I’ve just finished some research about the use of biosolids (human sewage sludge) as farm manure. The results will keep me awake at night.
¾ of biosolids in the UK are spread on farmland. The rules about what it can contain are not fit for purpose. Please read and share this 🧵

Biosolids typically contain a wide range of synthetic chemicals, including antibiotics and other pharmaceuticals, personal care products, microplastics and persistant organic pollutants, among them “forever chemicals”. Yet testing is restricted to a small number of contaminants.
Spreading them across the land means spreading them through the foodchain and the ecosystem. There’s plenty of evidence of uptake of many of these chemicals by crops, earthworms and other soil animals, and of large-scale antibiotic resistance developing among soil bacteria.
When soil is blown or washed off the land, these chemicals enter the air and water. Some seep into groundwater. We're likely to eat, drink and breathe them. It’s hard to say what the health thresholds are, or what the combined impact of this cocktail of synthetics might be.
Yet the issue has been wilfully neglected by governments. Regulation is negligible. Farmers in the UK are “responsible for knowing the levels of any potentially toxic elements” before spreading sludge. But how? With an on-farm lab that can test for 80,000 possible contaminants?
There’s no enforcement anyway. Even if there were strong rules, the crippling of the regulatory agencies by government cuts would ensure they remained a dead letter. There are scarcely any inspections or enforcement even of the existing rules.
What is the cumulative impact on human health?
What is the cumulative impact on ecosystems?
We haven’t the faintest idea.
One thing I haven’t discovered is whether biosolids are also being sold as garden fertilisers. I can’t find any garden fertiliser or manure application on sale which states that sewage is the source. Does anyone know?
In theory, we *should* be able to use biosolids to grow food. Closing the nutrient loop is an important aspect of the circular economy. But at the moment, in closing the nutrient loop we are opening the chemicals loop, spreading potentially dangerous toxins far and wide.

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Two things can be true at once:
1. There is an issue with hostility some academics have faced on some issues
2. Another academic who himself uses threats of legal action to bully colleagues into silence is not a good faith champion of the free speech cause


I have kept quiet about Matthew's recent outpourings on here but as my estwhile co-author has now seen fit to portray me as an enabler of oppression I think I have a right to reply. So I will.

I consider Matthew to be a colleague and a friend, and we had a longstanding agreement not to engage in disputes on twitter. I disagree with much in the article @UOzkirimli wrote on his research in @openDemocracy but I strongly support his right to express such critical views

I therefore find it outrageous that Matthew saw fit to bully @openDemocracy with legal threats, seeking it seems to stifle criticism of his own work. Such behaviour is simply wrong, and completely inconsistent with an academic commitment to free speech.

I am not embroiling myself in the various other cases Matt lists because, unlike him, I think attention to the detail matters and I don't have time to research each of these cases in detail.

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