It was while serving my time on the governments’ Advisory Committee on Pesticides (ACP), we were asked whether we could learn anything from the Approval process for GM crops - and whether we could offer them some advice.
It was our responsibility to risk assess every possible impact for using the particular pesticide, in order for that pesticide to gain 'approval'. 'Approval' is a legal term enabling a particular chemical to be spraying in ways, that the Committee determined. This was a legal entity, and funded under law by the manufacturers who may wish to take their chemicals to the market. Years before this I made the case that the use of pesticides should be a legal matter, not voluntary. So I took up the post.
We looked at impacts, or direct effects, on land, air , water, but especially people. We were asked whether it would be appropriate for GM crops to go through a process similar to the risk assessment we carried out for pesticides. There would be just one difference. Pesticides considered direct effects, while GM would also consider indirect impacts (ie the whole nature of farming may alter to fit the GM requirements). GM approval would need to look at all the changes. Interesting, I thought, I am glad I am not on that Committee; this one is difficult enough.
Then it hit me. Why didn’t I look at both direct and indirect impacts of herbicides together all those years ago? It doesn’t matter (to a soil animal when it is dead) whether the effect is direct or indirect, the animals have gone. No wonder I couldn’t find any real differences of direct effects all those years ago. The main effects are likely to be indirect – as that is the whole purpose of herbicides – to kill plants. So the soil animals have less to feed on. But the mesofauna are lost whether it is by direct toxic effects or loss of biomass to feed on. They don’t bother whether which effects, direct or indirect' they are dead. That’s what is important.
Why didn’t I look at the total number of dead and what that said about the state of the soil? Why don't I look back at the thesis and see how I can re-interpret it?
I would like to have had glyphosate (Roundup) to look at. If the toxicity is not relevant and it is the overall effects which are, then another herbicide having similar overall effects as glyphosate will do (eg Dalapon). But unfortunately I had only looked at the loss from grassland soils, not ploughed fields – where Glyphosate is often used. Glyphosate is in the news at the present, after the WHO IARC decided it was a 'probable' carcinogen. Since then all sorts of arguments have been flying round - see my 'Roundup Ready to go'? Some say this is to toxic 'ban it', others saying 'not enough evidence'. However, the point I am making here is that it is not the toxicity which is of concern. It is the proper function of weedkillers which is of concern. It is what it says on the tin 'Weedkiller'. It kills weeds. They may be 'weeds' to us, but they are life and death to some soil animals.
If Kenneth Mellanby were alive today to ask me the same question, I would now answer it completely differently. Obviously I would include glyphosate in my trials, as this is the herbicide used most widely worldwide. While almost benign in toxicity terms, it has a massive effect on the soils where it is applied.
I would look at what the loss of decaying plant material is to the overall soil environment, and whether anything moves in to fill the space, or whether it just degrades to look like sand or clay. Clearly there would be widely different results depending on the crops and soils involved.
Plough or Spray?
This needs working on..
In the past few years, as people became concerned about ploughing relaesing carbon from the soil, there has been an increas in 'No-Till' ie 'Don't Till/plough the earth.' Instead weedkillers are often used to keep the crops clean.
I had used grass as the starting point and a total herbicide like Dalapon and Glyphosate should get rid of most of the grass. This would be akin to ploughing up in terms of Soil Organic Matter (SOM) loss. It is the lack of grass herbage going back into the soil that is the problem.
Glyphosate is also used on ploughed fields to keep weeds - plants, other than the desired crop from growing. So the issue is the lack of weed herbage going back into the soil, so the saving on carbon released by ploughing, isnt as great as many may think. It is still lost with weedkillers. I would have set up the trial differently and compared ploughed land growing various crops, with different total herbicide treatments to see what the effects were. This would have indicated the damage to soil animals caused by lack of herbage going back to the ground.
This loss in arable land is often put down to ploughing. But it is unlikely that ploughing alone could explain SOM loss, and even if it did, whether it would explain such a loss when there is no sign of an increase in ploughing during that time. What is more likely is that there has been an increase in total herbicide usage that time. If so this could account for a large increase in CO2 left in the air instead of being utilised by the weeds and their herbage returned to the earth – as Soil carbon. Perhaps in future we will look to our weeds being climate friendly. See 'Save our Arable' Soils for more.
