Barry has over 20 years of experience in applied epidemiology and environmental and occupational health. In this time, he has had over 80 nationally and internationally focused papers published in peer reviewed journals. He has also been directly responsible for or involved in the development, operation and evaluation of numerous health surveillance systems. From 2000 to 2008 he managed Public Health Intelligence (PHI), the epidemiology group of the Ministry of Health, New Zealand, which was disestablished in 2008. He had previously worked as a senior epidemiologist for a number of health authorities, as well as the Public Health Commission of New Zealand. Since 1987, he has been the director of the New Zealand Birth Defects Monitoring Programme (NZBDMP). For the past 20 years, he has been on the committee of the international clearinghouse for Birth Defects Surveillance and Research (ICBDSR) serving as secretary, vice chair and Chair for 2 years.