International Year of Planet Earth 2. Earth and Health — Building a Safer Canadian Environment

This article reviews the current state of Earth and Health research in Canada, in commemoration of International Year of Planet Earth. Canadian geoscientists play a pivotal role in identifying sources and pathways of exposure to geochemical substances that may be beneficial or detrimental to human health. Application of geoscience techniques and expertise contributes to understanding the sources and pathways of natural versus anthropogenic contaminants; bioaccumulation and biomagnification of contaminants in remote settings; and regional variability in background levels of elements and their compounds in the environment. Internationally, the relationship of earth sciences to human health has become so important that it has given rise to a new field of study termed ‘Medical Geology’. Within Canada, there are vivid examples of the impact of geological materials and processes on human health. Mineralogists, geochemists and toxicologists have started collaborating to quantify proportions of metals in soil and dirt, household dust, and playground substrates that are soluble and potentially available for absorption in the body. Other current issues include the new radon guidelines; distribution patterns of mercury in Canadian Shield lakes and reservoirs; geological sources of arsenic and fluoride in groundwater; selenium in Cretaceous sediments; exposures to airborne particles, some of which have natural sources such as windblown dust, forest-fire debris, and volcanic ash; and urban geochemistry with focus on childhood exposures to lead. Geoscience research into sources and pathways of metals and other geochemical hazards improves the accuracy and reliability of human health risk assessments that underlie risk management policies and decision-making. SOMMAIRE À l'occasion de l'Année internationale de la planète Terre, le présent article passe en revue l'état de la recherche en sciences de la Terre et en sciences de la santé au Canada. Les géoscientifiques canadiens ont un rôle charnière dans la détermination des sources et des voies d'exposition aux substances géochimiques pouvant être bénéfiques ou nocives pour la santé. L'application des techniques et des connaissances géoscientifiques aident à déterminer les sources et les voies d'exposition naturelles et anthropogéniques, les mécanismes de bioaccumulation et de bioamplification sur des sites éloignés ainsi que la variabilité régionale des concentrations de fond des éléments et de leurs composés dans l'environnement. Sur le plan international, la relation entre les sciences de la Terre et les sciences de la santé est d'une importance telle qu'un nouveau champ de recherche est né, la "géologie médicale". Au Canada, on peut voir des exemples frappants de l'impact qu'ont des matériaux et des mécanismes géologiques sur la santé humaine. Les minéralogistes, les géochimistes et les toxicologistes ont commencé à mettre en commun leurs efforts dans le but de quantifier les proportions de métaux solubles présents dans le sol et la saleté, les poussières domestiques et les sols de terrains de jeux, pouvant être absorbés à travers l'épiderme. Parmi d'autres questions d'importance, il y a les nouvelles lignes directrices sur le radon; les profils de distribution du mercure dans les lacs et les réservoirs du Bouclier canadien; les sources d'arsenic et de fluorure dans les eaux souterraines; le sélénium dans les sédiments crétacés; les types d'exposition aux particules en suspension dans l'air, dont certaines sont d'origine naturelle comme les poussières éoliennes, les cendres de feux de forêt ou des éruptions volcaniques, et; la géochimie urbaine, avec un accent sur l'exposition au plomb des enfants. La recherche géoscientifique sur les sources les voies d'exposition des métaux et autres risques géochimiques permet d'améliorer la précision et la fiabilité des évaluations du risque pour la santé humaine qui sous-tendent les politiques et la prise de décision en matière de gestion de risque

The impact of drinking water, indoor dust and paint on blood lead levels of children aged 1-5 years in Montreal (Quebec, Canada)

Lead is neurotoxic at very low dose and there is a need to better characterize the impact of domestic sources of lead on the biological exposure of young children. A cross-sectional survey evaluated the contribution of drinking water, house dust and paint to blood lead levels (BLLs) of young children living in old boroughs of Montreal (Canada). Three hundred and six children aged 1 to 5 years and currently drinking tap water participated in the study. For each participant, residential lead was measured in kitchen tap water, floor dust, windowsill dust and house paint and a venous blood sample was analyzed. Multivariate logistic regression was used to evaluate the association between elevated BLL in the children (>/= 75th percentile) and indoor lead contamination by means of odds ratios (OR) using 95% confidence intervals (CI). There was an association between BLL >/=75th percentile (1.78 mug/dL) and water lead when the mean water concentration was >3.3 mug/L: adjusted OR=4.7 (95% CI: 2.1-10.2). Windowsill dust loading >14.1 mug/ft(2) was also associated with BLL >/=1.78 mug/dL: adjusted OR=3.2 (95% CI: 1.3-7.8). Despite relatively low BLLs, tap water and house dust lead contribute to an increase of BLLs in exposed young children

NF97-343 Returning CRP Land to Crops: Warm-Season Grass Management/Cropping Suggestions

This NebFact has information on returning CRP land to crop production including tillage and no-till recommendations

NF97-343 Returning CRP Land to Crops: Warm-Season Grass Management/Cropping Suggestions

This NebFact has information on returning CRP land to crop production including tillage and no-till recommendations

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

Determination of Total Mercury and Carbon in a National Baseline Study of Urban House Dust

