 

were generally highest near the outlet manhole. The highest observed styrene-adjusted TVOC 

concentration of 142.3 ppm was measured just downwind of the face of the outlet manhole during a

“pre-cure” task of a water-cured installation (Figure B3), in contrast to upwind of the inlet where 

styrene-adjusted TVOC air concentrations were low (<0.2 ppm). 

Figure B3. Area air sample collected during a water-cured CIPP installation using a real-time photoionization detector showing 

total volatile organic compound (TVOC) concentrations in parts per million (ppm) adjusted for styrene. Concentrations were 

higher downwind of the outlet manhole (red line) compared to upwind of the inlet manhole (blue line—almost indiscernible from 

the x-axis and fluctuating around the detection limit of the instrument), March 2019.

The highest real-time area monitoring styrene-adjusted TVOC concentration measured during a steamcured CIPP install was 44.1 ppm and was collected three meters downwind of the outlet manhole at the 

end of a “pre-cure” task and the beginning of a “cure” task (Figure B4). For CIPP installation area 

monitoring, styrene-adjusted TVOC concentrations were generally higher during “pre-cure” and “cure”

tasks near and, particularly, downwind of the outlet manhole (Figures B3 and B4).
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Figure B4. Area air samples upwind (blue line) and downwind (red line) of the outlet manhole collected during a steam-cured 

CIPP installation using real-time photoionization detector showing total volatile organic compound (TVOC) concentrations in 

parts per million (ppm) adjusted for styrene, June 2019.

For real-time PID personal monitoring during CIPP installations, the highest styrene-adjusted TVOC

concentration of 1,125 ppm was observed as an employee was checking thermocouples near the outlet 

manhole of a steam-cured install during a “cooldown” task (Figure B6). The highest styrene-adjusted 

TVOC concentration observed during water-cured CIPP installations was 117.6 ppm and occurred 

when general laborer-a was inside an outlet manhole performing a “cutting cured liner” task (Figure 

B4). Real-time styrene-adjusted TVOC personal monitoring results demonstrated that proximity to the 

liner was a driving factor for potential exposure to higher styrene concentrations before and during 

“inversion” tasks. In Figure B5, there are styrene-adjusted TVOC concentration spikes as both general 

laborer-a and general laborer-b were manually handling uncured sections of liner prior to an “inversion”

task. Similarly, close proximity to the inlet and outlet manholes during “pre-cure,” “cure,” “cooldown,”

and “cutting cured liner” tasks can lead to higher concentrations of personal styrene exposures. In 

Figure B6, styrene-adjusted TVOC concentration peaks are observed when employees were setting or 

checking thermocouples close to manhole openings during “pre-cure” and “cooldown” tasks. 
B-12

Figure B5. Personal air samples collected from employees during water-cured CIPP using real-time photoionization detector 

showing total volatile organic compound (TVOC) concentrations in parts per million (ppm) adjusted for styrene, March 2019.
B-13

Figure B6. Personal air samples collected from two employee during steam-cured CIPP using real-time photoionization detector 

showing total volatile organic compound (TVOC) concentrations in parts per million (ppm) adjusted for styrene, June 2019.

Real-time PID TVOC monitoring was also conducted at the CIPP liner wet-out facility. A diagram of 

approximate locations of area-sampling baskets containing PID monitors can be seen in Figure B1.

Overlaid plots of real-time, styrene-adjusted PID TVOC concentrations in different areas of the wetout facility on 12/04/2019 can be seen in Figure B7. The highest styrene-adjusted TVOC area 

concentration of 821.8 ppm was observed in the mixing area while an employee cleaned the resin-pump 

static mixer machine with acetone after wetting of a liner (Figure B7). Additional concentration peaks

were observed in the mixing area and near the resin-pump static mixer during rolling of a wetted liner 

(Figure B7). For personal exposure monitoring, the highest styrene-adjusted TVOC concentration of 

1,067 ppm was observed when an employee cleaned the resin-pump static mixer machine with acetone

(Figure B8). Additional elevated TVOC concentrations were observed for tasks including retrieving 

catalyst and styrene from the refrigerated storage area, injecting resin mixture into the liner, and liner 

rolling. Similar to trends during CIPP liner installations, close proximity to open containers of solvents 

(e.g., acetone) and the wetted liner can lead to higher levels of TVOC exposure. 
B-14

Figure B7. Area air samples from the wet-out facility collected using real-time photoionization detector showing total volatile 

organic compound (TVOC) concentrations in parts per million (ppm) adjusted for styrene, December 2019.

Figure B8. Personal air samples from two employees at the wet-out facility collected using real-time photoionization detector 

showing total volatile organic compound (TVOC) concentrations in parts per million (ppm) adjusted for styrene, December 2019.
B-15

Styrene emission from cured liner and other process materials 

We collected samples of cured liner and process material ingredients from the wet-out facility and both 

CIPP installation sites to estimate styrene emission rates. Emission factors for the steam-cured liner 

ranged from 3.7 to 47 mg styrene/kg material/hour (Table C5). Emission factors for the water-cured 

liner were much higher and ranged from 150 to 222 mg styrene/kg material/hour. The uncured resin 

catalyst mix emitted the lowest amount of styrene (89 mg styrene/kg material/hour) from the wet-out 

facility. The day 3 liner mixture containing styrene, resin, and catalyst emitted the highest amount of 

styrene (153,004 mg styrene/kg material/hour). The number of days since the sample was collected to 

the time it was tested ranged from 19 days to 152 days.

Methods: Review of safety data sheets

We collected safety data sheets (SDSs) to review process ingredients used during the site visits.

Results: Review of safety data sheets

We reviewed the SDSs, which contained information on styrene, tetrahydrofuran, resins, and 

polymerization initiators. Styrene content of resins was less than or equal to 40% by weight. Most of the 

process ingredients including styrene, tetrohydrofuran, resins, catalysts, and initiators were flammable. 

Most of the process ingredients were respiratory, dermal, and eye hazards. Exposure to styrene and 

tetrohydrofuran can affect the central nervous system. Direct contact of process ingredients such as 

initiators may result in eye damage and skin irritation. Some of the process ingredients also contained a 

hazard statement on reproductive toxicity because it may affect fertility or cause damage to unborn 

children. 

Discussion 

Employees in the vicinity of pipe rehabilitation might be exposed to a number of potentially hazardous 

substances, including irritants, carcinogens, flammable gases, and respirable and inhalable dusts. Our 

assessment focused on VOCs, specifically styrene, listed in the health hazard evaluation request. 

Additionally, we observed standard employee practices, workplace conditions, and the use of PPE. Our 

observations and results from the exposure and workplace assessments are further discussed below. 