The overall trend seems ominous: the loss of carbon from arable land in England & Wales Soil has been significant. In 15 years, soils with the highest concentrations of carbon - greater than 7%, dropped from 22% of soil to 10% of the total. Source:
These are the questions raised by this revisiting of the earlier work:
Has anybody asked this question recently - how much loss due to weedkilers?
Role of weedkillers / herbicides very widespread, esp with the “Herbicide Resistant” GM strains coming in across the world.. What is the loss of carbon in the soil and all its related biodiversity aspect lost with continual total herbicide (eg Dalapon, Glyphosate) use v traditional ploughed land?
There weren’t many soil zoologists in my day – perhaps a handful in the country. Now I bet there are even fewer. A few months ago, RASE raised concerns about the Dwindling Science base, as it poses a threat to soil health (See my 'Decline in Land based Science). And even they didn’t mention soil zoologists. It is quite an indictment on how we value our soils that there are so few.
Instead of loosing carbon from the soil, we should be considering soil sequestration, and rewarding landowners who an demonstarte improvement, If Agriculture were included in the Cap & Trade Emissions Scheme, we may be able to make some money to pay for more research. But farming is barely included in any 'Climate Change' initiatives, and virtaully forgotten by the government (See Government Policy) . It is far safer to consider ways to increase the amount of carbon in the soil, than pipe vast amounts of pressurised carbon dioxide all the way across the country into the North Sea from Carbon Capture and Storage Units' There are dangers in transportaion of carbon dioxide (more)
Why not have billions and billions of tiny Carbon Capture and Storage units. They are called plants. In this case they are dismissed as 'weeds'. Imagine Growing Weeds to save the World..
This change in the way I look at the issue represent part of a much wider change in our thinking about health and environmental concerns over th last 30 years. It is called a paradigm shift, and changes the way we approach issues, deciding the main problems, and what tests we carry out in order to develop that area of science.
30 years ago we were preoccupied with poisons killing us and the environment off - from DDT to PCB and dioxins. I was involved with exposing the hazards of dioxins when a chemical plant in Seveso Italy contaminated the community with dioxins. I also helped produce a couple of TV programmes om the newly found hazards of vinyl chloride while making PVC. As as result I set up a magazine called Hazards Bulletin (still going as 'Hazards' 40 years later). Now we are more worried about the naturally occurring materials - often in overdrive. 25 years ago all we bothered about was carbon monoxide. Now, although that is still as toxic as ever, we are more concerned about carbon dioxide because of its impact on global warming.
Similarly 25 years ago we were concerned about synthetic chemicals added to our food accidentally. There were the additives, made famous in the book 'A for additives'. I was concerned about pesticides residues in our food and co-authored 'P is Pesticides'. However now, out greatest concern regarding food is obesity, killing ten of times more people than additives. Yet obesity is about the presence of fat - a completely naturally occurring substance. Both the fat and carbon are naturally occurring substances, in excess.
This change in emphasis among ecologists and environmentalist from toxic concerns (eg DDT, Dieldrin, Dioxins & PCBs casing ozone depletion) to problems over the very natural chemical – carbon. match the a similar paradigm shift in nutrition. Concerns over food were often about safety (eg Salmonella) whereas it is the health effects of consuming too many calories causing obesity and diabetes, killing a lot more people. If I were to do a risk assessment on the main risks from food, deaths and illnesses from safety faults would be around the 1,000 per year mark, whereas early death from obesity and diabetes is estimated around the 80,000 mark. Yet again it is the naturally occurring carbon/carbohydrate related. Carbon and carbohydrate counting has risen up the environmental, nutritional and political agenda.
Similalry we may have been concerned about pesticide levels in soil. We are still concerned about fertiliser levels, witnessed by the Nitrogen Vulnerable Zones (NVZs - an EU idea). However an even bigger concern is this amount of carbon being lost from the soils. Again this is not the toxic aspects so much as natural substances in overdrive.
I would like do a similar risk assessment comparing the GHG emissions for all the airplanes in the country, and the loss of carbon from our arable soils in last 25 years. We may then see protesters in the middle of fields complaining about the loss of carbon from our arable soils plus the added GHG burden played by nitrogen fertilisers..it all ads up
The issue of how health aspects and environmental aspects of food production and consumption is called 'Sustainable Diets'