Responding to my response to his earlier response to Lindsay Brown’s letter to HRM Councilor Jerry Blumenthal decrying council’s decision to spend $50,000 repeating decades of studies that have confirmed the safety of biosolid use in agriculture, Cliff White writes:
Halifax Harbour is certainly cleaner then it was. Well, as long as it hasn’t rained in three days, and thank god we get so little precipitation here abouts. And it would be churlish of me to mention that the sewage plants don’t meet the new federal regulations for what can be released into the ocean, so I won’t.
Let me just point out that I originally sent the list from USEPA because you had suggested there was no scientific basis for the concern people were expressing about exposure to sewage sludge. My point was, and is, that there is valid scientific concern, or governments and other institutions, across the developed world at least, wouldn’t be testing the damn stuff.
Since 1999 Centre for Disease Control in the US has been measuring 219 chemicals found in people’s blood and urine. These of account for only a small number of the many tens of thousands of chemicals in use today, many more of which likely end up in our bodies. Besides the chemicals in the sludge, of course, there are also pathogens and there are many peer-reviewed papers looking at how sludge containing these products effects the environment, people, and other animals who live in it. The reality is the debate goes on, and it’s a valid one. It isn’t just the individual products in our bodies, the chemicals, heavy metals and bacteria, but how interact with one another.
If people are happy adding a few more dozen chemicals to their internal environment, that’s fine with me. But those who prefer to limit their intake should have an equal right to do so. If farmers want to use sewage sludge on their land, then the resulting products should be labelled to indicate they were produced in this way. Those who wish to add a few more of the above mentioned chemicals and such to their internal environment can do so freely, and everybody else can continue to try and avoid them.
Now there’s a thought. Does this mean the thousands of Nova Scotians who pay extra for local, organic food grown in untreated farm manure should have the benefit of warning labels to alert them to the pathogens and heavy metals that time-honored organic fertilizer contains? Here’s a slide Andrew Carpenter of Northern Tilth presented to the 2006 New England Residuals and Biosolids Conference:
So, poultry manure spread on fields has 48 times as much fecal coliform bacteria as uncomposted municipal biosolids; and 65,000 times as much as composted biosolids like those produced at HRM’s new plant. Cow manure has 125 times as much fecal coliform as untreated biosolids, and 171,000 times as much as composted biosolids.
For trace amounts of heavy metals, the picture is more mixed:
The values shown are in parts per million. NT means not tested. Biosolids and poultry manure were about on a par for most metals; cow manure slightly lower. All three were well below the levels contained in phosphate fertilizer. Remember, we are talking about metals that can be harmful in high concentrations, but which are essential to life in very small quantities. That’s why they are found in vitamin supplements:
The level of heavy metals in Rite Aid Central-Vite Multivitamin-Mineral tablets dwarfs that in biosolids and untreated manure. Of course, Rite Aid is a US brand, but Canadians can get multivitamin mineral tablets at — what do you call those places? Oh yeah, health food stores.
- FERTILIZERS, MANURE, OR BIOSOLIDS? – Researchers compare the benefits and risks of fertilizers and soil amendments by Steve Spicer in Water Environment & Technology Publication, Vol. 14, No. 7, July 2002, p. 32
- Biosolids verses other Plant Nutrient Sources: A Cursory Comparison of Benefits and Risks, presented by Andrew Carpenter of Northern Tilth at the New Engliand Residuals and Biosolids Conference, 2002.
- Biosolids: Targeted National Sewage Sludge Survey Report – Overview, US Environmental Protection Agency, 2009.