Carcinogenic metal(loid)s in house dust compared to soil: Concentrations and gastric bioaccessibility.

As a sink and a source of chemicals, house dust represents a relevant medium to assess indoor exposure to metal(loid)s via incidental ingestion or inhalation. However, nationally representative indoor data are scarce. Results from the Canadian House Dust Study (CHDS, 2007-2010; n = 1025) provide nationally representative mean, median and 95 percentile concentrations for 38 elements in typical urban house dust, along with their gastric bioaccessibility.

Viable spores not detected in the household dust of major Canadian cities.

causes infant botulism by colonising the intestines and producing botulinum neurotoxin Previous reports have linked infant botulism cases to spores in household dust, yet the baseline incidence of spores in residential households is currently unknown. Vacuum cleaner dust from 963 households in 13 major Canadian cities was tested for using a novel real-time PCR assay directed against all known subtypes of the botulinum neurotoxin gene. None of the samples tested positive for Analysis of a random subset of samples by MALDI Biotyper revealed that the most common anaerobic bacterial isolates were of the genus and the most common species recovered overall was Dust that was spiked with spores of each toxin type successfully produced positive real-time PCR reactions.

Relationships between House Characteristics and Exposures to Metal(loid)s and Synthetic Organic Contaminants Evaluated Using Settled Indoor Dust.

This study investigates associations between house characteristics and chemical contaminants in house dust, collected under the nationally representative Canadian House Dust Study (2007−2010). Vacuum samples (<80 µm fraction) were analysed for over 200 synthetic organic compounds and metal(loid)s. Spearman rank correlations between contaminant concentrations in dust and presence of children and pets, types of flooring, heating styles and other characteristics suggested a number of indoor sources, pointing to future research directions.

Selection of metric for indoor-outdoor source apportionment of metals in PM : mg/kg versus ng/m.

Trends in the elemental composition of fine particulate matter (PM ) collected from indoor, outdoor, and personal microenvironments were investigated using two metrics: ng/m and mg/kg. Pearson correlations that were positive using one metric commonly disappeared or flipped to become negative when the other metric was applied to the same dataset. For example, the correlation between Mo and S in the outdoor microenvironment was positive using ng/m (p < 0.

Characterizing the sources, concentrations and resuspension potential of metals and metalloids in the thoracic fraction of urban road dust.

Road dust is a sink and source of metals and metalloids of human health concern. To date, many studies have examined the composition of road dust but there remain critical knowledge gaps on the chemistry of thoracic fractions (< 10 μm) and their patterns of deposition and resuspension. The goal of this study is to characterize the elemental concentrations and sources of thoracic fractions of road dust and their resuspension potential for Toronto, Ontario, Canada.

Ovulation before or after intrauterine insemination does not affect live birth rates: a retrospective cohort study of 6701 cycles.

Research Question: Should intrauterine insemination be carried out before or after follicle rupture, and is there a difference in sex ratio, according to follicle rupture at the time of insemination?

Design: In this retrospective cohort study conducted at the Fertility Clinic, Odense University Hospital, Denmark, data from 6701 homologous insemination cycles were analysed. Follicle rupture was determined by transvaginal ultrasonography at the time of insemination. The pregnancy rate, clinical pregnancy rate (CPR) and live birth rate (LBR) were recorded.

Toward setting public health guidelines for chemicals in indoor settled dust?

Indoor settled dust may result in substantial human exposure to chemicals, especially by ingestion following hand-to-mouth or hand-to-object-to-mouth contact. As with other environmental media related to exposure, dust may thus be subject to regulation. An international scientific workshop was convened in Paris in September 2019 firstly to assess the relevance for public health of setting guidelines for indoor settled dust, and secondly to discuss scientific and technical challenges related to such guidelines.

Characterization of Commercial Metal Oxide Nanomaterials: Crystalline Phase, Particle Size and Specific Surface Area.

Physical chemical characterization of nanomaterials is critical to assessing quality control during production, evaluating the impact of material properties on human health and the environment, and developing regulatory frameworks for their use. We have investigated a set of 29 nanomaterials from four metal oxide families (aluminum, copper, titanium and zinc) with a focus on the measurands that are important for the basic characterization of dry nanomaterials and the determination of the dose metrics for nanotoxicology. These include crystalline phase and crystallite size, measured by powder X-ray diffraction, particle shape and size distributions from transmission electron microscopy, and specific surface area, measured by gas adsorption.

Influence of household smoking habits on inhalation bioaccessibility of trace elements and light rare earth elements in Canadian house dust.

In this study, total concentration and inhalation bioaccessibility (dissolution in simulated biological solution) of trace elements (TE) and rare earth elements (REE) were assessed in PM from Canadian house dust samples with smoking (n = 25) and non-smoking (n = 25) status. Compared to the natural background concentrations in Canadian soils, median Zn, Pb, Cd and Cu concentrations in PM were 10-23 fold higher, while median La, Ce and Pr concentrations were 1.6-2.

Physical and chemical characterization of McIntyre Powder: An aluminum dust inhaled by miners to combat silicosis.

