Cured-in-Place-Pipe (CIPP): Inhalation and Dermal Exposure Risks Associated with Sanitary Sewer, Storm Sewer, and Drinking Water Pipe Repairs

Background

Cured-in-place-pipe (CIPP) is the most popular water pipe repair method used in the U.S. for sanitary sewer, storm sewer, and is increasingly being used for drinking water pipe repairs. Today, approximately 50% of all damaged pipes are being repaired using CIPP technology. The CIPP procedure involves the chemical manufacture of a new plastic pipe called a CIPP inside a damaged water pipe. Before CIPP installation, workers precut and lay-up the felt and fiberglass liner and saturate it with a polyester, vinyl ester, or epoxy resin. The resin is sometimes mixed by hand or using an automated mechanical mixer, manually poured or drawn into the precut liner. Liners are then passed through rollers to ensure that the fibers are saturated with resin. The resin impregnated liner (referred to as an uncured resin tube) is typically refrigerated until use, as it may contain volatile and semi-volatile organic compounds (VOCs, SVOCs) and thermally sensitive chemicals. This uncured resin tube is often pulled through the damaged water pipe or inserted into the damaged water pipe and inflated using forced air or water. During the installation process, the curing is facilitated by periodically forcing steam into one end of the resin tube, recirculating hot water, and/or passing an ultraviolet (UV) light train through the tube. Plastic coatings are sometimes included inside and outside of the uncured resin tube for a variety of reasons. Once the facilitated curing process has ended, the hardened ends of the CIPP are cut and removed. Connections to pipe laterals are reinstated by cutting holes into the pipe walls. A reported advantage of this in-situ repair process is the avoidance of roadway shutdowns and open-trench excavations to remove the damaged pipe. The CIPP process is also being used to repair pipes in buildings.

Little is known about CIPP worker exposures and health risks. CIPP manufacturing sites are highly transient, with a single installation location being used from a few hours to a few days. Unlike traditional manufacturing operations, there is not a ‘permanent address’ to visit or inspect. Once the construction process is complete, the workers and equipment move on. The CIPP manufacturing process can expose workers to raw chemicals, forced air, steam, hot water, ultraviolet (UV) light, materials created and released into the air during manufacture, as well as liquids and solids generated by the process and worker activities. To date, CIPP air monitoring studies have been unable to comprehensively characterize occupational exposures because of a narrow focus on VOC vapors and the use of nonspecific detectors.  See below for information on the October 5^th free webinar “Public Health Implications and Occupational Exposures during Water Pipe Repair Activities” (to view webinar, click here ).

New Research on Health Hazards

A new peer-reviewed study published in the journal Environmental Science and Technology Letters found that during steam-cured CIPP installations, many different types of materials were created and released into the air. These materials included particulates, droplets, partially cured resin, organic vapors, and water vapor. While historically referred to as “steam” (and thus implying only water vapor), the emission instead is a “multi-phase mixture” or emission cloud. A variety of VOCs and SVOCs were measured in the emission cloud and included suspected carcinogens, hazardous air pollutants, suspected endocrine disrupting compounds, and other unidentified compounds. Some included acetophenone, benzaldehyde, benzoic acid, butylated hydroxytoluene (BHT), 4-tert-butylcyclohexanol, 4-tert-butylcyclohexanone, dibutyl phthalate (DBP), phenol, styrene, and 1-tetradecanol, among others. Because common equipment can be used by a contractor for a variety of resin compositions, chemical cross-contamination is also possible. For example, one CIPP installation that was measured featured a non-styrene based resin. However, styrene was emitted from this installation, notably at a much lower concentration than the styrene-based resins. This finding indicated contractors likely accidentally contaminated their equipment with a previous styrene-based compound. As such, contractor equipment handling and cleaning practices between CIPP installations should be further studied. Emissions from the CIPP sites tested were transient, varying second-by-second and exhibiting extreme spikes in chemical concentration. This concentration variation was influenced by environmental and meteorological conditions, worksite activities, and differed between CIPP installations even when the resin, pipe size, and contractor were the same.

