Air Pollution Harmful to Babies, Fetuses, Studies Say
Health: Smog is linked to stillbirths, infant deaths and low birth weight.
December 16, 2001
Los Angeles Times
E-mail story
By GARY POLAKOVIC , Times Environmental Writer
A growing body of research from around the world indicates that smog
is exacting a much greater toll than previously known on infants and
unborn babies.
Scientists have long known that the extreme levels of air pollution found
in the developing world can harm babies, and that lesser pollution in
U.S. cities can sicken or kill the elderly and infirm.
The new research
shows that the
harmful effects of
dirty air can extend
even into the
womb.
More than a dozen
studies in the
United States, Brazil, Europe, Mexico, South
Korea and Taiwan have linked smog to low
birth weight, premature births, stillbirths and
infant deaths.
In this country, the research has documented ill
effects on infants even in cities with modern
pollution controls, including Los Angeles.
The findings have helped prompt California officials to seek more stringent smog controls.
"Smog can harm the health of babies," said Beate Ritz, an epidemiologist at UCLA's Center for
Occupational and Environmental Health. "This should make us pause. Air pollution doesn't just
impact asthmatics and old people at the end of life, but it can affect people at the beginning of their
life, and that can disadvantage people throughout their life."
A UCLA study conducted by Ritz and scheduled for release Dec. 28, for the first time links air
pollution and birth defects in Southern California.
Other experts say that although worldwide research shows a strong correlation between air quality
and infant illnesses, it does not establish a conclusive cause-and-effect connection.
Most of the studies have been analyzed by disinterested scientists--a process called peer
review--and have been published in leading journals or will be soon. The studies differ on which
pollutants are of most concern.
Some implicate gases, others blame particles, and some point to both.
"The research is suggestive, but preliminary. It's something to be concerned about, but nothing to
panic about," said Tracey Woodruff, a senior scientist for the U.S. Environmental Protection
Agency and an author of one of the research papers.
"It's something we need to pay attention to."
Some Skeptical, Others Troubled
Frederick W. Lipfert, a New York environmental consultant hired by auto makers, the steel
industry, the U.S. Department of Energy and the Electric Power Research Institute to critique
several of the reports, downplayed the findings.
"These studies raise more suspicions than smoking guns," he said.
Nonetheless, the research, especially the studies focusing on U.S. cities where pollution levels have
been declining, is regarded by health experts as troubling.
"We know there are serious health effects from low levels of air pollution," said Aaron Cohen, an
epidemiologist and principal scientist for the Health Effects Institute in Boston, a joint enterprise of
the EPA and several pollution-generating industries, including oil companies and utilities.
"When something affects babies and children, everybody takes it seriously. I think it's a high priority
that we follow up on these studies," Cohen said.
In the latest research from UCLA, Ritz and a team of researchers found that women exposed to
high levels of ozone and carbon monoxide were three times more likely than others to have babies
with cleft lips and palates and defective heart valves.
The researchers looked at thousands of pregnant women in the Los Angeles area from 1987 to
1993, and compared those living in areas with relatively dirty air to those living in cleaner areas.
Virtually the entire study area, bounded roughly by San Bernardino, Santa Ana and Santa Clarita,
met federal standards for carbon monoxide, and much of the region complied with ozone
requirements.
The study, to be published in the American Journal of Epidemiology, found that the greatest risk
occurs during the second month of pregnancy, when a fetus gains most of its organs and much of its
facial structure.
The Clean Air Act regulates smog levels to protect certain sensitive groups, including children, the
elderly and people with respiratory ailments, but not babies or fetuses.
Pollutants inhaled by pregnant mothers can reach fetuses through the umbilical cord, research has
found.
Most of the studies about smog and babies came after the Clinton administration set new federal
limits for ozone and microscopic particles.
EPA officials say that before those standards can be strengthened, more research is needed to
determine which pollutants are most harmful and at what stage of pregnancy they do the most
damage.
