Earlier this year Nicole Davis arrived at one of the San Antonio, Tex., offices of the audiology practice she co-owns ready to see the day’s patients. But upon entering her office, Davis says she quickly noticed a noxious odor that smelled like paint thinner. Her eyes started burning. By noon, she felt nauseated and dizzy, with the burning sensation spreading to her nose and throat. Her mouth went numb. Co-workers in the building told Davis that they felt ill, too. By the evening, she says, she was vomiting.

Two days later, Davis received an e-mail from an employee for a construction firm that was doing work that week on municipal pipes below street-level near the building. The employee apologized in the e-mail for Davis’s “recent experience,” and attached a technical document describing the hazards and health risks associated with materials used to make plastic in the pipe project. The e-mail and attachment do not state that the work caused the odor or Davis’s reaction.

The company was renovating an underground sewer pipe with a widely and increasingly used technique called cured-in-place pipes. A felt or composite sleeve is saturated, typically with a polyester or vinyl ester resin. Workers thread the sleeve through an underground pipe and then inflate and heat it, often with steam or hot water. The sleeve hardens to form a continuous plastic liner along the old pipe’s inner walls. The technique is less expensive and takes less time than fully replacing old sewer-system pipes and stormwater culverts.

Davis has recovered from most of what she says her doctor told her were neurological effects from a chemical exposure. But she says she did not receive any advance notification of the work or of any associated odors or potential hazards, and thinks she should have been notified. When she sought information from local and regional public health authorities about the health risks noted in the technical document and any treatment she might need, she hit dead ends with local and regional public health authorities, she says. The construction company did not reply to repeated attempts by Scientific American to obtain comment for this story.

Davis’s experience reflects, in part, the scarcity of reliable, industry-independent research and public health advice about potential risks associated with the cured-in-place pipe, or CIPP, method. The practice has grown steadily in the past two decades, with more than 35,000 miles of the liners installed worldwide, according to a 2017 market report by BCC Research. CIPP is the most popular method among a group of pipe-renovation techniques that require minimal digging as compared with excavating an old pipe and replacing it. With billions of dollars spent and loaned annually in the U.S. alone to restore deteriorating pipes, the market for lower-cost renovation approaches is forecast to remain strong for several years.

Many residents say they are notified before these CIPP sites pop up, but some say they are not. The notifications typically state that the work is harmless. But accumulating evidence calls those claims into question. In many cases, the public receives incomplete, incorrect or scientifically unfounded information about potential health risks associated with CIPP emissions, emerging evidence suggests.

Andrew Whelton, a civil and environmental engineer, and his colleagues at Purdue University have collected details on more than 100 incidents spanning 29 U.S. states in the past 15 years in which people have raised concerns or called their fire department about odors and emissions from CIPP. Children have been mentioned in news stories and other reports in more than a dozen of those 100 cases, including a September incident in Seneca Falls, N.Y., in which middle school students reportedly felt sick from a CIPP job several hundred feet from their classroom. In some cases, symptoms persist, and residents relocate. Nancy Hoback of Salem, Va., says it took several weeks to feel better last year after claiming to have been exposed to emissions from a pipe-lining job she measured to be more than about 700 yards (640 meters) from her house. She says she experienced burning in her mucous membranes, headaches, dizziness, difficulty swallowing and shortness of breath.

Worrisome Exposures

Peer-reviewed research published in the past few years has started to clarify the complexity of CIPP emissions questions. Studies by Whelton’s group have revealed that jobs at study sites, where installers used steam to harden the resin, release a mixture of vaporized and liquid droplets of organic compounds and water, as well as particles of partially hardened resin, into the air. The compounds include hazardous air pollutants such as styrene and methylene chloride, as well as dibutyl phthalate, which some studies have identified as an endocrine disruptor. But other emitted compounds vary, possibly depending on the type of resin used and other operational differences. Styrene, which causes neurological effects, is classified as “reasonably anticipated to be a human carcinogen” by the U.S. National Toxicology Program. And methylene chloride is considered a potential, probable or reasonably anticipated carcinogen by various federal agencies.

A handful of other independent studies—including one published in January by the National Institute for Occupational Safety and Health, a U.S. federal agency that does research and makes safety recommendations to prevent worker injuries and illness—have identified airborne styrene levels at CIPP work sites that exceed worker safety thresholds set by the U.S. Occupational Safety and Health Administration.

