Tom Harner is a Senior Research Scientist at Environment and Climate Change Canada. He studies the sources, atmospheric transport and fate of pollutants in support of domestic and international chemicals management.
A passive air sampling network has been established to investigate polychlorinated dibenzo-p-diox... more A passive air sampling network has been established to investigate polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) at Global Atmospheric Passive Sampling (GAPS) sites and six additional sites in the Group of Latin American and Caribbean Countries (GRULAC) region. The air sampling network covers background, agricultural, rural and urban sites. Samples have been collected over four consecutive periods of 6 months, which started in January 2011 (period 1 (January 2011 - June 2011), period 2 (July 2011 - December 2011), period 3 (January 2012 - June 2012) and period 4 (July 2012 - January 2013)). Results show that: i) the GAPS passive samplers (PUF disk type) and analytical methodology are adequate for measuring PCDD/F burdens in air, and ii) PCDD/F concentrations in air across the GRULAC region are widely variable by almost two orders of magnitude. The highest concentrations in air of Σ4-8PCDD/Fs was found at the urban site São Luis (Brazil, UR) (i.e. 2560 fg/m3) followed by the sites in São Paulo (Brazil, UR), Mendoza (Argentina, RU) and Sonora (Mexico, AG) with 1690 fg/m3, 1660 fg/m3 and 1610 fg/m3, respectively. Very low concentrations of PCDD/Fs in air were observed at the background site Tapanti (Costa Rica, BA) with 10.8 fg/m3. This variability is attributed to differences in site characteristics and potential local/regional sources as well as meteorological influences. The measurements of PCDD/Fs in air agree well with model predicted concentrations performed using the Global EMEP Multi-media Modeling System (GLEMOS) and emission scenario constructed on the basis of the UNEP Stockholm Convention inventory of dioxins and furans emissions.
Background: Perfluorochemicals (PFCs) are detectable in the general population and in the human e... more Background: Perfluorochemicals (PFCs) are detectable in the general population and in the human environment, including house dust. Sources are not well characterized, but isomer patterns should enable differentiation of historical and contemporary manufacturing sources. Isomer-specific maternal-fetal transfer of PFCs has not been examined despite known developmental toxicity of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in rodents. Objectives: We elucidated relative
Thesis University of Toronto Source Dai B 60 01 P 276 Jul 1999 175 Pages, 1998
This thesis considers the measurement and partitioning of several classes of persistent organic p... more This thesis considers the measurement and partitioning of several classes of persistent organic pollutants (POPs-namely, polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), and polycyclic aromatic hydrocarbons (PAHs). Octanol-air partition coeffcients (KoA) were measured for 18 PCBs, 24 PCNs, and 4 PAHs over a range of environmentally relevant temperatures. The results show that in all cases the value of KoA varied log-linearly with the inverse absolute temperature and that in general, the enthalpy associated with the transition from octanol to air, ΔHOA, was similar to the enthalpy of vaporization, ΔHvap. Greater partitioning was observed for coplanar and mono-ortho PCBs. The utility of KOA as a particle-gas partitioning descriptor was tested using results from Chicago air samples. The particle-gas partition coefficient, Kp, was calculated and plotted against KOA and against the subcooled liquid vapor pressure, p°L. Log-log plots of Kp versus P°L showed enrichment for the coplana PCBs and PAHs. This enrichment was resolved by KOA for the coplanar PCBs but only partially resolved for the PAHs. A KoA-based absorption model of particle-gas partitioning was compared with the Junge- Pankow adsorption model. The KOA model provided a better fit for PCBs but not PAHs, which were underestimated. An advantage of the KOA model is that it only requires knowledge KOA and the fraction of organic matter on the particle which are both easily measured. The Chicago field study led to the investigation of a new compound class, PCNs. A method was developed for quantifying PCNs based on the FID response of individual congeners in Halowax 1014, a technical mixture of 2 to 8- Cl congeners. PCNs were quantified in air samples from Chicago and three Arctic locations-a cruise track of the Eastern Arctic Ocean, Alert (Canada), and Dunai Island (Russia). The results show that PCNs contribute significantly to dioxin-type toxicity in air and merit further study. A review is made of the transport processes, concentrations, and implications of organochlorine contamination of the Canadian Arctic. Speculations are made regarding the relationships of global warming, physical chemistry of the compounds, and future trends of contaminants.
