Health

Birth Defect Studies

Impact of pollution on children

(our thanks to Louise Sandberg )

This article includes a Hong Kong study showing that children from polluted areas have lower lung capacities (Spring 2003):

from the article:

– In a Czech Republic study, researchers examined births and air pollution levels in 67 districts. Women exposed to sulfur dioxide (created when sulfur-rich fuels like coal and diesel are burned), especially in their first trimester, had higher numbers of both low birth weight newborns and premature babies. Newborns of women exposed to total suspended particulate matter (soot, also a product of coal combustion) were also linked to low birth weight.(7)

– Exposure to sulfur dioxide also led to increased low-birth-weight newborns in a study of Boston, Philadelphia and four other northeastern cities, but so did carbon monoxide.(8) The link between carbon monoxide and low birth weight was also found in southern California.(9)

– All these pollutants-carbon monoxide, sulfur dioxide and total suspended particulate matter-were linked in Korea to newborns with increased low birth weight, and so was another, oxides of nitrogen (created by combustion, especially by power plants and vehicle engines).(10) Scientists compared 276,763 births to pollution levels collected from 21 monitoring sites, where, as was the case in California and the Northeast cities, motor vehicles were the dominant sources of pollution.

USA: January 1, 2002

WASHINGTON – Women exposed to air pollution during pregnancy are more likely to give birth to children with heart defects, researchers reported on Saturday.

They said their study, published in the American Journal of Epidemiology, is the first definitively to link air pollution with birth defects.

“There seems to be something in the air that can harm developing fetuses,” Beate Ritz, an epidemiologist who headed the study, said in a statement.

The team, at the University of California Los Angeles (UCLA) School of Public Health and the California Birth Defects Monitoring Program, said the two pollutants they measured were carbon monoxide and ozone – produced by the city’s well-known traffic jams.

“The greater a woman’s exposure to one of these two pollutants in the critical second month of pregnancy, the greater the chance that her child would have one of these serious cardiac birth defects,” Ritz said.

“More research needs to be done, but these results present the first compelling evidence that air pollution may play a role in causing some birth defects.”

Ritz’s team compared air pollution monitoring data from the Environmental Protection Agency with information from the California Birth Defects Monitoring Program – a statewide database on birth defects.

They looked at 9,000 babies born from 1987 to 1993. Pregnant women who were exposed to the highest levels of ozone and carbon monoxide because their homes were close to busy freeways were three times as likely to have a child with certain heart defects as women breathing the cleanest air.

The defects they found were specific – conotruncal heart defects, pulmonary artery/valve defects and aortic artery/valve defects, which can require open-heart surgery to save the baby. No other birth defects were linked with the pollution.

SOMETHING ELSE COULD BE THE CULPRIT

The researchers said it was not certain carbon monoxide and ozone were directly causing the defects. They could be a “marker” – something associated with the real cause.

“We’re not sure carbon monoxide is the culprit because it could be just a marker for something else in tailpipe exhaust,” Gary Shaw of the California Birth Defects Monitoring Program said in a statement.

“The fact that certain heart defects are turning up in the second month of pregnancy when hearts are being formed suggests something serious may be happening.”

Ritz said fine particles may be to blame. “We did a small study that showed ultrafine particles correlate extremely well with carbon monoxide,” she said in a telephone interview.

“When you move away from a freeway, 100 feet, 200 feet, you see the number of particles decrease very steeply. So does carbon monoxide.”

She said other researchers had shown that these ultrafine particles, which also come out of the tailpipes of cars, can carry toxic chemicals such as quinones and polycyclic aromatic hydrocarbons (PAHs). “They become a great delivery device for toxic agents,” Ritz said.

The same goes for ozone, which is generated when the sun cooks polluted air. The same process generates other chemicals, which are not measured.

“It’s easy as a knee-jerk reaction to say ‘Let’s get ozone down, let’s get carbon monoxide down.’ But if you are not doing anything to the other toxins, you might be on the wrong boat,” Ritz said.

Ritz said it also occurred to her that people living near freeways may also be poorer or have worse health in general, but said she factored that in. Some of the affected neighborhoods were actually very wealthy, she said.

