Soil pollution: a little-known, invisible danger
We never notice soil pollution unless there is an oil leak. It consists of the abnormal presence of chemicals in the ground, impossible to see and quantifiable only with the use of scientific equipment. Pollutants come from our agricultural, industrial, extractive and military activities, from our waste and from our sewage. They are released intentionally, in the case of fertilizers and pesticides, or by accident. In recent years, some of these pollutants have also been called “emerging” when they come from the pharmaceutical industry or if they are endocrine disruptors.
Depending on the type of soil and the type of contaminating chemicals, the degree of severity of the pollution can vary, as can the duration of the lifetime of the pollutant in the soil. In 2016, for example, a study observed a persistently high level of Cesium 137 in European soils, thirty years after the Chernobyl disaster. There is a wide range of variability factors, and it is hard to deduce the general trends in soil pollution as the only global study carried out on the subject dates from the 1990s.
While we know, for example, that 75% of the world’s soils have been transformed by humans and that 33% are degraded, we do not have data on the overall pollution of the world’s soils.
National assessment initiatives are mainly focused on developed countries, as the FAO pointed out in its report “Soil Pollution, a Hidden Reality”: “In low and middle-income countries, the lack of data and information makes one of the world’s biggest global problems invisible to the international community.” The use of pesticides is still increasing in developing countries; over the last ten years, it was multiplied by six in Bangladesh, Rwanda and Ethiopia, and by ten in Sudan.
Soil quality and the health of living organisms
Ninety-five percent of the world’s food production depends on the ecosystem services provided by soil, and only healthy soil can produce sufficient high-quality food supplies. By reducing farm yields and threatening crop quality, soil pollution is a threat to the world’s food safety.
Because it diffuses long-lasting toxic substances in our urban and rural soils and in our water, soil pollution is also a threat to human health. The effects of chlordecone on the populations of the islands of Guadeloupe and Martinique are still in the news, 27 years after it was banned from banana monoculture. The Kannari study by Santé Publique France, published in October 2018, found that 95% of the population in Guadeloupe and 92% in Martinique were contaminated. Chlordecone contamination leads to neurological disorders and increases the risk of prostate cancer: this disease is twice as common and more serious in the French West Indies than in Metropolitan France. And, with nearly 230 new cases per 100,000 men each year, Martinique has the highest rate of incidence of the disease in the world.
By devitalizing the soil and contributing to its acidification, chemical pollutants disrupt its ecosystem functions and destroy biodiversity. In doing so, they deprive us of the world’s third carbon sink and thus contribute to increased global warming.
Decontaminating and restoring our soil
How can we decontaminate our soils and promote the ecosystem services they perform for us? The “huge gaps” in our understanding of soil pollution criticized by the FAO in 2018 urgently need correcting by financing pollution rate measurements, assessing its exact impact and encouraging the search for integrated solutions.
Alternatives to polluting agricultural, industrial and extractive practices can also be found, for example by encouraging agroecology practices or, like the French Global Environment Facility, encouraging the development of alternatives to the extractive industries such as gold prospecting without the use of mercury in the Guianas.
Lastly, consumer responsibility for soil protection cannot be ignored. In developed countries, most people can change their methods of consumption and thereby reduce the number of polluted sites by transforming demand.