"Birth defects linked to car exhaust; Study of pregnant women links exhaust chemicals to common birth defects"
2013-03-30 by Drew Joseph from "San Francisco Chronicle" [http://www.sfchronicle.com/health/article/Birth-defects-linked-to-car-exhaust-4396195.php]:
(Photograph from Michael Macor, The Chronicle) Highway 99 cuts through
Fresno, traffic along the corridor is one of the many practices that
contribute to the poor air quality. The San Joaquin Valley has three of
the most polluted metropolitan areas in the US. Between 8 and 10 percent
of the central valley population has a lung disease like asthma. The
local air pollution board will voluntarily ask that the valley be
upgraded to "Extreme" category of air pollution from "Severe" putting
them in par with LA and giving them 5-7 more years to deal with the
women with high exposure to air heavily fouled by traffic pollution are
more likely have babies with birth defects, according to a new Stanford
study that focused on people living in the San Joaquin Valley.
women exposed to the highest levels of carbon monoxide were almost
twice as likely to give birth to a baby with certain defects of the
brain or spine as the women who breathed the lowest levels of the
pollutant, according to the study. Women who had the most contact with
nitrogen oxide had almost three times the risk of having a baby with
anencephaly - where the brain fails to develop fully - as women with
Researchers examined 849 women who had healthy
babies from 1997 to 2006 and 806 women who had babies with birth defects
during the same period. All the women lived in the San Joaquin Valley
for at least the first eight weeks of their pregnancy, "a known critical
period for congenital anomalies," according to the study.
researchers focused on five birth defects: cleft lip, cleft palate, two
neural tube deformations and gastroschisis, in which the intestines are
outside the body when the baby is born.
The researchers compared
birth-defect data and air-quality records for the eight counties of the
San Joaquin Valley, a region with some of the country's worst air
pollution. One big source of the region's terrible air quality is Bay
Area pollution that blows into the valley.
The study was published Thursday in the American Journal of Epidemiology.
in 33 babies develops a birth defect, according to Gary Shaw, a
professor of pediatrics at Stanford and the senior author of the study.
If a woman has diabetes before her pregnancy, she is more likely to have
a child with a defect. But other than that and genetic risk factors,
scientists are not sure what causes the defects.
"For the most part, we don't know a lot," Shaw said. "But it's critical to poke away to find answers."
study established an associative relationship between the
traffic-related pollutants and birth defects, so Shaw said scientists
should now try to determine whether the chemicals that make up the
pollution cause the defects in embryos.
Shaw noted that the
pollutants the researchers focused on are traffic-related and not
exclusive to the San Joaquin Valley, a point echoed by Seyed Sadredin,
head of the San Joaquin Valley Air Pollution Control District.
is something that anyone who lives near a heavily traveled roadway
should worry about," he said. "I'm sure that if this study was done in
the Bay Area next to I-80 or other high-traffic areas, you would
probably have the same results."