State Officials Push for Action
However, California officials say they have seen enough. Melanie Marty, chief of the air toxicology
and epidemiology unit at the state Office of Environmental Health Hazard Assessment, said the
studies linking smog and harm to babies are part of a body of evidence the state is relying on to
recommend that the Air Resources Board lower the statewide standard for airborne particle
pollution by 33%.
"These studies are very suggestive of effects in infants, and in terms of public health, you want to
protect against that rather than wait for the most perfect study in the world," Marty said.
Recently, more and more scientists--many of them women--have been investigating whether ill
effects of smog persist even where the pollution has been reduced, as in much of the United States.
A study by scientists from the Harvard School of Public Health and the University of Basel in
Switzerland concluded that as many as 11% of infant deaths in the United States--about 3,000 per
year--may be a result of microscopic particles in the air.
The study, which has yet to be published, expands on earlier research by the EPA and Centers for
Disease Control that looked at 4 million infants in 86 metropolitan areas and compared the
incidence of mortality with fluctuating rates of particulate pollution.
That study concluded that as particulate matter increased in the air, the infant mortality rate rose by
10% to 40%.
Carbon Monoxide, Underweight Babies
In a separate study, a team of researchers from the United States and Sweden found that pregnant
women in five U.S. cities who were exposed to elevated levels of carbon monoxide during their
third trimester were 31% more likely to give birth to underweight babies.
They found that when concentrations of carbon monoxide increased by 1 part per million, the risk
climbed by nearly one-third.
The researchers, from Johns Hopkins University, the Centers for Disease Control and Prevention
and the Nordic School of Public Health in Sweden, examined 90,000 births and air pollution trends
between 1994 and 1996 in Boston; Hartford, Conn.; Philadelphia; Pittsburgh; Springfield, Mass.;
and Washington, D.C.
The findings were published in June in the journal Environmental Health Perspectives.
Another study by UCLA researchers, which was published last year and focused on Southern
California, concluded that mothers are 20% more likely to have a baby prematurely when exposed
to elevated amounts of microscopic particles in the final six weeks of pregnancy.
The analysis, which examined 97,518 newborns between 1989 and 1993, found the highest rate of
premature births in eight communities where smog levels were among the highest in the nation
though generally in compliance with federal standards.
The communities are Anaheim, Burbank, central Los Angeles, El Toro, Glendora, Hawthorne, Long
Beach and Santa Clarita.
The researchers adjusted the findings to account for a variety of factors often related to premature
birth, including the mother's age, access to prenatal care, smoking and illnesses such as lung disease,
diabetes and hypertension. They excluded births by caesarean section.
In a 1998 study of pregnant women in Sao Paulo, Brazil, scientists found that women exposed to
high levels of nitrogen and sulfur oxides were 18% more likely to have their pregnancies terminate in
stillbirths.
Nitrogen and sulfur oxides, produced by fuel combustion in vehicles and factories, is more abundant
in Sao Paulo than in U.S. cities.
The Sao Paulo researchers also found evidence of carbon monoxide in the umbilical cords of 47
nonsmoking mothers.
The levels of carbon monoxide rose and fell with daily air pollution levels. Carbon monoxide can cut
off oxygen to a fetus, leading to death.
The discovery of carbon monoxide in umbilical cords helps explain how air pollutants reach a fetus
and cause damage.
"There really is evidence that levels of air pollution encountered in large cities worldwide may be
hazardous to the fetus," said Dana Loomis, a co-author of the study and an epidemiologist at the
University of North Carolina.
"This is something that has not been recognized before. It was always assumed the fetus was
isolated in the womb from things in the environment."
The EPA is weighing the emerging body of research as it considers whether to tighten its standard
for airborne particles.
"We do see the trend. There is a growing body of literature finding an association of conventional air
pollution and infant mortality," said John D. Bachmann, associate director of science policy in the
EPA's air division.
"Our review is in mid-process, and we are looking at all of this."
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