Probabilistic Models and Statistical Methods for Biomarker Based Exposure Assessment

June 20, 2003 - 12:00pm

Biomarker measurements such as blood lead concentrations and hair mercury concentrations are often used to make inferences about previous rates of toxicant intake. Exposure rates are typically estimated from these measurements using a "steady state" assumption. However, toxicant exposures are typically episodic and vary in magnitude over time, violating the steady state model. Treating each biomarker measurement as linear combination of previous daily exposure magnitudes is a simple but reasonable toxicokinetic model for many situations. When exposure patterns are intermittent each day's exposure magnitude is described by a mixture distribution with a probability mass at zero and some continuous density over a range of positive values, and each biomarker measurement can be represented as a convolution of differentially weighted mixture distributions across the entire exposure history. Likelihood functions are difficult to obtain in this setting, but generalized estimating equations can be applied successfully. Bayesian solutions are also available using Markov Chain Monte Carlo methods. I will present probability models for this setting, describe the frequentist and Bayesian approaches, and demonstrate the methods using blood mercury measurements.

Add event to Google Calendar

Announcement List

To be added to our seminar annoucement list please, email ETA Seminars. Seminars may change without notice, stay informed by joining our seminar email list. 

Site Access

For site access please email your request to ETA Seminars. To arrive at Building 90 via the LBNL shuttle, take "Blue Uphill". Click here for the shuttle schedule. To ensure your site access is set-up send your request 36 hours in advance of the seminar.

Remote Access

Not able to attend in person? Remote participants can use ReadyTalk Audio & Net conference to phone in to listen, while viewing the presentation via the ReadyTalk site.

Web Access Code: 4864835

USA & Canada call-in number:
1 (866) 740-1260
Access Code: 4864835#

International callers:
Please visit this website to see if a toll-free call-in number is available for your international location.

If not, you will need to pay for the call yourself and use this phone number:

(303) 248-0285.