Very first toxic airborne chemical detected in the western hemisphere

From time to time, scientific research looks like a detective work. Researchers are moving towards the field with a hypothesis and great hopes to find specific results, but sometimes there is a torsion in history which requires a deeper dive into the data.

This was the case for Boulder researchers from the Colorado University who led a field campaign in an agricultural region of Oklahoma. Using a high -tech instrument to measure how aerosol particles are formed and developed in the atmosphere, they came across something unexpected: the very first airborne measurements of medium chain chlorinated paraffins (MCCP), a kind of toxic organic pollutant, in the western hemisphere. Their results published Today in ACS Environmental at.

“It is very exciting as a scientist to find something unexpected like this one we are not looking for,” said Daniel Katz, Cu Boulder Chemistry PH.D. Student and principal author of the study. “We are starting to find out more about this toxic and organic pollutant that we know is there, and that we have to understand better.”

MCCPs are currently being studied for regulation by the Stockholm Convention, a global treaty to protect human health against longtime and widespread chemicals. Although toxic pollutants have been measured in Antarctica and Asia, researchers do not know how to document them in the atmosphere of the Western hemisphere so far.

MCCPs are used in fluids for metal work and in the construction of PVC and textiles. They are often found in wastewater and, therefore, can be found in biosolid fertilizers, also called sewer sludgewhich is created when the liquid is removed from wastewater in a treatment plant. In Oklahoma, the researchers suspect that the MCCP they identified came from the biosolid fertilizer in the fields near the place where they installed their instrument.

“When the sewers are spread over the fields, those toxic compounds could be released in the air, “said Katz.” We cannot directly show that it happens, but we think it is a reasonable way that they can end in the air. Speaking fertilizers have been shown to be freed from similar compounds. “”

The small cousins ​​of the MCCP, short chain chlorine paraffins (SCCP), are currently regulated by the Stockholm Convention, and since 2009, by EPA here in the United States. The regulation occurred after studies revealed that toxic pollutants, which travel far and last a long time in the atmosphere, were harmful to human health. But the researchers have hypothesized that the regulation of SCCP can have increased MCCP in the environment.

“We always have these involuntary consequences of the regulation, where you regulate something, and then there is still a need for the products in which they were,” said Ellie Browne, professor of chemistry CU Boulder, CIRS and co-author of the study. “So they are replaced by something.”

The measurement of aerosols led to a new surprising discovery

Using a nitrate chemical ionization mass spectrometer, which allows scientists to identify chemical compounds in the air, the team has measured the air on the agricultural site 24 hours a day for a month. As Katz cataloged the data, he documented the different isotopic models in the compounds.

The compounds measured by the team had distinct diagrams, and he noticed new models which he immediately identified as different from the known chemical compounds. With some additional research, he identified them as chlorinated paraffins found in MCCP.

Katz says that the composition of MCCP is similar to PFAS, durable toxic chemicals that slowly break down over time. Known as “Forever Chemicals”, their presence in the soils recently led the Oklahoma Senate to prohibit biosolid fertilizers.

Now that researchers know how to measure MCCP, the next step could be to measure pollutants at different times of the year to understand how the levels change every season. Many unknowns surrounding MCCP remain, and there is much more to learn about their environmental impacts.

“We have identified them, but we still do not know exactly what they do when they are in the atmosphere, and they must be studied more,” said Katz. “I think it is important that we continue to have government agencies capable of assessing science and regulating these chemicals if necessary for public health and security.”