1 Environmental Health Science and Research Bureau, Health Canada, 420-757 West Hastings St., Federal Tower, Vancouver, BC, V6C 1A1, Canada; School of Epidemiology and Public Health, University of Ottawa, Room 101, 600 Peter Morand Crescent, Ottawa, Ontario, K1G 5Z3, Canada. Electronic address: dave.stieb@canada.ca.
2 Department of Chemical Engineering, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada. Electronic address: greg.evans@utoronto.ca.
3 Dalla Lana School of Public Health, University of Toronto, Health Sciences Building, 155 College Street, 6th Floor, Toronto, Ontario, M5T 3M7, Canada; Child Health Evaluative Sciences, Research Institute, The Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada. Electronic address: teresa.to@sickkids.ca.
4 Department of Chemical Engineering, University of Toronto, 200 College Street, Toronto, Ontario, M5S 3E5, Canada; Dalla Lana School of Public Health, University of Toronto, Health Sciences Building, 155 College Street, 6th Floor, Toronto, Ontario, M5T 3M7, Canada. Electronic address: jeff.brook@utoronto.ca.
5 School of Epidemiology and Public Health, University of Ottawa, Room 101, 600 Peter Morand Crescent, Ottawa, Ontario, K1G 5Z3, Canada. Electronic address: rtburnett1@gmail.com.