EU single use plastics directive consultation: impact assessment - environmental report

8. Soil

Soil is a complex, variable and living medium. It has a role in providing a habitat and is important for human activities, landscape and heritage and provides raw materials. It performs many vital functions: as a growing medium for food, forestry and other biomass production, filtration of water, and storage of carbon and nitrogen.

Oxo-degradable plastics are predominantly used as a mulch film within Scottish agriculture and are prone to leakage into the surrounding soil. As such, effects of the proposed market restrictions on the topic area of soil relate principally to the restriction of oxo-degradable plastics, however, also consider the effects of single-use plastic items where relevant. Soil damage and degradation, as is caused by the breakdown of oxo-degradable plastics and subsequent leakage of microplastics, can have potential negative effects on human health, natural ecosystems and climate change, impacting our ability to grow crops and other food sources for humans and animals.

This section provides the contextual information to inform the assessment (in terms of the review of Plans, Programmes and Strategies (PPS) and the baseline information) as well as an assessment of the effects of the SUP Directive on soil.

8.1 Relationship with other Plans, Programmes and Strategies and Environmental Objectives

The PPS that have been assessed as relevant to the Soil topic are shown in Figure 8‑1 and summarised thereafter.

For the purposes of the review of the international plans and programmes for this SEA, it is assumed that the broad objectives of extant European Union (EU) legislation will be maintained once the UK has withdrawn from the EU and that similar or equivalent environmental protections will remain in place.

The relationship between the identified PPSs and the restriction of single-use and oxo-degradable plastic items placed on the Scottish market are outlined below.

United Nations (2015): Transforming our World - the 2030 Agenda for Sustainable Development sets out 17 global goals agreed by the United Nations. The goals of the Agenda are outlined in Section 5.1 (above). With respect to Soil quality, Goal 2 of the Agenda seeks to (among other aims) promote sustainable agriculture; with the specific objective to progressively improve land and soil quality. By reducing the volume of microplastic leakage into the soil in Scotland, the levels of contamination of that soil will be reduced and thus its quality improved in-line with the UN Agenda.

European Union (2019): Directive on the reduction of the impact of certain plastic products on the environment highlights significant negative environmental, health and economic impacts stemming from the continued use of certain plastic products. The aims and provisions of this Directive are outlined in Section 4.1 (above). Soil is referred to specifically within the Directive, which acknowledges that terrestrial pollution and contamination of soil by larger items of plastic and resulting fragments or microplastics can be significant, and that such plastic can leak into the marine environment. Reducing the volume of single-use and oxo-degradable plastic items placed on the market in Scotland will likely lead to a concurrent reduction in microplastic levels present within soil, and an overall improvement in soil quality.

European Union (2014): Seventh Environment Action Programme recognises that soil degradation is a serious challenge, and that degradation of soil has far-reaching implications on the prosperity of biodiversity within the EU. The Programme mentions a specific need to reduce the pressures on soil and soil quality, through the passing of targeted legislation. Implementing market restrictions on oxo-degradable plastics in Scotland will reduce the extent to which soil is contaminated by microplastics and will likely lead to an overall improvement in quality and purity of productive soil, in line with the aims of the Programme.

UK Government (1990): The Environmental Protection Act seeks to improve resource use and environmental conditions through the control of waste collections and management across the UK. The main requirements of the Act are outlined in Section 5.1 (above). The Act makes specific provision for the reduction of litter by making littering a criminal offence. As discussed previously, plastic litter is intrinsically linked with soil quality, as plastic leakage can lead to the presence of microplastics within fertile soil, thus reducing its utility. Implementing the proposed market restrictions in Scotland will lead to a likely reduction in plastic levels within Scottish soil.

