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Vegesafe

Publications

Laidlaw, M., Alankarage, D., Reichman, S., Taylor, M.P. 2018. Assessment of soil metal concentrations in residential and community vegetable gardens in Melbourne, Australia. Chemosphere, 199, 303-311.

  

Abstract:

Gardening and urban food production is an increasingly popular activity, which can improve physical and mental health and provide low cost nutritious food. However, the legacy of contamination from industrial and diffuse sources may have rendered surface soils in some urban gardens to have metals value in excess of recommended guidelines for agricultural production. The objective of this study was to establish the presence and spatial extent of soil metal contamination in Melbourne's residential and inner city community gardens. A secondary objective was to assess whether soil lead (Pb) concentrations in residential vegetable gardens were associated with the age of the home or the presence or absence of paint. The results indicate that most samples in residential and community gardens were generally below the Australian residential guidelines for all tested metals except Pb. Mean soil Pb concentrations exceeded the Australian HIL-A residential guideline of 300 mg/kg in 8% of 13 community garden beds and 21% of the 136 residential vegetable gardens assessed. Mean and median soil Pb concentrations for residential vegetable gardens was 204 mg/kg and 104 mg/kg (range <4–3341 mg/kg), respectively. Mean and median soil Pb concentration for community vegetable garden beds was 102 mg/kg and 38 mg/kg (range = 17–578 mg/kg), respectively. Soil Pb concentrations were higher in homes with painted exteriors (p = 0.004); generally increased with age of the home (p = 0.000); and were higher beneath the household dripline than in vegetable garden beds (p = 0.040). In certain circumstances, the data indicates that elevated soil Pb concentrations could present a potential health hazard in a portion of inner-city residential vegetable gardens in Melbourne.

 

Rouillon, M., Harvey, P.J, Kristensen, L.J., George, S.G., Taylor, M.P. 2017. VegeSafe: A community science program measuring soil-metal contamination, evaluating risk and providing advice for safe gardening. Environmental Pollution, 222, 557-566.

Abstract: The extent of metal contamination in Sydney residential garden soils was evaluated using data collected during a three year Macquarie University community science program called VegeSafe. Despite knowledge of industrial and urban contamination amongst scientists, the general public remains under-informed about the potential risks of exposure from legacy contaminants in their home garden environment. The community was offered free soil metal screening, allowing access to soil samples for research purposes. Participants followed specific soil sampling instructions and posted samples to the University for analysis with a field portable X-Ray Fluorescence (pXRF) spectrometer. Over the three year study period, >5200 soil samples, primarily from vegetable gardens, were collected from >1200 Australian homes. As anticipated, the primary soil metal of concern was lead: mean concentrations were 413 mg/kg (front yard), 707 mg/kg (drip line), 226 mg/kg (back yard) and 301 mg/kg (vegetable garden). The Australian soil lead guideline of 300 mg/kg for residential gardens was exceeded at 40% of Sydney homes, while concentrations >1000 mg/kg were identified at 15% of homes.The incidence of highest soil lead contamination was greatest in the inner city area with concentrations declining towards background values of 20-30 mg/kg at 30-40 km distance from the city. Community engagement with VegeSafe participants has resulted in useful outcomes: dissemination of knowledge related to contamination legacies and health risks; owners building raised beds containing uncontaminated soil and in numerous cases, owners replacing all of their contaminated soil.

 

Rouillon, M., Harvey, P.J, Kristensen, L.J., George, S.G., Taylor, M.P. Elevated lead levels in Sydney backyards: here's what you can do. The Conversation. January 17th, 2017.

 

 

Laidlaw, M.A.S. and Taylor M.P. 2011. Potential for Childhood Lead Poisoning in the Inner Cities of Australia Due to Exposure to Lead in Soil Dust. Environmental Pollution, 159(1), 1-9.

