Environmental impacts of Agricultural land uses

environmental, farming,

What are the Environmental Impacts associated with Agricultural Land uses in the UK?

This is the first instalment in a series of blog posts which will identify and evaluate the typical environmental impacts associated with day to day farm processes.

To sheep dip or not to sheep dip?


Figure 1: Image captured in September 2015.

There are numerous environmental impacts arising from farming processes. These impacts include effects to water bodies, humans and economic costs. Due to the nature of the potential contaminants and the common pathways associated with rural settings, environmental impacts not only affect the immediate vicinity but have the ability to spread to greater distances.

The UK’s most common impacts are associated with the use of pesticides, nitrogen compounds, livestock waste and soil erosion (1). Sheep dips are a prime example of a use of pesticides within the agricultural industry. One area of concern identified in an article by Skinner et al 1996, gave light to the extent to which pesticides reach rivers and lakes by leaching and runoff, since this may lead to impacts on aquatic life, humans and contamination of drinking water.

The UK is home to approximately 25million sheep and lambs and is one of the major sheep producers in Europe. The UK is the 7th largest lamb producer in the world (12). The production of lamb has increased to 307 tonnes in the last 4 years (2011-2015) (8). It is important that sheep dips are used properly and that appropriate controls are taken to minimise environmental and human health impacts. For the purpose of this blog we will be looking at sheep dips and washes and evaluating their environmental impacts.

What is a sheep dip and what are the processes involved?

A sheep dip is where shepherds and farmers immerse their sheep to remove external parasites or treat fungus. The term “sheep dip” can refer to the compounds used (which can come in the form of a powder, paste or liquid solution) or it can refer to the act of “dipping” the sheep themselves. Some sheep dip compounds contain organophosphorus (OP) or synthetic pyrethroids (SP) compounds which can leach through the soil and pollute groundwater (6).

Farmers involved with sheep dipping operations and purchasing OP in England, Wales and Northern Ireland must be properly trained (have a Certificate of Competence in Safe Use of Sheep Dips), or should be supervised by someone who holds the certification (7). These certificates are accredited and obtained by the City & Guilds and the NPTC or the Scottish Skills Testing Service (Scotland).

A risk assessment must be undertaken to assess who might be harmed and how. Correct selection of pesticide and required method of sheep dipping will enable famers to prevent and control parasites efficiently and to reduce risk of health implications for people involved (7). A plunge sheep dip is a commonly used method for treating external parasites. This is a permanent structure which involves a trough in the ground, or a mobile steel structure (9). Mobile sheep dips can also be used. Other methods of applying pesticides include showers and jetters (however, plunge sheep dip compounds are not authorised for use in these facilities) (7). In order to reduce the exposure of contaminants and to protect the environment, the Health and Safety Executive (HSE) suggest that pour on products (to control blowfly and ticks), and injectable treatments for scab control may be used as an alternative to plunge dipping (7). Consultation with veterinary staff is often advised and enables selection of appropriate methods.

The HSE advise the following controls are undertaken to minimise human health and environmental implications:

  • Ensuring ventilation, to prevent excessive vapour inhalation,
  • Use appropriate equipment such as a metal handed crook and wearing of personal and respiratory protective equipment (RPE and PPE),
  • An entry slope, splash boards and screens to reduce splashing from sheep entering the dip bath,
  • Ensure that the dip bath has no drains or leaks, and should be inspected prior to use,
  • Draining pens should be have an impermeable sloped floor which allows sheep dip compounds to drain into the bath,
  • Absorbent material such as sand, earth or sawdust should be used to soak up spillages and placed into a sealed container and labelled for disposal at a licensed waste disposal site,
  • Clean water supply for topping up the bath, decontamination and rinsing.
Figure 2: Edited from the HSE Agricultural Information Sheet No. 41.
In order to minimise environmental impacts, sheep dips, baths, drain pens and mobile facilities must be located:
  • As far away as possible (at least 10m) from a watercourse (2). This includes rivers, streams, ditches, drains, land drains and wetlands.
  • At least 50m from any well, spring or borehole (2).
  • At least 30m away from any watercourse which drains into a Site of Special Scientific Interest (SSSI). If the farm is located within a SSSI, further advice should be sought from the relevant regulatory body (Natural England, Scottish Natural Heritage, Natural Resources Wales) (6).

