The discovery of toxic chemicals in public tap water last year shocked North Carolina residents, but the chemicals might have escaped notice were it not for a recent technological breakthrough.
New methods of “non-targeted analysis” enable the rapid characterization of thousands of previously unknown compounds, such as the discovery of a group of chemicals—known as GenX—released from a Chemours Co. plant into the Cape Fear River.
Recent technical improvements in high resolution mass spectrometry—a main component of non-targeted analysis—have given researchers the ability to detect previously unknown compounds in water, blood, food, or other environmental media, often at parts per billion or parts per trillion concentrations.
A mass spectrometer is a device that is able to weigh molecules and report other information on a compound’s chemical structure.
“It’s really opened up this whole world of unknown chemicals we might have missed before,” according to Susan Richardson, an analytical chemist at the University of South Carolina who focuses on drinking water.
The technology represents a potential game-changer for public health regulators, Richardson told Bloomberg Environment.
“If we didn’t have these new capabilities, I am sure that the state EPA would not have found GenX, without a doubt,” she said.
Booming Diagnostics Sector
Traditional public health tools, including targeted analytical chemistry, can be extremely time-consuming and rely on knowing in advance what chemical is being sought. Non-target analyses, in comparison, can also detect compounds that researchers hadn’t known were present.
A new high-resolution mass spectrometer can cost upwards of half a million dollars. And while prices aren’t necessarily decreasing, companies such as Thermo-Fisher Scientific Inc., Shimadzu Corp., and Agilent Technologies Inc. are seeing growing demand for the next generation of those devices.
“We’re seeing a lot of interest from applied markets, like environmental cleanups, food testing, even homeland security,” said Jennifer Gushue, a manager at Agilent Technologies, based in Santa Clara, Calif. “Historically, a lot of work doing food testing had been done in a targeted way, but increasingly institutions want to know, ‘What else is in my sample?’”
Gushue told Bloomberg Environment recent improvements have made instrumentation and software better able to digest the enormous amount of data generated by high-resolution screenings, making non-targeted analysis more useful to a variety of agencies.
Environmental Protection Agency researchers are using the approach to study communities in New Hampshire and New Jersey to determine exposures to per- and polyfluoroalkyl substances (PFAS), a broad group of about 3,500 compounds.
The chemicals—used in consumer and industrial nonstick products and firefighting foam—are linked to reproductive and developmental effects, liver and kidney harms, and immunological effects as well as cancer, according to the EPA.
Protecting Public Health
The number of chemicals detected in surface water is increasing. These range from well-known pollutants and pesticides to pharmaceuticals that evade sewage treatment systems.
One of the major criticisms from environmental watchdogs of the EPA’s hazard assessments is that they rely on the classical targeted approach to look for chemicals already suspected of being present.
“But there are good reasons for that,” said Detlef Knappe, a professor of civil, construction, and environmental engineering at North Carolina State University. “For compliance purposes, we need these well-defined methodologies to be certain we are measuring the right compound at a certain concentration.”
Knappe was part of the team that detected the presence of GenX in the Cape Fear River. He told Bloomberg Environment that nothing is intrinsically wrong with targeted screenings, “but when it comes to the question of, ‘Is my water safe,’ that is something you can’t fully answer with a targeted approach.”
The Southern Environmental Law Center filed a lawsuit Aug. 29 against Chemours in the U.S. District Court for the Eastern District of North Carolina. The suit alleges that Chemours and its parent company, DuPont, knowingly polluted North Carolina’s environment with PFAS compounds in violation of the Clean Water Act and Toxic Substances Control Act.
“Chemours is reviewing the complaint and strongly disagrees with allegations that we are in violation of the laws cited,” Alvenia Scarborough, a company spokeswoman, said in a statement. “Chemours intends to defend itself vigorously against the claim.”
New Approach, New Challenges
While increased use of non-targeted screenings can help researchers determine the possible presence of a pollutant, it still takes considerable time and effort to make a positive identification and determine if it poses a threat to human health.
Even getting access to pure samples to calibrate the instrument, and then double- and triple-checking the data, can take months or years.
“It’s a lot of work,” Richardson said. “As you can imagine, oftentimes companies aren’t willing to just hand over these samples.”
These new analytical possibilities also pose new regulatory and legal issues: If, for example, a sample of corn tested for the presence of mycotoxin—a common grain toxin—also detects an illegal pesticide, can authorities take enforcement actions for the latter?
But in the short term, Richardson says non-targeted analysis’ biggest impact has been on moving chemical testing issues into mainstream scientific discussion.
EPA scientists are piloting a multi-phase project to evaluate the ability of non-targeted laboratory methods to consistently and correctly identify unknown chemicals.
The EPA’s Non-Targeted Analysis Collaborative Trial was formed in late 2015 and includes nearly 30 academic, government, and industry groups.
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