chapter  1
30 Pages

Exposure Analysis: A Receptor-Oriented Science

Exposure science differs from past approaches in the environmental sciences, because, instead of beginning with an assumed source of pollution and then trying to find out who or what may be affected, exposure science works from both directions — not just from the source but also backward from the receptor. In the past, environmental policy analysts have assumed some obvious source, such as a smokestack or a leaky drum, may be important and then tried to trace where the pollutant goes, often losing its complicated trail long before the much-diluted pollutant ever reaches any real people, plants, or animals. By following this older

source-oriented

approach, it has been difficult to show in epidemiological studies that traditional sources actually affect anyone’s health or that these assumed sources cause adverse exposure of humans to harmful concentrations. Exposure science, on the other hand, begins with the target itself, measuring the pollutant concentrations that actually reach people by using, for example, personal monitors worn by individuals. Then the analyst works backward from the personal exposure to find the actual source. By following this

receptor-oriented

approach and measuring pollutant concentrations at the contact boundary of the person, new sources have been discovered, and some sources originally thought to be important were found to make negligible contributions to exposure. Using direct measurements of exposure, many significant new indoor sources — consumer products, building materials, and personal activities — emerge as the main contributors to human exposure and thus are more likely to be

the causes of environment-related illness than traditional outdoor sources. Activity pattern surveys show that people spend on average more than 90% of their time indoors or in a vehicle, and efforts to protect public health from environmental pollution and to reduce personal exposure must consider both indoor air quality and outdoor air quality as well as other routes of exposure, such as dermal contact, drinking water, nondietary contact, and food.