Bradley Johnston, Dalhousie University (IMAGE) McMaster University Caption This is Bradley Johnston, PhD, corresponding author on the reviews and guideline and an associate professor of community health and epidemiology at Dalhousie University. Credit Dalhousie University Usage Restrictions To be used with stories about this research License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.