[1] US EPA, Off Res & Dev, Natl Hlth & Environm Effects Res Lab, Expt Toxicol Div, Res Triangle Pk, NC 27709 USA
[2] US EPA, Off Res & Dev, Natl Hlth & Environm Effects Res Lab, Div Environm Carcinogenesis, Res Triangle Pk, NC 27709 USA
[3] US EPA, Off Res & Dev, Natl Exposure Res Lab, Microbiol & Chem Exposure Assessmetn Res Div, Cincinnati, OH 45268 USA