Additionally, they should not be situated on or at the top of slopes where there is a risk that spillage might drain directly to a watercourse, or on roads or tracks. Especially in areas of heavy rainfall, where surface run off is often experienced. Pesticides are found more commonly in surface waters due to run off from the direct sources (1).

After sheep dipping, all equipment, exposed skin and clothing must be washed thoroughly to avoid contamination and reduce human health and environmental implications. FindLaw UK advises that it is best practice to dispose of the sheep dip waste as soon as possible. The waste solution can be spread onto surrounding land; however it is best practice to dispose the sheep dip waste at the same site the sheep are dipped. Authorisation from the Environment Agency or SEPA (in Scotland) must be obtained before you dispose of waste sheep dip (including List 1 and 2 substances) to land or groundwater, even in small quantities (2 & 6). If the dip is to be spread onto land, the solution must be diluted with at least 3 times the volume of water (2).

If you do not hold a licence or conditions are unsuitable for spreading your waste sheep dip, you should use impermeable storage containers kept in a bund in order to prevent spillage and potential contamination to land and water courses (2). Further advice can be obtained from the HSE Agriculture Information Sheet AIS16 Guidance on storing pesticides for farmers and other professional users (7). Further guidance can be sought from DEFRA who hold a list of separate guidance documents for each stage of the sheep dipping process.

Ensuring that adequate controls and preventative measures are taken is important to avoid contamination of controlled waters or land. Even small amounts of sheep dip can be dangerous to the environment (6).

What contaminants are typically associated with these features and what are the impacts?

Hazardous substances affect the environment and can have severe health implications when absorbed into the body in high levels. These substances can get into the body in 3 primary ways – dermal contact, ingestion of contaminated food and drink and by vapour inhalation (7). The most common form is from direct contact through the skin from concentrated and dilute solutions and from contaminated clothing.

People most at risk are farmers who work with organophosphate sheep dips (1). An article from April 2015 claimed that government officials were aware of the health risks of chemicals used in sheep dips between the 1980s and 1990s, but refused to end its compulsory use. It was recorded that at least 500 farmers across the UK were left with debilitating health problems after using OP, whose use was mandated until c.1992 (4). In New Zealand, the use of sheep dips was a legal requirement between c.1849 and c.1993. This lengthy historic legacy resulted in over 50, 000 former sheep dip sites (5).

Organophosphorus compounds produce a range of chronic symptoms (13) including acute poisoning, acute intermediate and delayed neurological effects, psychological and behavioural changes and respiratory effects. In some cases exposure resulted in hospitalisation and prolonged ill health. These symptoms are also listed in the HSE Agricultural Information Sheet No. 41.

OP and SP compounds are highly toxic to aquatic life, and once groundwater is contaminated with these compounds it will be unfit for drinking without treatment (5). OP can leach down the soil profile and can contaminate groundwater. The extent of leaching depends on the soil type, and greater leaching occurs in porous (sandy) soils. Contaminants are less likely to migrate large distances in more impermeable soils which contain high levels of clay. Surface contamination from sheep dips can spread up to 50m from the sheep dipping site (5).



Figure 3: Edited from the New Zealand Sheep Dipping Factsheet.


The Water, Soil and Air Code 2009 was formulated and designed to help farmers and people involved in the agricultural industry protect the environment and their land (3).

