EPA proposed plan is based upon faulty science
It has taken a great many months to review, in its entirety, the Toxicological Review of Libby Amphibole asbestos, but today I feel quite comfortable about speaking on this document.
There is one error, or oversight as the case may be, in the document that has great importance to the residents of Libby and their future decisions. This was brought up by one Libby resident’s commentary, tangential to this document recently.
In section 6.1.5, titled Susceptible Populations, EPA lists who those populations may be. Regrettably they have eliminated the very population the document addresses, the Libby population itself. Of even greater concern is that the Libby population was described previously by EPA as a “susceptible population,” in the documents leading up to the declaration of a public health emergency. The chances of the exclusion of the population of Libby as a susceptible population by oversight in the current document are slim, so the situation leans more towards an error of rather monstrous proportions. Residents were originally described as susceptible due to their large exposure leading up to the EPA cleanup. Naturally, the existing population would be extremely sensitive for cancer and non-cancer risks in the future since they had already been so heavily exposed. One just need read The Western News articles printed since December of 2014 to see how heavily Libby residents were exposed prior to EPA’s arrival.
What this means today is that those of age 16 to 80 or more, still residing in Libby, have had very large to extremely large exposures and every point in between. They become a sensitive population by virtue of the fact that any further exposure, no matter the level, may tip them over the edge. This was EPA’s reasoning in previous years. Today that reasoning has disappeared. However, it is as sound today as it was then. This is even more important today with EPA planning to leave behind potential sources of exposure.
A second issue arose at the time the document was being developed for public consumption and afterward. That was the best fit for the evidence of comparative exposure and the occurrence of disease and death due to mesothelioma.
There has been much discussion regarding this point. The evidence as collected from other fibers type, from LAA in other places such as Marysville, Ohio, Minneapolis, Minn., and other risk analysis, does not fit the Libby fiber and exposure scenario very well.
There have been all kinds of manipulations to attempt to make it fit. However there are two variables that make the model of Libby Amphibole Asbestos fit perfectly. Those two variables are the idea that the active mesotheliomagenic fiber of the mix is tremolite and tremolite alone at a six percent content of the fiber mix. Winchite 84 percent richtorite 10 percent with trace of magnesioriebeckite, edenite, and magnesio-arfvedsonite, are most certainly contributory to fibrous disorders of the lungs, but not mesothelioma. The second variable is the extremely discontinuous nature of amphibole exposures, even in occupational situations. No human has ever been exposed continuously to asbestos exposures, let alone amphibole exposures, anywhere on our planet.
A very similar thing occurs in Thetford Mines, Quebec, where there is a very low level of tremolite present, only less insidious. This explains the low level of mesothelioma observed in Libby in comparison to other much higher levels of mesothelioma incidence from high percentage tremolite exposures alone that exist around the world.
It is likely, and in some cases already known, that this core kernel of higher toxicity, combined with differential settling of fibers based upon density and charge, residing within varying morphological structures and matrices, is masking the true risk presented by any given exposure scenario. This is likely common throughout the world. It appears to be the case for Libby also.
Apparently the current plan, as proposed by EPA, is to allow an increase in fibrous disorders of the lungs and to allow the susceptible population as defined as “already heavily exposed,” to continue future exposures, perhaps allowing for a lower level of future mesothelioma only.
Not a great plan under the circumstances of not being able to control exposure levels.
— Terry Trent is a biologist and asbestos researcher