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1 including 2,4-D and Dicamba. On page 3 of this report, Dost states that 2,4-D breaks down at 300 degrees F into para-monochlorophenoxyacetic acid, indicating that one chlorine was lost from the original molecule. Page 4 states that no carbon -chlorine bonds were formed, which are needed for formation of toxic dioxins. The gravel in the kiln at Montgomery Pit reaches 280 degrees F but the _ heated air around the gravel is much hotter, to the order of 800-900 degrees F. At this temperature, 1 no carbon-chlorine bonds are formed. The paper also discusses the possibility of forming toxic substances by spraying fields with herbicides such as 2,4-D and allowing them to bum. Dr. Dost concludes that the potential is minimal. It is stated on page 17 that 2,4-D could possibly have very slight conversion to 2,7 dichloro-p-dibenzo dioxin, but its toxicity is so low that it is an issue of no consequence. It is not a member of the dirty seventeen dioxins. A phone conversation with Dr. Dost confirmed that it was highly unlikely that any toxic dioxins formed (in any important quantities) as a result of the burning of the material in the kiln at the Montgomery Pit. Larry Hammond, Chief Chemist with Dow AgroSciences, provided us with information on 2,7 dichloro-p-dibenzo dioxin, ~ showing its low toxicity. This information is enclosed in Appendix C. Les Lampazski, a chief chemist for Dow Chemical Company with experience on all types of dioxins and 2,4-D, discussed by phone the chemistry of 2,4-D in heating and combustion. He stated that the term dioxin is used loosely in that only certain types of dioxins are toxic. Those types of dioxin molecules that have 4 to 8 chlorine atoms attached are considered toxic. Any molecule that has less than 4 chlorine atoms of more than 8 atoms are considered harmless. The ambient temperature 2,4-D molecule has 2 chlorine atoms on each side. During heating, the 2,4-D condenses and ]chlorine is I lost from each side, which can form small quantities ofdichloro-dioxins, which are non-toxic. He stated that the chemistry of 2,4-D simply does not allow toxic forrns of dioxin to form upon heating and combustion. In summary, the following points aze made: 1) Very small quantities of chlorinated dioxins are formed in burning any type of organic material, including wood, paper ,grass and petroleum hydrocarbons. It is demonstrated that these products have minor amounts of chlorine (See Table 1 of Paper 3). 2) Furthermore, research shows that there is no correlation between chlorine content in the feed and dioxins produced. Therefore, it should not matter that there was a small amount of 2,4-D in the feed to the asphalt kiln. 3) Lastly, the research chemistry of 2,4-D indicates that the only potential form of dioxin that could be produced from burning 2,4-D is 2,7 dichloro-p-dibenzo dioxin, which is non-toxic. In view of this data, we feel that it is not necessary to test the bag house dust for PCDD/F. 13