Abstract: This article presents evidence demonstrating that the historical use of leaded gasoline and lead (Pb) in exterior paints in Australia has contaminated urban soils in the older inner suburbs of large cities such as Sydney and Melbourne. While significant attention has been focused on Pb poisoning in mining and smelting towns in Australia, relatively little research has focused on exposure to Pb originating from inner-city soil dust and its potential for childhood Pb exposures. Due to a lack of systematic blood lead (PbB) screening and geochemical soil Pb mapping in the inner cities of Australia, the risks from environmental Pb exposure remain unconstrained within urban population centres.

 

Harvey, P., Rouillon, M., Dong, C., Ettler, V., Handley, H.K., Taylor, M.P., Tyson, E., Tennant, P., Telfer, V.S., Trinh, R. 2017. Geochemical sources, forms and phases of soil contamination in an industrial city. Science of the Total Environment 584-585, 505-514.

Abstract: This study examines current soil contamination in an Australian industrial city, Newcastle. Public (roadside verges and parks) and private (homes) surface soils (n = 170) contained metal(loid)s elevated above their respective Australian Health Investigation Levels (HIL). Lead (Pb), the most common contaminant in the city, exceeds the HIL for residential soils (HIL-A, 300 mg/kg) in 88% of private soils (median: 1140 mg/kg). In-vitro Pb bio-accessibility analysis of selected soils (n = 11) using simulated gastric fluid showed a high affinity for Pb solubilisation (maximum Pb concentration: 5190 mg/kg, equating to 45% Pb bio-accessibility). Highly soluble Pb-laden Fe- and Mn-oxides likely contribute to the bio-accessibility of the Pb. Public and private space surface soils contain substantially less radiogenic Pb (range: ²⁰⁸Pb/²⁰⁷Pb: 2.345–2.411, ²⁰⁶Pb/²⁰⁷Pb: 1.068–1.312) than local background soil (²⁰⁸Pb/²⁰⁷Pb: 2.489, ²⁰⁶Pb/²⁰⁷Pb: 1.198), indicating anthropogenic contamination from the less radiogenic Broken Hill type Pb ores (²⁰⁸Pb/²⁰⁷Pb: 2.319, ²⁰⁶Pb/²⁰⁷Pb: 1.044). Source apportionment using Pb isotopic ratio quantification and soil mineralogy indicate the city's historic copper and steel industries contributed the majority of the soil contaminants through atmospheric deposition and use of slag waste as fill material. High-temperature silicates and oxides combined with rounded particles in the soil are characteristic of smelter dust emissions. Additionally, a preliminary investigation of polycyclic aromatic hydrocarbons in soils, sometimes associated with ferrous metal smelting, coal processing or burning of fossil fuels, shows that these too pose a health exposure risk (calculated in comparison to benzo(a)pyrene: n = 12, max: 13.5 mg/kg, HIL: 3 mg/kg). 

 

Taylor, M.P., Lanphear, B.P., Gore, D.B., Forbes, M., Zahran, S. 2013. Child lead exposure linked to crime in adulthood. The Conversation. April 10th, 2013.

 

Laidlaw, M.A.S., Zahran, S., Pingatore, N., Clague, J., Devlin, G., Taylor, M.P. 2014. Identifying and fingerprinting temporal lead sources in domestic homes. Environmental Pollution, 184, 238–246. 

Abstract: Interior and exterior dust, soil and paint were analysed at five brick urban Sydney homes over 15 months to evaluate temporal variations and discriminate sources of lead (Pb) exposure. Exterior dust gauge Pb loading rates (μg/m2/28 days), interior vacuum dust Pb concentrations (mg/kg) and interior petri-dish Pb loading rates (μg/m2/28 days), were correlated positively with soil Pb concentrations. Exterior dust gauge Pb loading rates and interior vacuum dust Pb concentrations peaked in the summer. Lead isotope and Pb speciation (XAS) were analysed in soil and vacuum dust samples from three of the five houses that had elevated Pb concentrations. Results show that the source of interior dust lead was primarily from soil in two of the three houses and from soil and Pb paint in the third home. IEUBK child blood Pb modelling predicts that children's blood Pb levels could exceed 5 μg/dL in two of the five houses.