An interlaboratory study was initiated to investigate consistency in reported concentrations of p... more An interlaboratory study was initiated to investigate consistency in reported concentrations of polychlorinated naphthalenes (PCNs). Results are reported from the first phase of a study that examined the variability associated with different quantification methodologies, instrumentation and standards. Nine participating labs from seven countries quantified individual homolog groups, summation operator PCN (the sum of 2-8 chlorinated homologs), and selected congeners in two test solutions derived from Halowax 1014. The means of the reported summation operator PCN values were within less than 15% of the known concentrations of the two test solutions and the relative standard deviation among laboratories was 11%. However, the among laboratory variability was in the range 20-40% for individual PCN homologs and individual PCN congeners. These results suggest the need for additional interlaboratory studies and for the development of reference materials for PCN analysis. Future PCN interlaboratory comparison exercises are discussed that will utilize control materials and unknowns consisting of suitable environmental matrices.
Potentially-harmful chemicals could be released from many indoor materials, including consumer pr... more Potentially-harmful chemicals could be released from many indoor materials, including consumer products and building materials, into indoor environments. Semi-volatile chemicals (SVOCs) due to their lower vapor pressure, are often present, either primarily in indoor dust or in both indoor air and indoor dust. Several types of SVOCs have been ,measured ,in indoor ,air and indoor dust of Ottawa residential
PFASs concentrations in dust samples collected from three microenvironments in Cairo ranged from ... more PFASs concentrations in dust samples collected from three microenvironments in Cairo ranged from 1.3 to 69 ng g(-1) with FTOHs being dominant. The 8:2 FTOH was detected in all samples. Among the FOSAs and FOSEs the MeFOSE was dominant while among ionic PFASs, PFOS and PFOA were most prominent. The concentrations of PFASs were among the lowest worldwide. Correlations between worldwide concentrations of PFOS + PFOA and country development indexes highlight higher usage and human exposure in more developed countries. Food packaging was analyzed for PFSAs, PFCAs and PAPs. The 6:2 and 8:2 monoPAPs were found to be above the MDL in 18% of the samples. PFOA was detected in 79% of the samples with median concentration of 2.40 ng g(-1). PFOS was detected in 58% of the samples with median concentration of 0.29 ng g(-1) while PFHxS and PFDS were below detection limit. Different human exposure scenarios were estimated.
A passive air sampling network has been established to investigate polychlorinated dibenzo-p-diox... more A passive air sampling network has been established to investigate polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) at Global Atmospheric Passive Sampling (GAPS) sites and six additional sites in the Group of Latin American and Caribbean Countries (GRULAC) region. The air sampling network covers background, agricultural, rural and urban sites. Samples have been collected over four consecutive periods of 6 months, which started in January 2011 (period 1 (January 2011 - June 2011), period 2 (July 2011 - December 2011), period 3 (January 2012 - June 2012) and period 4 (July 2012 - January 2013)). Results show that: i) the GAPS passive samplers (PUF disk type) and analytical methodology are adequate for measuring PCDD/F burdens in air, and ii) PCDD/F concentrations in air across the GRULAC region are widely variable by almost two orders of magnitude. The highest concentrations in air of Σ4-8PCDD/Fs was found at the urban site São Luis (Brazil, UR) (i.e. 2560 fg/m3) followed by the sites in São Paulo (Brazil, UR), Mendoza (Argentina, RU) and Sonora (Mexico, AG) with 1690 fg/m3, 1660 fg/m3 and 1610 fg/m3, respectively. Very low concentrations of PCDD/Fs in air were observed at the background site Tapanti (Costa Rica, BA) with 10.8 fg/m3. This variability is attributed to differences in site characteristics and potential local/regional sources as well as meteorological influences. The measurements of PCDD/Fs in air agree well with model predicted concentrations performed using the Global EMEP Multi-media Modeling System (GLEMOS) and emission scenario constructed on the basis of the UNEP Stockholm Convention inventory of dioxins and furans emissions.
