Michael Wu

National Measurement Institute, Sydney, New South Wales, Australia

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Publications (7)16.83 Total impact

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    ABSTRACT: We monitored 108 children ≤5 years on a 6-month basis for up to 5 years in a major urban setting. Samples (n ∼ 7000) included blood, urine, handwipes (interior, and after exterior playing), 6-day duplicate diet, drinking water, interior house and day care dust-fall accumulation using petri dishes, exterior dust-fall accumulation, exterior dust sweepings, paint, soil and urban air. The geometric mean blood Pb (PbB) was 2.1 μg/dL and blood Mn (MnB) was 10.0 μg/L. Following a path modelling approach, mixed model analyses for a fully adjusted model showed the strongest associations for PbB were with interior house dust and soil; for MnB there were no significant associations with any predictors. Predictor variables only explained 9% of the variance for Pb and 0.7% for Mn. Relationships between environmental measures and PbB in children are not straightforward; soil and dust sweepings contribute only about 1/5th of the amounts to PbB found in other studies.
    Environmental Pollution 04/2014; 191C:38-49. · 3.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We monitored 108 children ≤5 years on a 6-month basis for up to 5 years in a major urban setting. Samples (n ∼ 7000) included blood, urine, handwipes (interior, and after exterior playing), 6-day duplicate diet, drinking water, interior house and day care dust-fall accumulation using petri dishes, exterior dust-fall accumulation, exterior dust sweepings, paint, soil and urban air. The geometric mean blood Pb (PbB) was 2.1 μg/dL and blood Mn (MnB) was 10.0 μg/L. Following a path modelling approach, mixed model analyses for a fully adjusted model showed the strongest associations for PbB were with interior house dust and soil; for MnB there were no significant associations with any predictors. Predictor variables only explained 9% of the variance for Pb and 0.7% for Mn. Relationships between environmental measures and PbB in children are not straightforward; soil and dust sweepings contribute only about 1/5th of the amounts to PbB found in other studies.
    Environmental Pollution. 01/2014; 191:38–49.
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    ABSTRACT: There are limited data on essential nutrients in the whole blood of young children. As part of a longitudinal study of the impact on young children and the environment from the introduction of an organic Mn compound into unleaded gasoline in Australia, we have measured a suite of elements in whole blood. The children, aged between 6 and 31 months at recruitment, have been monitored at 6-month intervals for up to 5 years. Blood samples were analysed by inductively coupled plasma mass spectrometry for Ca, Mg, Fe, Mn, Cu, Zn and Pb. Mixed model analyses of 665 blood samples using backward elimination showed significant positive relationships between Ca, Mg and Zn and season, variable relationships with time, but no association with gender or traffic exposure. The elements Ca, Mg and Zn showed higher concentrations in summer compared with winter, whereas Fe and Pb showed lower concentrations in summer compared with winter. Concentrations of all elements except Fe showed significant effects over time: Ca, Cu, Mg, Pb and Mn showed decreases over time, whereas Zn showed an increase. The mixed model analyses with the individual elements as the dependent variable showed some interesting relationships and require further follow-up as some of these appear to conflict with pre-existing concepts, although the multi-element data on which these concepts are based are limited. The variance for blood Pb and blood Mn arising from the other elements was small with 0.5% in the case of blood Pb and 3.7% for blood Mn.
    Journal of Trace Elements in Medicine and Biology 02/2008; 22(3):206-14. · 2.49 Impact Factor
  • Chinese Journal of Geochemistry 02/2006; 25:62-62.
