1. Division of Epidemiology Biostatistics, and Environmental Health School of Public Health University of Memphis Memphis Tennessee USA
2. Human Development and Health Faculty of Medicine University of Southampton Southampton UK
3. College of Veterinary Medicine Michigan State University East Lansing Michigan USA
4. Clinical and Experimental Sciences Faculty of Medicine University of Southampton Southampton UK
5. The David Hide Asthma and Allergy Research Centre St Mary's, Hospital Newport UK
6. MRC Integrative Epidemiology Unit University of Bristol Bristol UK