Michael Kwan

Makivik Corporation · Nunavik Research Centre

Mercury is found in Arctic marine mammals that are important in the diet of northern Indigenous peoples. The objectives of the present long-term study, spanning a 45-yr period, were to 1) investigate the temporal trends of total mercury (THg; muscle and liver) and selenium (Se; liver) in ringed seals (Pusa hispida) from different regions of the Can...

“Migratory birds hunting in Nunavik is significantly far less important a source of dietary lead in comparison with ptarmigan hunting.”

Lead concentration in ptarmigans is extremely low. However, lead fragments from lead projectiles used in small caliber rifles for harvesting ptarmigans in Nunavik can significantly increase the lead concentration in the edible parts of the bird. The geometric mean lead concentration in 180 samples of edible parts from 36 ptarmigans is 1.90 μg /g w....

Concentrations of polybrominated diphenyl ethers (PBDEs) and alternative flame retardants were analyzed in ringed seal blubber (Phoca hispida) collected during aboriginal hunts between 1998 and 2012. Results indicated that the highest ΣPBDE concentrations (sum of 13 congeners) were found in seals in Nain (Labrador) as well as Inukjuaq and Arviat (H...

Mercury (Hg) has been detected in polar bear brain tissue, but its biological effects are not well known. Relationships between Hg concentrations and neurochemical enzyme activities and receptor binding were assessed in the cerebellum, frontal lobes, and occipital lobes of 24 polar bears collected from Nunavik (Northern Quebec), Canada. The concent...

Country foods are central to Inuit culture and replete in selenium (Se) and long-chain omega-3 polyunsaturated fatty acids (n-3 PUFA). However, some marine country foods bioaccumulate high concentrations of methylmercury (MeHg). Se and n-3 are associated with several health benefits in Nunavik, Northern Quebec, but, recent studies show that prenata...

The present study examined spatial trends of perfluoroalkyl compounds (PFCs) in liver samples from 11 populations of ringed seals (Phoca hispida) in the Canadian Arctic from 2002 to 2005. Trophic position and relative carbon sources were compared by analyzing stable nitrogen and carbon isotopes in muscle samples. Geometric mean concentrations of to...

Temporal trends in perfluoroalkyl compounds (PFCs) were investigated in liver samples from two ringed seal (Phoca hispida) populations in the Canadian Arctic, Arviat (Western Hudson Bay) (1992, 1998, 2004, 2005) and Resolute Bay (Lancaster Sound) (1972, 1993, 2000, 2004, 2005). PFCs analyzed included C7-C15 perfluorinated carboxylates (PFCAs) and t...

Elevated concentrations of organochlorines and mercury (Hg) have been reported in marine mammals on a global scale. While risk assessments are generally based on quantifying body burdens of toxicants, much less is known about associated adverse health effects and their underlying mechanisms. The purpose of this study was to characterize the inhibit...

summaryA study of influx and accumulation of Tl and Cd by Lemna minor has revealed a number of contrasting features which arise from the basic physicochemical properties of the two elements. Short-term influx of Cd over a range of concentration (0·1–10 üM) followed a linear trend while that of Tl over the same range produced a profile with a platea...

This review summarizes and synthesizes the significant amount of data which was generated on mercury (Hg) and persistent organic pollutants (POPs) in Canadian Arctic marine biota since the first Canadian Arctic Contaminants Assessment Report (CACAR) was published in 1997. This recent body of work has led to a better understanding of the current lev...

Mercury (Hg) and cadmium (Cd) concentrations in ringed seal liver and kidney were compared from 11 locations across the Arctic, from Alaska, Canada, Greenland, Svalbard to the White Sea. Adult and sub adult seals were evaluated separately to account for age accumulations of Hg and Cd. Only recently (1995-2001) collected samples were included to min...

Organochlorine contaminants (OCs) and stable isotopes of carbon (delta(13)C) and nitrogen (delta(15)N) were determined in 7 benthic and 7 pelagic marine invertebrate species from the North American Arctic to identify factors influencing OC concentrations. Values of VC separated benthic (enriched in C-13) from pelagic species and delta(15)N values g...

In order to evaluate the use of zebra mussels as biomonitors for metal bioavailability in the St. Lawrence River, we tested the hypothesis that the concentrations of 11 metals in zebra mussels vary significantly between sites along the river and that the season of collection and body size affect metal bioaccumulation. Mussels were collected at 14 s...

Gel filtration chromatography (with Sephadex G25, G50 and G100) was used to separate the different forms of thallium (Tl) and cadmium (Cd) in the cytosol fraction of Lemna minor and to examine the influence of the duration of metal exposure on the speciation of the two elements. A major proportion of Cd in the soluble phase was found to be bound to...

The distribution and chemical forms of thallium (Tl) and cadmium (Cd) in Lemna minor have been investigated using extractants of different polarity, enzyme digestion and ultrafiltration and chromatographic methods. Over 80% of Tl and 60% of Cd taken up by the plant was found in aqueous soluble forms. Water was more efficient than ethanol in extract...

Floating aquatic macrophytes such as the Lemnaceae have many attributes which commend their use in laboratory and field investigations to assess both the toxicity of substances and the quality of freshwater systems. As well as their more well known advantages of small size, relative structural simplicity, rapid growth and vegetative reproduction an...

The predominant pathway for human exposure to chromium in non‐occupationally exposed individuals is via food with a daily intake of around 30–100 μgd, with vegetables providing a major contribution. Unlike reports of chromium essentiality to man and animals, plants appear not to require chromium in spite of some early reports of a stimulatory growt...

The effect of thallium on frond production and the rates of increase in surface area and fresh weight in Lemna minor were examined in terms of concentrations of the element in the growth medium and in the plant. The toxicity indices, EC(50) and threshold concentration, indicate that curtailment of frond expansion occurs at a lower thallium exposure...

Theories in which leptons are composite lead to additional contributions (beyond those from the standard model) to the amplitudes for e-e+→e-e+ and e-e+→μ-μ+. Detailed models, constructed by analogy between QCD and compositeness/precolor interactions lead to specific forms for these extra terms. We demonstrate that compositeness scales M as high as...

Theories in which leptons are composite lead to additional contributions (beyond those from the standard model) to the amplitudes for e-italic/sup -/e/sup +/..-->..e/sup -/e/sup +/ and e-italic/sup -/e/sup +/..--> mu../sup -/..mu../sup +/. Detailed models, constructed by analogy between QCD and compositeness/precolor interactions lead to specific f...

We consider composite models in which quarks and leptons have constituents in common. Detailed amplitudes for subprocesses of the type quark+antiquark → lepton+antilepton are constructed sing the presumed similarity between QCD and compositeness/pre-color interactions. We demonstrate that sensitivity to compositeness scales, Λ, as high as 100 TeV t...

Theories in which leptons are composite lead to additional contributions (beyond those from the standard model) to the amplitudes for e-italic⁻e/sup +/..-->..e⁻e/sup +/ and e-italic⁻e/sup +/..--> mu..⁻..mu../sup +/. Detailed models, constructed by analogy between QCD and compositeness/precolor interactions lead to specific forms for these e...