 

Rouillon, M., Gore, D.B., Taylor, M.P. 2013. The nature and distribution of Cu, Zn, Hg, and Pb in urban soils of a regional city: Lithgow, Australia. Applied Geochemistry, 36, 83–91. 

Abstract: This study investigates the concentration and spatial distribution of Cu, Zn, Hg and Pb in the surface (0–2 cm) soils of a regional city in Australia. Surface soils were collected from road sides and analysed for their total Cu, Zn, Hg and Pb concentrations in the <180 μm and <2 mm grain size fractions. The average metal concentration of surface soils, relative to local background soils at 40–50 cm depth, are twice as enriched in Hg, more than three times enriched in Cu and Zn, and nearly six times as enriched in Pb. Median surface soil metal concentration values were Cu – 39 mg/kg (682 mg/kg max), Zn – 120 mg/kg (4950 mg/kg max), Hg – 44 μg/kg (14,900 μg/kg max) and Pb – 46 mg/kg (3490 mg/kg max). Five sites exceeded the Australian NEPC (1999) 300 mg/kg guideline for Pb in residential soils. Strong positive correlations between Cu, Zn and Pb, coupled with the spatial distribution of elevated soil concentrations towards the city centre and main roads suggest traffic and older housing as major sources of contamination. No spatial relationships were identified between elevated metal loadings and locations of past or present industries.

 

Green, D., Chakraborty, J., Taylor, M.P. 2014. Australia’s dirty secret: who’s breathing toxic air? The Conversation. 16th April 2014.

 

Taylor, M.P., Winder, C., Lanphear, B.P. 2014. Australia’s leading public health body delays action on the revision of the public health goal for blood lead exposures. Environment International, 70, 113–117. 

Abstract: Globally, childhood blood lead levels have fallen precipitously in developed countries since the 1970s following action by international bodies such as the WHO and Food and Agricultural Organization (FAO) of the United Nations. These reductions have been affected by the activities of national agencies such as the US EPA and US Centers for Disease Control and Prevention in the establishment of air lead and blood lead standards, the introduction of legislation to remove lead from petrol, paint and consumer products and tighter restrictions on lead emissions. The outcome of recent major international reviews of research into the effects of low-level lead exposures (e.g. by WHO, USA health and environmental agencies, German and Canadian health bodies) has resulted in recommendations to reduce and eliminate lead exposures. By contrast, Australian policy responses to the incontrovertible evidence that adverse neurocognitive and behavioural effects that occur at levels well below the current national goal of 10 μg/dL have stalled. The delayed response by Australia occurs at a time when blood lead levels in two of Australia's three primary lead mining and smelting cities: Port Pirie, South Australia and Broken Hill, New South Wales, are rising. In the third city, Mount Isa, Queensland, there is still no systematic, annual testing of childhood blood lead values. This is despite the fact that Mount Isa has the highest lead (and other toxic metals such as cadmium and arsenic) emissions to the environment (120 tonnes of lead in 2011/12) from any single point source in Australia. It is clear that both state and national policy approaches to the ongoing risks of lead exposure need to be revised urgently and in line with contemporary international standards. Recommended changes should include a new lower blood lead intervention level of no more than 5 μg/dL, with a national goal for all children under 5 years of age to have a blood lead level of below 1 μg/dL by 2020. In order to achieve any new lower exposure goals other relevant lead standards including air, dust, soil and water must also be revised downwards.

 

Taylor, M.P., Camenzuli, D., Kristensen, L.J., Forbes, M., Zahran, S. 2013. Environmental lead exposure risks associated with children’s outdoor playgrounds. Environmental Pollution, 178, 447-454.  

