Trish Mannes

Impact of ambient air pollution on birth weight in Sydney, Australia

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.

Impact of ambient air pollution on gestational age is modified by season in Sydney, Australia

BackgroundThe effect of individual pollutants and the period(s) during pregnancy when pollutant levels are likely to have most impact on preterm birth is not clear. We evaluated the effect of prenatal exposure to six common urban air pollutants in the Sydney metropolitan area on preterm birth.MethodsWe obtained information on all births in metropolitan Sydney between January 1, 1998 and December 31, 2000. For each birth, exposure to each air pollutant was estimated for the first trimester, the three months preceding birth, the first month after the estimated date of conception and the month prior to delivery. Gestational age was analysed as a categorical variable in logistic regression models.ResultsThere were 123 840 singleton births in Sydney in 1998–2000 and 4.9% were preterm. Preterm birth was significantly associated with maternal age, maternal smoking, male infant, indigenous status and first pregnancy. Air pollutant levels in the month and three months preceding birth had no significant effect on preterm birth after adjusting for maternal and infant covariates. Ozone levels in the first trimester of pregnancy and spring months of conception and sulphur dioxide were associated with increased risks for preterm births. Nitrogen dioxide was associated with a decreased risk of preterm births.ConclusionWe found more protective than harmful associations between ambient air pollutants and preterm births with most associations non-significant. In view of these inconsistent associations, it is important to interpret the harmful effects with caution. If our results are confirmed by future studies then it will be imperative to reduce Sydneys already low air pollution levels even further.

Effect of a chemical manufacturing plant on community cancer rates

BackgroundWe conducted a retrospective study to determine if potential past exposure to dioxin had resulted in increased incidence of cancer in people living near a former manufacturing plant in New South Wales, Australia. During operation, from 1928 to 1970, by-products of the manufacturing process, including dioxin and other chemical waste, were dumped into wetlands and mangroves, discharged into a nearby bay and used to reclaim land along the foreshore, leaving a legacy of significant dioxin contamination.MethodsWe selected 20 Census Collector Districts within 1.5 kilometres of the former manufacturing plant as the study area. We obtained data on all cases of cancer and deaths from cancer in New South Wales from 1972 to 2001. We also compared rates for some cancer types that have been associated with dioxin exposure. Based on a persons residential address at time of cancer diagnosis, or at time of death due to cancer, various geo-coding software and processes were used to determine which collector district the case or death should be attributed to. Age and sex specific population data were used to calculate standardised incidence ratios and standardised mortality ratios, to compare the study area to two comparison areas, using indirect standardisation.ResultsDuring the 30-year study period 1,106 cases of cancer and 524 deaths due to cancer were identified in the study area. This corresponds to an age-sex standardised rate of 3.2 cases per 1,000 person-years exposed and 1.6 deaths per 1,000 person-years exposed. The study area had a lower rate of cancer and deaths from cancer than the comparison areas. The case incidence and mortality due to lung and bronchus carcinomas and haematopoietic cancers did not differ significantly from the comparison areas for the study period. There was no obvious geographical trend in ratios when comparing individual collector districts to New South Wales according to distance from the potential source of dioxin exposure.ConclusionThis investigation found no evidence that dioxin contamination from this site resulted in increased cancer rates in the potentially exposed population living around the former manufacturing plant.

Investigation of an outbreak of acute illness in a school group visiting Sydney, September 2006

OBJECTIVE We describe the investigation into an outbreak of acute illness in approximately 40 people attending Darling Harbour in Sydney during a school music camp. METHODS We used three methods, including the Public Health Realtime Emergency Department Surveillance System, to obtain information on the food and travel history of the group and symptoms of the cases rapidly. RESULTS Forty-five cases of gastroenteritis were identified in people on the bus trip. Most dates of onset of illness were obtained from triage text fields in the NSW Public Health Real Time Emergency Department Surveillance System, and were verified through medical record review and interviews. No causative agent was identified. CONCLUSION The investigation suggested person-to-person transmission rather than a point source, and demonstrates how the NSW Public Health Real Time Emergency Department Surveillance System can assist with case finding in public health investigations.

An epidemiological investigation into an outbreak of rash illness among methadone maintenance clients in Australia

In late 2004, NSW Health received several reports of a serious desquamating rash among clients of the methadone program. We sought to identify the extent and likely cause of this outbreak. We initiated active surveillance for cases throughout Australia, a survey of dosing points in NSW, and a case control study of clients receiving methadone syrup (MS) at two clinics. Between October 2004 and March 2005, 388 cases were identified, largely in NSW. The dosing point survey found almost all cases were clients prescribed MS (attack rate 4.5%). In multivariate analysis of data from dosing points that dispensed MS, use of take away doses or location of the dosing point in greater western Sydney were associated with illness. In the case control study, MS injection, use of street MS, high doses of MS, frequent takeaway doses, or use of benzodiazepines were associated with illness. Testing found no abnormality in associated batches of MS. Batches of MS temporally associated with the outbreak were quarantined from use and the outbreak subsided. While a direct causal link could not be established, available evidence suggests that a contaminant may have caused the outbreak. Epidemiological analyses are important for assessing concerns about product safety following marketing approval.

Audit of post-exposure treatment to prevent lyssavirus infection in Sydney South West Area Health Service, 2005–2007

OBJECTIVES To describe the profile of people who received post-exposure treatment to prevent lyssavirus infection in Sydney South West Area Health Service between 2005 and 2007 and to assess treatment compliance with the current NSW Health protocol. METHODS Thirty-eight public health files and a subset of 11 medical records were reviewed to collect demographic, exposure and treatment information for the period. RESULTS Twenty-nine (76%) potential Lyssavirus exposures occurred overseas. Nine potential exposures occurred within Australia; eight of these resulted from a bat bite or scratch. Thirteen (34%) of all potential exposures resulted from handling an animal. CONCLUSION Many potential exposures were the result of a bite or scratch from a domesticated animal; the animals survival or health status was not routinely recorded. While all people who commenced post-exposure treatment completed the prescribed course, this was often not within the stipulated timeframe.