Long-term exposure to low air pollutant concentrations and hospitalisation for respiratory diseases in older men: A prospective cohort study in Perth, Australia.

Background: Acute exposure to ambient air pollution even at low concentrations has been associated with increased hospitalisation for respiratory diseases but the effects of long-term exposure are less certain. In this study, we investigated the associations between long-term exposures to PM2.5, PM2.5 absorbance and NO2 and hospitalisation for asthma, chronic obstructive pulmonary disease and pneumonia in a cohort of older men living in Perth, Western Australia, a city where the levels of air pollutants are well below the world standards. Materials and methods: The study population of 11,156 men with no prior hospitalisation for respiratory disease was drawn from the Health in Men Study (HIMS) cohort of men aged >65 years living in Perth, Western Australia between 1996-1999. PM2.5, PM2.5 absorbance (PM2.5a) and NO2 were measured across the Perth metropolitan area over three seasons in 2012. Land use regression (LUR) models were used to estimate annual concentrations of PM2.5, PM2.5 absorbance and NO2 at the residential address of each participant from inception (1996) to 2015. Hospitalisation for respiratory disease between inception and 2015 was ascertained using the Western Australian Data Linkage System. The association between exposure to air pollution with hospitalisation for respiratory disease was examined using Cox regression analysis. Results: No statistically significant associations were observed in the fully adjusted models. However, positive associations were observed with first hospitalisation for pneumonia (HR 1.08, 95% CI: 1.01-1.16) when adjusted for age, year of enrolment, smoking status, education, BMI and physical activity. Conclusions: In this longitudinal study of older men we found no evidence of associations between increased long-term exposure to low-level air pollution with increased risk of hospitalisation for respiratory diseases in Perth, Australia. More studies on respiratory morbidity associated with exposure to low levels of air pollution are needed for more comprehensive understanding of the overall risk.

Prenatal exposure to mixtures of persistent environmental chemicals and fetal growth outcomes in Western Australia.

BACKGROUND: Environmental chemicals have been implicated in the etiology of impaired fetal growth. However, few studies have assessed the effects of chemical mixtures or considered the possibility of non-monotonic exposure-response relationships for chemicals that act through the endocrine system. METHODS: We assessed exposure to polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluorinated alkyl substances in blood and urine samples collected approximately two weeks prior to delivery in 166 non-smoking pregnant women, and subsequent birth weight, length, and head circumference of neonates who were part of the Australian Maternal Exposures to Toxic Substances (AMETS) study. We used Bayesian structured additive regression models with spike-slab priors to estimate mixture effects, identify important exposures, and model non-linearity in exposure-response relationships. RESULTS: Mixtures of polybrominated diphenyl ethers, organochlorine pesticides, metals, and perfluorinated alkyl substances were not associated with fetal growth outcomes. Estimated change in fetal growth outcomes for an increase in exposure from the 25th to 75th percentile suggested no meaningful associations; the strongest evidence was for a small inverse association between birth weight and cesium exposure measured in whole blood (-124 g, 90% credible interval: -240 to -3 g). We identified several chemicals that may be associated with fetal growth non-linearly; however, 90% credible intervals contained small values consistent with no meaningful association. CONCLUSIONS: Using a Bayesian penalized regression method, we assessed the shapes of exposure-response relationships, controlled for confounding by co-exposure, and estimated the single and combined effects of a large mixture of correlated environmental chemicals on fetal growth. Our findings, based on a small sample of mother-neonate pairs, suggest that mixtures of persistent chemicals are not associated with birth weight, length, and head circumference. The potential for non-monotonic relationships between environmental chemicals and fetal growth outcomes warrants further study.

Polybrominated diphenyl ether (PBDE) concentrations in plasma of pregnant women from Western Australia.

PBDEs are a class of brominated flame retardants applied to consumer goods to reduce their flammability. These compounds are lipophilic, persistent and bioaccumulate through the food web. PBDEs have been detected in human blood, adipose tissue and breast milk. There are a small number of studies reporting concentrations of PBDEs in Australian populations. These indicate that concentrations are higher than in studies reporting concentrations from Europe but lower than those from Northern America. The aim of this paper was to determine the concentrations of PBDEs in the plasma of pregnant women participating in the Australian Maternal Exposure to Toxic Substances (AMETS) study in Western Australia. The samples comprised 164 pregnant women, aged 18 years and over, who were non-smokers and not occupationally exposed to persistent substances. Participants provided blood samples at 38 weeks gestation and these were analysed for five PBDE congeners. Maternal health and birth outcomes data were also obtained. The median for sum PBDE concentrations in plasma was 53.9 pg g(-1) (range 13.2 to 1390 pg g(-1)ww). Concentrations were adjusted for the estimated plasma lipid content. The concentrations of Σ5PBDE ranged from 2.44 to 258 ng g(-1) lipid with a median of 9.97 ng g(-1) lipid. BDE-47 was the dominant congener (median 21.4 pg g(-1), range <4.95 to 1030 pg g(-1)) followed by BDE-153 (median 12.2 pg g(-1), range <2.94 to 353 pg g(-1)). There were no significant associations between maternal, housing or dietary factors and concentrations of PBDEs in this study. Maternal PBDE concentrations were not associated with infant birth weight. This study builds upon previous Australian research and shows that concentrations in this sample of Western Australian women were higher than in parts of Europe.

Maternal exposure to organochlorine pesticides in Western Australia.

BACKGROUND: Organochlorine pesticides (OCPs) persist over long periods of time. Little is known about levels of OCPs in the plasma of non smoking pregnant women in Western Australia. The aim of this study was to (1) determine exposure concentrations in a sample of pregnant women in Western Australia; (2) to determine the significant environmental, lifestyle and activity contributors to maternal exposure concentrations of OCPs and (3) to compare the measured maternal exposure concentrations with those measured in other countries. METHODS: In a cross-sectional survey, 167 pregnant women located in rural and urban Western Australia provided plasma and answered questionnaires seeking information on lifestyle, demographics and the determinants of exposure to OCPs. RESULTS: Of the 10 OCPs examined only HCB, ß-HCH and p,p'DDE had concentrations above the limit of detection for more than 50% of samples. The mean level of HCB was 0.08 µg/L (range 0.005-2.0 µg/L), ß-HCH 0.18 µg/L (range 0.04-3.16 µg/L) and p,p'DDE 1.05 µg/L, (range 0.03-17.04 µg/L). HCB concentrations were higher in women who ate seafood during pregnancy and who were older and lower among those with a history of breastfeeding. Concentrations of ß-HCH were higher among women with a household income<$80,000 and lower among those with a history of breastfeeding. Concentrations of p,p'DDE were higher among women who lived within 1 km of industry and lower among those with a history of breastfeeding. CONCLUSIONS: Concentrations of pesticides were low in Western Australian mothers compared with international studies.