Sludge Potion Number Nine


On your next trip to Home Depot or Lowes make sure to stop by the garden section and find a bag of Milorganite 5-2-0 Fertilizer. The bag with a picture of  bright green turf, a nice home, a little boy and a fluffy dog playing ball, with the sun shining and the blue sky. Big letters will inform you – “Organic Nitrogen Lawn Fertilizer. For better results. Naturally. Eco Friendly”.

Ahhh, the joy of a natural, wholesome way of living….


I confess – I have a nasty habit of reading the small print, always trying to find some high fructose corn syrup in a can of “homemade” lemonade, or soybean meal in a bag of “all natural” dog food. And so here I am, doing it again. Safety Data Sheet (SDS) of Milorganite provides a wealth of information, if you care to comb through the 8 pages of it. 1

Product description – A fertilizer product manufactured from various microbes used to digest sewage sludge.  SupplierMilwaukee Metropolitan Sewerage District.

Let’s see if I can translate this; this bag is full of microbes that eat sewage. Milwaukee sewage to be precise. Or maybe it’s a bag of Milwaukee sewage sludge with some microbes in it? Either way – that doesn’t sound very organic.

This product is classified and labeled according to the Globally Harmonized System (GHS).2 Below – an exclamation mark inside a red square and a mysterious GHS07 code. According to the GHS means: “substances and mixtures irritating to the skin, eyes and respiratory tract”.

Hmmm. Shouldn’t that little boy on the picture wear protective gloves and eye/face protection?! That’s what the SDS advises on the bottom of the page 1 under Precautionary Statements.

And what about the fluffy dog?

On page 3 under the caption – Handling and Storage, I read with sinking heart:

“Some coprophagic canines may be attracted to the odor of biosolids, transfer their fecal attraction to Milorganite Fertilizer, rip open bags and over eat. A dog may be sick for 24-48 hours”.

“Vomiting that can lead to dehydration, incontinence (stiffness in hind legs), atrophy, depression…”

OK, now they really got my attention! I’m a dog person; I don’t want this sweet canine to suffer from atrophy and depression!

But let’s not stop here, my reading continues.

On page 2; Dangerous components. Activated sewage sludge, microbes. Skin irritant, eye irritant. Aquatic acute – code H401. I make a beeline back to the Globally Harmonized System; H401 stands for – Toxic to Aquatic Life.

Maybe that nice house has a goldfish pond in the back? Will the goldfish die? Somebody should tell the parents of that boy before he finds his goldfish floating belly up!

Special hazards arising from the substance or mixture: At high temperatures, this type of fertilizer can give off undefined fumes.

It is definitely sunny in the picture, so it’s possible that it’s hot.

Maybe I’m overreacting. Page 5 provides a momentary reassurance: Chemical stability: Stable under normal conditions.

On  second thought,  what are “normal conditions”?

Where was this picture taken? Maybe this is a suburb of Houston on an August afternoon? Likely the temperature will be around 100F and humidity at least 80%. Is that “normal”?

But let’s move along, bottom of this same page 5:

Biosolids have the potential to contain various pollutants. (…) The U.S. Environmental Protection Agency has extensively analyzed the risk from these pollutants. These analyses have considered over 400 compounds.


Let’s take a closer look at the EPA evaluation of those 400 compounds. EPA indeed in 2006-2007 conducted the Targeted National Sewage Sludge Survey (TNSSS), collecting 84 samples from 74 publicly owned treatment works (POTW).14 They analyzed collected sewage sludge samples for 145 analytes.  The analysis included anions, metals, polycyclic aromatic hydrocarbons, semi-volatiles, flame retardants, pharmaceuticals, steroids and hormones. The findings were published in 2009; anions, 27 metals, three steroids and flame retardants were found in every sample and semi-volatiles and aromatic hydrocarbons found in at least 72 samples.

What EPA usually does for “extensively assessing the risk” is a method called – Qualitative Risk Assessment (QRA).15 The method employs complex mathematical formulas to measure whether the practice, product or structure is reasonably safe. The QRA approach works fine when designing a bridge; you figure out how many rivets are needed on a particular section of a bridge that experiences heavy traffic during rush hours, using that amount will prevent the bridge from collapsing. When assessing a health risk from the exposure to a toxin, the method is an unfortunate choice.

For example; EPA can live with soil containing 300 ppm of lead.  They only consider a 150 lb male, ignore the unborn, elderly, ill; ignore other sources of lead exposure, and viola, if soil contains 300 ppm of lead–especially when averaged– in playgrounds and farms, it is safe.  In reality, NO amount of lead in soil is safe.11

The TNSSS reports warns – “It is not appropriate to speculate on the significance of the results until proper evaluation has been completed”.

OK, I will not speculate then.  But – wait! The report was issued in 2009, now we have the end of 2016. Seven years later maybe is an appropriate time to not so much speculate but perhaps – reach some conclusions on the significance of those findings?

The 503 rule16 – federal regulatory document remained unchanged since its implementation in 1993.  It calls for testing of nine heavy metals, two indicator bacteria, phosphorus and nitrogen. That’s it. Not “145 analytes” or “400 compounds”. Biosolids Class A, that’s what Milorganite is, if tested at all – is tested only in accordance with the 503 rule – nine heavy metals and two bacterial indicators.

I continue with the Safety Data Sheet, page 5 informs us that:

In biosolids, pathogens may present risk. (…) To destroy pathogens, Milorganite is heated to 176F and dried.