Background: Perfluorochemicals (PFCs) are detectable in the general population and in the human e... more Background: Perfluorochemicals (PFCs) are detectable in the general population and in the human environment, including house dust. Sources are not well characterized, but isomer patterns should enable differentiation of historical and contemporary manufacturing sources. Isomer-specific maternal-fetal transfer of PFCs has not been examined despite known developmental toxicity of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in rodents. Objectives: We elucidated relative
Thesis University of Toronto Source Dai B 60 01 P 276 Jul 1999 175 Pages, 1998
This thesis considers the measurement and partitioning of several classes of persistent organic p... more This thesis considers the measurement and partitioning of several classes of persistent organic pollutants (POPs-namely, polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), and polycyclic aromatic hydrocarbons (PAHs). Octanol-air partition coeffcients (KoA) were measured for 18 PCBs, 24 PCNs, and 4 PAHs over a range of environmentally relevant temperatures. The results show that in all cases the value of KoA varied log-linearly with the inverse absolute temperature and that in general, the enthalpy associated with the transition from octanol to air, ΔHOA, was similar to the enthalpy of vaporization, ΔHvap. Greater partitioning was observed for coplanar and mono-ortho PCBs. The utility of KOA as a particle-gas partitioning descriptor was tested using results from Chicago air samples. The particle-gas partition coefficient, Kp, was calculated and plotted against KOA and against the subcooled liquid vapor pressure, p°L. Log-log plots of Kp versus P°L showed enrichment for the coplana PCBs and PAHs. This enrichment was resolved by KOA for the coplanar PCBs but only partially resolved for the PAHs. A KoA-based absorption model of particle-gas partitioning was compared with the Junge- Pankow adsorption model. The KOA model provided a better fit for PCBs but not PAHs, which were underestimated. An advantage of the KOA model is that it only requires knowledge KOA and the fraction of organic matter on the particle which are both easily measured. The Chicago field study led to the investigation of a new compound class, PCNs. A method was developed for quantifying PCNs based on the FID response of individual congeners in Halowax 1014, a technical mixture of 2 to 8- Cl congeners. PCNs were quantified in air samples from Chicago and three Arctic locations-a cruise track of the Eastern Arctic Ocean, Alert (Canada), and Dunai Island (Russia). The results show that PCNs contribute significantly to dioxin-type toxicity in air and merit further study. A review is made of the transport processes, concentrations, and implications of organochlorine contamination of the Canadian Arctic. Speculations are made regarding the relationships of global warming, physical chemistry of the compounds, and future trends of contaminants.
An interlaboratory study was initiated to investigate consistency in reported concentrations of p... more An interlaboratory study was initiated to investigate consistency in reported concentrations of polychlorinated naphthalenes (PCNs). Results are reported from the first phase of a study that examined the variability associated with different quantification methodologies, instrumentation and standards. Nine participating labs from seven countries quantified individual homolog groups, summation operator PCN (the sum of 2-8 chlorinated homologs), and selected congeners in two test solutions derived from Halowax 1014. The means of the reported summation operator PCN values were within less than 15% of the known concentrations of the two test solutions and the relative standard deviation among laboratories was 11%. However, the among laboratory variability was in the range 20-40% for individual PCN homologs and individual PCN congeners. These results suggest the need for additional interlaboratory studies and for the development of reference materials for PCN analysis. Future PCN interlaboratory comparison exercises are discussed that will utilize control materials and unknowns consisting of suitable environmental matrices.
Potentially-harmful chemicals could be released from many indoor materials, including consumer pr... more Potentially-harmful chemicals could be released from many indoor materials, including consumer products and building materials, into indoor environments. Semi-volatile chemicals (SVOCs) due to their lower vapor pressure, are often present, either primarily in indoor dust or in both indoor air and indoor dust. Several types of SVOCs have been ,measured ,in indoor ,air and indoor dust of Ottawa residential
PFASs concentrations in dust samples collected from three microenvironments in Cairo ranged from ... more PFASs concentrations in dust samples collected from three microenvironments in Cairo ranged from 1.3 to 69 ng g(-1) with FTOHs being dominant. The 8:2 FTOH was detected in all samples. Among the FOSAs and FOSEs the MeFOSE was dominant while among ionic PFASs, PFOS and PFOA were most prominent. The concentrations of PFASs were among the lowest worldwide. Correlations between worldwide concentrations of PFOS + PFOA and country development indexes highlight higher usage and human exposure in more developed countries. Food packaging was analyzed for PFSAs, PFCAs and PAPs. The 6:2 and 8:2 monoPAPs were found to be above the MDL in 18% of the samples. PFOA was detected in 79% of the samples with median concentration of 2.40 ng g(-1). PFOS was detected in 58% of the samples with median concentration of 0.29 ng g(-1) while PFHxS and PFDS were below detection limit. Different human exposure scenarios were estimated.
Uploads