Do group responses mask the effects of air pollutants on potentially sensitive individuals in controlled human exposure studies?

To establish primary National Ambient Air Quality Standards (NAAQS) for criteria air pollutants such as nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2), US EPA relies in part on controlled human exposure studies. It has been suggested that evaluating average responses for all participants in these studies may not reflect the responses of sensitive participants in these studies. To evaluate this, we identified controlled exposure studies with multiple exposure concentrations or durations that provided individual-level lung function data.

Determining soil remedial action criteria for acute effects: the challenge of copper.

Gastrointestinal (GI) symptoms, the primary acute effect of the essential micronutrient copper, paradoxically occur at lower exposure levels than hepatotoxicity, the primary chronic effect. We developed a remedial action criterion (RAC) for copper to protect against GI symptoms, which primarily relate to the stomach copper concentration, and subside within an hour. Using Monte Carlo methods, we generated a distribution of RACs protective against GI symptoms for a 1 h exposure (hourly RACs) based on soil ingestion rate, volume of liquid and food in the stomach, and bioaccessibility.