Workplace Observations

We observed considerable differences in employee exposures between the two sampling days at the 

wet-out facility. On the first sampling day, wall ventilation fans in the facility were not operating, which 

was normal for the plant during the winter season depending on outside temperature. Not operating the 

fans contributed to higher measured concentrations of styrene in some full shift area samples. On the 

second sampling day, we sampled the same areas with the doors to the outside open and wall ventilation 

fans operating, which reduced some area air concentrations of styrene compared to the first sampling 

day. Continuously operating the wall ventilation fans at the wet-out facility during production could 

reduce area air concentrations in the facility and thereby reduce the overall burden of styrene exposures 

to employees.
B-16

Additionally, the potential for dermal exposure to process chemicals was observed. Employees manually 

conducted some tasks such as cutting and resealing the liner where dermal exposure to styrene and 

other process chemicals could be prevented with the use of chemically-resistant gloves. Nitrile or 

VitonTM gloves are recommended because latex gloves can cause allergic reactions in some individuals

[NIOSH 2009] and are poor protection against solvents like styrene. Gloves should be frequently 

replaced and when broken or soiled. Employees were eating food and drinking coffee in the facility 

around the liner wetting out site. An outside smoking area was located next to the process waste 

collection area which contained excess resin mixture, acetone, and other solvents. Additionally, open 

containers in the process area held ingredients used to prepare the resin mixtures. These ingredients and 

the final products emit various VOCs during the work shift. 

Steam-cured (liner diameter typically 24 inches or less) and water-cured (liner diameter typically 24 

inches or more) installations were performed outside at different locations and times depending on 

work orders and traffic conditions. Steam-cured installations during our visits were conducted during 

the daytime while water-cured installations were conducted during the nighttime. Low air flow and high 

humidity conditions made the work environment challenging, especially in enclosed spaces like the

manhole that contained cured liner. Occasionally, weather conditions such as rain prolonged the 

processes, resulting in a longer duration of exposure. We observed employees coughing after exposure 

to process emissions (e.g., styrene and other chemical vapor emissions). This exposure occurred after

entering the manhole to place thermocouples before curing began. Water- and steam-curing processes 

might have a number of differences that influence employee exposures. 

Exposure Assessment

Airborne exposure assessments are discussed below for styrene and other VOCs at wet-out liner 

preparation and two liner installations methods: steam-cured and water-cured.

Personal and area full-shift styrene concentrations at the wet-out facility

We conducted a limited characterization of employee full-shift exposures to styrene at the wet-out 

facility. The four full-shift measurements to styrene (3.4–6.0 ppm) were well below the NIOSH REL of 

50 ppm styrene. The full-shift measurements were similar despite employees having different roles in 

the process, possibly indicating a well-mixed environment. The highest area air concentrations of 

styrene were at the mixing station and mixing/injecting machine, followed by the reefer truck door. The 

use of wall ventilation fans appeared to be effective at reducing styrene air concentrations in the facility. 

General dilution ventilation should be used to control temperature and humidity for occupant comfort 

and to control air concentrations of non-hazardous pollutants. We note that dilution ventilation is less 

effective than local exhaust ventilation at controlling source emissions and should not be used 

exclusively to control hazardous source emissions. 

Personal task-based and area styrene concentrations at the CIPP installations

We characterized employee task-based exposures to styrene at the wet-out facility and at both CIPP 

installations to guide recommendations for controlling styrene emissions. The highest exposures 

occurred when employees were performing tasks in close proximity to process ingredients or resinimpregnated liners. For the wet-out facility, the highest measurement (12.5 ppm) occurred when a 

employee was getting styrene and catalyst from a refrigerated storage area. For water processes, the 
B-17

highest measurements (55.3 ppm) occurred during “cutting the cured liner” tasks when employees were 

in the access hole after the liner had been cured. For steam processes, the highest measurements (105.5

ppm) occurred when employees were doing tasks that generally occurred outside of the hole such as 

“inversions”, “pre-cure” and “cutting cured liner” tasks. The steam-cured repairs we observed were 

performed on sewer drain systems that limited or prohibited employee entry into the small access holes 

and also required more manual handling of the liner than the water-cured process. When the cured liner 

was cut, it released styrene trapped in the liner material and increased the air concentration in the access 

holes and breathing zone of the employees. Local exhaust ventilation equipped to the cutting tools may 

be effective at capturing dust and chemicals emitted from the cured liner when it is cut. A qualified 

ventilation engineering firm should be consulted when attempting to implement local exhaust 

ventilation to control source emissions. If styrene exposures exceed occupational exposure limits after 

ventilation or administrative controls, employees will need respiratory protection equipped with organic 

vapor cartridges as part of a comprehensive respiratory protection program that meets the requirements 

of OSHA’s Respiratory Protection standard (29 CFR 1910.134) and includes medical evaluations, fit 

testing, maintenance, and training.

Steam-cured installations occurred in residential settings; whereas, water-cured installations occurred in

highway settings near the gulf. This difference in location was the major factor for differences in wind 

speed: minimal air movement for steam-cured compared to moderate wind speeds for water-cured

processes. Low wind speeds promote higher concentrations around the source of styrene from process 

emissions, while higher wind speeds dilute and carry away the styrene concentrations downwind of the 

source. Some of the upwind concentrations might have been higher than the downwind concentration 

because of changing wind directions and low wind speed. Standing upwind or to the side when 

downwind so that employees are not directly downwind could reduce worker exposure. 

Area air sampling for styrene and acetone at or around sources using instantaneous canisters

We observed opportunities to control source emissions of styrene and acetone at the reefer truck door, 

at the refrigerated storage door, and during the task of cutting cured liner. These opportunities are 

important places in the process to control exposures. All instantaneous sampling results (0.001–253.3

ppm) were well below the NIOSH Immediately Dangerous to Life or Health (IDLH) of 700 ppm for 

styrene. Ventilating the reefer truck space with ambient air before employees enter the truck might

reduce peak exposures. Limiting the time spent in the reefer truck will also reduce exposures. 

Ventilating the refrigerated storage area at the wet-out facility and the confined space at CIPP 

installations with ambient air before entering might reduce process emissions, thereby reducing the 

chance for employee exposure to styrene and other VOCs. We expected to observe low concentrations 

upwind of the process emissions, but this was not always the case. On rare occasions, we measured

higher concentrations upwind compared to downwind because of wind direction changes and local 

disturbances to wind direction from highway traffic, but in general, employees should stand upwind of 

the manholes whenever possible to reduce exposures to process emissions. 
B-18

Real-time personal exposure and area monitoring for total volatile organic compounds using 

photoionization detectors

Physical proximity to the CIPP liner and the inlet and outlet manholes was the driving factor for 

increased TVOC exposure measurements during CIPP liner installation. The closer an employee was to 

the liner or the inlet and outlet manholes, the higher the likelihood of elevated TVOC concentrations. 

