Science for the Public 7/23/13. Marc Weisskopf, PhD, ScD, Associate Professor of Environmental and Occupational Epidemiology, Harvard School of Public Health. Autism rates seems to be increasing globally, and there are many conflicting hypotheses about the cause. Professor Weisskopf discusses the suspected environmental triggers of autism. He also discusses how epidemiologists investigate conditions of this sort, where genetic and external factors appear to combine in complex ways.