Sunday, May 22, 2005

It's an ill wind - necropsy results for air pollution effects.

A Brazilian study provides an effect level for lung pathology associated with air pollution. The study was co-authored by CA Pope, a lead investigator for associations between air pollution and mortality in the US. The investigators noted that in the high exposure area "PM10 attains annual concentrations ranging from 80 to 100 mcg/m3 (24 h mean) [checked the number i the paper] between 1991 and 1995, a level of pollution that was demonstrated to be associated with increased mortality in Sa˜o Paulo." The EPA NAAQS for PM10 is 50 ug/M3 annual average. The Sao Paulo exposures, which were higher than the EPA limit, were clearly an effect level. A "safe" exposure is an extrapolation factor below the no effect level, which would in turn be an extrapolation factor below the effect level observed here. For setting references doses based on laboratory studies, a 10-fold extrapolation factor would be used for each. Here, even a two-fold extrapolation factor gets us below the EPA 50 ug/M3 limit. Therefore, this study provides clear evidence that the NAAQS is not sufficiently protective.

Lung tissue samples were collected during necropsies of [84] individuals who died due to violent causes...The exposed group was composed of individuals who lived in an area with high mean levels of inhalable particles. Control individuals lived in two cities with economies based on agricultural activities...Information about cigarette smoking and occupational exposure was obtained from family members. ... Lungs collected from the high pollution area presented evidence of morehistopathologic damage in comparison to those from the clean environments.
Morphometric evaluation of the main bronchus was conducted to
determine the volume ratio of submucosal glands. Histopathologic alterations of the bronchioli
were evaluated by scoring the presence of inflammatory reaction, wall thickening, and secretory
hyperplasia. The number of spots of carbon deposition was counted along the regions of
lymphatic drainage (visceral pleura and axial connective tissue around bronchi and blood vessels). These effects were observed even after controlling for individual differences in age, sex, and cigarette smoking levels.


(CHEST 1998; 113:1312-18)

Respiratory Changes due to Long-term Exposure to Urban Levels of Air Pollution: A Histopathologic Study in Humans

Marcelo B. Souza, MD; Paulo H. N. Saldiva, MD, PhD, FCCP;
C. Arden Pope III, PhD; and Vera Luiza Capelozzi, MD, PhD

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