Physical contact with the liner should be avoided when possible. Time spent near the liner should be 

minimized when maintaining distance is not possible or practical. Prolonged contact or proximity to the 

uncured liner before and during “inversion” can lead to elevated personal exposures to TVOCs. 

Wind direction plays a major role in air concentrations of styrene around manholes during CIPP 

installations. Specifically, higher concentrations are present immediately downwind of the inlet and 

outlet manholes, with concentrations around the outlet manhole typically being higher than those 

around the inlet manhole. Employee exposures to TVOCs during the “pre-cure”, “cure”, and 

“cooldown” phases of CIPP liner installation can be reduced if employees remain aware of wind 

direction and their relative proximity to the inlet and outlet manholes.

Time spent setting up and monitoring thermocouples near manholes should be minimized as we 

observed the highest styrene-adjusted TVOC concentration of 1,125 ppm during this task. Consider 

incorporating an automated means of measuring thermocouple temperatures to reduce employee levels 

of TVOC exposure during temperature monitoring during the “pre-cure,” “cure,” and “cooldown”

phases of CIPP liner installation. Entering a manhole to engage in “cutting cured liner” was the task 

with the greatest potential for high exposures to TVOC concentrations, likely driven by styrene. Time 

spent in the confined space of the manhole should be minimized when possible. The manhole should 

be ventilated with a blower ventilator fan every time an employee enters the manhole and for the entire 

duration of the employee’s stay within the confined space.

For the wet-out facility, time spent in proximity to open containers of solvents such as styrene and 

acetone, time spent in enclosed spaces such as the refrigerated storage area or the reefer truck, and time 

spent in close proximity to the wetted liner were the main factors associated with higher concentrations

of personal TVOC exposures. To lower the potential for exposure during the wet-out process, consider 

ventilating the refrigerated storage area and reefer truck trailer before and during occupancy by 

employees, while also minimizing the amount of time spent inside. Additionally, capping mixing buckets 

and solvent buckets when not in use can lower ambient levels of TVOCs within the facility. Because

contact with the wetted liner is sometimes required during the wet-out process, potential for TVOC 

exposure can be reduced by minimizing time in contact with the liner and resin mixer, and also by 

wearing appropriate PPE such as nitrile gloves and safety glasses. 

Styrene emission from cured liner and other process materials 

We measured emission factors from cured liner and other process materials in the laboratory. Emission 

factors can be used to estimate styrene air concentrations when ventilation and room or space volume is 

known, but these estimated air concentrations should be confirmed with air sampling. Emission factors 

generally decrease over time as the amount of styrene in the material decreases at the boundary between 
B-19

the material and the air. In our tests, the emission factors did not always decrease with storage time 

because of variability in the technique and heterogeneity of the sample. The emission factors generated 

in these tests are worst-case emission estimates that are not realistic of real conditions where surface 

area available for emission is limited.

Emission factors for styrene from the cured and uncured process materials showed the potential for 

emission of styrene from materials. Much of the styrene in the uncured liner is consumed by the 

polymerization process or emitted into the atmosphere during the curing process, but some remains in 

the cured liner and can slowly emit over time. Steam-curing appeared to be more efficient at cooking 

off styrene as can be seen from the lower emission factors, but only one sample was tested for each 

curing method. Additional testing of styrene emission factors from cured liners should be conducted to 

assess the effectiveness of curing technique on emission factors. Flushing the freshly cured liner after 

curing, as well as before and during cutting the cured liner, might reduce employee exposures. 

Safety Data Sheets

The Occupatonal Safety and Health Administration’s (OSHA’s) Hazard Communication Standard, also 

known as the “Right to Know Law” [29 CFR 1910.1200] requires that employees are informed and 

trained on potential work hazards and associated safe practices, procedures, and protective measures. 

SDSs provide information on hazardous chemicals used in products but might not list all hazardous 

ingredients [LeBouf et al. 2018]. The SDS describes the material properties as well as the physical, 

health, and environmental hazards for each hazardous chemical used in the workplace. In addition, the 

SDS provides information on how to safely handle and store hazardous chemicals. The SDS must be 

easily available to all employees or provided to the employee when requested. Sometimes SDS are kept 

as a hard copy in a binder, other times they may be on a computer. All SDSs must contain the following 

sections: information on the chemical such as product identifiers, common names, or synonyms, 

contact information for the manufacturer, a description of intended use and any restrictions on use, 

hazard classification and warning information associated with the hazards, composition, safe handling 

practices, storage information, emergency control measures, physical and chemical properties, stability 

and reactivity information, toxicological information, exposure limits, required engineering controls, 

personal protective measures, and other information including the date of preparation or last revision 

[OSHA 2012a,b].

SDSs for process ingredients indicated hazardous chemicals with inhalation and dermal exposure routes

that can be controlled with ventilation and chemically resistant gloves. Employees should not eat, drink, 

or smoke in areas where these materials are used. Employees should wash their hands and face before 

eating. The precautions and safety information in these sheets reinforce our recommendations to 

increase ventilation of enclosed and confined spaces, especially for styrene, and to wear nitrile or 

VitonTM gloves when handling cured and uncured process materials. Latex gloves are not recommended 

because they are not as protective against styrene. Also, for some workers, exposure to latex can result 

in latex allergies [NIOSH 2009]. Gloves should be replaced often and when they break or become 

soiled.
B-20

Health Effects of Process Chemicals

Styrene

Styrene is a VOC with a sweet, pungent odor. Styrene is a component of the resin used in the CIPP 

liner. Exposure to styrene can occur by breathing air containing styrene or when skin comes into 

contact with resin containing styrene. Some health effects associated with styrene exposure are changes 

in color vision, tiredness, feeling drunk, slowed reaction time, concentration problems, balance 

problems, or hearing loss [ATSDR 2010; Campo et al. 2014; Estill et al. 2016]. Styrene exposure is also 

a potential risk factor for non-malignant respiratory disease among workers in industries using styrene 

[Nett et al. 2017a]. Respiratory diseases such as asthma and obliterative bronchiolitis have been reported 

among styrene-exposed workers [Culliman et al. 2013; Moscato et al. 1987]. The International Agency 

for Research on Cancer (IARC) has classified styrene as probably carcinogenic to humans based on 

limited evidence in humans and sufficient evidence in experimental animals for carcinogenicity [IARC 

Monographs Vol 121 Group]. “Probably carcinogenic” is the second of five categories that range from 

“carcinogenic to humans” to “probably not carcinogenic to humans” as defined by IARC [IARC 2019].

