USEPA Dioxin Workshop November,1996 - Summary
Every presentation of hard combustion emissions data demonstrated that there is no direct correlation between chlorine feed rate (input) and dioxin emissions.
There was general agreement that commercial incineration is very complex and that bench scale models need to be designed to reflect that complexity. In short, lab results do not always reflect reality.
EPA openly requested data of combustion units that had been tested more than once. Some participants pointed out that some units (e.g. cement kilns) had all been tested more than once and that EPA was in possession of that data. A list of that data was requested by EPA.
One presenter from academia stated that dioxin emissions have very little to do with combustion conditions.
A study in Sweden was cited where the area around a very bad acting incinerator had been sampled and there were no dioxins found in workers blood or cows milk.
Although an EPA representative raised the issue of a dioxin surrogate, for monitoring purposes, a number of panelists debunked that fantasy.
EPA openly debated the accurateness of their various databases during a discussion about medical waste incinerators.
Numerous European panelists and a number of US presenters either talked about data or presented data that indicated that there is no difference in dioxin emissions from combustors that burn hazardous waste fuels vs conventional fuels.
Despite all the overwhelming evidence to the contrary, one USEPA panelist was quite secretive about data he reportedly possessed that demonstrated that non-hazardous waste burning cement kilns emitted significantly lower dioxin. He did not (or could not) answer when queried as to the types of kilns to which he referred or raw material composition, both of which have a major impact on dioxin emissions.
Dr. Barry Commoner presented his "emissions from Texas are going into the Great Lakes" (based upon the NOAH air model) paper that has recently garnered media attention but admitted that he did not do any confirmation sampling. He did point out that a paper was due out in the next few months that will detail sample results from in and around an East Coast dairy farm.
A number of European researchers implicated wood burning, which would include forest fires, as major sources of dioxins. EPA didn't seem to take the hint.
One academia panelist presented data that showed how dioxin concentrations in lake sediments had gradually increased to a point, greatly increased until it topped out, then greatly decreased to present day, with at least an indication that there might be a leveling off (it was deemed the "camel's hump" graph). The graph generated much controversy as to what might have caused this, if a source or sources could even be pinned down and whether or not something that appeared to correlate with the graph was actually causative. [I defer to the much quoted Dr. Bruce Ames who has pointed out that the decline in birth rates in England can be directly correlated to the decline in the stork population, however, this does not mean that storks bring babies!] When queried by the EPA as to why the graph was presented if correlated items were not really causative, the presenter simply answered that it raises interesting questions.
One researcher pointed out that PCDD emissions may simply be a factor of not having destroyed the PCDD input into the combustor.
A Hazardous Waste Incinerator representative referenced data that demonstrated that dioxin emissions actually increased when activated carbon was used. A USEPA representative confirmed that activated carbon can in fact be a catalyst for dioxin formation.
One researcher presented data that indicated rapid dioxin formation under some conditions. Another panelist later raised the rapid dioxin formation again and then asked how quick does a quench have to be to be effective against dioxin formation? An EPA representative commented that an effective quench had to be rapid as well.
One cement kiln industry representative and a USEPA contractor both presented data acquired independent of each other that very strongly demonstrated that spiking copper, increasing chlorine input and various other parameters did not correlate with dioxin formation in the tested cement kiln(s). The only thing that did matter, in an overwhelmingly strong correlation, was APCD inlet temperature.
In many cases, EPA found out that their database was every bit as lacking as they already suspected that it was. At one point EPA asked the question as to whether the US should rely on European data. One German presenter told the EPA that they had to get their own data. A Canadian panelist commented that you can't invent data and at some point if you don't have the data then you simply have to admit that you don't know. A West Coast EPA representative pointed out numerous times throughout the three day workshop that European conditions are often quite different from US conditions, particularly in the area of emission from diesel engines.
Towards the end of the Workshop, the USEPA representative who appeared to be impervious to overwhelming data contrary to several of his positions, raised the "camels' hump" graph issue again. Apparently a number of lakes across the contiguous United States have yielded sediment samples that fit the "camel's hump" graph remarkably well. The concentrations were different from lake to lake but the graph was quite similar. [A related paper is reportedly to be published in the coming months in Environmental Science & Technology] Unfortunately, his presentation tried to equate the causative agent as the advent of USEPA and various environmental regulations. Most panelists jumped on this pretty hard but again the presenter was impervious to the resounding criticism of such a contention. [You might be able to justify your existence in front of a Congressional Committee with such a contention but the technical panelists were having none of it.]
All in all, it was a high powered technical panel that discussed dioxin formation in the three day USEPA dioxin workshop, interspersed with "environmentalist" illuminaries such as Pat Costner of Greenpeace and Barry Commoner.
Questions about the workshop can be sent to firstname.lastname@example.org.