Two years ago, a worker died on the job while inside an underground pipe being renovated with CIPP. An autopsy seen by this writer stated that the cause of death was drowning but that styrene toxicity contributed to it. The incident prompted an OSHA investigation. As a result, the company paid $55,000 in penalties, in part for exposing employees to levels of airborne styrene exceeding the agency’s worker safety limits. Many photographs show CIPP workers who are not using respirators that could protect them from inhaling emissions, raising questions about the safety culture at job sites.

Protecting the Public

Measures designed to protect workers have limited relevance for members of the public. People not doing the jobs are usually farther away from emissions. Some are in structures such as homes, schools or workplaces, which sounds safer. But airborne emissions make their way directly into buildings, as environmental and occupational health specialist James Morrison found in late 2004. At the time, he worked with the Wisconsin Department of Health and Family Services and was tasked by the federal Agency for Toxic Substances and Disease Registry (ATSDR) to figure out what happened to sicken office workers in a building in Milwaukee that was formerly a brewery. Emissions from a nearby CIPP job got indoors through cracks in the building’s foundation and irritated workers to the point that they evacuated, according to a report by Morrison and his colleagues. The report called the initial exposures a public health hazard. In telephone interviews in recent weeks, Morrison confirmed the incident and report details.

Chemical-exposure safety standards for the public are stricter than those for workers, Morrison says, for two primary reasons. For one, exposed workers are ensured recovery periods when the workday ends and on weekends, whereas public exposures can persist around the clock. In addition, worker safety standards are designed to protect a population of adult workers who are presumed to be healthy, whereas public safety standards are designed to go farther, to protecting children, seniors and others who may be more medically vulnerable to chemical exposures, Morrison says. Contractors and those who hire them should have a plan in place to refer people who feel sick to public health authorities, he adds.

Thresholds for airborne exposures of residents to some of the dozens of chemicals identified by Whelton’s group as present or emitted into the air at CIPP sites are set by the ATSDR as well as by the Environmental Protection Agency. But these thresholds are not public health regulations. They are meant to serve as reference information for health care workers or others who assess cases brought to their attention.

Toxicology Studies

This past summer some of the first findings to delve into the human health implications of exposures to CIPP emissions were published in the journal Inhalation Toxicology. The results came from a study of lab-grown mouse cells, which researchers often use to determine whether tests should be done on human cells and then lab animals. Study senior author Jonathan Shannahan, a toxicologist and a member of Whelton’s research team at Purdue, exposed lung immune and tissue cells to condensed emissions collected at three different CIPP work sites. The idea was to see which and how many cells died, but the results varied a fair amount by job site and concentrations of emissions, Shannahan says. Similarly, the team found alterations in gene expression and protein production in exposed cells, some of which are associated with changes in cancer, inflammation and injuries or with abnormal function in organs. Here again, the results differed from site to site, by the type of cells exposed, and by the genes and proteins examined.

The findings show the potential for adverse health effects in humans, Shannahan says. Yet the details of the link remain murky. “Is it related to every CIPP work site? We don't know. Is it related to the majority of them? We don't know,” he says. The effect of these emissions on people may also vary by genetic profile, age and underlying health, including the strength of one’s immune system.

A trade organization for CIPP and other methods of pipe repair, the National Association of Sewer Service Companies (NASSCO), has also taken steps to study the safety of airborne emissions for workers and the public. Last year it contracted researchers at Louisiana Tech University to collect, measure and model the dispersion distances of emissions of styrene and other chemicals under various weather conditions at several installation sites. The results are set to be publicized in a webinar on December 17, says Lynn Osborn, the organization’s technical director. “At NASSCO, our general emphasis is on safety. It’s always up front,” he says, adding that the group plans to update safety guidelines in response to the study once it is completed.

Rather than being stymied by variations at CIPP jobs, Shannahan and Whelton are now making a lab setting for controlled experiments—a chamber where they will create a cured-in-place pipe with two commonly used types of resin and then identify and measure how emissions vary. Later on, they will look for markers of liver and lung inflammation and stress, as well as other blood chemistry, in male and female mice exposed to emissions in the chamber. One goal of the project—which is funded by the National Institutes of Health—is to inform any future measures that could ensure that cured-in-place pipes are made in a safe and efficient way that also protects public health.

The scientific evidence so far may not present a clear case that CIPP work poses a risk to the public. But the number of cases involving people who raised concerns or felt sick from emissions, combined with the Purdue team’s early toxicology results, make the topic one that deserves more attention.

“We are at a very preliminary stage with a lot of the investigations of the health hazards associated with this. But then the question is, ‘Well, how do you get more people doing the science related to this?’” Shannahan says. “Sometimes what it takes is people just being told about it.”