Obliterative Bronchiolitis

Obliterative bronchiolitis is a serious, often disabling, lung disease that involves scarring of the very 

small airways (i.e., bronchioles). Symptoms of this disease can include cough, shortness of breath on 

exertion, and/or wheeze, that do not typically improve away from work [NIOSH 2012]. Occupational 

obliterative bronchiolitis has been identified in styrene-exposed workers in a variety of industries, 

including boat manufacturing, automotive repair, military aviation, and others [Cullinan 2013, Nett 

2017a, Nett 2017b]. 

Work-Related Asthma

Work-related asthma refers to asthma brought on by (“occupational asthma”) or made worse by 

(“work-exacerbated asthma” or “work-aggravated asthma”) workplace exposures [NIOSH 2017; Tarlo 

2016; Tarlo and Lemiere 2014; OSHA 2014; Henneberger et al. 2011]. It includes asthma because of 

sensitizers, which cause disease through immune (allergic) mechanisms, and irritants, which cause 

disease through non-immune mechanisms. Symptoms of work-related asthma include episodic 

shortness of breath, cough, wheeze, and chest tightness. The symptoms may begin early in a work shift, 

towards the end of a shift, or hours after a shift. The symptoms often improve or remit during periods 

away from work, such as on weekends or holidays. Styrene has been demonstrated in multiple cases to 

cause occupational asthma in exposed individuals [Fernandez-Nieto 2006; Moscato 1987; Hayes 1991].

Acetone

Exposure to acetone in the air can irritate the upper respiratory tract and eyes and cause gastrointestinal 

and central nervous system health effects. Workers regularly exposed to acetone are less likely to 

experience irritation effects than workers without repeated exposures [ATSDR 2011; Dalton et al. 

1997]. Human carcinogenicity for acetone has not been classified by the American Conference of 

Governmental Industrial Hygienists (ACGIH), IARC, or the National Toxicology Program. Significant 

acetone exposure (>500 ppm) can upregulate metabolic enzymes that can increase the cancer-causing 

potential of other chemicals like chloroform and benzene [ACGIH 2021]. 
B-21

Polyester Resin

Polyester resins can vary in composition, but typically contain a styrene monomer to reduce viscosity 

and thin the mixture [Zaske and Goodman 1998]. An acrylate is frequently included to promote the 

formation of chemical bonds (polymers) and increase the durability and strength of the final material. 

Health effects of composite materials like resin are difficult to assess unlike those of single materials like

styrene or acetone. However, it has been known for many years that dermal exposure to polyester resin 

can cause skin irritation and chemical sensitization [Bourne and Milner 1963]. Recent research on CIPP 

emissions have determined that styrene, benzaldehyde, phenol, and many other substances are often

present in the air during the curing process [Teimouri Sendesi et al. 2017]. Samples of these emissions 

have been shown to be harmful to lung cells, potentially predisposing exposed workers to the 

development or worsening of conditions such as fibrosis, obstructive pulmonary disease, and cancer 

[Kobos et al. 2019]. 

Catalysts/Initiators

Resin initiators, often referred to as catalysts, are used to start the series of chain reactions

(polymerization) that allow the resin to cure [Kamath and Gallagher 1980]. Organic peroxides are

thermally unstable chemicals, which can decompose while producing heat, and some compounds may 

react violently with other substances [OSHA 2013]. Organic peroxides are some of the most commonly 

used polymerization initiators. Acyl peroxide, benzoyl peroxide, cumyl peroxide, di-t-butyl peroxide, 

and methyl ethyl ketone peroxide are examples of peroxide initiators [Su 2013; CCOSH 2009]. Peroxide 

initiators, like resins, are frequently composite materials, meaning that their health effects are not as well 

understood as individual chemicals. These initiators might also have hazardous decomposition 

products. Depending on the composition of the initiator, dermal exposure can cause irritation and 

chemical burns. Based on a review of a catalyst SDS available online, components or decomposition 

products of an initiator might cause drowsiness, dizziness, or respiratory irritation. Inhalation, 

swallowing, or direct eye exposure can result in permanent damage [United Initiators, 2020].

Smoking

Smoking is a risk factor for lung disease. Evidence indicates that smoking can act in combination with 

hazardous agents to produce or increase the severity of a wide range of adverse health effects. We 

recommend implementing a smoking cessation program to assist employees to stop smoking. The 

Centers for Disease Control and Prevention offers tools and resources for setting up a smoking 

cessation program [CDC 2020].

Limitations 

We measured employees exposures and process emissions for a limited number of days. Exposures may 

be different on different days because of changes in the environment or work site conditions. We 

suggest further sampling of employee exposures at multiple installation sites across a variety of 

environmental conditions and whenever changes to the process are implemented that could affect 

exposures. We designed the exposure assessment to focus on task-based exposures because employees 

preparing liner or conducting CIPP installations were intermittently exposed to emissions from process 
B-22

ingredients. Task samples varied in duration and did not frequently enable direct comparison to STELs, 

which are set for 15-minute sample durations. 

Conclusions

The company proactively requested assistance from NIOSH to characterize and make 

recommendations to control employee exposures to styrene. Employees should follow confined space 

entry protocols outlined by the company and pursuant to OSHA regulations, including monitoring of 

hazardous atmospheres such as styrene air concentrations generated during the installation process. We 

identified locations and tasks such as the refrigerated storage area, the reefer truck, and cutting cured 

liner that are sources of styrene emissions and can be controlled using engineering and administrative 

controls. One employee’s exposure exceeded the NIOSH STEL for styrene during “pre-cure” at a 

steam-cured CIPP installation site. Respiratory protection with organic vapor cartridges may be needed 

if exposures to styrene above OELs cannot be controlled with substitution, ventilation, or 

administrative controls. Cured liner continues to emit styrene after installation, and the process of 

cutting the cured liner increases emissions. Ventilation fans should be operated continuously during 

production in the wet-out facility and during access of enclosed and confined spaces at CIPP 

installation sites. In the future, exposure monitoring should focus on personal STEL (15-minute 

duration) and ceiling (instantaneous) sampling at the wet-out facility and CIPP installation sites to 

ensure employee health is protected by remaining below occupational exposure limits. At the wet-out 

facility, we observed full-shift personal sampling exposures to styrene well below the NIOSH REL. We 

conducted limited full-shift sampling and exposures are affected by environmental and process 

conditions at the time of sampling. For these reasons, additional full-shift exposure monitoring should 

be conducted periodically at the wet-out facility to ensure exposures remain below occupational 

exposure limits.
C-1

Section C: Tables

Table C1. Environmental and site conditions during sampling at water-cured CIPP installation sites (March 2019) and steam-cured CIPP installation sites 

