| Babies at risk from pollution
July 28 2005 Women living in areas of Sydney with high levels of traffic pollution give birth to babies that are smaller than those born to women who breathe fewer fumes, state Health Department researchers have discovered. Vicky Sheppeard, from the department's environmental health branch, said babies exposed to the highest pollution levels before birth were on average about 12 grams lighter than those at the lowest end of the pollution range - the first time the effect has been confirmed in metropolitan Sydney. This was although pollution levels were generally low and only rarely exceeded national air-quality standards at any of the 11 monitoring stations studied by Dr Sheppeard, a senior policy analyst, and her colleagues. Babies who are born small despite a full-term pregnancy are at risk of a range of developmental and health conditions. The scientists matched measurements from the monitoring stations with birth records for all 138,000 Sydney babies born between 1998 and 2000. They calculated babies were up to 29 grams lighter for each additional part per million of carbon dioxide the mother was exposed to during middle and late pregnancy, and up to 34 grams lighter for each extra part per billion of nitrogen dioxide. Particulate matter, from domestic heating or bushfires, had a lesser effect. But Dr Sheppeard cautioned that these were not necessarily the chemicals most harmful to unborn babies, and might simply be evidence of a higher concentration of pollution that included other toxins. The contribution of pollution to lower birth weights was relatively small compared with other factors such as tobacco smoke, which could cause babies to be born hundreds of grams lighter, said Dr Sheppeard, whose research was published yesterday in the journal Occupational and Environmental Medicine . But mothers would be concerned because they had less control over pollution than other lifestyle factors. The research compared births among women living within five kilometres of the monitoring stations to Sydney averages, and was insufficiently detailed to show the effects of living on busy roads or spending more time outdoors. But Dr Sheppeard said the study could still be used by policy-makers. "This shows measures to reduce air pollution will also benefit unborn babies." The Sydney study adds to surveys from around the world that have concluded pollution affects unborn babies' growth - though they have differed on which phases of pregnancy and which pollutants are most crucial. Bruce Armstrong, head of the school of public health at the University of Sydney , said it was "hard to dismiss the body of evidence that indicates air pollution is associated with low birthweight … one has to consider this is probably cause and effect". Because pollution made a relatively small difference to babies' weight, it probably would have no effect on the health of otherwise healthy babies, Professor Armstrong said. But, for babies whose health was compromised for a different reason, the additional impact of pollution might make the child sicker. "It re-emphasises the point that we should be keeping air pollution as low as we possibly can."
IN UOW LIBRARY Abstract from Occupational and Environmental Medicine Impact of ambient air pollution on birth weight in Sydney , Australia T Mannes 1 , B Jalaludin 2 , G Morgan 3 , D Lincoln 4 , V Sheppeard 5 and S Corbett 5 1 NSW Public Health Officer Training Program, New South Wales Health Department, Australia? 2 Epidemiology Unit, South Western Sydney Area Health Service, Australia and School of Public Health and Community Medicine, University of New South Wales, Australia? 3 Northern Rivers Department of Rural Health, Sydney University, Australia? 4 NSW Biostatistical Officer Training Program, New South Wales Health Department, Australia? 5 Environmental Health Branch, New South Wales Health Department, Australia Correspondence to: ?Ms T F Mannes ?NSW Public Health Officer Training Program, New South Wales Health Department, LMB 961 North Sydney, Australia; paman@doh.health.nsw.gov.au Background: Studies in Asia, Europe, and the Americas have provided evidence that ambient air pollution may have an adverse effect on birth weight, although results are not consistent. Methods: Average exposure during pregnancy to five common air pollutants was estimated for births in metropolitan Sydney between 1998 and 2000. The effects of pollutant exposure in the first, second, and third trimesters of pregnancy on risk of "small for gestational age" (SGA), and of pollutant exposure during pregnancy on birth weight were examined. Results: There were 138 056 singleton births in Sydney between 1998 and 2000; 9.7% of babies (13 402) were classified as SGA. Air pollution levels in Sydney were found to be quite low. In linear regression models carbon monoxide and nitrogen dioxide concentrations in the second and third trimesters had a statistically significant adverse effect on birth weight. For a 1 part per million increase in mean carbon monoxide levels a reduction of 7 (95% CI –5 to 19) to 29 (95% CI 7 to 51) grams in birth weight was estimated. For a 1 part per billion increase in mean nitrogen dioxide levels a reduction of 1 (95% CI 0 to 2) to 34 (95% CI 24 to 43) grams in birth weight was estimated. Particulate matter (diameter less than ten microns) in the second trimester had a small statistically significant adverse effect on birth weight. For a 1 microgram per cubic metre increase in mean particulate matter levels a reduction of 4 grams (95% CI 3 to 6) in birth weight was estimated. Conclusion: These findings of an association between carbon monoxide, nitrogen dioxide, and particulate matter, and reduction in birth weight should be corroborated by further study. Abbreviations: ABS, Australian Bureau of Statistics; APHEA, Short-term Effects of Air Pollution and Health: A European Approach; CI, confidence interval; EPA, Environment Protection Authority; IRSD, Index of Relative Socioeconomic Disadvantage; IUGR, intrauterine growth retardation; LBW, low birth weight; LMP, last menstrual period; MDC, midwives data collection; NSW, New South Wales; PM 2.5 , particulate matter less than 2.5 microns diameter; PM 10 , particulate matter less than 10 microns diameter; ppb, parts per billion (10 –9 ); ppm, parts per million (10 –6 ); SD, standard deviation; SE, standard error; SES, socioeconomic status; SGA, small for gestational age; OR, odds ratio; Temp, temperature; TSP, total suspended particulates Keywords: small for gestational age; low birth weight; air pollution; air pollutants; environmental exposure; ozone; Australia; pregnancy outcomes; routinely collected data |