Abstract: This study examines exposure risks associated with lead smelter emissions at children's public playgrounds in Port Pirie, South Australia. Lead and other metal values were measured in air, soil, surface dust and on pre- and post-play hand wipes. Playgrounds closest to the smelter were significantly more lead contaminated compared to those further away (t(27.545) = 3.76; p = .001). Port Pirie post-play hand wipes contained significantly higher lead loadings (maximum hand lead value of 49,432 μg/m2) than pre-play hand wipes (t(27) = 3.57, p = .001). A 1% increase in air lead (μg/m3) was related to a 0.713% increase in lead dust on play surfaces (95% CI, 0.253–1.174), and a 0.612% increase in post-play wipe lead (95% CI, 0.257–0.970). Contaminated dust from smelter emissions is determined as the source and cause of childhood lead poisoning at a rate of approximately one child every third day.

 

Gore, D.B., Taylor, M.P., Pritchard, R.P., Fryirs, K.A. 2014. On-site teaching with XRF and XRD: training the next generation of industry and research professionals. Powder Diffraction. 

Abstract: There is a growing need for environmental scientists, geoscientists and analysts skilled in the use of X-ray fluorescence spectrometry and X-ray diffractometry in both industry and research. The challenge for educators is how to inspire, teach and make the next generation of professional X-ray users and analysts ready for employment. In this article we present vignettes from teaching applications of X-ray analytical techniques at three scaffolded levels, from senior high school students, undergraduate science students to postgraduate researchers. At each of these levels the pedagogical complexity increases, from simple data use at high school, to observing how data are generated and being able to constrain analytical uncertainty at undergraduate level, to generating high quality data themselves at postgraduate level. In all cases transportable equipment is used in on-site analytical programs, in order to inform the experimental design, level of sampling required and research outcomes.

 

Taylor, M.P., Winder, C., Lanphear, B.P. 2012. Eliminating Childhood Lead Toxicity in Australia: A call to lower the intervention level. Medical Journal of Australia, 197 (9), 493. 

Abstract: Presently, the National Health and Medical Research Council (NHMRC) recommends an increasingly obsolete intervention level that was established in 1993: blood lead levels of below 10 μg/dL. However, new and overwhelming evidence indicates that even levels below 5 μg/dL are associated with a range of adverse health outcomes, including decreased intelligence and academic achievement, sociobehavioural problems such as attention deficit hyperactivity disorder, learning difficulties, oppositional and conduct disorders, and delinquency. Importantly, the greatest relative effects on IQ occur at the lower blood lead levels.

 

Zahran, S., Laidlaw, M.A.S., McElmurry, S.P., Filippelli, G.M., Taylor, M.P. 2013. Linking source and effect: re-suspended soil lead, air lead and children’s blood lead levels in Detroit, Michigan. Environmental Science and Technology, 47(6), 2839–2845. 

Abstract: This study evaluates atmospheric concentrations of soil and Pb aerosols, and blood lead levels (BLLs) in 367 839 children (ages 0–10) in Detroit, Michigan from 2001 to 2009 to test a hypothesized soil → air dust → child pathway of contemporary Pb risk. Atmospheric soil and Pb show near-identical seasonal properties that match seasonal variation in children’s BLLs. Resuspended soil appears to be a significant underlying source of atmospheric Pb. A 1% increase in the amount of resuspended soil results in a 0.39% increase in the concentration of Pb in the atmosphere (95% CI, 0.28 to 0.50%). In turn, atmospheric Pb significantly explains age-dependent variation in child BLLs. Other things held equal, a change of 0.0069 μg/m3 in atmospheric Pb increases BLL of a child 1 year of age by 10%, while approximately 3 times the concentration of Pb in air (0.023 μg/m3) is required to induce the same increase in BLL of a child 7 years of age. Similarly, a 0.0069 μg/m3 change in air Pb increases the odds of a child <1 year of age having a BLL ≥ 5 μg/dL by a multiplicative factor of 1.32 (95% CI, 1.26 to 1.37). Overall, the resuspension of Pb contaminated soil explains observed seasonal variation in child BLLs.