(June 2019)

Process Day Number of Manholes/ Liner Length Humidity Range Temperature Wind Speed Wind Direction

Access Grates (feet) (%RH) Range (°F) Range (mph) Range*

Water 1 4 53 68.5–100.0 37.1–41.7 1.4–8.0 NNE to NNW

ater 2 3 39 52.8–86.3 41.5–48.7 1.2–5.0 NNE to NNW

Water 3 4 101 51.1–95.4 35.4–44.5 <0.1–4.2 S to N

Water 4 2 38 80.0–92.4 57.9–60.1 1.3–7.9 SSE to ESE

Steam 1 2 464 53.9–70.9 89.7–100.5 <0.1–0.8 SSW to S

Steam 2 2 464 90.6–99.3 70.3–77.8 <0.1–2.0 S to SSE

Steam 3 2 288 70.9–99.3 70.3–89.7 <0.1–2.3 N to W

Note: CIPP=cured-in-place pipe; RH=relative humidity; °F=degrees Fahrenheit; mph=miles per hour, S=South; N=North; W=West; NNE=North North East, 

NNW=North North West; SSW=South South West; SSE=South South East. 

*Wind directions from local measurements during water-cured installations and from regional airport data during steam-cured wind direction.
C-2

Table C2. Task-based personal breathing zone air sampling for styrene during tasks at water-cured CIPP installation site (March 2019), steam-cured CIPP 

installation site (June 2019), and wet-out facility (December 2019)

Process Task Name* Number Number Geometric Geometric Styrene Air Median Number 

of of Mean Styrene Standard Concentration (range) (percentage)

Samples Workers Air Deviation Range Sampling of Samples

Concentration (ppm) Duration below the

(ppm) (minutes) LOD

Steam ASSISTING CUTTING CURED LINER† 7 5 0.2 2.7 (<0.07–0.8) 28 (5 – 64) 6 (86%)

Steam CUTTING CURED LINER§ 9 5 2.2 5.0 (<0.21–29.6) 19 (2 – 26) 2 (22%)

Steam INVERSION¶ 21 6 9.3 5.0 (<0.07–43.4) 50 (4 – 70) 1 (5%)

Steam PRE-CURE/CURE/COOLDOWN** 9 7 0.4 16.1 (<0.02–105.5) 211 (16 – 281) 3 (33%)

Water ASSISTING CUTTING CURED LINER 13 6 0.9 3.3 (0.1–7.2) 116 (55 – 156) 0 (0%)

Water CUTTING CURED LINER 6 3 19.2 3.1 (2.2–55.3) 89 (58 – 118) 0 (0%)

Water INVERSION 23 8 0.4 3.8 (<0.02–2.4) 108 (68 – 235) 3 (13%)

Water OTHER TASKS 9 5 0.4 2.0 (0.1–0.9) 110 (11 – 157) 0 (0%)

Water PRE-CURE/CURE/COOLDOWN†† 3 1 0.2 1.1 (0.2–0.2) 181 (155 – 225) 0 (0%)

Wet-out ALL TASKS 9 4 4.1 2.3 (1.4–12.5) 97 (12 – 167) 0 (0%)

NIOSH Short-Term Exposure Limit value (ppm) 100

Note: CIPP=cured-in-place pipe; ppm=parts per million; LOD=limit of detection, which is the smallest mass that can be measured by the analysis method.

*Some task samples included additional tasks but were grouped by primary task or combined into a larger task group with similar proximity to source or exposure 

potential. 

†

ASSISTING CUTTING CURED LINER included one sample where the employee also cut the cured liner (5.0 ppm), six samples (one water and five steam) where the 

worker assisted with tearing down the work site after liner installation had been completed (maximum concentration 0.7 ppm), and two samples for water-curing where the 

worker was also supervising the installation (maximum concentration 0.6 ppm). 

§

CUTTING CURED LINER included nine samples for steam-curing where the worker assisted with tearing down the worksite after liner installation. 

¶

INVERSION samples were only collected during inversion of the liner. OTHER TASKS included assisting or directly tearing down the lift. 

**For steam-curing, PRE-CURE/CURE/COOLDOWN included one sample with only pre-cure and cure happening and two samples including all three tasks. 

 Employee task exposure of 105.5 ppm over 16-minute sample duration exceeded the ACGIH 15-minute short-term exposure limit (STEL) of 20 ppm and likely 

 exceeded the NIOSH 15-minute STEL limit of 100 ppm.

††For water-curing, PRE-CURE/CURE/COOLDOWN included three samples with only pre-cure happening and six samples including all three tasks. 
C-3

Table C3. Area air sampling for styrene during water-cured CIPP processes (March 2019) and steam-cured CIPP processes (June 2019)

Process Basket Location Location Number Geometric Geometric Area Styrene Median (range) Number 

Relative to of Mean Area Standard Air Sampling (percentage) of

Manhole/Grate* Samples Styrene Air Deviation Concentration Duration Samples below 

Concentration Range (ppm) (minutes) the LOD

(ppm)

Steam DOWNWIND INLET 10 0.2 3.1 (<0.05–1.2) 52 (8–200) 6 (60%)

Steam UPWIND INLET 22 0.3 5.0 (<0.04–8.7) 43 (6–147) 15 (68%)

Steam DOWNWIND OUTLET 16 0.4 4.5 (<0.08–6.2) 42 (5–157) 8 (50%)

Steam UPWIND OUTLET 16 0.2 3.3 (<0.08–3.3) 51 (6–101) 8 (50%)

Water DOWNWIND INLET 11 0.5 2.2 (0.2–1.5) 78 (23–174) 0 (0%)

Water UPWIND INLET 14 0.1 3.0 (<0.02–2.0) 78 (17–214) 10 (71%)

Water DOWNWIND MIDDLE 8 0.8 5.8 (0.1–5.6) 87 (43–127) 0 (0%)

Water DOWNWIND OUTLET 19 0.7 4.5 (0.1–13.6) 90 (32–133) 0 (0%)

Water FACE OUTLET 4 4.3 2.1 (2.0–10.6) 119 (44–128) 0 (0%)

Water UPWIND OUTLET 7 0.2 1.4 (0.1–0.3) 82 (35–120) 0 (0%)

Note: CIPP=cured-in-place pipe; ppm=parts per million; LOD=limit of detection, which is the smallest mass that can be measured by the analysis method. 

