NO30047

Written evidence submitted by the Sustainable Food Trust

The Sustainable Food Trust is a registered charity, based in Bristol, with a global remit to assist the transition to food systems which are more sustainable from natural capital and environmental perspectives, and produce food which contributes to human health and well-being, rather than to diet-related diseases.

Summary

• There is now over three times the amount of reactive nitrogen in the environment than planetary ecosystems can cope with, without severe damage occurring.[1] Over 70% of the nitrates in English waters come from farmland.[2]
• UK nitrogen fertiliser use has declined approximately 27% since the introduction of first NVZs in the early 1990s, making it appear that effective action is being taken. However, the decline has been almost entirely on grassland and is largely due to falling livestock numbers and low profitability, making it uneconomical for beef and sheep farmers to use much nitrogen. Use on cropland has barely changed, and far more nitrate is applied than crops can take up. Losses from cropland are typically more than 50% higher per hectare than from grassland.
• It is essential to reduce the use of nitrogen fertiliser further and achieve the objectives of the EU Nitrates Directive, inside or outside the EU, in order to protect the environment and public health.
• Codes of good agricultural and environmental practice have been beneficial, but we see the NVZs, in their current form, as an ineffective and largely unenforceable way to reduce the use of nitrogen fertiliser as well as most of the resulting nitrate losses to the environment.
• Instead, we propose the introduction of a tax on the nitrogen content of fertiliser. Approximately 1 million tonnes of nitrogen is applied in fertilisers in the UK every year. An initial 10% tax would encourage more efficient use, with little impact on yields, and raise approximately £75 million annually.
• It is not widely understood that most of the nitrogen in livestock manure comes from the nitrogen fertiliser applied to the crops the livestock consume.
• Ultimately, as with transport, we need to change to a renewable source of nitrogen fertility. This means the use of forage legumes, such as clover in grassland, and in crop production the use of short term grass breaks containing forage legumes, grown in rotation with crops, as well as increased use of leguminous seed crops, such as peas and beans, for both human and livestock consumption.

What is the scale of nitrate pollution in the UK and what is the likelihood of the pollution getting worse?

1. The most recent published data we have found on nitrate levels in water in the UK, only go up to 2006.[3] These show an average level in groundwater of between 14 ppm in the North West and 36 ppm in the Midlands. In some regions a high proportion of samples were in excess of 50 ppm (Anglian 36% and Midlands 31%).[4] The water companies manage to keep drinking water supplies below 50 ppm in high nitrate areas by blending in water from lower nitrate regions. The financial cost of this is passed to consumers in water bills without being identified.

2. Average levels in surface water were similar, ranging from 15 ppm in the North West to 39 ppm in the Anglian region. A significant proportion of samples exceeded 50 ppm in all regions (81% in the Anglian region, 51% in the Midlands, 47% in the Thames region and 16% in the North West).[5] In 2011, the European Commission listed Malta, the UK and Belgium as having the highest nitrate level in surface water in the EU.[6]

3. We have detailed knowledge of one source only, a spring on the scarp slope of the Cotswolds which produces 1.8 million litres a day. Detailed analyses for 7 consecutive years after the First World War shows that the highest level of nitrate recorded was 2 ppm.[7] In 1980 the nitrate level was 38.4 ppm. In 2014 it was 37.8 ppm. The pollution comes from continuous arable cropping on land in an NVZ higher up on the Cotswolds, where application rates have not fallen. Due to the high nitrate level, the current owners are unable to market this otherwise excellent quality water as a quality bottled water.

4. Modelling suggests that in some regions, such as those supplied by aquifers under chalk soils, nitrate levels will continue to increase for many decades, while in many others, any decline will be very slow.[8] However, reductions in nitrate applications and losses are needed now in order to protect the environment and the health of future generations.

What are the consequences of nitrate pollution for the environment and for human life?

5. There is extensive and compelling evidence of the negative impact of nitrates from farmland on the aquatic and terrestrial environments including on soil quality and biodiversity.[9] Less widely recognised is that ammonium nitrate fertilisers kills methanotrophic bacteria in soil, which use atmospheric methane as their energy source.[10] These bacteria only break down 5% of methane, but we estimate that this sink could have declined by about 20% since the 1950s resulting in 1% increase in net methane emissions annually.