 

Laidlaw, M.A.S., Zahran, S., Mielke, H., Taylor, M.P., Filippelli, G. 2012. Re-suspension of lead contaminated urban soil as a dominant source of atmospheric lead in Birmingham, Chicago, Detroit and Pittsburgh, USA. Atmospheric Environment, 49, 302-310. 

Abstract: Soils in older areas of cities are highly contaminated by lead, due largely to past use of lead additives in gasoline, the use of lead in exterior paints, and industrial lead sources. Soils are not passive repositories and periodic re-suspension of fine lead contaminated soil dust particulates (or aerosols) may create seasonal variations of lead exposure for urban dwellers. Atmospheric soil and lead aerosol data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) database were obtained for Pittsburgh (Pennsylvania), Detroit (Michigan), Chicago (Illinois), and Birmingham (Alabama), USA. In this study the temporal variations of atmospheric soil and lead aerosols in these four US cities were examined to determine whether re-suspended lead contaminated urban soil was the dominant source of atmospheric lead. Soil and lead-in-air concentrations were examined to ascertain whether lead aerosols follow seasonal patterns with highest concentrations during the summer and/or autumn. In addition, atmospheric soil and lead aerosol concentrations on weekends and Federal Government holidays were compared to weekdays to evaluate the possibility that automotive turbulence results in re-suspension of lead contaminated urban soil. The results show that the natural logs of atmospheric soil and lead aerosols were associated in Pittsburgh from April 2004 to July 2005 (R2 = 0.31, p < 0.01), Detroit from November 2003 to July 2005 (R2 = 0.49, p <0.01), Chicago from November 2003 to August 2005 (R2 = 0.32, p < 0.01), and Birmingham from May 2004 to December 2006 (R2 = 0.47, p < 0.01). Atmospheric soil and lead aerosols followed seasonal patterns with highest concentrations during the summer and/or autumn. Atmospheric soil and lead aerosols are 3.15 and 3.12 times higher, respectively, during weekdays than weekends and Federal Government holidays, suggesting that automotive traffic turbulence plays a significant role in re-suspension of contaminated roadside soils and dusts. In order to decrease urban lead aerosol concentrations, lead deposition and subsequent children’s seasonal exposure, lead contaminated urban soils need remediation or isolation because the legacy of lead continues to pose unnecessary and preventable health risks to urban dwellers.

 

Zahran, S., Mielke, H.W., McElmurry, S.P., Filippelli, G.M., Laidlaw, M.A.S., Taylor, M.P. 2013. Determining the relative importance of soil sample locations to predict risk of child lead exposure. Environment International, 60, 7–14. 

Abstract: Soil lead in urban neighborhoods is a known predictor of child blood lead levels. In this paper, we address the question where one ought to concentrate soil sample collection efforts to efficiently predict children at-risk for soil Pb exposure. Two extensive data sets are combined, including 5467 surface soil samples collected from 286 census tracts, and geo-referenced blood Pb data for 55,551 children in metropolitan New Orleans, USA. Random intercept least squares, random intercept logistic, and quantile regression results indicate that soils collected within 1 m adjacent to residential streets most reliably predict child blood Pb outcomes in child blood Pb levels. Regression decomposition results show that residential street soils account for 39.7% of between-neighborhood explained variation, followed by busy street soils (21.97%), open space soils (20.25%), and home foundation soils (18.71%). Just as the age of housing stock is used as a statistical shortcut for child risk of exposure to lead-based paint, our results indicate that one can shortcut the characterization of child risk of exposure to neighborhood soil Pb by concentrating sampling efforts within 1 m and adjacent to residential and busy streets, while significantly reducing the total costs of collection and analysis. This efficiency gain can help advance proactive upstream, preventive methods of environmental Pb discovery.