Sewer Sludge / Biosolids and the small matter of Determining Safety ...
Sewer sludge aka biosolids is NOT just human excrement - it is a concentration of all domestic and industrial pollutants that go down drains and sewers. It has some good stuff in it, which plants can use, but a huge load of thousands of other contaminants. "Land-applied municipal sewage sludge (biosolids) is a highly complex and unpredictable mixture of biological and chemical pollutants. Biosolids generated in our large industrialized urban centers is very likely the most pollutant- rich waste mixture of the 21st century." (Dr. Caroline Snyder)
The very limited testing done on contaminants in our sewage residuals relies on the old-fashioned single toxicity methodology. A recent article by Peter Montague, who has co-authored two books on toxic heavy metals, has outlined the many problems with this approach.
Firstly, he notes that,
"Risk assessment is easily manipulated. Two groups of fully qualified risk assessors, given identical data, can reach wildly different estimates of risk. Therefore, numerical risk assessment fails the acid test of science -- reproducible results -- and does not qualify as "science" or "scientific." Risk assessment is a political art that uses some scientific data. As EPA administrator William Ruckelshaus wrote in 1984, "We should remember that risk assessment can be like the captured spy: If you torture it long enough, it will tell you anything you want to know." "
Secondly, he notes that,
" Risk assessments have no reliable way to evaluate simultaneous exposures to multiple chemicals. Therefore, they create an imaginary world with a single-chemical exposure. In this imaginary world, a chemical exposure can be declared "safe" even though it actually may be quite harmful when combined with other exposures."
This is exactly what sludge defenders like Sally Brown and Lynda McCarthy do when they trot out their single toxin extrapolations around exposure and safety. Neither make any mention of the issues around combined exposures - this is simply poor science, and blinkered, biased support for the continuance of toxic sludge disposal on soils meant to sustain us.
This is the method used to support the assurances of safety by both the EPA and the OMRR regulations. It is faulty, simplistic and naïve.
Remember too that in order to qualify as Class A or Class B or Class A "EQ" ... they ONLY TEST for about a dozen metals and pathogens. This is absurd given the thousands of toxins known to be in these residuals. Not only do they not take into account the synergies between these contaminants, but they don't even test separately for things like solvents, PCBs, dioxins, microplastics, pharmaceuticals, fluoride, flame retardants, radioactive materials, nano-particles, superbugs and prions!!
Please read the article in full - http://www.truth-out.org/news/item/43517-the-precautionary-principle-asks-how-much-harm-is-avoidable-rather-than-how-much-harm-is-acceptable
For more on why the "risk assessments" made by both OMRR and EPA are faulty please see -
For more on the toxins found in our Sewer Sludges / "Biosolids" please see -
Household Chemicals and Drugs Found in Biosolids from Wastewater Treatment Plants https://toxics.usgs.gov/highlights/biosolids.html
Chemicals from Land-Applied Biosolids Persist in Soil https://toxics.usgs.gov/highlights/2014-06-10-biosolids_leach.html
Safety testing, by biosolids scientists, looks merely at single chemical toxicity amounts. This is faulty, simplistic, and outdated. As the scientists taking part in the Halifax Project have shown, it is the exposure to a variety of toxins in low-dose that can cause cancer. (The Halifax Project took place between 2012 and 2015 and it involved more than 350 cancer researchers and physicians from 31 countries … focused on the carcinogenic potential of low dose exposures to mixtures of chemicals in the environment - see http://www.gettingtoknowcancer.org/taskforce_environment.php) The absurd situation is that we have soil specialists, agronomists etc. determining the safety of something they are utterly unqualified to make such pronouncements about - this is the purview of chemists, doctors/oncologists.