I would like learn about the future perhaps long-term of risk assessment
and modeling. What is on the frontier of this science?
More research is needed. At least that is what I am supposed to say. The notion of long-term is both practical and philosophical. For example, as a practical matter, when we do a risk assessment we model the future exposures of a future population, using the best available information. But the future is always unknown. We may assume that, since there is city water available from a reservoir, residents of a local will not use ground water from wells for drinking. But will that be true in 50 or 100 years? The reservoir might become polluted and people start using their wells again. The dam might break and the utility go out of business. Someone may choose not to connect to city water. Municipalities sometimes go bankrupt.
I have been interested in this phenomenon regarding the Department of Energy's long term stewardship of underground nuclear test sites. Some of these will be highly contaminated for thousands of years. Here's a link to a (good) book on that topic. Long-term Institutional Management of U.S. Department of Energy Legacy Waste Sites .