The CHAP E-Flows mesocosm will be available for use in the Summer 2018. This is Europe’s most advanced edge-of-field water assessment facility which enables environmental testing of plant protection products to meet the most stringent regulatory standards, helping to introduce a wider range of more effective products to market more quickly and to help farmers tackle threats to their crops.

Serving the agrichemical industry

  • Optimising and standardising higher tier risk assessments.
  • Providing the industry with high quality regulatory evidence so that new plant protection products are granted regulatory approval.
  • Supporting the development of new crop protection products which are safe for our aquatic environment.

The end result is that there will be more choice for farmers and growers which will lead to increased yields for the food and farming industries.

The CHAP E-Flows mesocosm

The Edge of Field Waterbody Safety Assessment Facility (E-Flows) is the first facility of this nature to provide fully flow through streams that can receive chemicals at the treatment rates predicted to occur in the environment by accurately reproducing a real environment to test new products. Based at Sand Hutton near York in North Yorkshire, the combination of the aquatic laboratory facilities, offered by Fera Science Ltd, for lower tier studies and the E-Flows mesocosm, provided by CHAP, creates a complete platform for generating all the high quality data required for regulatory submission.

The largest mesocosm in Europe

Semi-field regulatory risk assessments using a mesocosm approach have often been considered unsatisfactory as there is a tendency for results to be too variable to constitute scientific robustness. The source of this problem is that the mesocosm units used are small volume static or recirculating chambers which tend to provide insufficient habitat for organisms and have limited capacity to buffer physico-chemical change.Even with regular bailing, these mesocosms have a within-experiment effective volume of <5000 litres per experimental unit, and manual water changes can increase the stress to the organisms.

In contrast, the E-Flows mesocosm with flow-through capacity can provide a mean within-experiment effective volume of 75,000 litres per experimental unit, which brings a huge increase in buffering capacity against diurnal and weather-driven change, stabilising the habitat and reducing variation of results.

E-flows comprises of 60 experimental units (all flow-through streams), with the dimensions of each stream (or ditch) being 10 metres long, up 0.4 m deep and up to 2 metres wide at the surface, with a v-shaped cross-section, and with each unit ending in a capture pond approximately 1 metre deep and 1 metre in diameter. Where the average experiment requires access to 20-30 units (according to EFSA Guidance) the E-flows facility has the capacity to support 2-3 independent concurrent experiments, reducing the waiting time for users.

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The flow though and experimental unit size of E-Flows can be varied to a great extent; the length of unit can be shortened and flow increased (giving a retention time of <0.1 days and an effective volume of 750,000 litres per unit) or otherwise independent units can be combined to increase the habitat area, and flow can be reduced to simulate slow ditches or static ponds.

The increased size and realism of the experimental units provide the scope for the establishment of a wide diversity of macrophytes and invertebrates, allowing a greater range of available resources and refugia, consequently reducing the stress associated with an artificial environment. This both increases the validity of the results for the Specific Protection Goal and reduces the chance of the design of the experiment adversely influencing the outcome of the risk assessment. By this means, the safety factors applied to the regulatory values can be reduced (as low as a factor of two).

The CHAP E-Flows mesocosm benefits from a continuous water supply via a borehole from the Grade A sandstone aquifer below it. It is also ideally placed in the northern extent of the lowland growing region, providing the best estimate of realistic to worst case risk assessment.

Contact Details

Dr Rachel Bensted – Lead Scientist

Visit the Fera website