Government Toxicity Test Misses Real World Reactions

Just last week we were posting about the cumulative impacts of air pollution that are never taken into account by EPA risk assement. Now a new University of North Carolina study concludes that the toxic soup of chemicals and particulates found in many metropolitan areas is more harmful to human health than a common test used by government often reveals.

Researchers used a sunlit rooftop chamber to combine car diesel exhaust with a mix of Volatile Organic Compounds (VOCs) simulating urban air. They compared two methods for measuring the concoction’s toxicity: directly exposing human lung cells to particulates in chamber air with an electrostatic system, and a widely used method – that filters the air, resuspends the filtered particulates in a solution, and then applies this mixture to lung cells.

The cells directly exposed to the mix in the chamber experienced inflamation, whereas those that went through the filtering process did not. Based on analysis, scientists  attributed the difference in reaction to semivolatile carbonyl compounds, which coat particles in air but are lost during filtration. Formaldehyde is one such carbonyl compound. Sunlight hitting VOCs in the atmosphere can create carbonyl compounds and coat very small soot particles, or Particulate Matter, suspended in air with the pollutants. When you breathe in the soot, you actually breathe in a tiny delivery device for these kinds of pollutants as well.

No risk assessment process incorporates these kinds of real world health impacts and it's just one reson why these assessments are not good models for actual human health impacts from pollution.