Last Word: Is CIPP Safe?

Lynn Osborn


Cured-in-Place Pipe (CIPP) was introduced in 1971 as an alternative to digging up and replacing sewers, and it was introduced to North America in 1976. Now, approaching 50 years since the introduction of CIPP, hundreds of millions of feet of rehabilitated pipe have been installed around the world. CIPP is proven to provide an economical and environmentally-friendly alternative to open-cut replacement, minimizing impact to traffic, businesses, the environment and neighborhoods while helping to prevent sanitary sewer overflows (SSOs) and groundwater contamination by leaking sewage.

RELATED: NASSCO Responds to Purdue University’s Findings on CIPP

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A report was recently published raising questions about the safety of steam-cured CIPP installations. The report by Dr. Andrew J. Whelton, assistant professor of engineering at Purdue University, is titled “Worksite Chemical Air Emissions and Worker Exposure during Sanitary Sewer and Stormwater Pipe Rehabilitation Using Cured-in-Place-Pipe (CIPP)” and was published July 26, 2017, in the Environmental Science & Technology Letters, a publication of the American Chemical Society (ACS).


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Upon discovery of the claims made in the report, NASSCO established a CIPP Workgroup consisting of industry experts, as well as highly respected organizations including the National Sanitation Foundation (NSF), the North American Society for Trenchless Technology (NASTT), American Composites Manufacturing Association (ACMA), the Water Research Centre (WRc) and the Water Environment and Reuse Foundation (WE&RF), among others. This knowledgeable group has reviewed the study — along with other articles, social media posts, webcasts and interviews — and based on the information available, has determined that claims made regarding the safety of steam-cured CIPP installations are premature and certainly not conclusive.

  • No evidence has been produced regarding the health effects of CIPP steam exhaust on either workers or the public. Dr. Whelton acknowledges this in his September 26, 2017, NIOSH Science Blog. Quoting from the Blog, Dr. Whelton stated, “Little is known about CIPP worker exposures and health risks … 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 they are transformed into more or less toxic materials in the air is currently unknown.” Unnecessary anxiety has resulted over what is just the start of investigations of CIPP job site emissions. Dr. Whelton will do more studies, as will others. Considering the number of decades that CIPP has been beneficially used in North America, we should know the facts before making quick decisions which could impact wastewater collection system owners and communities that benefit environmentally and economically from rehabilitated sewers.

  • There are questions concerning the source of some discharged organic chemicals. Dr. Whelton’s team found certain organic chemicals in the steam exhaust and other release points, and the CIPP Workgroup certainly agrees that the health effects of these emissions must be determined. However, some of these chemicals were not found in the uncured tubes. Previous testing indicated that chemicals found in CIPP installation cure water were not detected by CIPP sample leaching tests. Some of these chemicals are also not resin reaction byproducts, leaving their source unknown. This must be clarified in future studies.

  • Although it is already occurring, my hope is that our industry will show restraint and not use these study results as negative selling tools. Future studies will potentially show that: a) there are health risks that must be addressed; b) any health risks found are minimal; or c) there are no health risks. In any event, the CIPP industry will respond accordingly by emphasizing better job site housekeeping, adherence to installation best practices and, if needed, mitigation technologies for capturing possible contaminants in steam exhaust discharges. In fact, this is already happening as some CIPP installers are proactively investigating mitigation technologies. The CIPP Workgroup strongly encourages this and further recommends that updated best practices for the safe installation of steam cured CIPP be developed.

NASSCO takes worker and public safety and the accuracy of information very seriously. Therefore, it is my point of view that as a result of this study, we all work together – including Dr. Whelton and his team – to continually improve installation practices to protect the health and safety of workers and the public.

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RELATED: Pipe Relining Market Overview: CIPP Still the Relining Leader

NASSCO will continue to do what is best for our industry by partnering with respected industry leaders and organizations to facilitate a formal review of this and related studies, including additional sampling and analysis of emissions during the field installation of CIPP using the steam cure process. The research will be properly peer-reviewed to challenge or confirm the information previously published on this topic.

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To ensure objectivity in data collection, evaluation and conclusions, the study will be conducted by a third-party consisting of academia in conjunction with a professional environmental consultant with knowledge and experience in CIPP technology. The CIPP Workgroup’s goal in facilitating this effort is to uncover the truth, whatever it may be, and respond to the results while keeping the best interests of worker and public safety in mind.

Lynn E. Osborn is technical director at NASSCO.