When working with a sheep dip or associated chemical compounds farmers must comply with the Groundwater Regulations 1998. Failure to do so may result in contamination of groundwater (and potable water) supplies, with farmers facing serious penalties and costs to remediate (6). SEPA is responsible for groundwater regulations in Scotland, and have produced a separate code of practice for sheep dipping. Sheep dip compounds are highly toxic and contain substances that are classified as List 1 and List 2 dangerous substances under the Groundwater Regulations 1998 (2 & 6).

In order to help protect the environment, the Groundwater Regulations 1998 stipulate that you are prohibited from; discharging List 1 substances (found in sheep dips) to groundwater sources; from disposing List 1 substances to land, unless you have been authorised to do so from the Environment Agency; discharging List 2 substances to ground or disposing of land, without appropriate authorisation from the Environment Agency.

Other relevant legislation includes the “EU Water Framework Directive 1998” and the “Drinking Water Directive”.

The Water Framework Directive 1998 requires land owners to actively manage water quality and quantity throughout their catchment (3). This directive was designed to help protect surface and groundwater throughout the EU. One of the aims is to ensure that polluters pay the cost of any damage incurred (11). With this in mind, it is vital that farmers that undertake sheep dipping are licensed to do so and made aware of the health and environmental impacts that may occur should procedures not be undertaken in line with provided guidance.

The EC Drinking Water Directive 1998 (Council Directive 98/83/EC) on the quality of water intended for human consumption, stipulates that the maximum concentration of any pesticide in potable water supplies should be 0.1µg1-1 (1). Skinner et al refers to a study on drinking water quality in 1992, which showed that a large number of fluvial water samples taken during their investigation failed to meet the EC Drinking water directive. This highlights the importance of regulating and controlling the use of pesticides, particularly in sheep dips.



  1. Skinner. J.A et al.(1997). An Overview of the Environmental Impacts of Agricultural in the UK. Journal of Environmental Management, 50: 111-128.
  2. Find LawUK- Protecting water from Sheep Dip contamination. http://findlaw.co.uk/law/small_business/agriculture/farming/water_pollut…. Accessed 02/09/2015.DEFRA. Water, Soil and Air Code 2009: Protecting our Water, Soil and Air. A Code of Good Agricultural Practice for farmers, growers and land managers. http://adlib.everysite.co.uk/adlib/defra/content.aspx?id=252439.  Accessed 02/09/2015.
  3. (20/04/2015). Revealed: government knew of farm poisoning risk but failed to act http://www.theguardian.com/environment/2015/apr/20/revealed-government-k…. Date accessed 4/09/2015.
  4. Sheep Dip Factsheet No.1. Sheep Dips In New Zealand. http://www.trc.govt.nz/assets/Publications/guidelines-procedures-and-pub…. Date Accessed 22/09/2015
  5. DEFRA. 2001. The Groundwater Protection Code- the use and disposal of sheep dip compounds. http://adlib.everysite.co.uk/resources/000/015/589/PB12010.pdf. Date accessed 29/09/2015.
  6. Health and Safety Executive.2013. Agricultural Information Sheet No. 41. Sheep Dipping- advice for farmers and others involved in dipping sheep. www.hse.gov.uk/pubns/ais41.htm. Date accessed 22/09/2015
  7. DEFRA. 2015. Agricultural in the United Kingdom 2014. https://www.gov.uk/government/uploads/system/uploads/attachment_data/fil…. Date accessed. 22/09/2015.
  8. The EU Water Framework Directive- Integrated river basin management for Europe. http://ec.europa.eu/environment/water/water-framework/index_en.html. Date accessed. 29/09/2015.
  9. UK Agricultural. Sheep Shearing and Wool Production in the UK. http://www.ukagriculture.com/livestock/sheep_wool_production.cfm. Date accessed 29/09/2015.
  10. Steenland, K. et.al (1994). Chronic Neurological Sequelae to Organophosphate Pesticide Poisoning. American Journal of Public Health 84 (5):731-736.

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