She also looked at ethnicity and education level of the mothers and found no differences in the correlation between pollution and birth defects.

But she said they were unable to evaluate other potential risk factors for birth defects, including smoking, occupational exposures, vitamin supplement use, diet and obesity.

Story by Maggie Fox, Health and Science Correspondent

Story Date: 1/1/2002

Sunday, 30 December, 2001, 02:50 GMT: BBC News

Pollution linked to birth defects

Women exposed to high levels of ozone and carbon monoxide may be up to three times as likely to give birth to a baby with heart defects, American research suggests.

Scientists found the risk increased when women were exposed to high levels of the pollutants in the second month of their pregnancy.

That is the time when the heart and other organs begin to develop.

The research team suggest this is the first “compelling evidence” air pollution may play a role in causing some birth defects.

The research was carried out at the University of California Los Angeles (UCLA) School of Public Health and the California Birth Defects Monitoring Program (CBCMP)

Beate Ritz, a UCLA epidemiologist, who led the study, said: “The greater a woman’s exposure to one of these two pollutants in the critical second month of pregnancy, the greater the chance that her child would have one of these serious cardiac birth defects.”

Previous research by the same team has linked air pollution to harmful effects on pregnancy, including giving birth prematurely and low birth-weight babies.

Ozone gas is present in photochemical smog – produced by chemical reaction under ultraviolet light from the Sun.

Carbon monoxide is a colourless, odourless gas produced as a by-product of combustion – in vehicle exhaust fumes, for example.

Air quality checks

The study, published in the American Journal of Epidemiology, looked at information on more than 9,000 babies born between 1987 and 1993 in Los Angeles, Orange, San Bernardino and Riverside counties from the CBCMP.

They compared air quality near the children’s homes to that in the areas where healthy children lived, using measurements from the South Coast Air Quality Management District.

They found that pregnant women who were exposed to increased levels of ozone and carbon monoxide faced an higher risk of having a child with conotruncal heart defects – a group of severe heart problems, pulmonary artery or valve defects and aortic artery or valve defects.

Women who lived in areas with the highest levels of the pollutants had three times the risk of those living in areas with the cleanest air.

For women who lived in areas with moderately higher pollution, the risk of birth defects doubled.

This group of heart defects occurs 1.76 times per 1,000 births. Many babies need open-heart surgery before age one.

Cause for concern

Dr Ritz said: “These findings show that there are more health problems caused by air pollution than solely asthma and other respiratory illnesses.

“There seems to be something in the air that can harm developing foetuses.”

She added that although there had been a significant in ozone and carbon monoxide levels, there may be “secondary pollutants” occurring alongside the gases which were not yet measured or understood, and which could themselves pose health risks.

Gary Shaw of the CBCMP, who also worked on the research admitted: “We¿re not sure carbon monoxide is the culprit because it could be just a marker for something else in tailpipe exhaust.

“The fact that certain heart defects are turning up in the second month of pregnancy when hearts are being formed suggests something serious may be happening.

He called for further research: “Unlike other health factors like diet or lifestyle, a pregnant woman has almost no control over the quality of air she breathes – we need answers.”

The researchers admit the study is limited because it could only assess pregnant women’s exposure to pollutants by checking measurements of certain pollutants at monitoring stations, which could be up to 10 miles away.

They were also unable to look at other risk factors for birth defects, including maternal smoking, occupational exposures, vitamin supplement use, diet and obesity.

Small respirable particles less than 10 microns in diameter (PM10), and particularly very small particles (PM2.5) escape the filtering mechanisms of the respiratory system and can lodge in the deepest recesses of the lungs

They are associated with a wide range of health effects, including premature mortality, exacerbation of asthma, increased respiratory irritation symptoms, increased respiratory infections, decreased lung function.

Research conducted at the Chinese University of Hong Kong shows a tight correlation between increased levels of air pollution and increased hospital admissions of children for asthma.

Report on the Economic Costs of Air Pollution
FoE Hong Kong – 1997
Lai, C. , Pers. comm., Chinese University