6. Concern about a possible association between nitrates in drinking water and cancer dates from 1971, but the 50 ppm limit was set only to prevent infant methemoglobinaemia (blue baby syndrome),[11] not cancer or any other condition linked to high nitrates in food and water. Our view is that to reduce the risk of cancer we should aim to get nitrates in all drinking water below 25 ppm.

7. However, the UK Drinking Water Inspectorate states, ‘All of these studies [on nitrates and cancer] have given negative results and interestingly some have reported an inverse relationship – cancer incidence falls as nitrate levels in water rise’.[12]

8. We see this as a distortion of the scientific evidence. It is true that some studies have found no link with cancer and even an inverse relationship with one or two types of cancer, but many others have found an association and it was pointed out a decade ago the confusing evidence may be because there had been very few well-designed epidemiological studies.[13],[14] Several more recent studies have found increasing incidence of cancer associated with increasing nitrate levels in water – levels well below 50 ppm. For example, the Iowa Women’s Health Study found increased incidence of bladder and ovarian cancer.[15] A study in Spain found an increased risk of bladder cancer in people with long-term exposure to drinking water high in nitrates.[16] Similar results have come from a study in India in relation to gastro-intestinal cancer[17] and from the Shanghai Women’s Health Study, which found increased levels of colorectal cancer in women consuming water with higher nitrate levels, but only in a sub-group with lower than average vitamin C intake.[18] In most recent studies where positive associations between cancer and high nitrates in water were found, this was either in those exposed to high nitrates in water for a prolonged periods, those consuming low levels of antioxidants, like vitamin C, or those consuming foods containing added nitrate or nitrite.

9. Many vegetables are also high in nitrates. One scientific school argues that because we consume more nitrate from vegetables than from water, and diets high in vegetables are beneficial to health, then additional nitrate from water is insignificant. One of the responses to this is that nitrates in vegetables come with a large number of beneficial micronutrients, many of which are antioxidants, whereas the nitrates in water do not.[19]

10. However, high nitrate levels in vegetables are also seen as a threat to health. Both JECFA and the European Commission have set an Acceptable Daily Intake (ADI) of 0-3.7 mg nitrate per kg bodyweight. Average consumption in Europe is 50-140 kg per day[20] Given that permitted applications of nitrate fertilisers to vegetables can lead to very high levels, e.g. up to 6,100 mg/kg in lettuce[21] we suggest that the total daily nitrate intake of people consuming a wide range of diets should be assessed or reassessed.

11. High levels of nitrate nitrogen in many green vegetables could be linked to a further impact on human health. Two recent studies,[22],[23] show that the level of beneficial antioxidants in green vegetables decreases as applications of inorganic nitrogen fertiliser increase, while, many of these beneficial micronutrients actually increase when nitrogen is provided in an organic form, such as simple amino acids present in the soil.[24] This could increase the incidence of a wide range of diseases for a high proportion of the population.

How important are the different sources of nitrate pollution? Where should action be undertaken?

12. All forms are equally important, but agriculture is the major source, followed by human sewage.

How effectively does Government regulate nitrate usage so that nitrate pollution is reduced as quickly as possible?

13. We have been unable to find a more recent, publicly available, assessment of the effectiveness of Nitrate Vulnerable Zones (NVZs) than 2009. The authors of that study concluded that, ‘When compared to a control catchment, 31% of NVZs showed that water quality had got worse while only 29% could show a significant improvement’.[25] The Government states that, ‘Defra reviews NVZs every 4 years to take account of changes in water pollution’.[26] This suggests that the data is compiled, but not made publicly available. Regular, publicly available updates are needed.

14. Since the introduction of NVZs in the UK in the early 1990s, nitrogen fertiliser application rates have fallen by about 27%, from approximately 130kg–95kg/ha. However, while average application rates on grassland have declined from 130kg­–55kg/ha, those on cereals, oilseeds and vegetables have hardly declined at all.[27] This is particularly significant because nitrate levels in drainage water from many arable regions exceed 100 ppm and are typically more that 50% higher than from grassland.[28] Grass on some intensive dairy farms may be an exception to this.