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    ABSTRACT: A 4-year longitudinal study is being conducted to evaluate potential changes to the environment and exposure of young children associated with the introduction of methylcyclopentadienyl manganese tricarbonyl (MMT) into Australia in 2001. The cohort consists of 57 females and 56 males, with an age range of 0.29-3.9 years. Samples are collected every 6 months from children in residences located at varying distances from major traffic thoroughfares in Sydney. Environmental samples include air, house, and daycare center dustfall, soil, dust sweepings, and gasoline; samples from the children include blood, urine, handwipes prior to and after playing outdoors, and a 6-day duplicate diet. All samples are analyzed for a suite of 20 elements using inductively coupled plasma methods. Results are presented for the first three 6-month sampling periods for lead (Pb) and manganese (Mn). For dustfall accumulation, expressed as metal concentration/m2/30 days, there was no significant difference between homes and daycare centers for either Pb or Mn, no significant change over the three sampling periods (time) for Pb or Mn, and a positive relationship between "traffic exposure" (traffic volume and proximity to the road) and Pb but not Mn. Lead concentrations in soil was a significant predictor for Pb in the house dustfall. For handwipes, the concentrations of Pb and Mn in wipes taken from children after playing outdoors was usually significantly greater than those for wipes taken prior to playing. There was no significant association between the concentrations of either Pb or Mn in handwipes and traffic exposure, and there was no significant association between Pb concentrations in the handwipes and gender, although the latter showed a marginally significant association for Mn (P = 0.053). Age was related to Pb level in the handwipes, with older subjects having higher Pb levels, and there were significant decreases in Pb and Mn concentrations over time. Dustfall accumulation was a significant predictor for Pb in the handwipes, and dust sweepings were a significant predictor of Mn in handwipes. Blood lead (PbB) concentrations ranged from 0.6 to 19 microg/dL (GM 2.6) (n = 269), and manganese in blood (MnB) ranged from 1.8 to 45 microg/L (GM 11.6) (n = 254). There was no significant difference between females and males for either mean PbB or MnB; over time there was a significant decline in PbB but no significant change in MnB. The only significant predictor for PbB was dustfall accumulation, although dietary intake may also be important, and the only significant predictor for MnB was Mn in handwipes prior to playing. At this early stage of the investigation we have not been able to detect any increases in Mn in these environmental samples or blood samples potentially associated with the use of MMT; in fact the Mn levels in handwipes declined over time.
    Environmental Research 02/2006; 100(1):100-14. · 3.95 Impact Factor
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    ABSTRACT: A method is described for the direct determination of several transition elements in sea-water by reaction cell (RC)-inductively coupled plasma mass spectrometry (ICP-MS) using ammonia as a reaction gas. Results show significant improvement over standard quadrupole (Q) ICP-MS performance for direct sea-water analysis and were comparable to high resolution (HR) ICP-MS. In this study, the RC-ICP-MS was used to determine chromium, copper, manganese, nickel and vanadium in sea-water. Ammonia gas was passed through the reaction cell to reduce molecular ion interference. These interferences normally lead to false positive results when low resolution quadrupole ICP-MS (Q-ICP-MS) is used to analyze sea-water. Good recoveries were obtained for V-51, Cr-52 and Mn-55 in the 1∶10 diluted sea-water, CASS-4, NASS-4 and SLEW-3. Molecular ion interference was reduced significantly but not completely for Ni-58 and Cu-63, giving rise to a positive bias typically no more than 0.3 µg l−1. A matrix blank subtraction or matrix matched external calibration can be used to further improve the accuracy for these elements at levels below 0.5 µg l−1. Detection limits in the undiluted sea-water range from 0.02 µg l−1 for chromium to 0.3 µg l−1 for copper. The precision and accuracy of the method were checked against three certified reference standards.
    Journal of Analytical Atomic Spectrometry 06/2002; 17(6):587-591. · 3.40 Impact Factor
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    ABSTRACT: The concentrations of 22 trace elements have been determined in 482 samples of Australian and Brazilian orange juices and Australian peel extracts and deacidified juices using inductively coupled plasma–atomic emission spectrometry and inductively coupled plasma–mass spectrometry. Means and ranges of elements have been established over a five year survey. Regional differences were apparent for the levels of one or more trace elements in the juices of Australian origin. These could be related to differences in soil and rootstock. Multivariate analysis of trace elements in Australian and Brazilian juices showed a clear differentiation between them. Peel extracts were also differentiated from Australian and Brazilian juices.
    Food Chemistry 12/2000; 71(4):423-433. · 3.26 Impact Factor