Researchers from the University of Colorado Boulder have detected a toxic industrial chemical in the U.S. atmosphere for the first time, according to a new study conducted in Oklahoma. The discovery of Medium Chain Chlorinated Paraffins (MCCPs) in airborne particles is prompting new scrutiny over environmental exposure and possible health risks.

The finding emerged during an air quality field study in an agricultural region, where scientists were using advanced instrumentation to track how aerosol particles form and evolve. While analyzing the data, researchers identified previously unmeasured chemical signatures, later confirmed to be MCCPs, a class of pollutants not previously recorded in the Western Hemisphere’s atmosphere.

MCCPs are used in industrial applications such as metalworking fluids, plastics, and textiles. Researchers believe the chemicals may be entering the air through biosolid fertilizers, which are derived from treated sewage sludge and commonly spread on farmland. While the study did not establish a direct causal link, scientists say the pathway is a plausible explanation based on how similar compounds behave.

The discovery has raised concerns because MCCPs share characteristics with other persistent environmental pollutants, including long-lasting “forever chemicals” that can accumulate over time. Their chemical relatives, Short Chain Chlorinated Paraffins (SCCPs), are already regulated in the United States and internationally due to established health risks.

MCCPs are currently under review by the Stockholm Convention, which evaluates hazardous substances for potential global restrictions. Researchers noted that tighter regulations on related chemicals may have contributed to increased use of MCCPs as substitutes, a pattern sometimes seen in industrial regulation.

The study’s authors emphasized that significant unknowns remain about how MCCPs behave in the atmosphere and what risks they may pose to human health. Scientists say further monitoring will be needed to determine how widespread the contamination may be and whether concentrations vary over time or by region.

The findings come as policymakers and regulators continue to examine the environmental impact of biosolid fertilizers and other waste management practices, particularly in agricultural areas where such materials are widely used.