Metals and other heavier elements have many roles in biology. Some, like copper and iron, are needed at trace levels for health. Others, such as mercury and lead, have no known positive role but instead can behave as poisons. Many metals have dual roles. The metal’s chemical form or speciation is key to its role, whether toxic or beneficial, but is challenging to determine in biological tissues. Our research uses and develops synchrotron light techniques, such as are available at the Canadian Light Source, located at the University of Saskatchewan, to investigate the speciation and microscopic distribution of metals in biological materials, with impacts in the environment and human health.
An essential in trace amounts in the diet to maintain the health of humans and other animals. Required for many essential enzymes, it has been shown to provide protection against cancer. Selenium also interacts with several elements of concern including arsenic, mercury and cadmium, in many cases reducing their toxicity. However, there is only a small difference between "sufficient" and "excess" dietary selenium; relatively low selenium levels in surface water can bioaccumulate through a food web, causing defects in birds and fish. Many regions of Canada are rich in selenium and this is both an asset and a liability. When high soil selenium leads to crops rich in selenium, this may increase their nutritional benefit and hence their value for export to regions with low selenium status. However, elevated selenium in mining impacted areas may threaten our pristine northern environments. Our research uses and develops synchrotron tools to understand selenium's positive and negative roles both in the environment and as they impact human health.
An element for which there is no known positive biological role; indeed, it is the most toxic of the common elements. Humans are exposed to mercury in a variety of ways. Mercury has long been used in dental amalgams. Seafood contains organic mercury at trace levels, in most cases from natural background levels present in the ocean. These forms have vastly different toxic properties. Our group has developed the zebrafish model as a method to evaluate the toxicology of mercury, by exposing larvae to mercury species then investigating them using X-ray fluorescence imaging.