Scottish Biodiversity Strategy (2004) was supplemented by The Scottish Government's 2020 Challenge for Scotland's Biodiversity (2013) document; both of which combine to form the Scottish Biodiversity Strategy. The main aims of the strategy are documented in Section 7.1 (above), however in reference to soil specifically, the Strategy emphasizes that Soil biodiversity plays a key role in maintaining soil fertility and its many ecosystem services (such as providing clean water, nutrient cycling and climate regulation). It also mentions the need to protect soils from erosion, loss of organic matter, structural damage and pollution to sustain these services. As mentioned, restricting single-use and oxo-degradable plastics in Scotland will have the likely impact of reducing soil pollution consistent with the Strategy.

Scottish Natural Heritage: The Scotland Biodiversity Progress to 2020 Aichi Targets (2017) demonstrates Scotland's progress toward 20 global targets set by the UN Convention on Biological Diversity. The main observations of the report are outlined in Section 7.1 (above). With respect to soil, the report notes that Scottish soils are polluted by; among several other things; an excess of litter, and that there is a pressing need to reduce the extent to which soil fertility and utility is harmed by this excess. As mentioned, restricting oxo-degradable plastics will lead to a reduction in plastic litter and resultant leakage of microplastics into Scottish soil.

Scottish Government (2009) Scottish Soil Framework sought to ensure that soils are recognised as a vital part of the Scottish economy, environment and heritage, and are to be safeguarded for existing and future generations. The Framework laid out a wide range of activities that were devised to contribute to 13 soil outcomes. One such outcome (SO9) is the need to reduce contamination of soils in Scotland by litter and other pollutants. As mentioned, reducing the prevalence of oxo-degradable plastic products for use within agriculture will likely lead to a reduction in associated plastic leakage into Scottish soil, and an overall improvement in its quality.

Scottish Government (2016): The second land use strategy for Scotland, Getting the best from our land - A land use strategy for Scotland (2016-2020) promotes the need to utilise resources sustainably and to safeguard the quality of natural resources in Scotland. Soil is mentioned specifically within the strategy, with an identified focus on improving soil quality in Scotland. This again aligns with the likely outcome of the restriction on single-use and oxo-degradable plastic items in Scotland - that a reduction in plastic litter will precipitate an improvement in soil quality through reduced contamination.

8.2 Baseline Characteristics

Numerous publications have highlighted the impact of microplastics, in particular those made of oxo-degradable plastics, on the quality of soil. Although this section covers the impact of both conventional and oxo-degradable plastics on soil, further emphasis has been placed on the impact of oxo-degradable plastics on soil.

Oxo-degradable plastics, mostly made of polyethylene (PE), are polymers that contain special additives that cause them to degrade after a certain amount of exposure to either sunlight or heat. The degradation period depends on the concentration of additives and the amount of sunlight and/or heat to which it is exposed.^[101]

According to a study by Miles C. (2017),^[102] independent, third party data using standard ASTM & ISO biodegradation tests show only a small percentage or no plastic fragments of oxo-degradable plastic are utilized by soil microorganisms when oxo-degradable plastics are assessed in field tests. Even in laboratory environments with carefully controlled temperature and light conditions, oxo-degradable plastics biodegrade very slowly. No laboratory test has shown more than 91% degradation in soil for two years, and some show that degradation stops completely when 13 - 65% degradation has occurred.

Another report by Eunomia,^[103] commissioned by the European Union, concludes that use of oxo-degradable plastics has been found to pose a risk of significant environmental damage. Globally, the Ellen MacArthur Foundation, along with 150+ organizations, also is calling for a ban of oxo-degradable plastic packaging.^[104]

Oxo-degradable material is one of the commercially available products of agricultural mulch films. Oxo-degradable plastic is made with conventional plastic: high density PE (HDPE), low density PE (LDPE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), or polyvinylchloride (PVC). Oxo-degradable plastic includes additives that cause the material to become brittle and break apart into fragments when exposed to UV light, heat and/or oxygen.