*Location relative to wind direction are approximate because of variability in wind direction during sampling.
C-4

At Source or Task Sample Description Instantaneous Instantaneous 

Area Basket Styrene Air Acetone Air

Process Day Orientation Concentration Concentration

Relative to (ppm) (ppm)

Manhole/Grate

Steam 3 UPWIND CURE At breathing height 2.7 meters from inlet 0.001 0.002

Steam 2 UPWIND CUTTING CURED LINER At breathing height 2.3 meters from outlet 0.2 0.01

Steam 3 UPWIND CUTTING CURED LINER At breathing height 2.6 meters from inlet 0.1 0.02

Steam 1 SOURCE OPENING REEFER TRUCK At door when employee opened reefer truck 253.3* <0.002

Steam 2 SOURCE OPENING REEFER TRUCK At door when employee opened reefer truck 215.9* 2.7

Steam 3 SOURCE OPENING REEFER TRUCK At door when employee opened reefer truck 0.2† 0.007

Steam 3 SOURCE OPENING REEFER TRUCK At door when employee opened reefer truck 135.3 0.3

Steam 3 UPWIND REMOVING LINER At breathing height 2.4 meters from inlet 5.2 <0.002

Water 1 SOURCE CURE At face of outlet manhole 16.7 0.004

Water 1 SOURCE CUTTING CURED LINER At face of outlet manhole 12.1 <0.002

Water 2 UPWIND CUTTING CURED LINER At breathing height 3.0 meters from inlet 0.1 <0.002

Water 3 DOWNWIND CUTTING CURED LINER At breathing height 1.0 meters from outlet 16.6 <0.002

Water 3 DOWNWIND CUTTING CURED LINER At breathing height 2.0 meters from middle grate 0.4 <0.002

Water 3 SOURCE CUTTING CURED LINER At face of inlet manhole 35.9 <0.002

Water 4 UPWIND CUTTING CURED LINER At breathing height 2.3 meters from inlet 0.3 <0.002

Water 4 UPWIND CUTTING CURED LINER At breathing height 3.1 meters from outlet 9.8 0.004

Water 2 DOWNWIND INVERSION At breathing height 1.2 meters from outlet 0.1 0.003

Water 1 DOWNWIND PRE-CURE At breathing height 2.1 meters from inlet 0.3 <0.002

Water 2 SOURCE PRE-CURE At grate face between inlet and outlet sides 0.1 <0.002

Wet-out 1 SOURCE AT DOOR TO REFRIGERATED At door after worker opened refrigerated storage 23.4 10.5

STORAGE area

Wet-out 1 SOURCE INJECTING LIQUID IN LINER At pinch roller 3.6 42.5

Wet-out 1 SOURCE MIXING RESIN WITH At breathing height in mixing area 16.0 35.6

STYRENE

AND CATALYST

Wet-out 1 SOURCE NO TASK§ At breathing height in refrigerated storage area 8.0 35.5

Wet-out 1 SOURCE NO TASK¶ At breathing height in refrigerated storage area 6.3 37.3

Wet-out 1 SOURCE OPENING DOOR TO At door when employee opened refrigerated 24.7 12.1

REFRIGERATED STORAGE storage area

Table C4. Instantaneous source and area air sampling for styrene and acetone at water-cured CIPP processes (March 2019), steam-cured CIPP 

processes (June 2019), and wet-out facility (December 2019)
C-5

NIOSH Immediately Dangerous to Life and Health (IDLH) value (ppm) 700 2500

Occupational Safety and Health Administration Ceiling value (ppm) 200**

Note: NIOSH=National Institute for Occupational Safety and Health; OSHA=Occupational Safety and Health Administration; ppm=parts per million; "NA" =not 

applicable because OSHA does not have a ceiling value for acetone.

*Two samples exceeded the OSHA ceiling limit value while an employee was opening the reefer truck door indicating the potential for overexposure during this 

task. However, exposure limits above OSHA or NIOSH limits are not directly applicable to instantaneous canister samples in table because the samples were not 

collected in the breathing zone of an employee.

†

Measured concentration of 0.2 ppm seems low considering the sample was collected at the face of a refrigerated truck as an employee opened the door. Other 

samples collected during the same activity on different days were much higher (253.3 ppm and 215.9 ppm).

§

Employee entered area 14 minutes before sample to get styrene and catalyst.

¶

Employee entered area 16 minutes before sample to get styrene and catalyst.

**600 ppm 5-minute maximum in any 3 hour period

At Source or Task Sample Description Instantaneous Instantaneous 

Area Basket Styrene Air Acetone Air

Process Day Orientation Concentration Concentration

Relative to (ppm) (ppm)

Manhole/Grate

Table C4. Instantaneous source and area air sampling for styrene and acetone at water-cured CIPP processes (March 2019), steam-cured CIPP 

processes (June 2019), and wet-out facility (December 2019) (continued)
C-6

Table C5. Styrene emission factors for cured liners and process materials from wet-out facility and CIPP installations

Process Description Test Number Days since Emission Mass (g) Temperature (°C) Humidity

sample Factor (%RH)

collected (mg/kg/h)

Steam Cured liner 1 19 6.8 1.7 20.6 63

Steam Cured liner 2 26 47 1.1 20.7 63

Steam Cured liner 3 36 3.7 1.5 20.7 63

Steam Cured liner 4 61 8.2 1.2 20.3 63

Water Cured liner 1 20 222 0.88 22.3 58

Water Cured liner 2 32 155 1.3 22.6 61

Water Cured liner 3 152 150 1.5 20.7 67

Wet-out Uncured Resin Catalyst Mix 1 37 89 1.0 23.9 47

Wet-out Day 1 liner mixture containing styrene and uncured resin 1 55 88,200 0.31 22.9 46

catalyst mix

Wet-out Day 2 liner mixture containing styrene and uncured resin 1 82 66,145 0.25 23.7 41

catalyst mix

Wet-out Day 3 liner mixture containing styrene and uncured resin 1 53 153,004 0.26 25.6 47

catalyst mix

Wet-out Liner plus liner mixture (solidified naturally during storage) 1 97 102 0.25 23.9 36

Note: CIPP=cured-in-place pipe; mg/kg/h=milligrams styrene per kilogram of material per hour; g=grams; °C=degrees Celsius; RH=relative humidity.
D-1

Section D: Occupational Exposure Limits

NIOSH investigators refer to mandatory (legally enforceable) and recommended occupational exposure 

limits (OELs) for chemical, physical, and biological agents when evaluating workplace hazards. OELs 

have been developed by federal agencies and safety and health organizations to prevent adverse health 

effects from workplace exposures. Generally, OELs suggest concentrations of exposure that most 

employees may be exposed to for up to 10 hours per day, 40 hours per week, for a working lifetime, 

without experiencing adverse health effects. 