Mercury (Hg) is one of the top ten chemicals of concern for public health, according to the World Health Organization. This study investigates Hg concentrations in house dust collected from urban single family homes, to better understand typical indoor residential exposures. Using direct solid sample analysis, total Hg and carbon (TC) were determined in the n = 995). A small subset (9.0 mg/kg). A comparison of Hg concentrations in fresh dust and household vacuum dust collected from the same homes indicated no significant difference in the two sampling methods. Total carbon concentrations displayed a median/geomean of 29.3/28.5% (n = 1011). A significant correlation between total Hg and TC in house dust (p < 0.00001) reflects the association between Hg and organic carbon previously observed in soil and sediments. The results of this study indicate a 10-fold enrichment in house dust compared with the average background concentrations reported for soil and sediments (0.07 mg/kg). The observed enrichment is attributable to Hg emissions from indoor sources and/or Hg carried home from occupational sources

Wipe Sampling Methodologies to Assess Exposures to Lead and Cadmium in Urban Canadian Homes

Wipe sampling methods are widely used to quantify lead (Pb) loadings inside homes. In the present study we expand the wipe sampling method to investigate other elements in addition to Pb, namely cadmium (Cd) and the soil tracer yttrium (Y). Following the ASTM 1728 sampling protocol, 1372 wipe samples (including field blanks and duplicates) were collected from 222 homes using Ghost Wipes™. All wipe samples were digested according to a modified version of the ASTM 1644 digestion protocol in which hydrofluoric acid was added to enhance extraction efficiency, and analyzed using ICP-MS. Recoveries assessed using NIST certified reference materials were 93±6% for Pb and 88±14% for Cd (n=66). Results indicated that 43% of Pb and 23% of Cd samples were below LOD (932 ng m-2 and 125 ng m-2 respectively). Threshold values of 125 µg m-2 for Pb and 4.4 µg m-2 for Cd, identified using Q-Q plots, were used to distinguish “elevated” loading values from background loading values. Indoor sources and tracked-in soil were identified as potential contributors to elevated loading values. Spearman ranking indicated strong spatial associations amongst the metals. The study shows that wipe sampling provides useful information on room-to-room variability of metals, shedding light on possible sources of metals in residential environments

Determination of Metal Impurities in Carbon Nanotubes Sampled Using Surface Wipes

Residual metal impurities in carbon nanotubes (CNTs) provide a means to distinguish CNT from non-CNT sources of elemental carbon in environmental samples. A practical and cost-effective analytical approach is needed to support routine surface monitoring of CNT metal tracers using wipe sampling. Wipe sampling for CNT metal tracers is considered a qualitative indicator of the presence of CNTs, not a quantitative exposure metric. In this study, two digestion approaches (microwave-assisted nitric acid/H 2 O 2 digestion and ultrasonic nitric/HF acid digestion) in conjunction with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) determination were evaluated for their ability to extract metal impurities from CNT particles captured on wipe substrates. Aliquots of different carbon nanotubes (including NIST 2483 single-wall CNT) with and without GhostWipes6 (ASTM E-1792 compliant) were used to compare the performance of the digestion methods. The microwave digestion method accommodated the bulky wipe sample and also eliminated potential ICP-MS signal interferences related to incomplete digestion. Although quantitative recoveries requiring lengthy multistep digestion protocols may be necessary in other applications, the near-total recoveries achieved in the present study for CNT catalyst elements were adequate for identifying surface contamination of CNTs in the workplace using wipe sampling

Spatial and temporal variability of incidental nanoparticles in indoor workplaces: Impact on the characterization of point source exposures

This study deployed a suite of direct-reading instruments in six locations inside one building to characterize variability of the background aerosol, including incidental nanoparticles (NP), over a six month period. The instrument suite consisted of a portable Condensation Particle Counter (CPC) and a Scanning Mobility Particle Sizer (SMPS) for assessing particle number concentrations and size distributions in the nano-scale range; an Aerodynamic Particle Sizer (APS) for assessing micron-scale particle number concentrations and size distributions; plus a desktop Aerosol Monitor (DustTrak DRX) and a Diffusion Charger (DC2000CE) for assessing total particle mass and surface area concentrations respectively. In terms of number concentration, NPs (<100 nm) were the dominant particles observed in the background aerosol, contributing up to 53-93% of the total particle number concentrations. The particle size distributions were bimodal with maxima around 19-79 nm and 50-136 nm, respectively, depending on workplace locations. The average detected background particle number, surface area and total mass concentrations were below 7.1 7 103 # cm-3, 22.9 \u3bcm2 cm-3 and 33.5 \u3bcg m-3, respectively in spring samples and below 1.8 7 103 # cm-3, 10.1 \u3bcm2 cm-3 and 12.0 \u3bcg m-3, respectively in winter samples. A point source study using an older model laser printer as the emission source indicated that NPs emitted from the investigated printer were distinguishable from background. However, more recent low emitting printers are likely to be indistinguishable from background, and chemical characterization (e.g. VOCs, metals) would be required to help identify emission sources.Peer reviewed: YesNRC publication: Ye