8.3 Consideration of Reasonable Alternatives

8.3.1 Methodology

Targeted single-use plastic products are expected to be replaced with alternatives made from shorter lived, largely biodegradable (wood, paper etc.) materials. This material shift will not only reduce microplastics entering the soil, but will the degradation of littered items, thereby reducing the 'litter begets litter' behavioural effect which occurs when litter accumulates over time.

Impacts of plastics on the quality of soil has been qualitatively assessed using available literature in this area and our understanding to the potential impacts of alternative options on soil.

8.3.2 Results

Literature is abundant with studies that confirm the degradation of plastics produces microplastics that affect the quality of soil.^[105] This section provides a summary of potential impacts of proposed market restrictions on the quality of soil.

The key to each assessment score is shown below:

Score Key:

++ : Significant positive effect
+ : Minor positive effect
0 : No overall effect
- : Minor negative effect
-- : Significant negative effect
? : Score uncertain

NB: where more than one symbol is presented in a box it indicates that the SEA has found more than one score for the category. Where the scores are both positive and negative, the boxes are deliberately not coloured (i.e. 'no overall effect'). Where a box is coloured but also contains a "?" this indicates uncertainty over whether the effect could be a minor or significant effect although a professional judgement is expressed in the colour used. A conclusion of uncertainty arises where there is insufficient evidence for expert judgement to conclude an effect.

Measure No 1 - 6

Material/item to be restricted: See Table 7.1

The alternative option: See Table 7.1

Notes:

SEA criteria: Will the proposal contribute to reducing levels of soil contamination?

Score: Minor positive effect

Commentary:

Microplastics could potentially be produced by the degradation of plastic products (especially products coated with a thin layer of plastic lining such as plates). Researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB)^[106] carried out a study to investigate the impacts of plastics on ecosystems on dry land. Results reveal that the impact of microplastics in soils could have a long-term negative effect on such ecosystems. The authors say terrestrial microplastic pollution is much higher than marine microplastic pollution - estimated at four to 23 times higher, depending on the environment.

Market restrictions on plastic product will reduce the likelihood of microplastic leakages to the soil and consequently improve the quality of soil.

Measure No 7

Material/item to be restricted: Cups and beverage containers made of expanded polystyrene

The alternative option: Plastic-coated paper cups

Notes:

SEA criteria: Will the proposal contribute to reducing levels of soil contamination?

Score: Minor positive effect / Score uncertain

Commentary:

Although cups and beverage containers made of expanded polystyrene will be replaced by plastic-coated paper cups, we still expect a reduction in the amount of microplastic leaked to soil as the amount of plastic in paper cups is 75% less than EPS cups and beverage containers.

In short, market restrictions on EPS cups will reduce the amount of microplastic that is likely to be leaked into soil and will consequently improve the quality of soil.

Measure No 8

Material/item in scope: Oxo-degradable HDPE

The alternative option: Conventional HDPE

Notes:

SEA criteria: Will the proposal contribute to reducing levels of soil contamination?

Score: Minor positive effect / Score uncertain

Commentary:

Oxo-degradable material is used as an agricultural mulch as outlined earlier in Section 8.2.

As the oxo-degradable material is designed to degrade in situ there is the potential for microplastics produced by the breakdown of this material to have an impact on soil quality. According to DEFRA, it is suggested that oxo-degradable plastics left in the open environment in the UK degrade to small fragments within 2 to 5 years.^[107] Removal and replacement of this material would therefore be likely to have a direct positive impact on soil.

The paucity of data has made it difficult to quantity the amount of oxo-degradable plastics used in Scotland. However, we believe that imposing market restrictions on oxo-degradable plastics is expected to reduce the amount of microplastics leaked to the soil and hence lead to a minor positive effect.

8.4 Mitigation and Enhancement

As single-use plastic items targeted by market restrictions will be replaced by paper or wood alternatives that could be recycled, it would be imperative to design a clear and targeted awareness campaign to ensure that citizens are well informed about the best recycling route to each item to ensure that material value is preserved.