In Depth: Glyphosate – What is it and why does it matter?

Image: Floating Pennywort being removed from a watercourse in the Netherlands (by Water Board Aa en Maas)

What is it?

Glyphosate is the active ingredient in the world’s most widely used herbicide, one of the most recognisable brands is Roundup. It is widely used in the UK and internationally in variety of different areas – in farming, sports grounds, golf courses, public open spaces, railway lines, private gardens – and has been used safely for more than 40 years.

Why is it important to water level management?

It is the only active ingredient currently licenced in the UK for use directly within waterbodies for aquatic plant management purposes. It has a long history of use within the land drainage, flood risk management, navigation and conservation sectors, managing plant growth on the surface, fringes and banks of waterbodies. It is not effective against submerged plant growth.

Water managers use glyphosate as a cost effective management tool to control a variety of different types of aquatic plants including:

Floating plants

Many of these species can block out light to submerged species causing them to die off, worsening water quality and altering the waterbody’s ecology. Duckweeds (Lemna spp., Spirodela spp.) and Water Fern (Azolla filiculoides) can block water intakes, pumps and filters. These and other species such as Arrowhead (Sagittaria sagittifolia) and Floating Pennywort (Hydrocotyle ranunculoides) can form dense stands and in narrow watercourses impeding flows and reducing channel capacity leading to flood risk issues.

Reed growth

Dense networks of rhizomes in species such as Common Reed (Phragmites australis), reedmaces (Typha spp.) and Branched bur-reed (Sparganium erectum) can form large stands which impede flows in watercourses. Once established, the roots and rhizomes trap silt and extend the area that they can colonise, which further impedes water flow in the long-term.

Emergent species

These plants, including the invasive non-native Australian swamp stonecrop (Crassula helmsii), can cause problems by forming dense beds which can block channels and impede water flow. Many of these species are also quite fragile and, during high water flows, fragments can become dislodged and block bridges, culverts and other structures, leading to localised flood risk issues.

Bankside plants

There are a number of bankside species, such as Himalayan Balsam (Impatiens glandulifera) and Giant Hogweed (Heracleum mantegazzianum), that are damaging to bank stability making them more prone to erosion, especially in winter when species tend to die back. Others, such as the highly invasive Japanese Knotweed (Fallopia japonica) can form dense stands along watercourse banks impeding access for management, outcompeting native species, and with roots that can penetrate concrete structures and embankments.

What is the issue with glyphosate?

All pesticide products used within EU nations, including the UK, periodically have to be reauthorised for use by the EU following a review of the evidence surrounding their safety. Glyphosate was originally due for reauthorisation last year.

In 2015, the International Agency for Research on Cancer (IARC) published a paper concluding that glyphosate is “probably carcinogenic to humans” based on limited evidence in humans and sufficient evidence in experimental animals.

Then in November 2015, the European Food Safety Authority (EFSA) recommended glyphosate be reauthorised for use in the EU for 15 years. This would normally have then been approved by the EU. However, because of the above study, environmental lobbying and political sensitivities a number of countries abstained from voting in favour of the recommendation. Eventually, glyphosate was reauthorised for use by European Commissioners, but for only 18 months with some restrictions attached. This was to allow further investigations to be carried out and the results of a safety review by the European Chemicals Agency (ECHA) to be published. A decision to reauthorisation of glyphosate is due to be made by the EU before the end of 2017.

So is glyphosate safe?

The EFSA review concluded that glyphosate poses minimal risk to non-target plants and animals when used appropriately. These conclusions were consistent with the outcome of other regulatory evaluations of glyphosate around the world, in countries including the United States, Canada, Australia, New Zealand, Germany and Switzerland – all of which supported the conclusion that glyphosate posed no unacceptable risk when used correctly. This view was also upheld in a joint report from the World Health Organisation and the Food and Agriculture Organisation of the UN.

The only body to conclude that glyphosate might pose a health risk is the IARC. A review of the carcinogenic potential of glyphosate by four independent expert panels published in the scientific journal Critical Reviews in Toxicology in September 2016 found that, ‘The overall weight of evidence from the genetic toxicology data supports a conclusion that glyphosate does not pose a genotoxic hazard and therefore, should not be considered support for the classification of glyphosate as a genotoxic carcinogen.’

ADA’s view on herbicides and glyphosate

ADA has previously articulated the risk to flood and water level management of not having an effective suite of management controls that can tackle emergent, floating, submerged, algal and bankside vegetation. This includes by mechanical and herbicide means as well as other potential novel techniques including, dyes, matting and ultrasound which have been trialled in the UK and abroad.

Effective management will be especially important in the future given the combined risk from climate change and invasive non-native species such as floating pennywort and water primrose etc. Such aquatic plant species are likely to become more widespread and rigorous as milder winters provide them with a longer growing season.

Regulatory bodies across the globe have studied the scientific evidence on glyphosate and concluded that it is unlikely to pose a human health risk when used correctly. ADA therefore considers that it is very important for water level management across Europe for glyphosate to be reauthorised by the EU in 2017.