I breathe a sigh of relief, I should be able to reach an educated conclusion on this piece of information. By pure coincident, I recently happened to read a very interesting research article from Canada. 13

Researchers in this study collected several sewage sludge samples from two different biosolids treatment facilities over a period of one year. One plant treats waste activated sludge by anaerobic digestion and dewatering process. A second plant participating in the study treats sludge by a dewatering/pelletization process, combined with thermal drying. Several cutting-edge molecular techniques were used to assess the pathogen content of samples collected. The study concluded that the technology used by the second plant was more effective in killing off the bacterial load in sludge. Two indicator bacterial species that are federally regulated were indeed undetected in the treated sludges. The problem is – other bacteria were detected, species that are not required to be monitored. An opportunistic pathogen, such as Clostridium spp., produces endospores that are heat resistant and survive both modes of treatment. Clostridium is a causative agent for botulism, tetanus and enterocolitis.

If indeed the Milorganite is heated to 176F, what do you think happens to the heat-resistant Clostridium endospores? That’s right – nothing.

Another published study done by the Yale University scientists concludes that all samples of municipal wastewater residuals they collected contained pathogens.3 In this study researchers found DNA fingerprints of opportunistic pathogens in all collected samples, 61% of those pathogens were of the genera Clostridium and Mycobacterium.

It just happens that Mycobacterium tuberculosis, a causative agent of pneumonia is heat resistant.4 If heating those bugs to 176F doesn’t kill experimental colonies on a petri dish, do you think it will kill them at the wastewater treatment plant? Maybe that sheds some light on why so many residents exposed to the dust from biosolids amended soils suffer from respiratory conditions.




It’s impossible to truly assess the pollutant and pathogen content of a bag of Milorganite. Or any other sludge-derived “natural fertilizer”. The methods of monitoring implemented by the EPA are grotesquely inadequate, if anything, they do more harm than good. To a poorly informed public they give an illusion of protection, of an orderly and well-organized practice compliant with the main mission of the EPA – to protect the natural environment.

Treated sewage sludge, be it Class A (Milorganite, etc.) or Class B (agricultural biosolids), is mostly an unknown and unknowable mixture of toxins, pollutants, pathogens and just about any naturally occurring and man-made harmful substance. It’s concentrated million folds during the dewatering process and only partially deactivated. Not only do we have a very poor understanding of what exactly are the harmful components of sludge, but we know even less about all of  the possible interactions that take place when all the components of sludge are treated/heated and then spread on the land. The permutations of possible interactions are practically endless. 8

If you pick up a bag of Cheetos and look at the list of ingredients; you know you will be eating a highly processed corn product with artificial coloring and preservatives. You can make an informed decision to eat it or toss the bag.

Nobody truly knows what toxins and in what quantities hide in a bag of biosolids; what bacterial and viral pathogens mixed with a myriad of other toxins are spread in the parks and gardens across the country. 5,6 Polycyclic aromatic hydrocarbons; semi-volatile organics; inorganic anions; polybrominated diphenyl ethers (PBDEs); antibiotics and their degradation products, disinfectants and other antimicrobials, steroids, hormones, the list goes on and on and on…..7,9,10,12

What is needed to assess risks from the biosolids exposure is exposure studies. Most importantly – we need to stop the practice of spreading pollutants and toxins on the land.


  1. 36lb/16kg bag Milorganite 5-2-0. Safety Data Sheet (SDS) OSHA HazCom Standard 29 CFR 1910.1200(g) and GHS Rev 03.
  2. A Guide to The Globally Harmonized System of Classification and Labeling of Chemicals (GHS).
  3. Bibby K, Viau E, Peccia J. Pyrosequencing of the 16S rRNA gene to reveal bacterial pathogen diversity in biosolids. Water Res. 2010 Jul;44(14):4252-60.
  4. Doig C, Seagar AL, Watt B, Forbes KJ. The efficacy of the heat killing ofMycobacterium tuberculosis. Journal of Clinical Pathology. 2002;55(10):778-779.
  5. Harrison, E.Z., McBride, M.B. and Bouldin, D.R. (1999) ‘Land application of sewage sludges: an appraisal of the US regulations’, Int. J. Environment and Pollution, Vol. 11, No. 1, pp.1–36.
  6. Jones C.C. 2011. Environmental Justice in Rural Context: Land Application of Biosolids in Central Virginia. Environmental Justice, vol 4, no 1, pp 1-15.
  7. Kim, S. et al. 2007. Potential ecological and human health impacts of antibiotics and antibiotic-resistant bacteria from wastewater treatment plants. Journal of Toxicology and Environmental Health Part B–Critical Reviews 10: 559-573.
  8. Lewis, D. L. et al. 2002. Interactions of pathogens and irritant chemicals in land applied sewage sludges (biosolids). BMC 2: 11. 2458/2/11 43.
  9. Lewis D.L. (1998) Microbes in the environment: challenges to exposure assessment. Science and the Unpleasant: Risk Assessment and Urban Sewage Sludge. Panel Presentation at the American Association for the Advancement of Science
  10. Peccia J. 2016. A Guide to Sewage Sludge Exposure during Land Application.
  11. Snyder, C. 2008. Baltimore sludge pilot project puts children at additional risk. Int. J. Occup. Environ. Health14(3): 241
  12. Snyder, C. 2005. The Dirty Work of Promoting the “Recycling” of American Sewage Sludge. Int. J. Occup. Environ. Health 11: 415-427. IJOEH_1104_Snyder.pdf
  13. Yergeau, E. et al. 2016.Comparison of Methods to Identify Pathogens and Associated Virulence Functional Genes in Biosolids from Two Different Wastewater Treatment Facilities in Canada. Plos One 11(4): e0153554.
  14. Targeted National Sewage Sludge Survey. Sampling and Analysis Technical Report. United States Environmental Protection Agency. January 2009.
  15. Sustainable Futures / P2 Framework Manual 2012 EPA-748-B12-001 13. Quantitative Risk Assessment Calculations.
  16. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA/832/R-93/003 September 1994
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