Katherine D Walker, ScD,
Senior Scientist,
Health Effects Institute,
Boston, USA

Dr. Katherine D. Walker is an environmental health scientist with 20 years of experience in 
public health risk assessment and its application to the regulatory process. Dr. Walker has 
been responsible for numerous risk analyses spanning a wide range of topics including cancer 
risks of volatile organic chemicals in drinking water, public health and environmental risks
 of hazardous (chemical and nuclear) waste sites, the cost effectiveness of risk management 
decisions at hazardous waste sites, and implications of pesticide exposure profiles for 
regulatory decisions, among others.

Dr. Walker specializes in the analysis of uncertainty in human exposures and health risks. 
In her most recent work in this area, Dr. Walker has served as the senior scientific consultant
on EPA’s pilot and expanded studies on the use expert judgment elicitation to characterize 
uncertainty in the concentration response relationship between PM2.5 and mortality.   
Her doctoral research at Harvard School of Public Health involved the elicitation of 
probabilistic expert judgments from benzene exposure assessment experts about both the 
variability and uncertainty in ambient, indoor, and personal exposures to benzene.  
Her study was one of the first studies of subjective expert judgment to assess quantitatively
the quality, or calibration, of the experts’ judgments about uncertainty using monitoring 
data collected as part of the USEPA National Human Exposure Survey (NHEXAS) on the same
benzene distributions the experts were asked to predict.

She holds a D.Sc in Environmental Health Sciences from the Harvard School of Public Health.  
She has served as the chair of the exposure assessment specialty group for the Society for 
Risk Analysis (SRA) (2004-5) and as a member of SRA’s Conference and Workshops Committee 
(2005 to present).

Walker reviewed and evaluated the project through several meetings with the PI, the 
project team and managers of industrial factories. She spent one week in Alexandria
and gave highly appreciated suggestions and ideas. The project was then reviewed by the 
Regional Advisory Panel for the African and Eastern Mediterranean regions (RAP) of the
Department of Reproductive Health and Research in its 8th meeting, that took place, in 
the period 27-30 November in Alexandria, Egypt and was approved for funding 
(RAP Approval letter).