Document pmnaRvvgv1LZaoB5wrL0bwJNw

Monsanto Monsanto Company 800 N Lindbergh Boulevard St, Louis, Missouri 63167 Phone: (314)694-1000 November 3, 1993 David Bayliss, Ph.D. Office of Research and Development Environmental Protection Agency 401 M Street S.W. Washington, D.C., 20460 Dear Dr. Bayliss: Enclosed you will find our comments on the review draft Chapter 7, Epidemiology/Human Data for the EPA reassessment of dioxin. We disagree with your conclusions and find that the studies when taken together and critically reviewed are not supportive of an association between TCDD exposure and soft tissue sarcoma or lung cancer. We would also like to take this opportunity to respond to comments submitted by Richard Klapp at Dioxin Peer Review Workshop on September 8, 1993 concerning the Collins et al. study. Dr. Klapp refers to the editorial written by Thomas Sinks which was critical of the Collins et al. study. We have pointed out in a subsequent letter to the editor which we have enclosed that Sinks characterized our paper incorrectly. Sinks suggests that our use of chloracne as an indicator of dioxin exposure has lead to misclassification which may obscure an association. He correctly points out, as we did in our article, that not everyone exposed to dioxin develops chloracne. However, everyone with chloracne was almost certainly exposed to relatively high levels of dioxin. Comparing our chloracne subcohort with the external reference group used in our study minimizes the possibility of exposure misclassification. Our findings cannot be attributed to the misclassification of unexposed workers as exposed. Sinks also mistakenly characterizes our study as not including all workers who were potentially exposed to dioxin. Contrary to Sinks' assertion, we did consider all the workers with potential dioxin exposure in addition to the workers who developed chloracne. In another unrelated issue, we were also a little confused on the content of the correspondence you had with C. Rappe which you mention on page 51 relating to tissue levels of TCDD and STSs in the Hardell et al. studies. Could you provide us with a copy of these correspondences? Please let us know if you would like any clarification of our comments or more information on our study.