The discovery of forgotten or accidental pollution has necessitated the development of appropriate responses to these challenges, which lie at the intersection of health concerns, environmental and resource protection, and the sustainable use of land.

Why and how can soil become contaminated?

Several sources can cause soil contamination:

• Natural sources, related to the geological nature of rocks and their evolution over time

• Human-made, associated in particular with current or former industrial operations.

Various pollutants have been identified, such as:

• Metallic elements, which are frequently found: lead, zinc, arsenic, chromium, cadmium… Their presence may be linked to the natural evolution of the soil rock or to the impacts of human activities.

• Organic compounds, which are primarily introduced by humans: notably hydrocarbons detected at 40% of the sites identified in the Basol database (polycyclic aromatic hydrocarbons (PAHs), halogenated solvents such as trichloroethylene, for example, volatile organic compounds (VOCs), etc.).

What are the possible routes of exposure for the population?

Soil is an environmental medium closely linked to other media (water, air). There are many potential exposure routes, whether through ingestion or inhalation, and the most common are:

• Ingestion of soil by young children, who are particularly at risk due to their behavior. When playing on the ground, they may directly ingest soil that has settled on their hands or on objects they put in their mouths

• Ingestion of plant-based foods grown on contaminated soil

• Ingestion of water, resulting from the transfer of a substance present in the soil into the groundwater

• Inhalation of dust emitted from contaminated soil

• Inhalation resulting from the potential volatilization of the pollutant from the soil.

What are the risks associated with soil pollution?

The populations most exposed to the effects of soil pollution are those present on or near polluted sites or soils.

• Many chemicals measured in contaminated soils are known to cause a variety of health effects.

• While it is often possible to describe health effects in a population living on or near a contaminated site, it is difficult to determine whether the site’s contamination is indeed responsible for these effects. At least one reason for this is the difficulty in estimating population exposure to soil pollutants, as the transfer of pollutants from soil into the human body is poorly understood.

• Today, this exposure is increasingly estimated by measuring biomarkers, primarily the pollutant itself or its metabolites in blood or urine.