it is well known that there is a range of human susceptibility to effects of given environmental exposures. This range is due in part to endogenous factors such as genetics and epigenetics, physiology,
lifestage, and other biological differences.
Variability in individual exposures also contributes significantly to variability in human susceptibility, but this workshop
focuses on the endogenous/biological factors.

The 2010 National Research Council report Science and Decisions: Advancing Risk Assessment notes that it is difficult to estimate an average population risk without understanding how the risk varies among individuals in the population. However, the default approach in risk
assessment to account for individual variability is to assume that a ten-fold decrease in allowable exposure will protect the most sensitive subpopulations, even though seldom it is known whether such approach may be overprotective or insufficient.

Emerging Molecular Techniques, such as next generation sequencing, are advancing scientists' ability to characterize how individuals differ inherently (genetically and otherwise). Such information can also be used to predict how such individual differences may affect
one's susceptibility to a given exposure. While it may not be feasible to determine susceptibility of each individual to each potential exposure, clearly we can characterize the range and a distribution of biological variability in humans at a more granular level than assuming a ten-fold uncertainty factor.

This workshop will explore new and innovative approaches to characterizing individual variability arising from endogenous/biological factors and its impact on susceptibility to risks from environmental exposures. Discussions will also delve into how to bring new data
collection and analytic approaches to bear and layer them with conventional data on variability. Topics will span a range of approaches, from molecular analyses to
the use of human cells and animal models as experimental systems, and how these approaches can be used to better characterize individual variability linked to
endogenous factors in toxicity, epidemiology, and genome-wide-association studies.

The workshop will also consider the implications of emerging approaches to policies designed to address susceptibility in public health and risk assessment. Workshop participants will address
approaches for and challenges to describing the relationships among individual variability, disease susceptibility,
and public health.

Some questions that will be used to guide the workshop discussions include the following:

• What are the current and emerging technologies that can better inform us about the distribution of
  individual variability within a population that are due to endogenous/biological factors?
• How does such individual variability help us understand general population variability, sensitive
  subpopulations and related risks?
• What does the public need to understand about the implications of such individual variability, and how could/should the public health and risk assessment community start addressing this need?