Skip main navigation

New offer! Get 30% off your first 2 months of Unlimited Monthly. Start your subscription for just £29.99 £19.99. New subscribers only. T&Cs apply

Find out more

Soil Health

A video on soil pollution and health.
In addition to air and water pollution, soil pollution due to chemical contaminants, heavy metals, pesticides, drugs, microbes, and/or parasites, can lead to the contamination of food of both vegetable and animal origin. Contamination of land may or may not be deliberate. Deliberate contamination may involve waste disposal or the control of animals, plants, or microorganisms with biocides. Accidental contamination may be the result of short-term or long-term aerial transport, flooding by rivers or seas, or collisions of tankers and trucks carrying toxic chemicals. The use of sewage sludge as fertilizer on agricultural land constitutes another source of pollution, as they may contain heavy metals, nitrates, phosphates, and detergents. Moreover, soil pollution may occur in the immediate vicinity of domestic and industrial premises.
As well, it may reach land after traveling considerable distances with surface waters, rain, or snow, or with associated dust particles.
In the industrialized world, heavy metal deposition may be serious, with soils being important compartments in the process of heavy metal accumulation, mobilization, or immobilization within the ecosystems. Industrial processing of raw materials that contain heavy metals involves the danger that they will be released into the environment. Industrial dust from high temperature processing mostly contain oxides of heavy metals, which may be soluble and diffusely distributed. However, application of phosphate fertilizers and sewage sludge are considered the highest sources of cadmium and lead to agricultural land.
In veterinary medicine, antibiotics are widely administered to food-producing animals for therapeutic purposes, and the classes of antibiotics are mostly the same used in human medicine, increasing the risk of emergence and spread of resistant bacteria. Large amounts of antibiotics are normally excreted by animals, both as the parent substance or metabolites, which may also still be acting. In manure, antibiotics can be very stable, or even increase their concentration, due to re-transformation of metabolites back to the parent compound. Consequently, high proportions of applied veterinary antibiotics and their active metabolites reach agricultural fields by manual fertilization or via dung and urine of animals grazing on pastures.
They can persist for months to years in soil, affecting the bacteria population and leading to both the imbalance of the biosystem, and the development and spread of antibiotic resistance. Moreover, soil also contains microorganisms which are capable of causing diseases in humans, particularly in the case of wound, respiratory tract, or gastrointestinal infections. Soil-borne microbes that are pathogenic for humans include protozoa, fungi, bacteria, and also viruses, which require a host for their survival. Soil organisms may potentially enter surface water and ground water via the soil. Thus, soil is often the origin of waterborne infections. Enteric pathogens can survive for prolonged periods of time in animal manures, and may serve as potential inoculum onto plants in the field.
Many studies have demonstrated the presence of food-borne pathogenic bacteria on crops grown in soil to which naturally or artificially contaminated manure was applied. Additionally, poor hygiene practices by field workers and the lack of on-site sanitation facilities may result in produce-associated outbreaks, particularly enteric illnesses such as Shigellosis, which is easily contracted from human feces because of the low-infectious dose of the causal agent Shigella. Crop irrigation with contaminated water also is considered as a primary source of inoculum in the field. This is of particular concern for the production of vegetables and fruits in areas where the supply of fresh water is scarce, and where water reclaimed for effluents increasingly serves for agricultural purposes.
Several soil-borne diseases are capable of transmission to the air, e.g., Q fever, aspergillosis, tularemia, sporotrichosis, and may be then transported by dust. These diseases are therefore likely to be those most directly affected by land management practices and land use change. Any activity which is associated with increased wind erosion seems likely to increase the incidence of such diseases in the surrounding area. Related activities could include land use change, for example, by converting grassland into arable land, ploughing or tilling soil that is too dry, etc. These conditions may also increasingly occur under climate change, as that can lead to enhanced incidence of drought periods.
A constant dialogue between public health, veterinary, and food safety experts, with multidisciplinary skills, is essential in order to signal new threats, to monitor changing trends in well recognized diseases, to detect emerging pathogens, to monitor the correct use of veterinary drugs, especially antibiotics, and the outbreak of hazardous environmental contaminants. The final goal is to develop control effective strategies, able to ensure food safety during all the production and processing stages from farm to fork.

Soil pollution is an important issue for food, both vegetable and animal origin. It may be caused by chemicals and microbes and/or parasites. Among the chemicals heavy metals, pesticides, phosphate fertilizers and drugs are the main issues. Among the soil-borne microbes there are protozoa, fungi, bacteria, and also viruses that can lead to many diseases such as shigellosis, Q fever, aspergillosis, tularemia, sporotrichosis.

Moreover, beside industrial activities, which may cause heavy metal accumulation, mobilization or immobilization within the ecosystems, agricultural and zootechnical activities may contribute to soil pollution. In fact, the use of sewage sludge as fertilizer may be a cause of pollution on agricultural land. On the other hand, drugs and antibiotics administered to food producing animals for therapeutic purposes, may affect the bacteria population in the soil leading to the spread of antibiotic resistance.

The multidisciplinary skills of public health, veterinary and food safety experts are involved together to ensure food safety during all the production and processing stages from farm to fork.

This article is from the free online

Farm to Fork: Sustainable Food Production in a Changing Environment

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now