McIntyre Powder (MP) is a finely ground aluminum powder that was used between 1943 and 1979 as a prophylaxis for silicosis. Silicosis is a chronic lung disease caused by the inhalation of crystalline silica dust and was prevalent in the Canadian mining industry during this time period. The McIntyre Research Foundation developed, patented, and produced the MP and distributed it to licensees in Canada, the United States, Mexico, Chile, Belgian Congo, and Western Australia.

Short-chain and medium-chain chlorinated paraffins in Canadian house dust and NIST SRM 2585.

A method for the analysis of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) in house dust was developed. The method is based on sonication extraction, sample cleanup by solid phase extraction (SPE), and separation and detection by gas chromatography coupled with mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode. The method is sensitive, with method detection limits (MDLs) down to 0.

An assessment of the inhalation bioaccessibility of platinum group elements in road dust using a simulated lung fluid.

Metal enrichment of road dust is well characterized but available data on the bioaccessibility of metals in particle size fractions relevant to human respiratory health remain limited. The study goal was to investigate the bioaccessibility of platinum group elements (PGE), which are used as catalysts in automotive exhaust converters, in the inhalable fraction of road dust. Street sweepings were provided by the City of Toronto, Canada, collected as part of its Clean Roads to Clean Air program.

Rare earth elements and select actinoids in the Canadian House Dust Study.

Nationally representative baseline data are presented for rare earth elements (REE), thorium (Th) and uranium (U) in house dust sampled from 1025 urban homes, in units of concentrations (μg g ), loadings (μg m ), and loading rates (ng m  d ). Spearman rank correlations indicate that, in addition to outdoor sources, consumer products and building materials can influence indoor dust concentrations of REE, Th, and U. Correlations (P<.

Comparison of Gastric versus Gastrointestinal PBET Extractions for Estimating Oral Bioaccessibility of Metals in House Dust.

Oral bioaccessibility estimates for six metals which are prevalent as contaminants in Canada (zinc, lead, cadmium, copper, nickel, and chromium) are investigated for house dust using the simple gastric phase versus the two-phase physiologically-based extraction technique (PBET). The purpose is to determine whether a complete gastrointestinal (GI) assay yields a more conservative (i.e.

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.

Influence of pH, particle size and crystal form on dissolution behaviour of engineered nanomaterials.

Solubility is a critical component of physicochemical characterisation of engineered nanomaterials (ENMs) and an important parameter in their risk assessments. Standard testing methodologies are needed to estimate the dissolution behaviour and biodurability (half-life) of ENMs in biological fluids. The effect of pH, particle size and crystal form on dissolution behaviour of zinc metal, ZnO and TiO was investigated using a simple 2 h solubility assay at body temperature (37 °C) and two pH conditions (1.

Non-PBDE halogenated flame retardants in Canadian indoor house dust: sampling, analysis, and occurrence.

An analytical method was developed for the measurement of 18 novel halogenated flame retardants in house dust. Sample preparation was based on ultrasound-assisted solvent extraction and clean up with solid phase extraction (SPE). Sample extracts were analyzed by gas chromatography-mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode.

Detection of Carbon Nanotubes in Indoor Workplaces Using Elemental Impurities.

This study investigated three area sampling approaches for using metal impurities in carbon nanotubes (CNTs) to identify CNT releases in workplace environments: air concentrations (μg/m3), surface loadings (μg/cm2), and passive deposition rates (μg/m2/h). Correlations between metal impurities and CNTs were evaluated by collecting simultaneous colocated area samples for thermal-optical analysis (for CNTs) and ICP-MS analysis (for metals) in a CNT manufacturing facility. CNTs correlated strongly with Co (residual catalyst) and Ni (impurity) in floor surface loadings, and with Co in passive deposition samples.

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.

Evaluating the capabilities of aerosol-to-liquid particle extraction system (ALPXS)/ICP-MS for monitoring trace metals in indoor air.

This study investigates the application of the Aerosol-to-Liquid Particle Extraction System (ALPXS), which uses wet electrostatic precipitation to collect airborne particles, for multi-element indoor stationary monitoring. Optimum conditions are determined for capturing airborne particles for metal determination by inductively coupled plasma-mass spectrometry (ICP-MS), for measuring field blanks, and for calculating limits of detection (LOD) and quantification (LOQ). Due to the relatively high flow rate (300 L min(-1)), a sampling duration of 1 hr to 2 hr was adequate to capture airborne particle-bound metals under the investigated experimental conditions.

Zinc in house dust: speciation, bioaccessibility, and impact of humidity.

Indoor exposures to metals arise from a wide variety of indoor and outdoor sources. This study investigates the impact of humid indoor conditions on the bioaccessibility of Zn in dust, and the transformation of Zn species during weathering. House dust samples were subjected to an oxygenated, highly humid atmosphere in a closed chamber for 4 to 5 months.

Simultaneous determination of thirteen organophosphate esters in settled indoor house dust and a comparison between two sampling techniques.

An analytical method for the simultaneous determination of 13 organophosphate esters (OPEs) in house dust was developed. The method is based on solvent extraction by sonication, sample cleanup by solid phase extraction (SPE), and analysis by gas chromatography-positive chemical ionization-tandem mass spectrometry (GC/PCI-MS/MS). Method detection limits (MDLs) ranged from 0.