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From: jay on 6 Aug 2008 01:18
http://goliath.ecnext.com/coms2/gi_0199-3119052/Aryl-hydrocarbon-receptor-mediated-activity.html

The Paso del Norte airshed is composed of a basin formed by mountains
that surround El Paso, Texas, and Sunland Park, New Mexico, in the
United States and Ciudad Juarez, Chihuahua, in Mexico. With a
population exceeding two million, it is one of the largest
metropolitan areas along the border. Visibility in the Paso del Norte
airshed is frequently poor, especially in winter, and respiratory
problems are common. El Paso has been designated as a federal
nonattainment area, associated with exceedances of ozone and
particulate matter < 10 [micro]m in aerodynamic diameter (P[M.sub.
10]). Recently, an index was developed to reflect long-term exposure
to air pollutants. U.S. cities were ranked according to a weighted
estimate of exposure to criteria air pollutants; El Paso was ranked
sixth worst in the nation, following Los Angeles, California; Phoenix,
Arizona; Riverside, California; Orange County, California; and New
York City, New York.

Sources of P[M.sub.10] in the Paso del Norte airshed share some
similarities with other urbanized areas, but some aspects of emissions
and climatology are unique to this region. High ambient P[M.sub.10]
levels result from a wide range of emission sources, and their
presence in air is affected by meteorologic conditions; in particular,
strong inversions trap P[M.sub.10] in the winter. Emissions are
particularly high in the Paso del Norte airshed because of the high
percentage of older vehicles, many without catalytic converters; a
significant amount of diesel exhaust associated with North American
Free Trade Agreement--related truck traffic at U.S.--Mexico border
crossings; and the use of wood, tires, and other scrap fuels for both
residential heating and the firing of bricks. These sources of P[M.sub.
10] are known to produce particulate organic material (POM) mixtures
of thousands of organic compounds, including polycyclic aromatic
hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and
polychlorinated dibenzo-p-dioxins, many of which are highly toxic and
carcinogenic. Numerous epidemiologic studies have shown an association
between ambient air particulates and increased morbidity and
mortality. Recent studies have shown that ultra-fine particles may
play an important role in cardiopulmonary diseases. The mechanism by
which PM causes these adverse effects is the topic of significant
study. PAHs, including nitro-derivatives, account for approximately
80% of mutagenic activity in urban PM extracts. In addition to their
mutagenicity, PAHs can interfere with certain developmental processes
and nourishment of the fetus. Environmental exposure to PAHs in
heavily polluted areas such as Krakow, Poland, has caused increased
levels of white blood cell PAH-DNA adducts in both mothers and
infants. In this study, our goals were to identify the presence of
these potentially harmful PAHs in POM by using two in vitro assays, to
quantify levels of selected PAHs, and, to the degree possible, relate
these findings to the risk of adverse health effects.
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