15. The available evidence suggests that addressing the issue of nitrate pollution has been a very low priority for the UK Government and that it has done this in an ineffective way.

Our view is based on the fact that:

• The Drinking Water Inspectorate appears not to be concerned about high nitrates in drinking water, see above.
• MAFF failed to implement the 1991 Nitrates Directive fully and had to be forced to do so by the European Court of Justice.[29]
• It did not publish proposals for implementing the Directive until 2001 and was still only considering entering into discussions with farms about how to do this in 2002.[30]
• Defra’s 2001 review of diffuse pollution was rushed, focused mainly on surface water pollution and contained no data on groundwater pollution by nitrates.[31]
• While Austria, Denmark, Finland, Germany, Ireland, Lithuania, Luxembourg, Malta, the Netherlands, Slovenia, as well as the regions of Flanders and Northern Ireland designated all their farmland as NVZs, [32] the UK initially only designated 10%, then added a further 45% and has only recently increased the area to 58%.[33]
• The UK Government has obtained a derogation from the European Commission to allow some livestock farmers to apply more than the permitted 170kg/ha of nitrogen annually in the form of livestock manure and allows arable farmers to apply substantially higher applications of nitrogen fertiliser to crops than permitted under basic NVZ rules, if they are growing milling wheat or simply believe they will produce higher than average crop yields. Wheat can receive up to 220kg/ha, oilseed rape 250kg/ha and vegetables 280kg/ha. Grassland can receive 300kg/ha.[34] This principally applies to high-yielding dairy farms.

Are other nations taking more effective action on nitrates that the UK can learn from?

16. We have no reliable information.

What more could Government do to reduce nitrate pollution as quickly as possible?

17. Academics calculate that the optimum agronomic rate for a farmer is 175kg/ha. But that if the nitrogen externalities are included, this falls to 120kg/ha.[35] This should be a target.

18. Since the UK, has such a wide mix of soil types and underlying geology, the introduction of NVZs on only a proportion of farmland fails to address the problem because they cover many extensive grassland farms which are already using minimal amounts of nitrogen, yet miss many other farms which still use high nitrogen rates. This also creates unfair competition between farmers. Regulation of nitrogen fertiliser use should be the same nationwide, as in many European countries.

19. While losses could be reduced further by better agricultural practice, it is almost impossible to monitor farm use of nitrogen accurately and there is enormous potential for farmers to use more than the recommended amounts via readily available derogations or unrecorded transfers between claimed use on extensive grassland and actual use on arable crops.

20. An academic review of NVZs in 2009 concluded, ‘The lack of objective success for NVZ designation suggests that nitrate pollution control strategies based on input management need to be rethought’.[36] We suggest that conclusion is still valid. Our recommendation is that, instead, the Government should introduce a tax on nitrogen fertiliser. According to the OECD taxes are one of the most efficient ways to make changes to benefit public health.[37] Fertiliser taxes were used in Austria, Norway, Finland and Sweden before they joined the European Union and are also used in California and West Virginia in the US. A tax would be fair to all farmers and an initial tax of 10% of the price of nitrogen would raise approximately £75 million annually in the UK. Subject to Treasury agreement these funds could contribute to paying farmers to introduce control strategies such as planting cover crops.

21. The European Nitrogen Assessment[38] and subsequent analysis by contributing scientists[39] has estimated that in the EU the financial costs of the negative impact of nitrogen use in agriculture is €35–230 billion annually.[40] This equates to between €138 and €2,422 per tonne of 34.5% ammonium nitrate fertiliser which costs approximately £250 per tonne in the UK. Based on the proportion of total EU nitrogen used in the UK, the mid-point of this range has been put at a cost to society of £11.88 billion (£185 per person).[41] These costs could be used to justify a much higher tax, and contrast with the commercial benefit to farmers from using nitrogen fertiliser, which was estimated to be worth €20–80 billion annually in the EU-27.[42]

22. However, a tax only needs to be set at a rate which would discourage farmers from using more nitrogen than their crops can utilise, speed the transition to more precise ways of applying fertiliser and also encourage greater use of legumes. Nitrogen can also be lost from the use of legumes, but the extent of such losses is very much smaller.

January 2018