Results of the new study suggest the importance of both inhalation and dermal exposure routes. No organic vapor respiratory protection was observed for workers during CIPP installations reported in our study. Workers were in chemical plumes and inhaled the chemical-laden air. Their skin and clothing were exposed. Some CIPP workers handled the uncured resin tube with their bare hands. Others were exposed to liquid-like materials during insertion of the uncured resin tube and curing. The multi-phase mixture emitted into the air was collected and tested to see if it was toxic to mouse cells. Tests indicated that samples collected from 2 of 4 CIPP sites were cytotoxic (caused cell death). Non-styrene compounds appeared responsible.

The new study also cited 59 CIPP air contamination incidents. Incidents involved public complaints of illness, building evacuations, emergency service personnel responses, and in many cases these incidents were reported in the popular press. Since the new study was published, several chemical incidents associated with CIPP sewer repairs have occurred in Nyack, NY, Dublin, CA, Lee’s Summit, MO, Beaver, PA, and San Diego, CA all reported in local media outlets. These exposure reports primarily originated from the general public who were not associated with the installation work being performed. The California Department of Public Health also issued a CIPP safety alert based on their own investigation.

While different types of materials are created and emitted into air during CIPP installations, the distance the materials travel from the worksite emission points, extent of spatial and temporal variations in material concentrations, and whether or not they are transformed into more or less toxic materials in the air is currently unknown. Different work tasks and a wide array of site, environmental, and pipe conditions, resins, manufacturing processes, and other variables should be considered in documenting occupational health risks. Also lacking is an understanding of what materials are emitted from hot water- and UV-cured CIPP sites. Compound- and phase-specific intakes, doses, and any associated acute and chronic health effects among workers must be determined. Because methods commonly used for air sampling and for industrial process monitoring only capture vapors, additional air sampling procedures are needed. These procedures should help understand occupational exposures and potential health risks when particulates and semi-cured compounds may also be present in the air.

Next Steps

The new study identifies concerns about potential health risks to CIPP workers and underscores a need for additional investigation. Occupational risks for municipal and consulting engineer employees, separate from CIPP companies, who visit and supervise CIPP job sites, should be investigated. Also needed is an understanding of public health risks for persons nearby. Until more is known about the exposures generated by CIPP and the health implications for workers, the authors recommended that inhalational and dermal exposures be minimized through a combination of engineering and administrative controls and the use of appropriate personal protective equipment. The authors also recommended exposure monitoring of the multi-phase emissions to ensure the emissions are being captured.

The study authors at Purdue University and workplace safety experts at the National Institute of Safety and Health (NIOSH) are seeking partners for future studies. Persons who install CIPP, visit, and supervise CIPP sites can request health hazard evaluations from NIOSH. Test results are being sought for the emission points and worker exposure monitoring from those organizations that have conducted prior air testing. This may include CIPP companies, consulting companies, local, county, state, and federal agencies, private and public utilities, and insurance companies, among other organizations.

For more information on the new peer-reviewed study Worksite Chemical Air Emissions and Worker Exposure during Sanitary Sewer and Stormwater Pipe Rehabilitation Using Cured-in-Place-Pipe (CIPP) visit the website or http://pubs.acs.org/doi/10.1021/acs.estlett.7b00237.   The scientific report, supporting Information file and video files can be downloaded free of charge.

Webinar

The National Environmental Health Association is hosting a free webinar on October 5^th from 3-4 EST “Public Health Implications and Occupational Exposures during Water Pipe Repair Activities”.  Speakers from NIOSH and Purdue University will present information to help local, state, and county health professionals better understand public health and occupational exposures with cured-in-place-pipe.

To view the webinar click here .

Andrew J. Whelton, PhD, is an assistant professor in the Lyles School of Civil Engineering and Division of Environmental and Ecological Engineering at Purdue University.

Jonathan Shannahan, PhD, is an assistant professor in the School of Health Sciences at Purdue University.

Brandon E. Boor, PhD, is an assistant professor in the Lyles School of Civil Engineering at Purdue University.

John A. Howarter, PhD, is an assistant professor in the School of Materials Engineering and Division of Environmental and Ecological Engineering at Purdue University.

Jeffrey P. Youngblood, PhD, is a professor in the School of Materials Engineering at Purdue University.

Chad T. Jafvert, PhD, is a professor of civil engineering in the Lyles School of Civil Engineering and Division of Environmental and Ecological Engineering at Purdue University.

This work was funded by the U.S. National Science Foundation RAPID Grant CBET-1624183, Purdue University, and crowdfunding.