However, not all employees will be protected if their exposures are maintained below these levels. Some 

may have adverse health effects because of individual susceptibility, a pre-existing medical condition, or 

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

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

produce adverse health effects. Most OELs address airborne exposures, but some substances can be 

absorbed directly through the skin and mucous membranes.

Most OELs are expressed as a time-weighted average (TWA) exposure. A TWA refers to the average 

exposure during a normal 8- to 10-hour workday. Some chemical substances and physical agents have 

recommended short term exposure limits (STEL) ceiling values. Unless otherwise noted, the STEL is a 

15-minute TWA exposure. It should not be exceeded at any time during a workday. The ceiling limit 

should not be exceeded at any time.

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

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

recommendations. 

• The U.S. Department of Labor OSHA permissible exposure limits (PELs) (29 CFR 1910 

[general industry]; 29 CFR 1926 [construction industry]; and 29 CFR 1917 [maritime industry]) 

are legal limits. These limits are enforceable in workplaces covered under the Occupational 

Safety and Health Act of 1970. OSHA STELs are the legal maximum average exposure for a 15-

minute time period. Some chemicals also have an OSHA ceiling value that represents 

concentrations that must not be exceeded at any time.

• NIOSH recommended exposure limits (RELs) are recommendations based on a critical review 

of the scientific and technical information and the adequacy of methods to identify and control 

the hazard. RELs as TWA concentrations that should not be exceeded over an 8 or 10-hour 

work shift, during a 40-hour workweek [NIOSH 2020]. NIOSH also provides STELs that are 

15-minute TWAs. For some chemicals, NIOSH has Immediately Dangerous to Life or Health 

(IDLH) values. An IDLH value is a concentration of an air contaminant that can cause death or 

immediate or delayed permanent adverse health effects or prevent escape from such an 

environment. NIOSH RELs are published in the NIOSH Pocket Guide to Chemical Hazards 

[NIOSH 2020]. NIOSH also recommends risk management practices (e.g., engineering controls, 
D-2

safe work practices, employee education/training, personal protective equipment, and exposure 

and medical monitoring) to minimize the risk of exposure and adverse health effects.

• Other OELs commonly used and cited in the United States include the threshold limit values 

(TLVs®), which are recommended by ACGIH, a professional organization. The ACGIH TLVs 

are developed by committee members of this professional organization from a review of the 

published, peer-reviewed literature. TLVs are not consensus standards. They are considered 

voluntary exposure guidelines for use by industrial hygienists and others trained in this discipline 

“to assist in the control of health hazards” [ACGIH 2021]. ACGIH provides TLV-TWA 

guidelines that are concentrations that should not be exceeded during any 8-hour workday of a 

40- hour workweek. ACGIH also provides TLV-STEL guidelines that are 15-minute exposure 

concentrations that should not be exceeded during a workday.

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

include legal and recommended limits. The Institut für Arbeitsschutz der Deutschen Gesetzlichen 

Unfallversicherung (Institute for Occupational Safety and Health of the German Social Accident 

Insurance) maintains a database of international OELs from European Union member states, Canada 

(Québec), Japan, Switzerland, and the United States. The database, available at 

http://www.dguv.de/ifa/GESTIS/GESTIS-Stoffdatenbank/index-2.jsp, contains international limits 

for more than 1,500 hazardous substances and is updated periodically. 

OSHA requires an employer to furnish employees a place of employment free from recognized hazards 

that cause or are likely to cause death or serious physical harm [Occupational Safety and Health Act of 

1970 (Public Law 91–596, sec. 5(a)(1))]. This is true in the absence of a specific OEL. It also is 

important to keep in mind that OELs may not reflect current health-based information.

When multiple OELs exist for a substance or agent, NIOSH investigators generally encourage 

employers to use the lowest OEL when making risk assessment and risk management decisions.

Occupational Exposure Limits for Styrene and Acetone

Occupational Safety and Health Administration (OSHA) [Mandatory]

For styrene, the OSHA PEL is 100 ppm, and the OSHA ceiling value is 200 ppm [OSHA 2019]. OSHA 

does not have a STEL for styrene. Further, there is a limit of 600 ppm 5-minute maximum peak in any 

3 hours, meaning that a 5-minute exposure above the ceiling value, but never above the maximum peak, 

is allowed in any 3 hours during an 8-hour workday [OSHA 2019]. 

For acetone, the OSHA PEL is 1000 ppm [OSHA 2019]. 

American Conference of Governmental Industrial Hygienists (ACGIH) [Recommended] 

For styrene, the ACGIH TLV is 10 ppm, and the ACGIH STEL is 20 ppm [ACGIH 2021]. In January 

2020, ACGIH reduced the previous TLV of 20 ppm and STEL of 40 ppm by half and added 

designations of ototoxicant (hearing hazard) and A3 carcinogen, which is a “confirmed animal 
D-3

carcinogen with unknown relevance to humans” [ACGIH 2021]. These changes were made after the 

last site visit associated with this health hazard evaluation request in December 2019. 

For acetone, the ACGIH TLV is 250 ppm and STEL 500 ppm [ACGIH 2021].

National Institute for Occupational Safety and Health (NIOSH) [Recommended]

For styrene, the NIOSH REL is 50 ppm, the NIOSH STEL is 100 ppm, and the IDLH is 700 ppm.

For acetone, the NIOSH REL is 250 ppm, and IDLH is 2500 ppm [NIOSH 2020]. Raleigh et al. 

mentioned symptoms such as headache, lightheadedness, and irritation in eye, nose, and throat among 

workers exposed to acetone concentrations higher than 1000 PPM [Raleigh et al. 1972]. For safety 

considerations, IDLH for acetone was set at 2500 ppm as 10% of the lower explosive limit of 2.5%

[NIOSH 2020].
E-1

Section E: References

Health Effects of Styrene

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Public Health Service, Agency for Toxic Substances & Disease Registry,

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E-2

NIOSH [2012]. Flavoring-related lung disease. Information for healthcare providers. Department of 

Health and Human Services, Centers for Disease Control and Prevention, DHHS (NIOSH) Publication 

No. 2012-148 (supersedes 2012-107), http://www.cdc.gov/niosh/docs/2012-148/.

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to styrene: two case reports. J Occup Med 29(12):957-960.

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https://www.cdc.gov/niosh/topics/asthma/default.html.

