Roundup impairs soil fungi

December 2017

Modern farmers are proud to grow crop plants in isolated splendour; they make sure nothing much ever gets a chance to live alongside them in the fields. Their yields are impressive, and the drain on soil health even more so.

Soil is a living material. It generates the nutrients plants need, and its resilience comes from a vast living, interacting biodiversity of bacteria, fungi, single-cell organisms, plants and animals. Agrichemicals designed to kill change all that.

Scientific methods are, of course, used to check out the effects of agrichemicals on select representative soil life-forms. For example, tests of key features of the well-characterised soil fungus, Aspergillus nidulans, include growth rate, spore germination and germination delay, pigmentation and organisation of the fungal strands. If no effects are detected at some measured level of exposure to a pesticide, the chemical is pronounced safe for the soil at any lower concentrations.

However, science has moved on a long way from looking at gross changes under a microscope such as the above. And, none of the chemicals tested in isolation in the laboratory is ever present in isolation in the field.

A recently published study based on state-of-the-art 'proteomic' analyses revealed subtle biochemical disturbances in A. nidulans exposed to glyphosate. This raises a number of concerns.

'Proteomics' is a powerful tool which screens the whole range of cell proteins and enables the study of global cellular responses to different conditions, such as exposure to environmental toxins. It can detect not only individual proteins but adaptive variations of these proteins to perform specific functions.

A. nidulans, was exposed to 'GT plus' Roundup herbicide formulation at a dilution of 0.007%, a level known to cause no morphological changes in the fungus.

Proteomic analyses of the exposed fungus found 82 differences in proteins: 36 were increased; 14 were present only in Roundup-treated fungi; 25 were decreased; and 7 disappeared altogether in the exposed organisms. The changes represented 6% of total detected proteins.

The affected proteins were involved in a range of vital cellular functions including stress reactions, detoxification, protein synthesis, and energy pathways. Although direct interference by glyphosate may have caused some of the protein changes, others were identified as probable secondary responses.

Also evident were reactive changes to prevent excess water ingress into the cell, which the authors suggest is a compensatory response to the 'surfactants' included in Roundup formulations for helping glyphosate penetrate into plant cells.

Roundup is supposed to kill plants by interfering with the synthesis of one class of 'amino acid', the building blocks of proteins: effectively the weeds are starved of a vital nutrient. Experiments have made it clear, however, that even organisms which don't have the biochemical pathway disturbed by glyphosate experience multiple cellular effects which vary with species and cell type.

"The current assumption underlying pesticide regulation - that chemicals that pass a battery of tests in the laboratory or in field trials are environmentally benign when they are used at industrial scales - is false. Future regulation to deal with this issue may have to vary regionally because of differing cost-benefit analyses, but the effects of dosing whole landscapes with chemicals have been a largely ignored by regulatory systems. This can and should be changed." [1]

Even the UK which "has one of the most developed regulatory and monitoring systems for pesticides ... has no systematic monitoring of pesticide residues in the environment, and no equivalent to MRL (maximum residue level) in foods exist for the environment. There is no consideration of safe pesticide limits at landscape scales." [1]


OUR COMMENT


This is a disturbing finding. Biochemical cycles are critical to soil quality and resilience. Soil micro-organisms are key agents in maintaining these cycles.

Roundup is used on most GM crops: in conventional farming, the herbicide is relied on increasingly to speed up the drying out of crops such as wheat to aid harvesting. A lot of the applied herbicidal formula ends up in the soil [2].

It seems the surfactant moiety of Roundup landing in the soil will stress the water-balance of the soil organisms. Moreover, surfactant function is to increase the toxicity of toxins, and they may well aid other harmful substances into the bacterial and fungal cells besides glyphosate. Due to their tiny size, the microbes and fungi in the soil present a huge combined surface area for the surfacytants in Roundup to act on.

The inevitable additive effects of low-levels of multiple agrichemical exposure suggest the life in our soils is chronically and precariously stressed.

The tiny 'safe' levels of Roundup in our food may well be having similar detrimental effects on the microbes in our gut needed for our own health.

Ask for modern science to be applied to the safety of agrichemicals in the form and in combinations to which the environment, our animals and ourselves are actually exposed to.

Background
[1] Alice M. Milner and Ian L. Boyd, Toward pesticidovigilance, Science Magazine 357, 22.09.17. Professor Boyd is an Scottish physiological ecologist and Chief Scientific Adviser at DEFRA
[2] GLYPHOSATE IN EUROPEAN SOILS - December 2017

SOURCES:
  • Florence Poirier, et al., September 2017, Proteomic analysis of the soil filamentous fungus Aspergillus nidulans exposed to a Roundup formulation at a dose causing no macroscopic effect: a functional study, Environmental Science Pollution Research.
  • New research challenges assumption of substantial equivalence for Roundup-tolerant GMOs, GM Watch 5.10.17

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