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Pollution shrinks fetuses, researchers say

Jan. 8, 2008
Courtesy Queens­land 
Un­ivers­ity of Tech­nol­o­gy
and World Science staff

Ex­po­sure to air pol­lu­tion sig­nif­i­cantly re­duces fe­tus size dur­ing preg­nan­cy—which bodes ill for the af­fect­ed chil­dren’s life­long health, sci­en­tists are re­port­ing.

Adri­an Bar­nett of Aus­trali­a’s Queens­land Un­ivers­ity of Tech­nol­o­gy and col­leagues com­pared fe­tus sizes as shown in more than 15,000 ul­tra­sound scans, to air pol­lu­tion lev­els in the ar­ea of Bris­bane, Aus­tral­ia.

Major roadways can be sources of air pollution. (Image courtesy NSF)


“Moth­ers with a high­er ex­po­sure to air pol­lu­tion had fe­tuses that were, on av­er­age, small­er” as re­vealed by three key meas­ures, Bar­nett said. 

“While we need to get more da­ta from in­di­vid­ual moth­ers be­fore we can be more cer­tain about the ef­fects of air pol­lu­tion on fe­tal de­vel­op­ment, we would rec­om­mend that where pos­si­ble preg­nant wom­en re­duce their ex­po­sure to air pol­lu­tion.” Avoid­ing ma­jor roads when pos­si­ble may help, he said.

The 10-year stu­dy, con­ducted with with Craig Han­sen of the U.S. En­vi­ron­men­tal Pro­tec­tion Agen­cy, ex­am­ined fe­tuses in mid-pregnancy and ap­peared in the Dec. 17 on­line is­sue of the re­search jour­nal En­vi­ron­men­tal Health Per­spec­tives

“To our knowl­edge this is the first study of its kind as it uses ul­tra­sound meas­ure­ment as a di­rect es­ti­mate of growth, rath­er than us­ing birth weight as a de­layed meas­ure of growth,” Bar­nett said. “When an­a­lys­ing scans from wom­en at dif­fer­ent dis­tances to mon­i­tor­ing sites, we found that there was a neg­a­tive rela­t­ion­ship be­tween pol­lu­tants such as sul­phur di­ox­ide found in die­sel emis­sions, and ul­tra­sound meas­ure­ment.”

Fe­tal size is im­por­tant, Bar­nett said, be­cause “birth weight is a ma­jor pre­dic­tor of lat­er health; for ex­am­ple, big­ger ba­bies have been shown to have high­er IQs in child­hood and low­er risk of car­di­o­vas­cu­lar dis­ease” lat­er. 

The findings may be par­tic­u­larly sur­pris­ing in light of the fact that Bris­bane is seen as a rel­a­tively clean ­city, he added. “Some peo­ple may think there is no air pol­lu­tion in Bris­bane be­cause the air looks so clean,” he not­ed. But “you have to re­mem­ber that most air pol­lu­tants are not vis­i­ble to the na­ked eye, peo­ple do have a very out­door lifestyle, and homes are de­signed to max­im­ise airflow. So al­though the ac­tu­al lev­els of pol­lu­tion are low our ex­po­sure to what­ev­er is out there is rel­a­tively high. This is par­tic­u­larly a prob­lem for peo­ple who live near ma­jor roads.” Mo­tor ve­hi­cles cause most of the air pol­lu­tion in Bris­bane, he added, as in many oth­er ci­ties.


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Exposure to air pollution significantly reduces fetus size during pregnancy—which bodes ill for the affected children’s lifelong health, scientists are reporting. Adrian Barnett of Australia’s Queensland University of Technology and colleagues compared fetus sizes as shown in more than 15,000 ultrasound scans, to air pollution levels in the area of Brisbane, Australia. “Mothers with a higher exposure to air pollution had fetuses that were, on average, smaller” as revealed by three key measures, Barnett said. “While we need to get more data from individual mothers before we can be more certain about the effects of air pollution on fetal development, we would recommend that where possible pregnant women reduce their exposure to air pollution.” Avoiding major roads when possible may help, he said. The 10-year study, conducted with with Craig Hansen of the U.S. Environmental Protection Agency, examined fetuses in mid-pregnancy and appeared in the Dec. 17 online issue of the research journal Environmental Health Perspectives. “To our knowledge this is the first study of its kind as it uses ultrasound measurement as a direct estimate of growth, rather than using birth weight as a delayed measure of growth,” Barnett said. “When analysing scans from women at different distances to monitoring sites, we found that there was a negative relationship between pollutants such as sulphur dioxide found in diesel emissions, and ultrasound measurement. Fetus size is important, Barnett said, because research shows that bigger babies are healthier in childhood and adulthood. “Birth weight is a major predictor of later health; for example, bigger babies have been shown to have higher IQs in childhood and lower risk of cardiovascular disease” later. The results may be particularly surprising in light of the fact that Brisbane is seen as a relatively clean city, he added. “Some people may think there is no air pollution in Brisbane because the air looks so clean,” he noted. But “you have to remember that most air pollutants are not visible to the naked eye, people do have a very outdoor lifestyle, and homes are designed to maximise airflow. So although the actual levels of pollution are low our exposure to whatever is out there is relatively high. This is particularly a problem for people who live near major roads.” Motor vehicles cause most of the air pollution in Brisbane, he added, as in many other cities.