OSHA [2014]. OSHA Fact sheet: Do you have work-related asthma? A guide for you and your doctor. 

Washington, D.C.: U.S. Department of Labor, Occupational Safety and Health Administration,

https://www.osha.gov/Publications/OSHA3707.pdf. 

Tarlo SM, Lemiere C [2014]. Occupational asthma. N Engl J Med 370:640-649,

https://doi.org/10.1056/NEJMra1301758.

Tarlo SM [2016]. Update on work-exacerbated asthma. Int J Occup Med Environ Health 29(3):369-374.

https://doi.org/10.13075/ijomeh.1896.00676.

Health Effects of Acetone

ATSDR [2011]. Addendum to the toxicological profile for acetone. Atlanta, GA: U.S. Department of 

Human Services, Centers for Disease Control and Prevention, Agency for Toxic Substances and 

Disease Registry, https://www.atsdr.cdc.gov/toxprofiles/acetone_addendum.pdf.

Dalton P, Wysocki CJ, Brody MJ, Lawley HJ [1997]. Perceived odor, irritation, and health symptoms 

following short-term exposure to acetone. Am J Ind Med 31(5):558-69, 

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Raleigh LR, McGee WA [1972]. Effects of short, high-concentration exposures to acetone as 

determined by observation in the work area. J Occup Med 14(2):607-610. 

Health Effects of Polyester Resin

Bourne LB, Milner FJM [1963]. Polyester Resin Hazards. Br J Ind Med 20(2):100-109,

https://dx.doi.org/10.1136%2Foem.20.2.100.

Kobos L, Teimouri Sendesi SM, Whelton AJ, Boor BE, Howarter JA, Shannahan J [2019]. In vitro 

toxicity assessment of emitted materials collected during the manufacture of water pipe plastic linings. 

Inhal. Toxicol 31(4):131-146, https://doi.org/10.1080/08958378.2019.1621966.

Teimouri Sendesi,SM, Ra K, Conkling EN, Boor BE, Nuruddin M, Howarter JA, Youngblood JP, 

Kobos LM, Shannahan JH, Jafvert CT, Whelton AJ [2017]. Worksite chemical air emissions and worker 

exposure during sanitary sewer and stormwater pipe rehabilitation using cured-in-place-pipe (CIPP). 

Environ. Sci. Technol. Lett 4(8):325-333, https://doi.org/10.1021/acs.estlett.7b00237.

Zaske OC, Goodman SH [1998]. Unsaturated Polyester and Vinyl Ester Resins. In Goodman SH (Ed). 

Handbook of Thermoset Plastics Second Edition (pp 97-168). Westwood: Noyes Publications.
E-3

Health Effects of Catalyst/Initiators

CCOSH [2009]. OSH answers fact sheets: organic peroxides – hazards. Canadian Centre for 

Occupational Health and Safety, 

https://www.ccohs.ca/oshanswers/chemicals/organic/organic_peroxide.html.

Kamath VR and Gallagher RB [1980]. Initiator systems for unsaturated polyester resins. In Pritchard G 

(Ed). Developments in Reinforced Plastics—1 (pp 121-144). Essex: Applied Science Publishers.

OSHA [2013]. 29 CFR 1910.1200 Hazard communication standard, Appendix B. Washington, DC: U.S. 

Department of Labor, Occupational Safety and Health Administration, https://www.osha.gov/lawsregs/regulations/standardnumber/1910/1910.1200AppB

Su W-F [2013]. Chapter 7: Radical Chain Polymerization. In Su W-F (Ed). Principles of Polymer Design 

and Synthesis (pp 137-183). Berlin: Springer Berlin Heidelberg.

Latex Allergies

NIOSH [2009]. Latex allergies. National Institute for Occcupational Safety and Health, 

https://www.cdc.gov/niosh/topics/latex/.

Smoking

CDC [2020]. Smoking & tobacco use – tobacco control plans. Centers for Disease Control and 

Prevention, 

https://www.cdc.gov/tobacco/stateandcommunity/tobacco_control_programs/index.htm.

Methods 

NIOSH [2018]. Volatile organic compounds, C1 to C10, Canister method: Method 3900. Cincinnati, 

OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease 

Control and Prevention, National Institute for Occupational Safety and Health, 

https://www.cdc.gov/niosh/nmam/pdf/3900.pdf.

OSHA [1991]. OSHA Method ORG-89: divinylbenzene, ethylvinylbenzene, styrene. Occupational 

Safety and Health Administration, 

https://www.osha.gov/dts/sltc/methods/organic/org089/org089.html.

Occupational Exposure Limits 

ACGIH [2021]. 2021 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

agents and biological exposure indices. Cincinnati, OH: American Conference of Governmental 

Industrial Hygienists.

NIOSH [2020]. NIOSH pocket guide to chemical hazards, National Institute for Occupational Safety 

and Health, https://www.cdc.gov/niosh/npg/.

OSHA [2019]. Permissible exposure limits – Annotated OSHA Z-1 and Z-2 Table, Washington, DC: 

U.S. Department of Labor, Occupational Safety and Health Administration, 

https://www.osha.gov/dsg/annotated-pels/index.html.
E-4

Confined Space Entry 

OSHA [2015a] 29 CFR 1926 Construction industry confined space standard, subpart AA, sections

1200-1213. Washington, DC: U.S. Department of Labor, Occupational Safety and Health 

Administration, https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926SubpartAA.

OSHA [2015b]. Protecting construction workers in confined spaces: Small entity compliance guide. 

Washington, DC: U.S. Department of Labor, Occupational Safety and Health Administration,

https://www.osha.gov/Publications/OSHA3825.pdf.

Safety Data Sheets

OSHA [2012a]. OSHA brief - hazard communication standard: safety data sheets. Occuypational Safety 

and Health Administration, https://www.osha.gov/sites/default/files/publications/OSHA3514.pdf.

OSHA [2012b] CFR 1910.1200 Appendix D safety data sheets (mandatory), U.S. Department of Labor, 

Ocupational Safety and Health Administratoin, https://www.osha.gov/lawsregs/regulations/standardnumber/1910/1910.1200AppD. 

LeBouf RF, Hawley B, Cummings KJ [2018]. Potential hazards not communicated in safety data sheets 

of flavoring formulations, including diacetyl and 2,3-pentanedione. Ann Work Exp Health 63(1):124-

130, https://doi.org/10.1093/annweh/wxy093. 

United Initiators [2020]. NOROC-MEKP-925 Material safety and data sheet. https://www.unitedinitiators.com/files/NOROX%C2%AEMEKP-925/United_Initiators_NOROX%C2%AEMEKP925_MSDS_CN_EN.pdf
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